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Valente R, Mourato A, Xavier J, Sousa P, Domingues T, Tavares P, Avril S, Tomás A, Fragata J. Experimental Protocols to Test Aortic Soft Tissues: A Systematic Review. Bioengineering (Basel) 2024; 11:745. [PMID: 39199703 PMCID: PMC11351783 DOI: 10.3390/bioengineering11080745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Accepted: 07/18/2024] [Indexed: 09/01/2024] Open
Abstract
Experimental protocols are fundamental for quantifying the mechanical behaviour of soft tissue. These data are crucial for advancing the understanding of soft tissue mechanics, developing and calibrating constitutive models, and informing the development of more accurate and predictive computational simulations and artificial intelligence tools. This paper offers a comprehensive review of experimental tests conducted on soft aortic tissues, employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology, based on the Scopus, Web of Science, IEEE, Google Scholar and PubMed databases. This study includes a detailed overview of the test method protocols, providing insights into practical methodologies, specimen preparation and full-field measurements. The review also briefly discusses the post-processing methods applied to extract material parameters from experimental data. In particular, the results are analysed and discussed providing representative domains of stress-strain curves for both uniaxial and biaxial tests on human aortic tissue.
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Affiliation(s)
- Rodrigo Valente
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (R.V.); (A.M.)
| | - André Mourato
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (R.V.); (A.M.)
| | - José Xavier
- UNIDEMI, Department of Mechanical and Industrial Engineering, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal; (R.V.); (A.M.)
- Intelligent Systems Associate Laboratory, LASI, 4800-058 Guimarães, Portugal
| | - Pedro Sousa
- INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; (P.S.); (P.T.)
| | - Tiago Domingues
- INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; (P.S.); (P.T.)
| | - Paulo Tavares
- INEGI, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; (P.S.); (P.T.)
| | - Stéphane Avril
- Mines Saint-Etienne, University of Lyon, Inserm, Sainbiose U1059, Campus Santé Innovation, 10, rue de la Marandière, 42270 Saint-Priest-en-Jarez, France;
| | - António Tomás
- Department of Cardiothoracic Surgery, Santa Marta Hospital, Rua de Santa Marta, 1169-024 Lisboa, Portugal; (A.T.); (J.F.)
| | - José Fragata
- Department of Cardiothoracic Surgery, Santa Marta Hospital, Rua de Santa Marta, 1169-024 Lisboa, Portugal; (A.T.); (J.F.)
- Department of Surgery and Human Morphology, NOVA Medical School, Universidade NOVA de Lisboa, Campo Mártires da Pátria, 1169-056 Lisboa, Portugal
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Concannon J, Máirtín EÓ, FitzGibbon B, Hynes N, Sultan S, McGarry JP. On the Importance of Including Cohesive Zone Models in Modelling Mixed-Mode Aneurysm Rupture. Cardiovasc Eng Technol 2024:10.1007/s13239-024-00740-3. [PMID: 38987509 DOI: 10.1007/s13239-024-00740-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 06/21/2024] [Indexed: 07/12/2024]
Abstract
INTRODUCTION The precise mechanism of rupture in abdominal aortic aneurysms (AAAs) has not yet been uncovered. The phenomenological failure criterion of the coefficient of proportionality between von Mises stress and tissue strength does not account for any mechanistic foundation of tissue fracture. Experimental studies have shown that arterial failure is a stepwise process of fibrous delamination (mode II) and kinking (mode I) between layers. Such a mechanism has not previously been considered for AAA rupture. METHODS In the current study we consider both von Mises stress in the wall, in addition to interlayer tractions and delamination using cohesive zone models. Firstly, we present a parametric investigation of the influence of a range of AAA anatomical features on the likelihood of elevated interlayer traction and delamination. RESULTS We observe in several cases that the location of peak von Mises stress and tangential traction coincide. Our simulations also reveal however, that peak von Mises and intramural tractions are not coincident for aneurysms with Length/Radius less than 2 (short high-curvature aneurysms) and for aneurysms with symmetric intraluminal thrombus (ILT). For an aneurysm with (L/R = 2.0), the peak σ vm moves slightly towards the origin while the peak T t is near the peak bulge with a separation distance of ~ 17 mm. Additionally, we present three patient-specific AAA models derived directly from CT scans, which also illustrate that the location of von Mises stress does not correlate with the point of interlayer delamination. CONCLUSION This study suggests that incorporating cohesive zone models into clinical based FE analyses may capture a greater proportion of ruptures in-silico.
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Affiliation(s)
- J Concannon
- Biomedical Engineering, University of Galway, Galway, Ireland.
| | - E Ó Máirtín
- Biomedical Engineering, University of Galway, Galway, Ireland
| | - B FitzGibbon
- Biomedical Engineering, University of Galway, Galway, Ireland
| | - N Hynes
- Department of Vascular and Endovascular Surgery, Galway University Hospitals, Galway, Ireland
| | - S Sultan
- Department of Vascular and Endovascular Surgery, Galway University Hospitals, Galway, Ireland
| | - J P McGarry
- Biomedical Engineering, University of Galway, Galway, Ireland
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Manopoulos C, Seferlis K, Raptis A, Kouerinis I, Mathioulakis D. Mechanics of ascending aortic aneurysms based on a modulus of elasticity dependent on aneurysm diameter and pressure. Comput Methods Biomech Biomed Engin 2023:1-16. [PMID: 38008970 DOI: 10.1080/10255842.2023.2285722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 11/15/2023] [Indexed: 11/28/2023]
Abstract
The mechanical stresses and strains are examined, in ascending thoracic aortic aneurysm (aTAA) models, in a patient-specific aTAA as well as in healthy thoracic aortic models, via Finite Element Analysis. The aneurysms are assumed spherical, 1.5 mm thick, with diameters between 47 mm and 80 mm, eccentrically positioned. The geometry and wall thickness distribution of the aorta along its length are based on open literature data for an average patient age of 66.25 years, accounting for the Body Surface Area (BSA) parameter. The vessel wall material is assumed isotropic and incompressible, with its Young's modulus varying with the aneurysm diameter and the applied intraluminal pressure (120 mmHg to 240 mmHg). In the aTAAs, peak stresses were found to increase nonlinearly with aneurysm diameter (for a given pressure) tending to reach a plateau, appearing at the proximal area of the aneurysm, whereas lower stresses were found at its distal part and even smaller at the aneurysm maximum diameter. Regarding the patient-specific aTAA model, the peak stresses appeared at the distal part of the aneurysm where a tear of the intima layer was detected during surgical intervention. Peak strains exhibited for each pressure a maximum at a certain aneurysm diameter beyond which they dropped so that essentially the vessel wall's distensibility was thus reduced. Examining more than 100 geometry cases and employing a failure stress criterion, the rupture diameter thresholds were estimated to be 65, 52.5, 50 and 47.5 mm for a pressure of 120, 160, 200 and 240 mmHg respectively.
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Affiliation(s)
- Christos Manopoulos
- Laboratory of Biofluid Mechanics and Biomedical Technology, School of Mechanical Engineering, National Technical University of Athens, Athens, Greece
| | - Konstantinos Seferlis
- Laboratory of Biofluid Mechanics and Biomedical Technology, School of Mechanical Engineering, National Technical University of Athens, Athens, Greece
| | - Anastasios Raptis
- Laboratory of Biofluid Mechanics and Biomedical Technology, School of Mechanical Engineering, National Technical University of Athens, Athens, Greece
| | - Ilias Kouerinis
- 1st Department of Cardiothoracic Surgery, 'Hippocration' Hospital; National and Kapodistrian University of Athens Medical School, Athens, Greece
| | - Dimitrios Mathioulakis
- Laboratory of Biofluid Mechanics and Biomedical Technology, School of Mechanical Engineering, National Technical University of Athens, Athens, Greece
- School of Engineering, Bahrain Polytechnic, Isa Town, Kingdom of Bahrain
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Davis ZR, Gossett PC, Wilson RL, Kim W, Mei Y, Butz KD, Emery NC, Nauman EA, Avril S, Neu CP, Chan DD. Intervertebral Disc Elastography to Relate Shear Modulus and Relaxometry in Compression and Bending. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555817. [PMID: 37732250 PMCID: PMC10508717 DOI: 10.1101/2023.09.01.555817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Intervertebral disc degeneration is the most recognized cause of low back pain, characterized by the decline of tissue structure and mechanics. Image-based mechanical parameters (e.g., strain, stiffness) may provide an ideal assessment of disc function that is lost with degeneration but unfortunately remains underdeveloped. Moreover, it is unknown whether strain or stiffness of the disc may be predicted by MRI relaxometry (e.g. T1 or T2), an increasingly accepted quantitative measure of disc structure. In this study, we quantified T1 and T2 relaxation times and in-plane strains using displacement-encoded MRI within the disc under physiological levels of compression and bending. We then estimated shear modulus in orthogonal image planes and compared these values to relaxation times and strains within regions of the disc. Intratissue strain depended on the loading mode, and shear modulus in the nucleus pulposus was typically an order of magnitude lower than the annulus fibrosis, except in bending, where the apparent stiffness depended on the loading. Relative shear moduli estimated from strain data derived under compression generally did not correspond with those from bending experiments, with no correlations in the sagittal plane and only 4 of 15 regions correlated in the coronal plane, suggesting that future inverse models should incorporate multiple loading conditions. Strain imaging and strain-based estimation of material properties may serve as imaging biomarkers to distinguish healthy and diseased discs. Additionally, image-based elastography and relaxometry may be viewed as complementary measures of disc structure and function to assess degeneration in longitudinal studies.
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Affiliation(s)
- Zachary R. Davis
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Paull C. Gossett
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Robert L. Wilson
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
| | - Woong Kim
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Yue Mei
- State Key Laboratory of Structural Analysis for Industrial Equipment and International Research Center for Computational Mechanics, Department of Engineering Mechanics, Dalian University of Technology, Dalian, China
- Mines Saint-Étienne, Université Jean Monnet, INSERM, U 1059 Sainbiose, 42023, SaintÉtienne, France
| | - Kent D. Butz
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Nancy C. Emery
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Eric A. Nauman
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, USA
| | - Stéphane Avril
- Mines Saint-Étienne, Université Jean Monnet, INSERM, U 1059 Sainbiose, 42023, SaintÉtienne, France
| | - Corey P. Neu
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
- Paul M. Rady Department of Mechanical Engineering, University of Colorado, Boulder, CO, USA
- Biomedical Engineering Program, University of Colorado, Boulder, CO, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO, USA
| | - Deva D. Chan
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
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Ghafarinatanzi M, Perie D. Estimation of anisotropic properties of CMR patient-specific left ventricle using the virtual field method. Biomech Model Mechanobiol 2023; 22:695-710. [PMID: 36692846 DOI: 10.1007/s10237-022-01675-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 12/08/2022] [Indexed: 01/25/2023]
Abstract
Left ventricle (LV) myocardial dysfunction has been recently investigated using the estimation of isotropic myocardial stiffness from magnetic resonance imaging (MRI). However, Myocardium is known to have a 3D complex geometry with anisotropic stiffness. The assessment of the anisotropy properties characterizes structural changes in myocardium as a consequence of heart failure (HF). From image data, the virtual field method (VFM) can determine material stiffness in a non-invasive manner. In the present work, the objective is to compare two inverse identification methods, given the isotropic and anisotropic models in the characterization of properties of myocardium in acute lymphoblastic leukemia (ALL) survivors using VFM and MRI. Two types of VFM approach are presented. Using the first, the virtual displacements (VFs) allow whole-field LV to be imposed into VFM formulation and caused to directly estimate two independent parameters from isotropic constitutive relation. With the second, anisotropic parameters are estimated using piece-wise (Finite element-based) VFM. The resulting values showed significant differences between the subjects in comparative study of leukemia survivors, and variance in estimated parameters by two different VFM approach. This approach would be an efficient tool to characterize early cardiac dysfunction. This work elucidates the benefits and shortcomings of using VFM to determine anisotropic parameters of LV myocardium in linear elastic and of using the FEM application to generate meshes of patient-specific LVs from MRI images.
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Affiliation(s)
- Mehdi Ghafarinatanzi
- Department of Mechanical Engineering, Polytechnique Montreal, Station Centre-Ville, P.O. Box 6079, Montréal, QC, H3C 3A7, Canada. .,Sainte-Justine University Health Center, Research Center, Montreal, Canada.
| | - Delphine Perie
- Department of Mechanical Engineering, Polytechnique Montreal, Station Centre-Ville, P.O. Box 6079, Montréal, QC, H3C 3A7, Canada.,Sainte-Justine University Health Center, Research Center, Montreal, Canada
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Experimental Study of the Propagation Process of Dissection Using an Aortic Silicone Phantom. J Funct Biomater 2022; 13:jfb13040290. [PMID: 36547550 PMCID: PMC9788384 DOI: 10.3390/jfb13040290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/14/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The mortality of acute aortic dissection (AD) can reach 65~70%. However, it is challenging to follow the progress of AD formation. The purpose of this work was to observe the process of dissection development using a novel tear-embedded silicone phantom. METHODS Silicone phantoms were fabricated by embedding a torn area and primary tear feature on the inner layer. CT scanning and laser lightening were conducted to observe the variations in thickness and volume of the true lumen (TL) and false lumen (FL) during development. RESULTS The model with a larger interlayer adhesion damage required a lower pressure to trigger the development of dissection. At the initiation stage of dissection, the volume of TL increased by 25.5%, accompanied by a 19.5% enlargement of tear size. The force analysis based on the change of tear size verified the deduction of the process of interlaminar separation from the earlier studies. CONCLUSIONS The primary tear and the weakening adhesion of the vessel layers are key factors in AD development, suggesting that some forms of primary damage to the arterial wall, in particular, the lumen morphology of vessels with straight inner lumen, should be considered as early risk predictors of AD.
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Pires FSM, Avril S, Livens P, Cordioli JA, Dirckx JJJ. Material Identification on Thin Shells Using the Virtual Fields Method, Demonstrated on the Human Eardrum. J Biomech Eng 2022; 144:1119463. [PMID: 34505875 DOI: 10.1115/1.4052381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Indexed: 11/08/2022]
Abstract
Characterization of material parameters from experimental data remains challenging, especially on biological structures. One of such techniques allowing for the inverse determination of material parameters from measurement data is the virtual fields method (VFM). However, application of the VFM on general structures of complicated shape has not yet been extensively investigated. In this paper, we extend the framework of the VFM method to thin curved solids in three-dimensional, commonly denoted shells. Our method is then used to estimate the Young's modulus and hysteretic damping of the human eardrum. By utilizing Kirchhoff plate theory, we assume that the behavior of the shell varies linearly through the thickness. The total strain of the shell can then be separated in a bending and membrane strain. This in turn allowed for an application of the VFM based only on data of the outer surface of the shell. We validated our method on simulated and experimental data of a human eardrum made to vibrate at certain frequencies. It was shown that the identified material properties were accurately determined based only on data from the outer surface and are in agreement with literature. Additionally, we observed that neither the bending nor the membrane strain in an human eardrum can be neglected and both contribute significantly to the total strain found experimentally.
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Affiliation(s)
- Felipe S M Pires
- Department of Physics, University of Antwerp, Antwerp 2020, Belgium
| | - Stéphane Avril
- U 1059 INSERM-SAINBIOSE Mines Saint-Étienne, Université Lyon, Saint-Étienne 42023, France
| | - Pieter Livens
- Department of Physics, University of Antwerp, Antwerp 2020, Belgium
| | - Júlio A Cordioli
- Vibration and Acoustic Laboratory, Federal University of Santa Catarina, Florianópolis 88040-900, Brazil
| | - Joris J J Dirckx
- Department of Physics, University of Antwerp, Antwerp 2020, Belgium
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Genovese K, Badel P, Cavinato C, Pierrat B, Bersi M, Avril S, Humphrey J. Multi-view digital image correlation systems for in vitro testing of arteries from mice to humans. EXPERIMENTAL MECHANICS 2021; 61:1455-1472. [PMID: 35370297 PMCID: PMC8972080 DOI: 10.1007/s11340-021-00746-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 06/08/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Digital image correlation (DIC) methods are increasingly used for non-contact optical assessment of geometry and deformation in soft tissue biomechanics, thus providing the full-field strain estimates needed for robust inverse material characterization. Despite the well-known flexibility and ease of use of DIC, issues related to spatial resolution and depth-of-field remain challenging in studies of quasi-cylindrical biological samples such as arteries. OBJECTIVE After demonstrating that standard surrounding multi-view DIC systems are inappropriate for such usage, we submit that both the optical setup and the data analysis need to be specifically designed with respect to the size of the arterial sample of interest. Accordingly, we propose novel and optimized DIC systems for two distinct ranges of arterial diameters: less than 2.5 mm (murine arteries) and greater than 10 mm (human arteries). METHODS We designed, set up, and validated a four-camera panoramic-DIC system for testing murine arteries and a multi-biprism DIC system for testing human arteries. Both systems enable dynamic 360-deg measurements with refraction correction over the entire surface of submerged samples in their native geometries. RESULTS Illustrative results for 3D shape and full-surface deformation fields were obtained for a mouse infrarenal aorta and a latex cylinder of size similar to the human infrarenal aorta. CONCLUSION Results demonstrated the feasibility and accuracy of both proposed methods in providing quantitative information on the regional behavior of arterial samples tested in vitro under physiologically relevant loading.
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Affiliation(s)
- K. Genovese
- School of Engineering, University of Basilicata, Italy
| | - P. Badel
- Mines Saint-Etienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U 1059 Sainbiose, Centre CIS, Saint-Etienne, France
| | - C. Cavinato
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - B. Pierrat
- Mines Saint-Etienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U 1059 Sainbiose, Centre CIS, Saint-Etienne, France
| | - M.R. Bersi
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, MO, USA
| | - S. Avril
- Mines Saint-Etienne, Univ. Lyon, Univ. Jean Monnet, INSERM, U 1059 Sainbiose, Centre CIS, Saint-Etienne, France
| | - J.D. Humphrey
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
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Liu M, Liang L, Ismail Y, Dong H, Lou X, Iannucci G, Chen EP, Leshnower BG, Elefteriades JA, Sun W. Computation of a probabilistic and anisotropic failure metric on the aortic wall using a machine learning-based surrogate model. Comput Biol Med 2021; 137:104794. [PMID: 34482196 DOI: 10.1016/j.compbiomed.2021.104794] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/20/2021] [Accepted: 08/21/2021] [Indexed: 01/15/2023]
Abstract
Scalar-valued failure metrics are commonly used to assess the risk of aortic aneurysm rupture and dissection, which occurs under hypertensive blood pressures brought on by extreme emotional or physical stress. To compute failure metrics under an elevated blood pressure, a classical patient-specific computer model consists of multiple computation steps involving inverse and forward analyses. These classical procedures may be impractical for time-sensitive clinical applications that require prompt feedback to clinicians. In this study, we developed a machine learning-based surrogate model to directly predict a probabilistic and anisotropic failure metric, namely failure probability (FP), on the aortic wall using aorta geometries at the systolic and diastolic phases. Ascending thoracic aortic aneurysm (ATAA) geometries of 60 patients were obtained from their CT scans, and biaxial mechanical testing data of ATAA tissues from 79 patients were collected. Finite element simulations were used to generate datasets for training, validation, and testing of the ML-surrogate model. The testing results demonstrated that the ML-surrogate can compute the maximum FP failure metric, with 0.42% normalized mean absolute error, in 1 s. To compare the performance of the ML-predicted probabilistic FP metric with other isotropic or deterministic metrics, a numerical case study was performed using synthetic "baseline" data. Our results showed that the probabilistic FP metric had more discriminative power than the deterministic Tsai-Hill metric, isotropic maximum principal stress, and aortic diameter criterion.
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Affiliation(s)
- Minliang Liu
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Liang Liang
- Department of Computer Science, University of Miami, Coral Gables, FL, USA
| | - Yasmeen Ismail
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Hai Dong
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Xiaoying Lou
- Emory University School of Medicine, Atlanta, GA, USA
| | - Glen Iannucci
- Emory University School of Medicine, Atlanta, GA, USA
| | - Edward P Chen
- Emory University School of Medicine, Atlanta, GA, USA
| | | | | | - Wei Sun
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
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Nagaraja S, Leichsenring K, Ambati M, De Lorenzis L, Böl M. On a phase-field approach to model fracture of small intestine walls. Acta Biomater 2021; 130:317-331. [PMID: 34119714 DOI: 10.1016/j.actbio.2021.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 12/15/2022]
Abstract
We address anisotropic elasticity and fracture in small intestine walls (SIWs) with both experimental and computational methods. Uniaxial tension experiments are performed on porcine SIW samples with varying alignments and quantify their nonlinear elastic anisotropic behavior. Fracture experiments on notched SIW strips reveal a high sensitivity of the crack propagation direction and the failure stress on the tissue orientation. From a modeling point of view, the observed anisotropic elastic response is studied with a continuum mechanical model stemming from a strain energy density with a neo-Hookean component and an anisotropic component with four families of fibers. Fracture is addressed with the phase-field approach, featuring two-fold anisotropy in the fracture toughness. Elastic and fracture model parameters are calibrated based on the experimental data, using the maximum and minimum limits of the experimental stress-stretch data set. A very good agreement between experimental data and computational results is obtained, the role of anisotropy being effectively captured by the proposed model in both the elastic and the fracture behavior. STATEMENT OF SIGNIFICANCE: This article reports a comprehensive experimental data set on the mechanical failure behavior of small intestinal tissue, and presents the corresponding protocols for preparing and testing the samples. On the one hand, the results of this study contribute to the understanding of small intestine mechanics and thus to understanding of load transfer mechanisms inside the tissue. On the other hand, these results are used as input for a phase-field modelling approach, presented in this article. The presented model can reproduce the mechanical failure behavior of the small intestine in an excellent way and is thus a promising tool for the future mechanical description of diseased small intestinal tissue.
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Liu M, Dong H, Lou X, Iannucci G, Chen EP, Leshnower BG, Sun W. A Novel Anisotropic Failure Criterion With Dispersed Fiber Orientations for Aortic Tissues. J Biomech Eng 2020; 142:111002. [PMID: 32766773 DOI: 10.1115/1.4048029] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Indexed: 12/14/2022]
Abstract
Accurate failure criteria play a fundamental role in biomechanical analyses of aortic wall rupture and dissection. Experimental investigations have demonstrated a significant difference of aortic wall strengths in the circumferential and axial directions. Therefore, the isotropic von Mises stress and maximum principal stress, commonly used in computational analysis of the aortic wall, are inadequate for modeling of anisotropic failure properties. In this study, we propose a novel stress-based anisotropic failure criterion with dispersed fiber orientations. In the new failure criterion, the overall failure metric is computed by using angular integration (AI) of failure metrics in all directions. Affine rotations of fiber orientations due to finite deformation are taken into account in an anisotropic hyperelastic constitutive model. To examine fitting capability of the failure criterion, a set of off-axis uniaxial tension tests were performed on aortic tissues of four porcine individuals and 18 human ascending thoracic aortic aneurysm (ATAA) patients. The dispersed fiber failure criterion demonstrates a good fitting capability with the off-axis testing data. Under simulated biaxial stress conditions, the dispersed fiber failure criterion predicts a smaller failure envelope comparing to those predicted by the traditional anisotropic criteria without fiber dispersion, which highlights the potentially important role of fiber dispersion in the failure of the aortic wall. Our results suggest that the deformation-dependent fiber orientations need to be considered when wall strength determined from uniaxial tests are used for in vivo biomechanical analysis. More investigations are needed to determine biaxial failure properties of the aortic wall.
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Affiliation(s)
- Minliang Liu
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30313
| | - Hai Dong
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30313
| | - Xiaoying Lou
- Emory University School of Medicine, Atlanta, GA 30332
| | - Glen Iannucci
- Emory University School of Medicine, Atlanta, GA 30332
| | - Edward P Chen
- Emory University School of Medicine, Atlanta, GA 30332
| | | | - Wei Sun
- Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Technology Enterprise Park, Room 206 387 Technology Circle, Atlanta, GA 30313
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Mahutga RR, Barocas VH. Investigation of Pathophysiological Aspects of Aortic Growth, Remodeling, and Failure Using a Discrete-Fiber Microstructural Model. J Biomech Eng 2020; 142:111007. [PMID: 32766738 PMCID: PMC7580844 DOI: 10.1115/1.4048031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 07/27/2020] [Indexed: 01/03/2023]
Abstract
Aortic aneurysms are inherently unpredictable. One can never be sure whether any given aneurysm may rupture or dissect. Clinically, the criteria for surgical intervention are based on size and growth rate, but it remains difficult to identify a high-risk aneurysm, which may require intervention before the cutoff criteria, versus an aneurysm than can be treated safely by more conservative measures. In this work, we created a computational microstructural model of a medial lamellar unit (MLU) incorporating (1) growth and remodeling laws applied directly to discrete, individual fibers, (2) separate but interacting fiber networks for collagen, elastin, and smooth muscle, (3) active and passive smooth-muscle cell mechanics, and (4) failure mechanics for all three fiber types. The MLU model was then used to study different pathologies and microstructural anomalies that may play a role in vascular growth and failure. Our model recapitulated many aspects of arterial remodeling under hypertension with no underlying genetic syndrome including remodeling dynamics, tissue mechanics, and failure. Syndromic effects (smooth muscle cell (SMC) dysfunction or elastin fragmentation) drastically changed the simulated remodeling process, tissue behavior, and tissue strength. Different underlying pathologies were able to produce similarly dilatated vessels with different failure properties, providing a partial explanation for the imperfect nature of aneurysm size as a predictor of outcome.
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Affiliation(s)
- Ryan R. Mahutga
- Department of Biomedical Engineering, University of Minnesota—Twin Cities, Minneapolis, MN 55455
| | - Victor H. Barocas
- Department of Biomedical Engineering, University of Minnesota—Twin Cities, 7-105 Nils Hasselmo Hall, 312 Church St SE, Minneapolis, MN 55455
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13
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Lane BA, Lessner SM, Vyavahare NR, Sutton MA, Eberth JF. Null strain analysis of submerged aneurysm analogues using a novel 3D stereomicroscopy device. Comput Methods Biomech Biomed Engin 2020; 23:332-344. [PMID: 32068431 PMCID: PMC7289678 DOI: 10.1080/10255842.2020.1724974] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 12/13/2019] [Accepted: 01/29/2020] [Indexed: 01/05/2023]
Abstract
To measure the inhomogeneous 3D-strain fields present during inflation-extension testing of physiologically submerged micro-aneurysms, a Stereo Digital Image Correlation (StereoDIC) microscopy system is developed that revolves 15° stereo-angle cameras around a centrally-mounted target. Calibration is performed using submerged dot patterns and system accuracy verified using strain and deformation analyses for rigid body motions of speckle-patterned, micro-aneurysmal surrogates. In terms of the Green-Lagrange strain tensor and the 3D displacement fields, the results are stable even after 120 minutes, with maxima in both strain bias and strain standard deviation less than 2E-03 for all components, and micron-level displacement standard deviation.
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Affiliation(s)
- Brooks A. Lane
- Biomedical Engineering, University of South Carolina, Columbia, USA
| | - Susan M. Lessner
- Biomedical Engineering, University of South Carolina, Columbia, USA
- Cell Biology and Anatomy, University of South Carolina, Columbia, USA
| | | | | | - John F. Eberth
- Biomedical Engineering, University of South Carolina, Columbia, USA
- Cell Biology and Anatomy, University of South Carolina, Columbia, USA
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14
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Iliopoulos DC, Sokolis DP. Ascending aorta mechanics in bicuspid aortopathy: controversy or fact? Asian Cardiovasc Thorac Ann 2020; 29:592-604. [PMID: 32447961 DOI: 10.1177/0218492320928731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bicuspid aortic valve is the most common congenital cardiovascular defect, often associated with proximal aortic dilatation, and the ideal management strategy is debated. The inconsistency in previous and present guideline recommendations emphasizes the insufficiency of the maximal diameter as the sole criterion for prophylactic repair. Our ability to guide clinical decisions may improve through an understanding of the mechanical properties of ascending thoracic aortic aneurysms in bicuspid compared to tricuspid aortic valve patients and non-aneurysmal aortas, because dissection and rupture are aortic wall mechanical failures. Such an understanding of the mechanical properties has been attempted by several authors, and this article addresses whether there is a controversy in the accumulated knowledge. The available mechanical studies are briefly reviewed, discussing factors such as age, sex, and the region of mechanical examination that may be responsible for the lack of unanimity in the reported findings. The rationale for acquiring layer-specific properties is presented along with the main results from our recent study. No mechanical vulnerability of ascending thoracic aortic aneurysms was evidenced in bicuspid aortic valve patients, corroborating present conservative guidelines concerning the management of bicuspid aortopathy. Weakening and additional vulnerability was evidenced in aged patients and those with coexisting valve pathology, aortic root dilatation, hypertension, and hyperlipidemia. Discussion of these results from age- and sex-matched subjects, accounting for the region- and layer-specific aortic heterogeneity, in relation to intact wall results and histologic confirmation, helps to reconcile previous findings and affords a universal interpretation of ascending aorta mechanics in bicuspid aortopathy.
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Affiliation(s)
- Dimitrios C Iliopoulos
- Department of Cardiac Surgery, National and Kapodistrian University of Athens, and 4th Cardiac Surgery Department, Hygeia Hospital, Athens, Greece
| | - Dimitrios P Sokolis
- Biomechanics Laboratory, Center of Clinical, Experimental Surgery, and Translational Research, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
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15
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Fertuzinhos A, Teixeira MA, Ferreira MG, Fernandes R, Correia R, Malheiro AR, Flores P, Zille A, Dourado N. Thermo-Mechanical Behaviour of Human Nasal Cartilage. Polymers (Basel) 2020; 12:polym12010177. [PMID: 31936593 PMCID: PMC7023433 DOI: 10.3390/polym12010177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/18/2019] [Accepted: 12/20/2019] [Indexed: 01/06/2023] Open
Abstract
The aim of this study was to undergo a comprehensive analysis of the thermo-mechanical properties of nasal cartilages for the future design of a composite polymeric material to be used in human nose reconstruction surgery. A thermal and dynamic mechanical analysis (DMA) in tension and compression modes within the ranges 1 to 20 Hz and 30 °C to 250 °C was performed on human nasal cartilage. Differential scanning calorimetry (DSC), as well as characterization of the nasal septum (NS), upper lateral cartilages (ULC), and lower lateral cartilages (LLC) reveals the different nature of the binding water inside the studied specimens. Three peaks at 60–80 °C, 100–130 °C, and 200 °C were attributed to melting of the crystalline region of collagen matrix, water evaporation, and the strongly bound non-interstitial water in the cartilage and composite specimens, respectively. Thermogravimetric analysis (TGA) showed that the degradation of cartilage, composite, and subcutaneous tissue of the NS, ULC, and LLC take place in three thermal events (~37 °C, ~189 °C, and ~290 °C) showing that cartilage releases more water and more rapidly than the subcutaneous tissue. The water content of nasal cartilage was estimated to be 42 wt %. The results of the DMA analyses demonstrated that tensile mode is ruled by flow-independent behaviour produced by the time-dependent deformability of the solid cartilage matrix that is strongly frequency-dependent, showing an unstable crystalline region between 80–180 °C, an amorphous region at around 120 °C, and a clear glass transition point at 200 °C (780 kJ/mol). Instead, the unconfined compressive mode is clearly ruled by a flow-dependent process caused by the frictional force of the interstitial fluid that flows within the cartilage matrix resulting in higher stiffness (from 12 MPa at 1 Hz to 16 MPa at 20 Hz in storage modulus). The outcomes of this study will support the development of an artificial material to mimic the thermo-mechanical behaviour of the natural cartilage of the human nose.
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Affiliation(s)
- Aureliano Fertuzinhos
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Universidade do Minho, Campus de Azurém, 4804-533 Guimarães, Portugal; (A.F.); (P.F.)
| | - Marta A. Teixeira
- 2C2T—Centro de Ciência e Tecnologia Têxtil, Universidade do Minho, Campus de Azurém, 4804-533 Guimarães, Portugal; (M.A.T.); (A.Z.)
| | - Miguel Goncalves Ferreira
- Department of Otolaryngology, Head and Neck Surgery, Santo António Hospital, 4099-001 Porto, Portugal;
| | - Rui Fernandes
- HEMS—Histology and Electron Microscopy, i3S-Instituto de Investigação e Inovação em Saúde, University of Porto, 4200-135 Porto, Portugal; (R.F.); (R.C.); (A.R.M.)
- IBMC—Instituto de Biologia Molecular e Celular, University of Porto, 4200-135 Porto, Portugal
| | - Rossana Correia
- HEMS—Histology and Electron Microscopy, i3S-Instituto de Investigação e Inovação em Saúde, University of Porto, 4200-135 Porto, Portugal; (R.F.); (R.C.); (A.R.M.)
- Ipatimup—Institute of Molecular Pathology and Immunology of the University of Porto, 4200-135 Porto, Portugal
| | - Ana Rita Malheiro
- HEMS—Histology and Electron Microscopy, i3S-Instituto de Investigação e Inovação em Saúde, University of Porto, 4200-135 Porto, Portugal; (R.F.); (R.C.); (A.R.M.)
- IBMC—Instituto de Biologia Molecular e Celular, University of Porto, 4200-135 Porto, Portugal
| | - Paulo Flores
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Universidade do Minho, Campus de Azurém, 4804-533 Guimarães, Portugal; (A.F.); (P.F.)
| | - Andrea Zille
- 2C2T—Centro de Ciência e Tecnologia Têxtil, Universidade do Minho, Campus de Azurém, 4804-533 Guimarães, Portugal; (M.A.T.); (A.Z.)
| | - Nuno Dourado
- CMEMS-UMinho, Departamento de Engenharia Mecânica, Universidade do Minho, Campus de Azurém, 4804-533 Guimarães, Portugal; (A.F.); (P.F.)
- Correspondence:
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16
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Korenczuk CE, Dhume RY, Liao KK, Barocas VH. Ex Vivo Mechanical Tests and Multiscale Computational Modeling Highlight the Importance of Intramural Shear Stress in Ascending Thoracic Aortic Aneurysms. J Biomech Eng 2019; 141:121010. [PMID: 31633165 PMCID: PMC7104749 DOI: 10.1115/1.4045270] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 10/17/2019] [Indexed: 11/08/2022]
Abstract
Ascending thoracic aortic aneurysms (ATAAs) are anatomically complex in terms of architecture and geometry, and both complexities contribute to unpredictability of ATAA dissection and rupture in vivo. The goal of this work was to examine the mechanism of ATAA failure using a combination of detailed mechanical tests on human tissue and a multiscale computational model. We used (1) multiple, geometrically diverse, mechanical tests to characterize tissue properties; (2) a multiscale computational model to translate those results into a broadly usable form; and (3) a model-based computer simulation of the response of an ATAA to the stresses generated by the blood pressure. Mechanical tests were performed in uniaxial extension, biaxial extension, shear lap, and peel geometries. ATAA tissue was strongest in circumferential extension and weakest in shear, presumably because of the collagen and elastin in the arterial lamellae. A multiscale, fiber-based model using different fiber properties for collagen, elastin, and interlamellar connections was specified to match all of the experimental data with one parameter set. Finally, this model was used to simulate ATAA inflation using a realistic geometry. The predicted tissue failure occurred in regions of high stress, as expected; initial failure events involved almost entirely interlamellar connections, consistent with arterial dissection-the elastic lamellae remain intact, but the connections between them fail. The failure of the interlamellar connections, paired with the weakness of the tissue under shear loading, is suggestive that shear stress within the tissue may contribute to ATAA dissection.
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Affiliation(s)
- Christopher E. Korenczuk
- Department of Biomedical Engineering, University of Minnesota,7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455e-mail:
| | - Rohit Y. Dhume
- Department of Mechanical Engineering, University of Minnesota,7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455e-mail:
| | - Kenneth K. Liao
- Department of Surgery, University of Minnesota,420 Delaware Street SE, MMC 207, Minneapolis, MN 55455e-mail:
| | - Victor H. Barocas
- Department of Biomedical Engineering, University of Minnesota,7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455e-mail:
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17
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Sherifova S, Holzapfel GA. Biomechanics of aortic wall failure with a focus on dissection and aneurysm: A review. Acta Biomater 2019; 99:1-17. [PMID: 31419563 PMCID: PMC6851434 DOI: 10.1016/j.actbio.2019.08.017] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 08/05/2019] [Accepted: 08/08/2019] [Indexed: 12/12/2022]
Abstract
Aortic dissections and aortic aneurysms are fatal events characterized by structural changes to the aortic wall. The maximum diameter criterion, typically used for aneurysm rupture risk estimations, has been challenged by more sophisticated biomechanically motivated models in the past. Although these models are very helpful for the clinicians in decision-making, they do not attempt to capture material failure. Following a short overview of the microstructure of the aorta, we analyze the failure mechanisms involved in the dissection and rupture by considering also traumatic rupture. We continue with a literature review of experimental studies relevant to quantify tissue strength. More specifically, we summarize more extensively uniaxial tensile, bulge inflation and peeling tests, and we also specify trouser, direct tension and in-plane shear tests. Finally we analyze biomechanically motivated models to predict rupture risk. Based on the findings of the reviewed studies and the rather large variations in tissue strength, we propose that an appropriate material failure criterion for aortic tissues should also reflect the microstructure in order to be effective. STATEMENT OF SIGNIFICANCE: Aortic dissections and aortic aneurysms are fatal events characterized by structural changes to the aortic wall. Despite the advances in medical, biomedical and biomechanical research, the mortality rates of aneurysms and dissections remain high. The present review article summarizes experimental studies that quantify the aortic wall strength and it discusses biomechanically motivated models to predict rupture risk. We identified contradictory observations and a large variation within and between data sets, which may be due to biological variations, different sample sizes, differences in experimental protocols, etc. Based on the findings of the reviewed literature and the rather large variations in tissue strength, it is proposed that an appropriate criterion for aortic failure should also reflect the microstructure.
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Affiliation(s)
- Selda Sherifova
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/2, 8010 Graz, Austria
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/2, 8010 Graz, Austria; Department of Structural Engineering, Norwegian Institute of Science and Technology (NTNU), 7491 Trondheim, Norway.
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18
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Cavinato C, Molimard J, Curt N, Campisi S, Orgéas L, Badel P. Does the Knowledge of the Local Thickness of Human Ascending Thoracic Aneurysm Walls Improve Their Mechanical Analysis? Front Bioeng Biotechnol 2019; 7:169. [PMID: 31380360 PMCID: PMC6646470 DOI: 10.3389/fbioe.2019.00169] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 07/02/2019] [Indexed: 12/22/2022] Open
Abstract
Ascending thoracic aortic aneurysm (ATAA) ruptures are life threatening phenomena which occur in local weaker regions of the diseased aortic wall. As ATAAs are evolving pathologies, their growth represents a significant local remodeling and degradation of the microstructural architecture and thus their mechanical properties. To address the need for deeper study of ATAAs and their failure, it is required to analyze the mechanical behavior at the sub-millimeter scale by making use of accurate geometrical and kinematical measurements during their deformation. For this purpose, we propose a novel methodology that combined an accurate tool for thickness distribution measurement of the arterial wall, digital image correlation to assess local strain fields and bulge inflation to characterize the physiological and failure response of flat unruptured human ATAA specimens. The analysis of the heterogeneity of the local thickness and local physiological stress and strain was carried out for each investigated subject. At the subject level, our results state the presence of a non-consistent relationship between the local wall thickness and the local physiological strain field and high heterogeneity of the variables. At the inter-subject level, thicknesses were studied in relation to physiological strain and stress and load at rupture. The rupture pressure was correlated with neither the average thickness nor the lowest thickness of the specimens. Our results confirm that intrinsic material strength (hence structure) differs a lot from a subject to another and even within the same subject.
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Affiliation(s)
- Cristina Cavinato
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Jerome Molimard
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Nicolas Curt
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
| | - Salvatore Campisi
- Department of CardioVascular Surgery, CHU Hôpital Nord Saint-Etienne, Saint-Etienne, France
| | - Laurent Orgéas
- UMR 5521, Univ. Grenoble Alpes, CNRS, Grenoble INP, 3SR Lab, Grenoble, France
| | - Pierre Badel
- Mines Saint-Etienne, Centre CIS, INSERM, U 1059 Sainbiose, Univ Lyon, Univ Jean Monnet, Saint-Etienne, France
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19
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McGuire JA, Crandall CL, Abramowitch SD, De Vita R. Inflation and rupture of vaginal tissue. Interface Focus 2019; 9:20190029. [PMID: 31263539 DOI: 10.1098/rsfs.2019.0029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2019] [Indexed: 01/10/2023] Open
Abstract
Around 80% of women experience vaginal tears during labour when the diameter of the vagina must increase to allow the passage of a full-term baby. Current techniques for evaluating vaginal tears are qualitative and often lead to an incorrect diagnosis and inadequate treatment, severely compromising the quality of life of women. In order to characterize the failure properties of the vaginal tissue, whole vaginal tracts from rats (n = 18) were subjected to free-extension inflation tests until rupture using a custom-built experimental set-up. The resulting deformations were measured using the digital image correlation technique. Overall, the strain and changes in curvature in the hoop direction were significantly larger relative to the axial direction. At a failure pressure of 110 ± 23 kPa (mean ± s.d.), the hoop and axial stresses were computed to be 970 ± 340 kPa and 490 ± 170 kPa, respectively. Moreover, at such pressure, the hoop and axial strains were found to be 12.8 ± 4.4 % and 6.4 ± 3.7 % , respectively. Rupture of the vaginal specimens always occurred in the hoop direction by tearing along the axial direction. This knowledge about the rupture properties of the vaginal tissue will be crucial for the development of clinical approaches for preventing and mitigating vaginal tearing and the associated short- and long-term traumatic conditions.
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Affiliation(s)
- Jeffrey A McGuire
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Christie L Crandall
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
| | - Steven D Abramowitch
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Raffaella De Vita
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
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20
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Failure damage mechanical properties of thoracic and abdominal porcine aorta layers and related constitutive modeling: phenomenological and microstructural approach. Biomech Model Mechanobiol 2019; 18:1709-1730. [DOI: 10.1007/s10237-019-01170-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/12/2019] [Indexed: 12/17/2022]
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21
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Korenczuk CE, Votava LE, Dhume RY, Kizilski SB, Brown GE, Narain R, Barocas VH. Isotropic Failure Criteria Are Not Appropriate for Anisotropic Fibrous Biological Tissues. J Biomech Eng 2019; 139:2613842. [PMID: 28334369 DOI: 10.1115/1.4036316] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The von Mises (VM) stress is a common stress measure for finite element models of tissue mechanics. The VM failure criterion, however, is inherently isotropic, and therefore may yield incorrect results for anisotropic tissues, and the relevance of the VM stress to anisotropic materials is not clear. We explored the application of a well-studied anisotropic failure criterion, the Tsai–Hill (TH) theory, to the mechanically anisotropic porcine aorta. Uniaxial dogbones were cut at different angles and stretched to failure. The tissue was anisotropic, with the circumferential failure stress nearly twice the axial (2.67 ± 0.67 MPa compared to 1.46 ± 0.59 MPa). The VM failure criterion did not capture the anisotropic tissue response, but the TH criterion fit the data well (R2 = 0.986). Shear lap samples were also tested to study the efficacy of each criterion in predicting tissue failure. Two-dimensional failure propagation simulations showed that the VM failure criterion did not capture the failure type, location, or propagation direction nearly as well as the TH criterion. Over the range of loading conditions and tissue geometries studied, we found that problematic results that arise when applying the VM failure criterion to an anisotropic tissue. In contrast, the TH failure criterion, though simplistic and clearly unable to capture all aspects of tissue failure, performed much better. Ultimately, isotropic failure criteria are not appropriate for anisotropic tissues, and the use of the VM stress as a metric of mechanical state should be reconsidered when dealing with anisotropic tissues.
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22
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Material characterization of cardiovascular biomaterials using an inverse finite-element method and an explicit solver. J Biomech 2018; 79:207-211. [PMID: 30060921 DOI: 10.1016/j.jbiomech.2018.07.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 05/28/2018] [Accepted: 07/14/2018] [Indexed: 11/23/2022]
Abstract
The ability to accurately model soft tissue behavior, such as that of heart valve tissue, is essential for developing reliable numerical simulations and determining patient-specific care options. Although several material models can predict soft tissue behavior, complications may arise when these models are implemented into finite element (FE) programs, due to the addition of an arbitrary penalty parameter for numerically enforcing material incompressibility. Herein, an inverse methodology was developed in MATLAB to use previously published stress-strain data from experimental planar equibiaxial testing of five biomaterials used in heart valve cusp replacements, in conjunction with commercial explicit FE solver LS-DYNA, to optimize the material parameters and the penalty parameter for an anisotropic hyperelastic strain energy function. A two-parameter optimization involving the scaling constant of the strain energy function and the penalty parameter proved sufficient to produce acceptable material responses when compared with experimental behaviors under the same testing conditions, as long as analytically derived material constants were available for the other non-optimized parameters and the actual tissue thickness was not much less than 1 mm. Variations in the penalty parameter had a direct effect on the accuracy of the simulated responses, with a practical range determined to be 5×108-9×108 times the scaling constant of the strain energy function.
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23
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Sang C, Maiti S, Fortunato RN, Kofler J, Robertson AM. A Uniaxial Testing Approach for Consistent Failure in Vascular Tissues. J Biomech Eng 2018; 140:2675125. [PMID: 29560496 PMCID: PMC5938069 DOI: 10.1115/1.4039577] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although uniaxial tensile testing is commonly used to evaluate failure properties of vascular tissue, there is no established protocol for specimen shape or gripping method. Large percentages of specimens are reported to fail near the clamp and can potentially confound the studies, or, if discarded will result in sample waste. The objective of this study is to identify sample geometry and clamping conditions that can achieve consistent failure in the midregion of small arterial specimens, even for vessels from older individuals. Failure location was assessed in 17 dogbone specimens from human cerebral and sheep carotid arteries using soft inserts. For comparison with commonly used protocols, an additional 22 rectangular samples were tested using either sandpaper or foam tape inserts. Midsample failure was achieved in 94% of the dogbone specimens, while only 14% of the rectangular samples failed in the midregion, the other 86% failing close to the clamps. Additionally, we found midregion failure was more likely to be abrupt, caused by cracking or necking. In contrast, clamp failure was more likely to be gradual and included a delamination mode not seen in midregion failure. Hence, this work provides an approach that can be used to obtain consistent midspecimen failure, avoiding confounding clamp-related artifacts. Furthermore, with consistent midregion failure, studies can be designed to image the failure process in small vascular samples providing valuable quantitative information about changes to collagen and elastin structure during the failure process.
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Affiliation(s)
- Chao Sang
- Department of Mechanical Engineering and
Materials Science,
University of Pittsburgh,
636 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
| | - Spandan Maiti
- Department of Bioengineering,
University of Pittsburgh,
302 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
| | - Ronald N. Fortunato
- Department of Mechanical Engineering and
Materials Science,
University of Pittsburgh,
636 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
| | - Julia Kofler
- Department of Pathology,
University of Pittsburgh,
S701.3 Scaife Hall,
Pittsburgh, PA 15261
e-mail:
| | - Anne M. Robertson
- Department of Mechanical Engineering and
Materials Science,
University of Pittsburgh,
440 Benedum Hall 3700 O'Hara Street,
Pittsburgh, PA 15261
e-mail:
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24
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Disney CM, Lee PD, Hoyland JA, Sherratt MJ, Bay BK. A review of techniques for visualising soft tissue microstructure deformation and quantifying strain Ex Vivo. J Microsc 2018; 272:165-179. [PMID: 29655273 DOI: 10.1111/jmi.12701] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/08/2018] [Accepted: 03/16/2018] [Indexed: 12/16/2022]
Abstract
Many biological tissues have a complex hierarchical structure allowing them to function under demanding physiological loading conditions. Structural changes caused by ageing or disease can lead to loss of mechanical function. Therefore, it is necessary to characterise tissue structure to understand normal tissue function and the progression of disease. Ideally intact native tissues should be imaged in 3D and under physiological loading conditions. The current published in situ imaging methodologies demonstrate a compromise between imaging limitations and maintaining the samples native mechanical function. This review gives an overview of in situ imaging techniques used to visualise microstructural deformation of soft tissue, including three case studies of different tissues (tendon, intervertebral disc and artery). Some of the imaging techniques restricted analysis to observational mechanics or discrete strain measurement from invasive markers. Full-field local surface strain measurement has been achieved using digital image correlation. Volumetric strain fields have successfully been quantified from in situ X-ray microtomography (micro-CT) studies of bone using digital volume correlation but not in soft tissue due to low X-ray transmission contrast. With the latest developments in micro-CT showing in-line phase contrast capability to resolve native soft tissue microstructure, there is potential for future soft tissue mechanics research where 3D local strain can be quantified. These methods will provide information on the local 3D micromechanical environment experienced by cells in healthy, aged and diseased tissues. It is hoped that future applications of in situ imaging techniques will impact positively on the design and testing of potential tissue replacements or regenerative therapies. LAY DESCRIPTION: The soft tissues in our bodies, such as tendons, intervertebral discs and arteries, have evolved to have complicated structures which deform and bear load during normal function. Small changes in these structures can occur with age and disease which then leads to loss of function. Therefore, it is important to image tissue microstructure in 3D and under functional conditions. This paper gives an overview of imaging techniques used to record the deformation of soft tissue microstructures. Commonly there are compromises between obtaining the best imaging result and retaining the samples native structure and function. For example, invasive markers and dissecting samples damages the tissues natural structure, and staining or clearing (making the tissue more transparent) can distort tissue structure. Structural deformation has been quantified from 2D imaging techniques (digital image correlation) to create surface strain maps which help identify local tissue mechanics. When extended to 3D (digital volume correlation), deformation measurement has been limited to bone samples using X-ray micro-CT. Recently it has been possible to image the 3D structure of soft tissue using X-ray micro-CT meaning that there is potential for internal soft tissue mechanics to be mapped in 3D. Future application of micro-CT and digital volume correlation will be important for soft tissue mechanics studies particularly to understand normal function, progression of disease and in the design of tissue replacements.
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Affiliation(s)
- C M Disney
- Centre for Doctoral Training in Regenerative Medicine, University of Manchester, Manchester, U.K.,Division of Cell Matrix Biology and Regenerative Medicine, University of Manchester, Manchester, U.K
| | - P D Lee
- School of Materials, University of Manchester, Manchester, U.K
| | - J A Hoyland
- Division of Cell Matrix Biology and Regenerative Medicine, University of Manchester, Manchester, U.K.,NIHR Manchester Biomedical Research Centre, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, U.K
| | - M J Sherratt
- Division of Cell Matrix Biology and Regenerative Medicine, University of Manchester, Manchester, U.K
| | - B K Bay
- School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, Oregon, U.S.A
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Gültekin O, Dal H, Holzapfel GA. Numerical aspects of anisotropic failure in soft biological tissues favor energy-based criteria: A rate-dependent anisotropic crack phase-field model. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2018; 331:23-52. [PMID: 31649410 PMCID: PMC6812520 DOI: 10.1016/j.cma.2017.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A deeper understanding to predict fracture in soft biological tissues is of crucial importance to better guide and improve medical monitoring, planning of surgical interventions and risk assessment of diseases such as aortic dissection, aneurysms, atherosclerosis and tears in tendons and ligaments. In our previous contribution (Gültekin et al., 2016) we have addressed the rupture of aortic tissue by applying a holistic geometrical approach to fracture, namely the crack phase-field approach emanating from variational fracture mechanics and gradient damage theories. In the present study, the crack phase-field model is extended to capture anisotropic fracture using an anisotropic volume-specific crack surface function. In addition, the model is equipped with a rate-dependent formulation of the phase-field evolution. The continuum framework captures anisotropy, is thermodynamically consistent and based on finite strains. The resulting Euler-Lagrange equations are solved by an operator-splitting algorithm on the temporal side which is ensued by a Galerkin-type weak formulation on the spatial side. On the constitutive level, an invariant-based anisotropic material model accommodates the nonlinear elastic response of both the ground matrix and the collagenous components. Subsequently, the basis of extant anisotropic failure criteria are presented with an emphasis on energy-based, Tsai-Wu, Hill, and principal stress criteria. The predictions of the various failure criteria on the crack initiation, and the related crack propagation are studied using representative numerical examples, i.e. a homogeneous problem subjected to uniaxial and planar biaxial deformations is established to demonstrate the corresponding failure surfaces whereas uniaxial extension and peel tests of an anisotropic (hypothetical) tissue deal with the crack propagation with reference to the mentioned failure criteria. Results favor the energy-based criterion as a better candidate to reflect a stable and physically meaningful crack growth, particularly in complex three-dimensional geometries with a highly anisotropic texture at finite strains.
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Affiliation(s)
- Osman Gültekin
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/II, 8010, Graz, Austria
| | - Hüsnü Dal
- Department of Mechanical Engineering, Middle East Technical University, Dumlupınar Bulvarı No. 1, Çankaya, 06800, Ankara, Turkey
| | - Gerhard A. Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/II, 8010, Graz, Austria
- Faculty of Engineering Science and Technology, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
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Mousavi SJ, Farzaneh S, Avril S. Computational predictions of damage propagation preceding dissection of ascending thoracic aortic aneurysms. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2018; 34:e2944. [PMID: 29171175 DOI: 10.1002/cnm.2944] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/10/2017] [Accepted: 11/12/2017] [Indexed: 06/07/2023]
Abstract
Dissections of ascending thoracic aortic aneurysms (ATAAs) cause significant morbidity and mortality worldwide. They occur when a tear in the intima-media of the aorta permits the penetration of the blood and the subsequent delamination and separation of the wall in 2 layers, forming a false channel. To predict computationally the risk of tear formation, stress analyses should be performed layer-specifically and they should consider internal or residual stresses that exist in the tissue. In the present paper, we propose a novel layer-specific damage model based on the constrained mixture theory, which intrinsically takes into account these internal stresses and can predict appropriately the tear formation. The model is implemented in finite-element commercial software Abaqus coupled with user material subroutine. Its capability is tested by applying it to the simulation of different exemplary situations, going from in vitro bulge inflation experiments on aortic samples to in vivo overpressurizing of patient-specific ATAAs. The simulations reveal that damage correctly starts from the intimal layer (luminal side) and propagates across the media as a tear but never hits the adventitia. This scenario is typically the first stage of development of an acute dissection, which is predicted for pressures of about 2.5 times the diastolic pressure by the model after calibrating the parameters against experimental data performed on collected ATAA samples. Further validations on a larger cohort of patients should hopefully confirm the potential of the model in predicting patient-specific damage evolution and possible risk of dissection during aneurysm growth for clinical applications.
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Affiliation(s)
- S Jamaleddin Mousavi
- CIS-EMSE, Ecole des Mines de Saint-Étienne, F-42023 Saint-Étienne, France
- INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France
- Université de Lyon, F-69000 Lyon, France
| | - Solmaz Farzaneh
- CIS-EMSE, Ecole des Mines de Saint-Étienne, F-42023 Saint-Étienne, France
- INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France
- Université de Lyon, F-69000 Lyon, France
| | - Stéphane Avril
- CIS-EMSE, Ecole des Mines de Saint-Étienne, F-42023 Saint-Étienne, France
- INSERM, U1059, SAINBIOSE, F-42023 Saint-Étienne, France
- Université de Lyon, F-69000 Lyon, France
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Smoljkić M, Verbrugghe P, Larsson M, Widman E, Fehervary H, D'hooge J, Vander Sloten J, Famaey N. Comparison of in vivo vs. ex situ obtained material properties of sheep common carotid artery. Med Eng Phys 2018; 55:16-24. [PMID: 29580793 DOI: 10.1016/j.medengphy.2018.03.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 03/02/2018] [Accepted: 03/13/2018] [Indexed: 11/29/2022]
Abstract
Patient-specific biomechanical modelling can improve preoperative surgical planning. This requires patient-specific geometry as well as patient-specific material properties as input. The latter are, however, still quite challenging to estimate in vivo. This study focuses on the estimation of the mechanical properties of the arterial wall. Firstly, in vivo pressure, diameter and thickness of the arterial wall were acquired for sheep common carotid arteries. Next, the animals were sacrificed and the tissue was stored for mechanical testing. Planar biaxial tests were performed to obtain experimental stress-stretch curves. Finally, parameters for the hyperelastic Mooney-Rivlin and Gasser-Ogden-Holzapfel (GOH) material model were estimated based on the in vivo obtained pressure-diameter data as well as on the ex situ experimental stress-stretch curves. Both material models were able to capture the in vivo behaviour of the tissue. However, in the ex situ case only the GOH model provided satisfactory results. When comparing different fitting approaches, in vivo vs. ex situ, each of them showed its own advantages and disadvantages. The in vivo approach estimates the properties of the tissue in its physiological state while the ex situ approach allows to apply different loadings to properly capture the anisotropy of the tissue. Both of them could be further enhanced by improving the estimation of the stress-free state, i.e. by adding residual circumferential stresses in vivo and by accounting for the flattening effect of the tested samples ex vivo. • Competing interests: none declared • Word count: 4716.
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Affiliation(s)
- Marija Smoljkić
- Biomechanics Section, Mechanical Engineering Department, KU Leuven, Leuven, Belgium
| | - Peter Verbrugghe
- Clinical Cardiac Surgery, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Matilda Larsson
- School of Technology and Health, Department of Medical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Erik Widman
- School of Technology and Health, Department of Medical Engineering, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - Heleen Fehervary
- Biomechanics Section, Mechanical Engineering Department, KU Leuven, Leuven, Belgium
| | - Jan D'hooge
- Cardiovascular Imaging and Dynamics, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
| | - Jos Vander Sloten
- Biomechanics Section, Mechanical Engineering Department, KU Leuven, Leuven, Belgium
| | - Nele Famaey
- Clinical Cardiac Surgery, Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
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A Brief Review on Computational Modeling of Rupture in Soft Biological Tissues. COMPUTATIONAL METHODS IN APPLIED SCIENCES 2018. [DOI: 10.1007/978-3-319-60885-3_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Oomen PJA, van Kelle MAJ, Oomens CWJ, Bouten CVC, Loerakker S. Nondestructive mechanical characterization of developing biological tissues using inflation testing. J Mech Behav Biomed Mater 2017; 74:438-447. [PMID: 28709754 DOI: 10.1016/j.jmbbm.2017.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 06/25/2017] [Accepted: 07/04/2017] [Indexed: 11/17/2022]
Abstract
One of the hallmarks of biological soft tissues is their capacity to grow and remodel in response to changes in their environment. Although it is well-accepted that these processes occur at least partly to maintain a mechanical homeostasis, it remains unclear which mechanical constituent(s) determine(s) mechanical homeostasis. In the current study a nondestructive mechanical test and a two-step inverse analysis method were developed and validated to nondestructively estimate the mechanical properties of biological tissue during tissue culture. Nondestructive mechanical testing was achieved by performing an inflation test on tissues that were cultured inside a bioreactor, while the tissue displacement and thickness were nondestructively measured using ultrasound. The material parameters were estimated by an inverse finite element scheme, which was preceded by an analytical estimation step to rapidly obtain an initial estimate that already approximated the final solution. The efficiency and accuracy of the two-step inverse method was demonstrated on virtual experiments of several material types with known parameters. PDMS samples were used to demonstrate the method's feasibility, where it was shown that the proposed method yielded similar results to tensile testing. Finally, the method was applied to estimate the material properties of tissue-engineered constructs. Via this method, the evolution of mechanical properties during tissue growth and remodeling can now be monitored in a well-controlled system. The outcomes can be used to determine various mechanical constituents and to assess their contribution to mechanical homeostasis.
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Affiliation(s)
- P J A Oomen
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands.
| | - M A J van Kelle
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands
| | - C W J Oomens
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands
| | - C V C Bouten
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands
| | - S Loerakker
- Department of Biomedical Engineering, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, 5600MB Eindhoven, Netherlands.
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Ruiz de Galarreta S, Cazón A, Antón R, Finol EA. A Methodology for Verifying Abdominal Aortic Aneurysm Wall Stress. J Biomech Eng 2017; 139:2554137. [PMID: 27636678 DOI: 10.1115/1.4034710] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 11/08/2022]
Abstract
An abdominal aortic aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta of at least 1.5 times its normal diameter. Although the criterion of maximum diameter is still used in clinical practice to decide on a timely intervention, numerical studies have demonstrated the importance of other geometric factors. However, the major drawback of numerical studies is that they must be validated experimentally before clinical implementation. This work presents a new methodology to verify wall stress predicted from the numerical studies against the experimental testing. To this end, four AAA phantoms were manufactured using vacuum casting. The geometry of each phantom was subject to microcomputed tomography (μCT) scanning at zero and three other intraluminal pressures: 80, 100, and 120 mm Hg. A zero-pressure geometry algorithm was used to calculate the wall stress in the phantom, while the numerical wall stress was calculated with a finite-element analysis (FEA) solver based on the actual zero-pressure geometry subjected to 80, 100, and 120 mm Hg intraluminal pressure loading. Results demonstrate the moderate accuracy of this methodology with small relative differences in the average wall stress (1.14%). Additionally, the contribution of geometric factors to the wall stress distribution was statistically analyzed for the four phantoms. The results showed a significant correlation between wall thickness and mean curvature (MC) with wall stress.
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Affiliation(s)
- Sergio Ruiz de Galarreta
- Department of Mechanical Engineering, TECNUN, University of Navarra, Paseo Manuel de Lardizabal, 13, San Sebastián 20018, Spain e-mail:
| | - Aitor Cazón
- Department of Mechanical Engineering, TECNUN, University of Navarra, Paseo Manuel de Lardizabal, 13, San Sebastián 20018, Spain e-mail:
| | - Raúl Antón
- Department of Mechanical Engineering, TECNUN, University of Navarra, Paseo Manuel de Lardizabal, 13, San Sebastián 20018, Spain e-mail:
| | - Ender A Finol
- Department of Biomedical Engineering, The University of Texas at San Antonio, One UTSA Circle, AET 1.360, San Antonio, TX 78249-0669 e-mail:
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Kermani G, Hemmasizadeh A, Assari S, Autieri M, Darvish K. Investigation of inhomogeneous and anisotropic material behavior of porcine thoracic aorta using nano-indentation tests. J Mech Behav Biomed Mater 2016; 69:50-56. [PMID: 28040607 DOI: 10.1016/j.jmbbm.2016.12.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 12/19/2016] [Accepted: 12/23/2016] [Indexed: 10/20/2022]
Abstract
This study investigates the inhomogeneity and anisotropy of porcine descending thoracic aorta in three dimensions using a custom-made nano-indentation technique and a quasi-linear viscoelastic modeling approach. The indentation tests were conducted in axial, circumferential, and radial orientations with about 100 μm spatial resolution. The ratio of the elastic moduli obtained in different orientations was used to quantify the tissue local anisotropy. The distal sections were generally stiffer than the proximal ones in both axial and circumferential indentations. Four distinct layers were identified across the thickness with significantly different mechanical properties. The stiffness of the medial quadrant was significantly lower than all other quadrants in axial indentation. The anisotropic behavior of the tissue was more pronounced in the lateral quadrant of the distal sections. The results of this study can be used to better understand the mechanisms of aorta deformation and improve the spatial accuracy of computational models of aorta.
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Affiliation(s)
- Golriz Kermani
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122, United States
| | - Ali Hemmasizadeh
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122, United States
| | - Soroush Assari
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122, United States
| | - Michael Autieri
- Department of Physiology, School of Medicine, Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, United States
| | - Kurosh Darvish
- Department of Mechanical Engineering, College of Engineering, Temple University, 1947 N. 12th Street, Philadelphia, PA 19122, United States.
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Verification of a virtual fields method to extract the mechanical properties of human optic nerve head tissues in vivo. Biomech Model Mechanobiol 2016; 16:871-887. [PMID: 27909833 DOI: 10.1007/s10237-016-0858-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 11/18/2016] [Indexed: 01/09/2023]
Abstract
We aimed to verify a custom virtual fields method (VFM) to estimate the patient-specific biomechanical properties of human optic nerve head (ONH) tissues, given their full-field deformations induced by intraocular pressure (IOP). To verify the accuracy of VFM, we first generated 'artificial' ONH displacements from predetermined (known) ONH tissue biomechanical properties using finite element analysis. Using such deformations, if we are able to match back the known biomechanical properties, it would indicate that our VFM technique is accurate. The peripapillary sclera was assumed anisotropic hyperelastic, while all other ONH tissues were considered isotropic. The simulated ONH displacements were fed into the VFM algorithm to extract back the biomechanical properties. The robustness of VFM was also tested against rigid body motions and noise added to the simulated displacements. Then, the computational speed of VFM was compared to that of a gold-standard stiffness measurement method (inverse finite element method or IFEM). Finally, as proof of principle, VFM was applied to IOP-induced ONH deformation data (obtained from one subject's eye imaged with OCT), and the biomechanical properties of the prelamina and lamina cribrosa (LC) were extracted. From given ONH displacements, VFM successfully matched back the biomechanical properties of ONH tissues with high accuracy and efficiency. For all parameters, the percentage errors were less than 0.05%. Our method was insensitive to rigid body motions and was also able to recover the material parameters in the presence of noise. VFM was also found 125 times faster than the gold-standard IFEM. Finally, the estimated shear modulus for the prelamina and the LC of the studied subject's eye were 33.7 and 63.5 kPa, respectively. VFM may be capable of measuring the biomechanical properties of ONH tissues with high speed and accuracy. It has potential in identifying patient-specific ONH biomechanical properties in the clinic if combined with optical coherence tomography.
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Gültekin O, Dal H, Holzapfel GA. A phase-field approach to model fracture of arterial walls: Theory and finite element analysis. COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2016; 312:542-566. [PMID: 31649409 PMCID: PMC6812523 DOI: 10.1016/j.cma.2016.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
This study uses a recently developed phase-field approach to model fracture of arterial walls with an emphasis on aortic tissues. We start by deriving the regularized crack surface to overcome complexities inherent in sharp crack discontinuities, thereby relaxing the acute crack surface topology into a diffusive one. In fact, the regularized crack surface possesses the property of Gamma-Convergence, i.e. the sharp crack topology is restored with a vanishing length-scale parameter. Next, we deal with the continuous formulation of the variational principle for the multi-field problem manifested through the deformation map and the crack phase-field at finite strains which leads to the Euler-Lagrange equations of the coupled problem. In particular, the coupled balance equations derived render the evolution of the crack phase-field and the balance of linear momentum. As an important aspect of the continuum formulation we consider an invariant-based anisotropic constitutive model which is additively decomposed into an isotropic part for the ground matrix and an exponential anisotropic part for the two families of collagen fibers embedded in the ground matrix. In addition we propose a novel energy-based anisotropic failure criterion which regulates the evolution of the crack phase-field. The coupled problem is solved using a one-pass operator-splitting algorithm composed of a mechanical predictor step (solved for the frozen crack phase-field parameter) and a crack evolution step (solved for the frozen deformation map); a history field governed by the failure criterion is successively updated. Subsequently, a conventional Galerkin procedure leads to the weak forms of the governing differential equations for the physical problem. Accordingly, we provide the discrete residual vectors and a corresponding linearization yields the element matrices for the two sub-problems. Finally, we demonstrate the numerical performance of the crack phase-field model by simulating uniaxial extension and simple shear fracture tests performed on specimens obtained from a human aneurysmatic thoracic aorta. Model parameters are obtained by fitting the set of novel experimental data to the predicted model response; the finite element results agree favorably with the experimental findings.
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Affiliation(s)
- Osman Gültekin
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/II, 8010, Graz, Austria
| | - Hüsnü Dal
- Department of Mechanical Engineering, Middle East Technical University, Dumlupınar Bulvarı No. 1, Çankaya, 06800, Ankara, Turkey
| | - Gerhard A. Holzapfel
- Institute of Biomechanics, Graz University of Technology, Stremayrgasse 16/II, 8010, Graz, Austria
- Corresponding author. (G.A. Holzapfel)
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Biaxial rupture properties of ascending thoracic aortic aneurysms. Acta Biomater 2016; 42:273-285. [PMID: 27345137 DOI: 10.1016/j.actbio.2016.06.028] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 05/11/2016] [Accepted: 06/22/2016] [Indexed: 12/22/2022]
Abstract
UNLABELLED Although hundreds of samples obtained from ascending thoracic aortic aneurysms (ATAA) of patients undergoing elective surgical repair have already been characterized biomechanically, their rupture properties were always derived from uniaxial tensile tests. Due to their bulge shape, ATAAs are stretched biaxially in vivo. In order to understand the biaxial rupture of ATAAs, our group developed a novel methodology based on bulge inflation and full-field optical measurements. The objective of the current paper is threefold. Firstly, we will review the failure properties (maximum stress, maximum stretch) obtained by bulge inflation testing on a cohort of 31 patients and compare them with failure properties obtained by uniaxial tension in a previously published study. Secondly, we will investigate the relationship between the failure properties and the age of patients, showing that patients below 55years of age display significantly higher strength. Thirdly, we will define a rupture risk based on the extensibility of the tissue and we will show that this rupture risk is strongly correlated with the physiological elastic modulus of the tissue independently of the age, ATAA diameter or the aortic valve phenotype of the patient. STATEMENT OF SIGNIFICANCE Despite their medical importance, rupture properties of ascending thoracic aortic aneurysms (ATAA) subjected to biaxial tension were inexistent in the literature. In order to address this lack, our group developed a novel methodology based on bulge inflation and full-field optical measurements. Here we report rupture properties obtained with this methodology on 31 patients. It is shown for the first time that rupture occurs when the stretch applied to ATAAs reaches the maximum extensibility of the tissue and that this maximum extensibility correlates strongly with the elastic properties. The outcome is a better detection of at-risk individuals for elective surgical repair.
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Trabelsi O, Duprey A, Favre JP, Avril S. Predictive Models with Patient Specific Material Properties for the Biomechanical Behavior of Ascending Thoracic Aneurysms. Ann Biomed Eng 2015; 44:84-98. [DOI: 10.1007/s10439-015-1374-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 06/24/2015] [Indexed: 02/07/2023]
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Teng Z, Feng J, Zhang Y, Huang Y, Sutcliffe MPF, Brown AJ, Jing Z, Gillard JH, Lu Q. Layer- and Direction-Specific Material Properties, Extreme Extensibility and Ultimate Material Strength of Human Abdominal Aorta and Aneurysm: A Uniaxial Extension Study. Ann Biomed Eng 2015; 43:2745-59. [PMID: 25905688 PMCID: PMC4611020 DOI: 10.1007/s10439-015-1323-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 04/12/2015] [Indexed: 11/26/2022]
Abstract
Mechanical analysis has the potential to provide complementary information to aneurysm morphology in assessing its vulnerability. Reliable calculations require accurate material properties of individual aneurysmal components. Quantification of extreme extensibility and ultimate material strength of the tissue are important if rupture is to be modelled. Tissue pieces from 11 abdomen aortic aneurysm (AAA) from patients scheduled for elective surgery and from 8 normal aortic artery (NAA) from patients who scheduled for kidney/liver transplant were collected at surgery and banked in liquid nitrogen with the use of Cryoprotectant solution to minimize frozen damage. Prior to testing, specimen were thawed and longitudinal and circumferential tissue strips were cut from each piece and adventitia, media and thrombus if presented were isolated for the material test. The incremental Young’s modulus of adventitia of NAA was direction-dependent at low stretch levels, but not the media. Both adventitia and media had a similar extreme extensibility in the circumferential direction, but the adventitia was much stronger. For aneurysmal tissues, no significant differences were found when the incremental moduli of adventitia, media or thrombus in both directions were compared. Adventitia and media from AAA had similar extreme extensibility and ultimate strength in both directions and thrombus was the weakest material. Adventitia and media from AAA were less extensible compared with those of NAA, but the ultimate strength remained similar. The material properties, including extreme extensibility and ultimate strength, of both healthy aortic and aneurysmal tissues were layer-dependent, but not direction-dependent.
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Affiliation(s)
- Zhongzhao Teng
- Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK.
- Department of Engineering, University of Cambridge, Cambridge, UK.
| | - Jiaxuan Feng
- Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China
| | - Yongxue Zhang
- Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK
- Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China
| | - Yuan Huang
- Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK
| | | | - Adam J Brown
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK
| | - Zaiping Jing
- Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China
| | - Jonathan H Gillard
- Department of Radiology, School of Clinical Medicine, University of Cambridge, Cambridge Biomedical Campus, Box 218, Cambridge, CB2 0QQ, UK
| | - Qingsheng Lu
- Department of Vascular Surgery, Changhai Hospital, 168 Changhai Rd., Shanghai, 200433, China.
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38
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Avanzini A, Battini D, Bagozzi L, Bisleri G. Biomechanical evaluation of ascending aortic aneurysms. BIOMED RESEARCH INTERNATIONAL 2014; 2014:820385. [PMID: 24991568 PMCID: PMC4065659 DOI: 10.1155/2014/820385] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 04/21/2014] [Indexed: 11/27/2022]
Abstract
The biomechanical properties of ascending aortic aneurysms were investigated only in the last decade in a limited number of studies. Indeed, in recent years, there has been a growing interest in this field in order to identify new predictive parameters of risk of dissection, which may have clinical relevance. The researches performed so far have been conducted according to the methods used in the study of abdominal aortic aneurysms. In most cases, uniaxial or biaxial tensile tests were used, while in a smaller number of studies other methods, such as opening angle, bulge inflation, and inflation-extension tests, were used. However, parameters and protocols of these tests are at present very heterogeneous in the studies reported in the literature, and, therefore, the results are not comparable and are sometimes conflicting. The purpose of this review then thence to provide a comprehensive analysis of the experimental methodology for determination of biomechanical properties in the specific field of aneurysms of the ascending aorta to allow for better comparison and understanding of the results.
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Affiliation(s)
- Andrea Avanzini
- Department of Industrial and Mechanical Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Davide Battini
- Department of Industrial and Mechanical Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Lorenzo Bagozzi
- Division of Cardiac Surgery, University of Brescia, P.le Spedali Civili 1, 25123 Brescia, Italy
| | - Gianluigi Bisleri
- Division of Cardiac Surgery, University of Brescia, P.le Spedali Civili 1, 25123 Brescia, Italy
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Nontraumatic acute aortic emergencies: Part 2, Pre- and postsurgical complications related to aortic aneurysm in the emergency clinical setting. AJR Am J Roentgenol 2014; 202:666-74. [PMID: 24555606 DOI: 10.2214/ajr.13.11438] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The aim of this article is to illustrate the imaging findings and spectrum of disease entities affecting the aorta. The clinical presentation and assessment of acute aortic pathology can be elusive or deceptive, making the diagnosis challenging. The widespread availability of advanced cross-sectional imaging technology in the emergency setting puts the radiologist at the forefront of accurate and timely diagnosis. CONCLUSION Cross-sectional imaging plays a pivotal role in the diagnosis and delineation of aortic pathology. Awareness of the imaging findings and complications can help in swift and accurate diagnosis.
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40
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Romo A, Badel P, Duprey A, Favre JP, Avril S. In vitro analysis of localized aneurysm rupture. J Biomech 2014; 47:607-16. [DOI: 10.1016/j.jbiomech.2013.12.012] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 10/25/2022]
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41
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Avril S, Badel P, Gabr M, Sutton MA, Lessner SM. Biomechanics of porcine renal arteries and role of axial stretch. J Biomech Eng 2013; 135:81007. [PMID: 23722353 DOI: 10.1115/1.4024685] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 05/30/2013] [Indexed: 11/08/2022]
Abstract
It is known that arteries experience significant axial stretches in vivo. Several authors have shown that the axial force needed to maintain an artery at its in vivo axial stretch does not change with transient cyclical pressurization over normal ranges. However, the axial force phenomenon of arteries has never been explained with microstructural considerations. In this paper we propose a simple biomechanical model to relate the specific axial force phenomenon of arteries to the predicted load-dependent average collagen fiber orientation. It is shown that (a) the model correctly predicts the authors' experimentally measured biaxial behavior of pig renal arteries and (b) the model predictions are in agreement with additional experimental results reported in the literature. Finally, we discuss the implications of the model for collagen fiber orientation and deposition in arteries.
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Affiliation(s)
- Stéphane Avril
- Ecole Nationale Supe´rieure des Mines CIS-ENSMSE, CNRS:UMR5146 Saint-Etienne F-42023, France
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42
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Bel-Brunon A, Coret M, Bruyère-Garnier K, Combescure A. Compared prediction of the experimental failure of a thin fibrous tissue by two macroscopic damage models. J Mech Behav Biomed Mater 2013; 27:262-72. [PMID: 23773977 DOI: 10.1016/j.jmbbm.2013.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 05/16/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
Abstract
Several models for fibrous biological tissues have been proposed in the past, taking into account the fibrous microstructure through different homogenization methods. The aim of this paper is to compare theoretically and experimentally two existing homogenization methods - the Angular Integration method and the Generalized Structure Tensor method - by adapting them to a damage model for a planar fibrous tissue made of linear elastic and brittle fibers. The theoretical implementation of the homogenization methods reveals some differences once damage starts in the fibrous tissue; in particular, the anisotropy of the tissue evolves differently. The experimental aspect of this work consists in identifying the parameters of the damage model, with both homogenization methods, using inflation tests until rupture on a biological membrane. The numerical identification method is based on the simulation of the tests with the real geometry of the samples and the real boundary conditions computed by Stereo Digital Image Correlation. The identification method is applied to human liver capsule. The collagen fibers Young's modulus (19±6MPa) as well as their ultimate longitudinal strain (33±4%) are determined; no significant difference was observed between the two methods. However, by using the experimental boundary conditions, we could observe that the damage progression is faster for the Angular Integration version of the model.
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Affiliation(s)
- A Bel-Brunon
- Université de Lyon, Lyon F-69000, France; INSA-Lyon, LaMCoS UMR5259, F-69621, France; Ifsttar, UMRT9406, LBMC, F-69675 Bron, France; Université Lyon 1, F-69622 Villeurbanne, France.
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