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Fracture behaviour of human skin in deep needle insertion can be captured using validated cohesive zone finite-element method. Comput Biol Med 2021; 139:104982. [PMID: 34749097 DOI: 10.1016/j.compbiomed.2021.104982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/10/2021] [Accepted: 10/23/2021] [Indexed: 11/24/2022]
Abstract
Medical needles have shown an appreciable contribution to the development of novel medical devices and surgical technologies. A better understanding of needle-skin interactions can advance the design of medical needles, modern surgical robots, and haptic devices. This study employed finite element (FE) modelling to explore the effect of different mechanical and geometrical parameters on the needle's force-displacement relationship, the required force for the skin puncture, and generated mechanical stress around the cutting zone. To this end, we established a cohesive FE model, and identified its parameters by a three-stage parameter identification algorithm to closely replicate the experimental data of needle insertion into the human skin available in the literature. We showed that a bilinear cohesive model with initial stiffness of 5000 MPa/mm, failure traction of 2 MPa, and separation length of 1.6 mm can lead to a model that can closely replicate experimental results. The FE results indicated that while the coefficient of friction between the needle and skin substantially changes the needle reaction force, the insertion velocity does not have a noticeable effect on the reaction force. Regarding the geometrical parameters, needle cutting angle is the prominent factor in terms of stress fields generated in the skin tissue. However, the needle diameter is more influential on the needle reaction force. We also presented an energy study on the frictional dissipation, damage dissipation, and strain energy throughout the insertion process.
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Lama SBC, Maçôas ES, Coda FE, Alemán C, Pineda E, Ferreira FC. Investigation of the mechanical properties and biocompatibility of planar and electrospun alkene-styrene copolymers against P(VDF-TrFE) and porcine skin: Potential use as second skin substrates. J Mech Behav Biomed Mater 2021; 119:104481. [PMID: 33813332 DOI: 10.1016/j.jmbbm.2021.104481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Revised: 04/01/2020] [Accepted: 03/14/2021] [Indexed: 12/22/2022]
Abstract
Elastomers have been used in a variety of biomedical fields, including tissue engineering, soft robotics, prostheses, and cosmetics. Elastomers used for skin grafting scaffolds tend to be biodegradable, but other applications require perdurable elastomers. Advances in perdurable elastomers would allow for the development of a range of substrates useful in the creation of joint prostheses, chronic neural electrodes, implantables, and wearables. Still, for these, tailored mechanical properties and biocompatibility are required. In this work, several perdurable alkene-styrene elastomers and novel polymer blends are investigated for their stress-strain curves; with quantification of Young's moduli, fatigue behavior and standard biocompatibility. In particular, this study attempts to study polymers with mechanical properties similar to the complex characteristics of skin, through comparison with porcine skin samples. Poly (vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), a flexible polymer previously used as a wearable sensor and second skin component, was here used for comparison studies. Interestingly, this study points out that elastomer mechanical properties can be modulated to better replicate the elastic modulus of skin, in particular for KratonTM D1152, a Styrene-Butadiene-Styrene block copolymer. Namely, this is the case when such an elastomer is prepared as an electrospun matrix or as a flat dense film under low temperatures. Moreover, a specific method was optimized to obtain electrospun fibers of this alkene-styrene copolymer.
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Affiliation(s)
- Siddhi B C Lama
- Department of Bioengineering and IBB - Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Ermelinda S Maçôas
- Centro de Química-Física Molecular/Centro de Química Estrutural do Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Francesc Estrany Coda
- Departament d'Enginyeria Química (EEBE) and Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, C/ Eduard Maristany, 10-14, Ed. I2, 08019, Barcelona, Spain
| | - Carlos Alemán
- Departament d'Enginyeria Química (EEBE) and Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, C/ Eduard Maristany, 10-14, Ed. I2, 08019, Barcelona, Spain
| | - Eloi Pineda
- Departament de Física (EEBE) and Barcelona Research Center for Multiscale Science and Engineering, Universitat Politècnica de Catalunya, Avda. Eduard Maristany, 16, Ed. C, 08019, Barcelona, Spain
| | - Frederico Castelo Ferreira
- Department of Bioengineering and IBB - Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
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Subject-Specific Finite Element Modelling of the Human Hand Complex: Muscle-Driven Simulations and Experimental Validation. Ann Biomed Eng 2019; 48:1181-1195. [PMID: 31845127 PMCID: PMC7089907 DOI: 10.1007/s10439-019-02439-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 12/10/2019] [Indexed: 11/16/2022]
Abstract
This paper aims to develop and validate a subject-specific framework for modelling the human hand. This was achieved by combining medical image-based finite element modelling, individualized muscle force and kinematic measurements. Firstly, a subject-specific human hand finite element (FE) model was developed. The geometries of the phalanges, carpal bones, wrist bones, ligaments, tendons, subcutaneous tissue and skin were all included. The material properties were derived from in-vivo and in-vitro experiment results available in the literature. The boundary and loading conditions were defined based on the kinematic data and muscle forces of a specific subject captured from the in-vivo grasping tests. The predicted contact pressure and contact area were in good agreement with the in-vivo test results of the same subject, with the relative errors for the contact pressures all being below 20%. Finally, sensitivity analysis was performed to investigate the effects of important modelling parameters on the predictions. The results showed that contact pressure and area were sensitive to the material properties and muscle forces. This FE human hand model can be used to make a detailed and quantitative evaluation into biomechanical and neurophysiological aspects of human hand contact during daily perception and manipulation. The findings can be applied to the design of the bionic hands or neuro-prosthetics in the future.
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Blacklow SO, Li J, Freedman BR, Zeidi M, Chen C, Mooney DJ. Bioinspired mechanically active adhesive dressings to accelerate wound closure. SCIENCE ADVANCES 2019; 5:eaaw3963. [PMID: 31355332 PMCID: PMC6656537 DOI: 10.1126/sciadv.aaw3963] [Citation(s) in RCA: 239] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 06/20/2019] [Indexed: 05/21/2023]
Abstract
Inspired by embryonic wound closure, we present mechanically active dressings to accelerate wound healing. Conventional dressings passively aid healing by maintaining moisture at wound sites. Recent developments have focused on drug and cell delivery to drive a healing process, but these methods are often complicated by drug side effects, sophisticated fabrication, and high cost. Here, we present novel active adhesive dressings consisting of thermoresponsive tough adhesive hydrogels that combine high stretchability, toughness, tissue adhesion, and antimicrobial function. They adhere strongly to the skin and actively contract wounds, in response to exposure to the skin temperature. In vitro and in vivo studies demonstrate their efficacy in accelerating and supporting skin wound healing. Finite element models validate and refine the wound contraction process enabled by these active adhesive dressings. This mechanobiological approach opens new avenues for wound management and may find broad utility in applications ranging from regenerative medicine to soft robotics.
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Affiliation(s)
- S. O. Blacklow
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
- School of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - J. Li
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
- Department of Mechanical Engineering, McGill University, Montreal, QC H3A 0G4, Canada
- Department of Biomedical Engineering, McGill University, Montreal, QC H3A 0G4, Canada
| | - B. R. Freedman
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - M. Zeidi
- Department of Mechanical Engineering, McGill University, Montreal, QC H3A 0G4, Canada
| | - C. Chen
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
| | - D. J. Mooney
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA 02138, USA
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Liang J, Smith KD, Lu H, Seale TW, Gan RZ. Mechanical properties of the Papio anubis tympanic membrane: Change significantly from infancy to adulthood. Hear Res 2018; 370:143-154. [PMID: 30388572 DOI: 10.1016/j.heares.2018.10.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 10/05/2018] [Accepted: 10/14/2018] [Indexed: 11/16/2022]
Abstract
Mechanical properties of the tympanic membrane (TM) are important for studying the transfer function of the auditory system. However, nearly all reported human data are limited to adults because of the unavailability of temporal bones from children. In this study, we used the baboon (Papio anubis), a genetically close human relative, as a model to address the occurrence of age-dependent changes of the human TM. Forty-five baboon TMs were characterized in five age groups: <1 year, 1 to <2 years, 2 to <3 years, 3 to <5, and >5 years of age, comparable to human ages ranging from newborn to adult. The elastic properties of the baboon TMs were characterized by a micro-fringe projection technique. Volume displacement of the TM under quasi-static pressure was first determined from its micro-fringe pattern. Subsequently, these displacement values were used in a finite element model to derive mechanical properties. The Young's modulus of the baboon TM exhibited a modest decrease from 29.1 MPa to 26.0 MPa over the age groups. The average Young's modulus was ∼1.4 times higher than that of the adult human TM. This is the first time that age-related TM mechanical properties of high primate are reported. These new findings may help to explore the potential value of the baboon as a new primate model for future age-related hearing research on the normal and diseased ear.
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Affiliation(s)
- Junfeng Liang
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, USA; Dept. of Mechanical Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Kyle D Smith
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, USA
| | - Hongbing Lu
- Dept. of Mechanical Engineering, University of Texas at Dallas, Richardson, TX, USA
| | - Thomas W Seale
- Dept. of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Rong Z Gan
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, USA.
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Lutz JC, Hostettler A, Agnus V, Nicolau S, George D, Soler L, Rémond Y. A New Software Suite in Orthognathic Surgery : Patient Specific Modeling, Simulation and Navigation. Surg Innov 2018; 26:5-20. [PMID: 30270757 DOI: 10.1177/1553350618803233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Orthognathic surgery belongs to the scope of maxillofacial surgery. It treats dentofacial deformities consisting in discrepancy between the facial bones (upper and lower jaws). Such impairment affects chewing, talking, and breathing and can ultimately result in the loss of teeth. Orthognathic surgery restores facial harmony and dental occlusion through bone cutting, repositioning, and fixation. However, in routine practice, we face the limitations of conventional tools and the lack of intraoperative assistance. These limitations occur at every step of the surgical workflow: preoperative planning, simulation, and intraoperative navigation. The aim of this research was to provide novel tools to improve simulation and navigation. We first developed a semiautomated segmentation pipeline allowing accurate and time-efficient patient-specific 3D modeling from computed tomography scans mandatory to achieve surgical planning. This step allowed an improvement of processing time by a factor of 6 compared with interactive segmentation, with a 1.5-mm distance error. Next, we developed a software to simulate the postoperative outcome on facial soft tissues. Volume meshes were processed from segmented DICOM images, and the Bullet open source mechanical engine was used together with a mass-spring model to reach a postoperative simulation accuracy <1 mm. Our toolset was completed by the development of a real-time navigation system using minimally invasive electromagnetic sensors. This navigation system featured a novel user-friendly interface based on augmented virtuality that improved surgical accuracy and operative time especially for trainee surgeons, therefore demonstrating its educational benefits. The resulting software suite could enhance operative accuracy and surgeon education for improved patient care.
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Affiliation(s)
- Jean-Christophe Lutz
- 1 Maxillo-Facial and Plastic Surgery Department, Strasbourg University Hospital, France.,2 Department of Computer Science, Research and Development, IRCAD, France.,3 Laboratory of Engineering Science, Computer Science and Imaging, CNRS, University of Strasbourg, France
| | | | - Vincent Agnus
- 2 Department of Computer Science, Research and Development, IRCAD, France
| | - Stéphane Nicolau
- 2 Department of Computer Science, Research and Development, IRCAD, France
| | - Daniel George
- 3 Laboratory of Engineering Science, Computer Science and Imaging, CNRS, University of Strasbourg, France
| | - Luc Soler
- 2 Department of Computer Science, Research and Development, IRCAD, France
| | - Yves Rémond
- 3 Laboratory of Engineering Science, Computer Science and Imaging, CNRS, University of Strasbourg, France
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Chanda A. Biomechanical Modeling of Human Skin Tissue Surrogates. Biomimetics (Basel) 2018; 3:biomimetics3030018. [PMID: 31105240 PMCID: PMC6352690 DOI: 10.3390/biomimetics3030018] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 07/16/2018] [Accepted: 07/19/2018] [Indexed: 11/22/2022] Open
Abstract
Surrogates, which precisely simulate nonlinear mechanical properties of the human skin at different body sites, would be indispensable for biomechanical testing applications, such as estimating the accurate load response of skin implants and prosthetics to study the biomechanics of static and dynamic loading conditions on the skin, dermatological and sports injuries, and estimating the dynamic load response of lethal and nonlethal ballistics. To date, human skin surrogates have been developed mainly with materials, such as gelatin and polydimethylsiloxane (PDMS), based on assumption of simplified mechanical properties, such as an average elastic modulus (estimated through indentation tests), and Poisson’s ratio. In addition, pigskin and cowhides, which have widely varying mechanical properties, have been used to simulate human skin. In the current work, a novel elastomer-based material system is developed, which precisely mimics the nonlinear stress–stretch behavior, elastic modulus at high and low strains, and fracture strengths of the natural human skin at different body sites. The manufacturing and fabrication process of these skin surrogates are discussed, and mechanical testing results are presented.
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Affiliation(s)
- Arnab Chanda
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, AL 35401, USA.
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Soetens JFJ, van Vijven M, Bader DL, Peters GWM, Oomens CWJ. A model of human skin under large amplitude oscillatory shear. J Mech Behav Biomed Mater 2018; 86:423-432. [PMID: 30031246 DOI: 10.1016/j.jmbbm.2018.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 07/03/2018] [Accepted: 07/04/2018] [Indexed: 10/28/2022]
Abstract
Skin mechanics is of importance in various fields of research when accurate predictions of the mechanical response of skin is essential. This study aims to develop a new constitutive model for human skin that is capable of describing the heterogeneous, nonlinear viscoelastic mechanical response of human skin under shear deformation. This complex mechanical response was determined by performing large amplitude oscillatory shear (LAOS) experiments on ex vivo human skin samples. It was combined with digital image correlation (DIC) on the cross-sectional area to assess heterogeneity. The skin is modeled as a one-dimensional layered structure, with every sublayer behaving as a nonlinear viscoelastic material. Heterogeneity is implemented by varying the stiffness with skin depth. Using an iterative parameter estimation method all model parameters were optimized simultaneously. The model accurately captures strain stiffening, shear thinning, softening effect and nonlinear viscous dissipation, as experimentally observed in the mechanical response to LAOS. The heterogeneous properties described by the model were in good agreement with the experimental DIC results. The presented mathematical description forms the basis for a future constitutive model definition that, by implementation in a finite element method, has the capability of describing the full 3D mechanical behavior of human skin.
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Affiliation(s)
- J F J Soetens
- Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, Gem-Z. 4.11, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
| | - M van Vijven
- Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, Gem-Z. 4.11, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - D L Bader
- Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, Gem-Z. 4.11, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Faculty of Health Sciences, University of Southampton, Southampton, United Kingdom
| | - G W M Peters
- Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - C W J Oomens
- Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, Gem-Z. 4.11, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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A step-by-step review on patient-specific biomechanical finite element models for breast MRI to x-ray mammography registration. Med Phys 2017; 45:e6-e31. [DOI: 10.1002/mp.12673] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 09/27/2017] [Accepted: 11/03/2017] [Indexed: 01/08/2023] Open
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Li W, Luo X. An Invariant-Based Damage Model for Human and Animal Skins. Ann Biomed Eng 2016; 44:3109-3122. [PMID: 27066788 PMCID: PMC5042997 DOI: 10.1007/s10439-016-1603-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/31/2016] [Indexed: 11/29/2022]
Abstract
Constitutive modelling of skins that account for damage effects is important to provide insight for various clinical applications, such as skin trauma and injury, artificial skin design, skin aging, disease diagnosis, surgery, as well as comparative studies of skin biomechanics between species. In this study, a new damage model for human and animal skins is proposed for the first time. The model is nonlinear, anisotropic, invariant-based, and is based on the Gasser-Ogden-Holzapfel constitutive law initially developed for arteries. Taking account of the mean collagen fibre orientation and its dispersion, the new model can describe a wide range of skins with damage. The model is first tested on the uniaxial test data of human skin and then applied to nine groups of uniaxial test data for the human, swine, rabbit, bovine and rhino skins. The material parameters can be inversely estimated based on uniaxial tests using the optimization method in MATLAB with a root mean square error ranged between 2.15% and 12.18%. A sensitivity study confirms that the fibre orientation dispersion and the mean fibre angle are among the most important factors that influence the behaviour of the damage model. In addition, these two parameters can only be reliably estimated if some histological information is provided. We also found that depending on the location of skins, the tissue damage may be brittle controlled by the fibre breaking limit (i.e., when the fibre stretch is greater than 1.13-1.32, depending on the species), or ductile (due to both the fibre and the matrix damages). The brittle damages seem to occur mostly in the back, and the ductile damages are seen from samples taken from the belly. The proposed constitutive model may be applied to various clinical applications that require knowledge of the mechanical response of human and animal skins.
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Affiliation(s)
- Wenguang Li
- School of Engineering, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Xiaoyu Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow, G12 8QW, UK
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Mohd Sahri MR, Muhamad CMKIC, Abd Latif MJ, Mahmud J. Parametric Study of Low Velocity Impact Using Finite Element Analysis. APPLIED MECHANICS AND MATERIALS 2013; 393:397-402. [DOI: 10.4028/www.scientific.net/amm.393.397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
An aircraft structural and material response is very complex when subjected to impact. It involves both elastic and plastic deformation in instant. Nevertheless, investigating this phenomenon is challenging yet interesting. Therefore, this research attempts to investigate the effect of selected parameters variation (i.e. material type, skin thickness and impact velocity) to the resulting equivalent plastic shear strain using finite element analysis (FEA). The finite element (FE) models were developed using commercially modeling and FE software to replicate an aircraft fuselage (target) and projectile according to the experimental setup and data established by other researcher [. The current study only focuses on the materials response and deformation behavior due low velocity (30 150 m/s) impact of a blunt object to a square shape target made of Al 2024-T3 and aluminum alloy 7475 (AA 7475). In all cases (parameters variation), the resulting equivalent plastic strain has been determined and compared to the established data. It is found that the currents results are very close to the actual material response measured in experiments. This proves that simulated results are validated and the study contributed some knowledge to understanding the behaviour of the structural and material response in a low impact velocity. By varying selected parameters, the impact resistivity of the structure could be improved.
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