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Wadsworth MS, Deloyer MJ, Vanli OA, Zeng C. A Split-Plot Experimentation Strategy for Making Causal Inferences in Advanced Materials: Auxetic Polyurethane Foam Manufacturing and Processing Analysis. MATERIALS (BASEL, SWITZERLAND) 2024; 17:3280. [PMID: 38998362 PMCID: PMC11243020 DOI: 10.3390/ma17133280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/27/2024] [Accepted: 06/30/2024] [Indexed: 07/14/2024]
Abstract
Development of advanced materials is often time consuming and expensive because of the large number of variables involved and experiments needed. An effective experimentation strategy would accelerate development by reducing the required amount of experiments without sacrificing the obtainable information. In this paper, the development of auxetic polyurethane (PU) foams was discussed as a case study. Auxetic materials are materials with a negative Poisson's ratio and have potential in many structural and functional applications. Auxetic PU foams are the most studied auxetic materials, and their manufacturing and properties are affected by many processing and environmental factors. This paper introduces a sophisticated design of experimental methodology to help reduce the experimental effort while effectively screening these factors. This methodology is then applied in an experiment to illustrate its utility and distinct advantages that greatly facilitate material development.
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Affiliation(s)
- Matthew S Wadsworth
- Department of Industrial and Manufacturing Engineering, FAMU-FSU College of Engineering, High Performance Materials Institute, Florida State University, 2525 Pottsdamer St., Tallahassee, FL 32310, USA
| | - Md Jahan Deloyer
- Department of Industrial and Manufacturing Engineering, FAMU-FSU College of Engineering, High Performance Materials Institute, Florida State University, 2525 Pottsdamer St., Tallahassee, FL 32310, USA
| | - Omer Arda Vanli
- Department of Industrial and Manufacturing Engineering, FAMU-FSU College of Engineering, High Performance Materials Institute, Florida State University, 2525 Pottsdamer St., Tallahassee, FL 32310, USA
| | - Changchun Zeng
- Department of Industrial and Manufacturing Engineering, FAMU-FSU College of Engineering, High Performance Materials Institute, Florida State University, 2525 Pottsdamer St., Tallahassee, FL 32310, USA
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2
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Kim DY, Kim HS, Kamath SS, Hou X, Choi JW, Park SH. TPMS-based auxetic structure for high-performance airless tires with variable stiffness depending on deformation. Sci Rep 2024; 14:11419. [PMID: 38763924 PMCID: PMC11102911 DOI: 10.1038/s41598-024-62101-3] [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: 02/22/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024] Open
Abstract
A novel auxetic structure applicable to airless tire spokes is designed based on the primitive-type triply periodic minimal surface (P-TPMS) to have higher stiffness through deformation under compressive force. For becoming higher stiffness by deformation, an unit cell of auxetic structure is proposed and its characteristics according to design parameters are studied. Based on the parametric study, a rotated primitive-type auxetic structure (RPAS) is designed, and the deformative behaviors of an airless tire with the RPAS spokes are compared with a generally used honeycomb spoke. Simulation and experiment results show that the designed RPAS tire exhibits more stable behavior through higher rigidity depending on the deformation state when compressed on flat ground and obstacles. This variable stiffness characteristic of RPAS tires can be advantageous for shock absorption and prevention of large local deformations. Also, the manufacturability of the designed auxetic structure is evaluated using real rubber-based additive manufacturing processes for practical application in the tire manufacturing industry.
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Affiliation(s)
- Do-Yeon Kim
- Graduate School of Mechanical Engineering, Pusan National University, Busan, 46241, Korea
| | - Hong-Seok Kim
- Graduate School of Mechanical Engineering, Pusan National University, Busan, 46241, Korea
| | - Sarath Suresh Kamath
- Department of Mechanical Engineering, The University of Akron, Akron, OH, 44325, USA
| | - Xiangying Hou
- National Key Laboratory of Science and Technology On Helicopter Transmission, Nanjing University of Aeronautics, Nanjing, China
| | - Jae-Won Choi
- Department of Mechanical Engineering, The University of Akron, Akron, OH, 44325, USA.
| | - Sang-Hu Park
- School of Mechanical Engineering, Pusan National University, Busan, 46241, Korea.
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3
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Galea Mifsud R, Muscat GA, Grima-Cornish JN, Dudek KK, Cardona MA, Attard D, Farrugia PS, Gatt R, Evans KE, Grima JN. Auxetics and FEA: Modern Materials Driven by Modern Simulation Methods. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1506. [PMID: 38612021 PMCID: PMC11012591 DOI: 10.3390/ma17071506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/04/2024] [Accepted: 03/18/2024] [Indexed: 04/14/2024]
Abstract
Auxetics are materials, metamaterials or structures which expand laterally in at least one cross-sectional plane when uniaxially stretched, that is, have a negative Poisson's ratio. Over these last decades, these systems have been studied through various methods, including simulations through finite elements analysis (FEA). This simulation tool is playing an increasingly significant role in the study of materials and structures as a result of the availability of more advanced and user-friendly commercially available software and higher computational power at more reachable costs. This review shows how, in the last three decades, FEA proved to be an essential key tool for studying auxetics, their properties, potential uses and applications. It focuses on the use of FEA in recent years for the design and optimisation of auxetic systems, for the simulation of how they behave when subjected to uniaxial stretching or compression, typically with a focus on identifying the deformation mechanism which leads to auxetic behaviour, and/or, for the simulation of their characteristics and behaviour under different circumstances such as impacts.
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Affiliation(s)
- Russell Galea Mifsud
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
| | - Grace Anne Muscat
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
| | - James N. Grima-Cornish
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
| | - Krzysztof K. Dudek
- Institute of Physics, University of Zielona Gora, ul. Szafrana 4a, 65-069 Zielona Gora, Poland;
| | - Maria A. Cardona
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
| | - Daphne Attard
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
| | - Pierre-Sandre Farrugia
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
| | - Ruben Gatt
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
- Centre for Molecular Medicine and Biobanking, University of Malta, MSD 2080 Msida, Malta
| | - Kenneth E. Evans
- Department of Engineering, Faculty of Environment, Science and Economy, University of Exeter, North Park Road, Exeter EX4 4QF, UK;
| | - Joseph N. Grima
- Metamaterials Unit, Faculty of Science, University of Malta, MSD 2080 Msida, Malta; (R.G.M.); (G.A.M.); (J.N.G.-C.); (M.A.C.); (D.A.); (P.-S.F.); (R.G.)
- Department of Chemistry, University of Malta, MSD 2080 Msida, Malta
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4
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Tao T, Li L, He Q, Wang Y, Guo J. Mechanical Behavior of Bio-Inspired Honeycomb-Core Composite Sandwich Structures to Low-Velocity Dynamic Loading. MATERIALS (BASEL, SWITZERLAND) 2024; 17:1191. [PMID: 38473662 DOI: 10.3390/ma17051191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 01/29/2024] [Accepted: 02/07/2024] [Indexed: 03/14/2024]
Abstract
In order to improve the impact resistance of sandwich panels under low-velocity impact, the lotus leaf vein is selected as a biological prototype to design a bio-inspired honeycomb (BIH) sandwich panel. ABAQUS is used to establish and effectively verify the finite element (FE) model of the BIH sandwich panel. To systematically compare and study the mechanical properties of BIH and conventional hexagonal honeycomb sandwich panels under low-velocity impact, the maximum displacement of face-sheets, the deformation mode, the plastic energy consumption and the dynamic response curve of the impact end are presented. At the same time, the performance differences between them are revealed from the perspective of an energy absorption mechanism. Furthermore, the influence of the circumscribed circle diameter ratio of the BIH trunk to branch (γ), the thickness ratio of the trunk to branch (K) and the impact angle (θ) on impact resistance is studied. Finally, the BIH sandwich panel is further optimized by using the response surface method. It can be concluded that, compared to conventional hexagonal honeycomb sandwich panels, the addition of walls in the BIH sandwich panel reduces the maximum deformation of the rear face-sheet by 10.29% and increases plastic energy consumption by 8.02%. Properly adjusting the structural parameters can effectively enhance the impact resistance of the BIH sandwich panel.
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Affiliation(s)
- Tao Tao
- Guangzhou Metro Design & Research Institute Co., Ltd., Guangzhou 510010, China
| | - Lizheng Li
- School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, China
| | - Qiang He
- School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, China
| | - Yonghui Wang
- School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, China
| | - Junlan Guo
- School of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, China
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Wang H, Li T, Chen Z, Zhu W, Lin W, Wang H, Liu X, Li Z. High out-of-plane negative Poisson's ratios and strong light harvesting in two-dimensional SiS 2 and its derivatives. NANOSCALE 2023; 15:16155-16162. [PMID: 37771318 DOI: 10.1039/d3nr04483a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Two-dimensional (2D) materials with negative Poisson's ratios (NPRs) hold tremendous potential in diverse electronic devices. However, most 2D auxetic materials exhibit small out-of-plane NPRs and materials with bi-directional NPRs are rare. In this work, the SiS2 monolayer and its derivatives MX2 (M = Si, Ge, Sn and X = S, Se, Te) are systematically studied via first-principles simulation. We demonstrate that a SiS2 monolayer possesses a remarkable out-of-plane NPR with a value of -1.09 and an in-plane NPR (-0.13). Furthermore, a higher out-of-plane NPR (-1.79) can be achieved in a SnS2 monolayer by element substitution. Remarkably, SiS2 and its derivative MX2 monolayers exhibit excellent light harvesting over the ultraviolet and visible range, and the corresponding electronic properties show robustness against strains. Our results confirm that MX2 monolayers provide an ideal platform to explore auxeticity in two-dimensional limits.
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Affiliation(s)
- Haidi Wang
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
| | - Tao Li
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
| | - Zhao Chen
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
| | - Weiduo Zhu
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
| | - Wei Lin
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
| | - Huimiao Wang
- School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei, Anhui 230601, China
| | - Xiaofeng Liu
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
| | - Zhongjun Li
- School of Physics, Hefei University of Technology, Hefei, Anhui 230601, China.
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Han Z, Xiao X, Chen J, Wei K, Wang Z, Yang X, Fang D. Bifunctional Metamaterials Incorporating Unusual Geminations of Poisson's Ratio and Coefficient of Thermal Expansion. ACS APPLIED MATERIALS & INTERFACES 2022; 14:50068-50078. [PMID: 36283006 DOI: 10.1021/acsami.2c11702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Natural materials overwhelmingly shrink laterally under stretching and expand upon heating. Through incorporating Poisson's ratio and coefficient of thermal expansion (PR and CTE) in unusual geminations, such as positive PR and negative CTE, negative PR and positive CTE, and even zero PR and zero CTE, bifunctional metamaterials would generate attractive shape control capacity. However, reported bifunctional metamaterials are only theoretically constructed by simple skeletal ribs, and the magnitudes of the bifunctions are still in quite narrow ranges. Here, we propose a methodology for generating novel bifunctional metamaterials consisting of engineering polymers. From concept to refinement, the topology and shape optimization are integrated for programmatically designing bifunctional metamaterials in various germinations of the PR and CTE. The underlying deformation mechanisms of the obtained bifunctions are distinctly revealed. All of the designs with complex architectures and material layouts are fabricated using the multimaterial additive manufacturing, and their effective properties are experimentally characterized. Good agreements of the design, simulation, and experiments are achieved. Especially, the accessible range of the bifunction, namely, PR and CTE, is remarkably enlarged nearly 4 times. These developed approaches open an avenue to explore the bifunctional metamaterials, which are the basis of myriad mechanical- and temperature-sensitive devices, e.g., morphing structures and high-precision components of the sensors/actuators in aerospace and electronical domains.
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Affiliation(s)
- Zhengtong Han
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan410082, People's Republic of China
| | - Xiaoyujie Xiao
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan410082, People's Republic of China
| | - Jiaxin Chen
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan410082, People's Republic of China
| | - Kai Wei
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan410082, People's Republic of China
- State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha, Hunan410083, People's Republic of China
| | - Zhonggang Wang
- State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha, Hunan410083, People's Republic of China
| | - Xujing Yang
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan410082, People's Republic of China
| | - Daining Fang
- Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing100081, People's Republic of China
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Li R, Chen H, Choi JH. Auxetic Two-Dimensional Nanostructures from DNA*. Angew Chem Int Ed Engl 2021; 60:7165-7173. [PMID: 33403767 DOI: 10.1002/anie.202014729] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/10/2020] [Indexed: 11/09/2022]
Abstract
Architectured materials exhibit negative Poisson's ratios and enhanced mechanical properties compared with regular materials. Their auxetic behaviors emerge from periodic cellular structures regardless of the materials used. The majority of such metamaterials are constructed by top-down approaches and macroscopic with unit cells of microns or larger. There are also molecular auxetics including natural crystals which are not designable. There is a gap from few nanometers to microns, which may be filled by biomolecular self-assembly. Herein, we demonstrate two-dimensional auxetic nanostructures using DNA origami. Structural reconfigurations are performed by two-step DNA reactions and complemented by mechanical deformation studies using molecular dynamics simulations. We find that the auxetic behaviors are mostly defined by geometrical designs, yet the properties of the materials also play an important role. From elasticity theory, we introduce design principles for auxetic DNA metamaterials.
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Affiliation(s)
- Ruixin Li
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Haorong Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Jong Hyun Choi
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
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8
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Li R, Chen H, Choi JH. Auxetic Two‐Dimensional Nanostructures from DNA**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ruixin Li
- School of Mechanical Engineering Purdue University West Lafayette IN 47907 USA
| | - Haorong Chen
- School of Mechanical Engineering Purdue University West Lafayette IN 47907 USA
| | - Jong Hyun Choi
- School of Mechanical Engineering Purdue University West Lafayette IN 47907 USA
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9
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Abstract
Auxetic foams have previously been shown to have benefits including higher indentation resistance than their conventional counterparts, due to their negative Poisson’s ratio, making them better at resisting penetration by concentrated loads. The Poisson’s ratio and Young’s modulus of auxetic open cell foams have rarely been measured at the high compressive strain rates typical during impacts of energy absorbing material in sporting protective equipment. Auxetic closed cell foams are less common than their open cell counterparts, and only their quasi-static characteristics have been previously reported. It is, therefore, unclear how the Poisson’s ratio of auxetic foam, and associated benefits such as increased indentation resistance shown at low strain rates, would transfer to the high strain rates expected under impact. The aim of this study was to measure the effect of strain rate on the stiffness and Poisson’s ratio of auxetic and conventional foam. Auxetic open cell and closed cell polymer foams were fabricated, then compression tested to ~80% strain at applied rates up to 200 s−1, with Poisson’s ratios obtained from optical full-field strain mapping. Open cell foam quasi-static Poisson’s ratios ranged from −2.0 to 0.4, with a narrower range of −0.1 to 0.3 for closed cell foam. Poisson’s ratios of auxetic foams approximately halved in magnitude between the minimum and maximum strain rates. Open cell foam quasi-static Young’s moduli were between 0.02 and 0.09 MPa, whereas closed cell foams Young’s moduli were ~1 MPa, which is like foam in protective equipment. The Young’s moduli of the auxetic foams approximately doubled at the highest applied strain rate of 200 s−1.
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Mills ST, Young TS, Chatham LS, Poddar S, Carpenter RD, Yakacki CM. Effect of foam densification and impact velocity on the performance of a football helmet using computational modeling. Comput Methods Biomech Biomed Engin 2020; 24:21-32. [PMID: 32840119 DOI: 10.1080/10255842.2020.1807015] [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: 10/23/2022]
Abstract
The NFL recently released validated helmet-impact models to study the performance of currently used helmets. This study used the model of a Riddell Speed Classic helmet to determine the influence of the properties of protective foam padding on acceleration and deformation at two common impact locations to cause concussions. The performance of the helmet was measured before and after manipulating the material properties of the protective foam liner material using FEA software. The densification strain was adjusted by using the scale factor tool in LS-DYNA to create four material categories - soft, standard, stiff, and rigid. The helmet was tested under side and rear impacts using the four material properties at 2.0, 5.5, 7.4, 9.3 and 12.3 m/s impact speeds using the NOCSAE linear impactor model. This study suggests that the standard foam material compresses to a range that could be considered to have "bottomed out" at impact speeds at 5.5 m/s for side impacts. Despite testing a wide range of material properties, the measured accelerations did not vary dramatically across material properties. Rather, impact speed played the dominant role on measured acceleration. This is the first study to demonstrate how open-source impact models can be used to run a design of experiments and investigate the role between different materials used inside a helmet and football helmet performance.
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Affiliation(s)
- Samuel T Mills
- Department of Mechanical Engineering, University of Colorado Denver, Denver, CO, USA
| | - Trevor S Young
- Department of Mechanical Engineering, University of Colorado Denver, Denver, CO, USA
| | | | - Sourav Poddar
- School of Medicine, University of Colorado Denver, Denver, CO, USA
| | - R Dana Carpenter
- Department of Mechanical Engineering, University of Colorado Denver, Denver, CO, USA
| | - Christopher M Yakacki
- Department of Mechanical Engineering, University of Colorado Denver, Denver, CO, USA.,Research and Development, Impressio Inc., Denver, CO, USA
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Computational Fatigue Analysis of Auxetic Cellular Structures Made of SLM AlSi10Mg Alloy. METALS 2020. [DOI: 10.3390/met10070945] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In this study, a computational fatigue analysis of topology optimised auxetic cellular structures made of Selective Laser Melting (SLM) AlSi10Mg alloy is presented. Structures were selected from the Pareto front obtained by the multi-objective optimisation. Five structures with different negative Poisson’s ratios were considered for the parametric numerical analysis, where the fillet radius of cellular struts has been chosen as a parameter. The fatigue life of the analysed structures was determined by the strain–life approach using the Universal Slope method, where the needed material parameters were determined according to the experimental results obtained by quasi-static unidirectional tensile tests. The obtained computational results have shown that generally less auxetic structures tend to have a better fatigue life expectancy. Furthermore, the fillet radius has a significant impact on fatigue life. In general, the fatigue life decreases for smaller fillet radiuses (less than 0.3 mm) as a consequence of the high-stress concentrations, and also for larger fillet radiuses (more than 0.6 mm) due to the moving of the plastic zone away from the edge of the cell connections. The obtained computational results serve as a basis for further investigation, which should be focused on the experimental testing of the fabricated auxetic cellular structures made of SLM AlSi10Mg alloy under cyclic loading conditions.
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12
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Describing headform pose and impact location for blunt impact testing. J Biomech 2020; 109:109923. [PMID: 32807308 DOI: 10.1016/j.jbiomech.2020.109923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 06/26/2020] [Accepted: 06/26/2020] [Indexed: 11/22/2022]
Abstract
Reproduction of anthropomorphic test device (ATD) head impact test methods is a critical element needed to develop guidance and technologies that reduce the risk for brain injury in sport. However, there does not appear to be a consensus for reporting ATD pose and impact location for industry and researchers to follow. Thus, the purpose of this article is to explore the various methods used to report impact location and ATD head pose for sport-related head impact testing and provide recommendations for standardizing these descriptions. A database search and exclusion process identified 137 articles that met the review criteria. Only 4 of the 137 articles provided a description similar to the method we propose to describe ATD pose and impact location. We thus propose a method to unambiguously convey the impact location and pose of the ATD based on the sequence, quantifiable design, and articulation of ATD mount joints. This reporting method has been used to a limited extent in the literature, but we assert that adoption of this method will help to standardize the reporting of ATD headform pose and impact location as well as aid in the replication of impact test protocols across laboratories.
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Signetti S, Nicotra M, Colonna M, Pugno NM. Modeling and simulation of the impact behavior of soft polymeric-foam-based back protectors for winter sports. J Sci Med Sport 2018; 22 Suppl 1:S65-S70. [PMID: 30477930 DOI: 10.1016/j.jsams.2018.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 07/13/2018] [Accepted: 10/23/2018] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Winter sports are high-energy outdoor activities involving high velocities and acrobatic maneuvers, thus raising safety concerns. Specific studies on the impact mechanics of back protectors are very limited. In this study analytical and numerical models are developed to rationalize results of impact experiments and propose new design procedures for this kind of equipment. DESIGN Different soft-shell solutions currently available on the market are compared. In particular, the role of dynamic material constitutive properties and of environmental temperature (which affects mainly material stiffness) on energy absorption capability are evaluated. METHODS Starting from dynamic mechanical-thermal characterization of the closed-cell polymeric foams constituting the protectors, we exploited analytical modeling and Finite Element Method simulations to interpret experimental data from drop weight impact test and to characterize protectors at different temperatures and after multiple impacts. RESULTS The temperature and frequency dependent properties of these materials characterize their impact behavior. Modeling results are in good agreement with impact tests. Results demonstrate how ergonomic soft-shell solution provides an advantage with respect to traditional hard-shell in terms of impact protection. Moreover, it can maintain nearly unaltered its protective properties after multiple impacts on the same point. CONCLUSIONS The coupled analytical-simulation approach here presented could be extensively used to predict the impact behavior of such equipment, starting from material characterization, allowing to save costs and time for physical prototyping and tests for design and optimization.
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Affiliation(s)
- Stefano Signetti
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Italy
| | - Marco Nicotra
- Department of Civil, Chemistry, Environmental and Materials Engineering, University of Bologna, Italy
| | - Martino Colonna
- Department of Civil, Chemistry, Environmental and Materials Engineering, University of Bologna, Italy.
| | - Nicola M Pugno
- Laboratory of Bio-Inspired and Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Italy; School of Engineering and Materials Science, Queen Mary University of London, UK; Ket-Lab, Edoardo Amaldi Foundation, Italian Space Agency, Italy.
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14
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Review of Auxetic Materials for Sports Applications: Expanding Options in Comfort and Protection. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8060941] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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