A NONLINEAR HYPERELASTIC BEHAVIOR TO IDENTIFY THE MECHANICAL PROPERTIES OF RAT SKIN UNDER UNIAXIAL LOADING

Skin is a thin membrane which provides many biological functions, such as thermoregulation and protection from mechanical, bacterial, and viral insults. The mechanical properties of skin tissue are extremely hard to measure and may vary according to the anatomical locations of a body. However, the mechanical properties of skin at different anatomical regions have not been satisfactorily simulated by conventional engineering models. In this study, the linear elastic and nonlinear hyperelastic mechanical properties of rat skin at different anatomical locations, including back and abdomen, are investigated using a series of tensile tests. The Young's modulus and maximum stress of skin tissue are measured before the incidence of failure. The nonlinear mechanical behavior of skin tissue is also experimentally and computationally investigated through constitutive equations. Hyperelastic strain energy density functions are adjusted using the experimental results. A hyperelastic constitutive model is selected to suitably represent the axial behavior of the skin. The results reveal that the maximum stress (20%) and Young's modulus (35%) of back skin are significantly higher than that of abdomen skin. The Ogden model is selected to closely address the nonlinear mechanical behavior of the skin which can be used in further biomechanical simulations of the skin tissue. The results might have implications not only for understanding of the mechanical behavior of skin tissue at different anatomical locations, but also to give an engineering insight for a diversity of disciplines, such as dermatology, cosmetics industry, clinical decision making, and clinical intervention.

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Measurement of the axial and circumferential mechanical properties of rat skin tissue at different anatomical locations

Biomedical Engineering / Biomedizinische Technik ◽

10.1515/bmt-2014-0084 ◽

2015 ◽

Vol 60 (2) ◽

Cited By ~ 2

Author(s):

Alireza Karimi ◽

Maedeh Haghighatnama ◽

Mahdi Navidbakhsh ◽

Afsaneh Motevalli Haghi

Keyword(s):

Mechanical Properties ◽

Elastic Modulus ◽

Mechanical Behavior ◽

Clinical Decision Making ◽

Mechanical Response ◽

The Body ◽

Skin Tissue ◽

Linear Elastic ◽

Biomechanical Models ◽

Nonlinear Mechanical

AbstractSkin tissue is not only responsible for thermoregulation but also for protecting the human body from mechanical, bacterial, and viral insults. The mechanical properties of skin tissue may vary according to the anatomical locations in the body. However, the linear elastic and nonlinear hyperelastic mechanical properties of the skin in different anatomical regions and at different loading directions (axial and circumferential) so far have not been determined. In this study, the mechanical properties during tension of the rat abdomen and back were calculated at different loading directions using linear elastic and nonlinear hyperelastic material models. The skin samples were subjected to a series of tensile tests. The elastic modulus and maximum stress of the skin tissues were measured before the incidence of failure. The nonlinear mechanical behavior of the skin tissues was also computationally investigated through a constitutive equation. Hyperelastic strain energy density function was calibrated using the experimental data. The results revealed the anisotropic mechanical behavior of the abdomen and the isotropic mechanical response of the back skin. The highest elastic modulus was observed in the abdomen skin under the axial direction (10 MPa), while the lowest one was seen in the back skin under axial loading (5 MPa). The Mooney-Rivlin material model closely addressed the nonlinear mechanical behavior of the skin at different loading directions, which can be implemented in the future biomechanical models of skin tissue. The results might have implications not only for understanding of the isotropic and anisotropic mechanical behavior of skin tissue at different anatomical locations but also for providing more information for a diversity of disciplines, including dermatology, cosmetics industry, clinical decision making, and clinical intervention.

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Material properties in unconfined compression of gelatin hydrogel for skin tissue engineering applications

Biomedical Engineering / Biomedizinische Technik ◽

10.1515/bmt-2014-0028 ◽

2014 ◽

Vol 59 (6) ◽

Cited By ~ 18

Author(s):

Alireza Karimi ◽

Mahdi Navidbakhsh

Keyword(s):

Mechanical Properties ◽

Tissue Engineering ◽

Young’S Modulus ◽

Maximum Stress ◽

Young's Modulus ◽

Material Model ◽

Skin Tissue ◽

Unconfined Compression ◽

Engineering Applications ◽

Skin Tissue Engineering

AbstractGelatin (Gel) has been reported as a promising candidate in tissue engineering owing to its easy availability, biocompatibility, and biodegradability. Gel hydrogel is of potential to be cross-linked with different materials to enhance their biocompatibility for cell culture for tissue engineering applications. The mechanical properties of this versatile material, however, have not been thoroughly determined. In this study, the linear elastic (Young’s modulus and maximum stress) and non-linear hyperelastic (hyperelastic coefficients) mechanical properties of prepared hydrogels at different contents of Gel (wt%) were measured, and its Young’s modulus was compared with that of skin tissue. The prepared cylindrical Gel hydrogels were subjected to a series of unconfined compression tests. The hyperelastic strain energy density function was calibrated using the compressive experimental data. The potential ability of the Yeoh hyperelastic constitutive equation, which has been proposed as the best material model to represent the non-linear behavior of hydrogels, was verified using finite element (FE) simulations. The results revealed that the Young’s modulus and maximum stress of hydrogels are increased by the addition of Gel. The highest Young’s modulus (81 kPa) and maximum stress (24 kPa) were observed for hydrogels with 15 wt% Gel. Results also showed that the hydrogels with a relatively lower content (<7.5 wt%) of Gel have suitable Young’s modulus compared with those with a higher content (>7.5 wt%) for skin tissue engineering. The Yeoh material model was closely fitted with the experimental data and could be used in further biomechanical simulations of the hydrogels. The experimental results were also compared well with those predicted by the FE models. The results of this study might have implications not only for the understanding of the mechanical properties of Gel hydrogel but also for the fabrication of polymeric substrate materials suitable for skin tissue engineering applications.

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The improvement of mechanical properties of conventional concretes using carbon nanoparticles using molecular dynamics simulation

Scientific Reports ◽

10.1038/s41598-021-99616-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Liang Zhao ◽

Mahyuddin K. M. Nasution ◽

Maboud Hekmatifar ◽

Roozbeh Sabetvand ◽

Pavel Kamenskov ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Nanotubes ◽

Molecular Dynamics ◽

Mechanical Behavior ◽

Young’S Modulus ◽

Carbon Nanoparticles ◽

Young's Modulus ◽

Dynamics Simulation ◽

Matrix Structure ◽

Concrete Matrix

AbstractIn the present study, the improvement of mechanical properties of conventional concretes using carbon nanoparticles is investigated. More precisely, carbon nanotubes are added to a pristine concrete matrix, and the mechanical properties of the resulting structure are investigated using the molecular dynamics (MD) method. Some parameters such as the mechanical behavior of the concrete matrix structure, the validation of the computational method, and the mechanical behavior of the concrete matrix structure with carbon nanotube are also examined. Also, physical quantities such as a stress–strain diagram, Poisson's coefficient, Young's modulus, and final strength are calculated and reported for atomic samples under external tension. From a numerical point of view, the quantities of Young's modulus and final strength are converged to 35 GPa and 35.38 MPa after the completion of computer simulations. This indicates the appropriate effect of carbon nanotubes in improving the mechanical behavior of concrete and the efficiency of molecular dynamics method in expressing the mechanical behavior of atomic structures such as concrete, carbon nanotubes and composite structures derived from raw materials is expressed that can be considered in industrial and construction cases.

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Fluid-Structure Interaction Simulation of an Aortic Phantom with Uncertain Young's Modulus Using the Polynomial Chaos Expansion

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.807.34 ◽

2015 ◽

Vol 807 ◽

pp. 34-44

Author(s):

Jonas Kratzke ◽

Michael Schick ◽

Vincent Heuveline

Keyword(s):

Numerical Simulations ◽

Uncertainty Quantification ◽

Young’S Modulus ◽

Clinical Decision Making ◽

Polynomial Chaos ◽

Young's Modulus ◽

Clinical Decision ◽

Von Mises Stress ◽

Strong Impact ◽

Fluid Structure

To add reliability to numerical simulations, Uncertainty Quantification is considered to be a crucial tool for clinical decision making. This especially holds for risk assessment of cardiovascular surgery, for which threshold parameters computed by numerical simulations are currently being discussed. A corresponding biomechanical model includes blood flow, soft tissue deformation, as well as fluid-structure coupling. Thereby, structural material parameters have a strong impact on the dynamic behavior. In practice, however, particularly the value of the Young's modulus is rarely known in a precise way, and therefore, it reflects a natural level of uncertainty. In this work we introduce a stochastic model for representing variations in the Young's modulus and quantify its effect on the wall sheer stress and von Mises stress by means of the Polynomial Chaos method. We demonstrate the use of uncertainty quantification in this context and provide numerical results based on an aortic phantom benchmark model.

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Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

Matériaux & Techniques ◽

10.1051/mattech/2018063 ◽

2019 ◽

Vol 107 (2) ◽

pp. 207 ◽

Cited By ~ 2

Author(s):

Jaroslav Čech ◽

Petr Haušild ◽

Miroslav Karlík ◽

Veronika Kadlecová ◽

Jiří Čapek ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Alloying ◽

Young’S Modulus ◽

Milling Time ◽

Young's Modulus ◽

Element Model ◽

X Ray Diffraction ◽

X Ray ◽

Powder Particles ◽

Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

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Mechanical behavior of glass fiber‐reinforced Nylon‐6 syntactic foams and its Young's modulus numerical study

Journal of Applied Polymer Science ◽

10.1002/app.50648 ◽

2021 ◽

Vol 138 (27) ◽

pp. 50648 ◽

Cited By ~ 1

Author(s):

Roberto Yáñez‐Macías ◽

Jorge E. Rivera‐Salinas ◽

Silvia Solís‐Rosales ◽

Daniel Orduña‐Altamirano ◽

David Ruíz‐Mendoza ◽

...

Keyword(s):

Mechanical Behavior ◽

Glass Fiber ◽

Young’S Modulus ◽

Young's Modulus ◽

Numerical Study ◽

Nylon 6 ◽

Syntactic Foams ◽

Fiber Reinforced ◽

Glass Fiber Reinforced

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First principles computation of composition dependent elastic constants of omega in titanium alloys: implications on mechanical behavior

Scientific Reports ◽

10.1038/s41598-021-91594-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

R. Salloom ◽

S. A. Mantri ◽

R. Banerjee ◽

S. G. Srinivasan

Keyword(s):

Mechanical Properties ◽

Young’S Modulus ◽

First Principles ◽

Young's Modulus ◽

Group Vi ◽

Group V ◽

Β Phase ◽

Ti Alloys ◽

Ω Phase ◽

Stabilizer Concentration

AbstractFor decades the poor mechanical properties of Ti alloys were attributed to the intrinsic brittleness of the hexagonal ω-phase that has fewer than 5-independent slip systems. We contradict this conventional wisdom by coupling first-principles and cluster expansion calculations with experiments. We show that the elastic properties of the ω-phase can be systematically varied as a function of its composition to enhance both the ductility and strength of the Ti-alloy. Studies with five prototypical β-stabilizer solutes (Nb, Ta, V, Mo, and W) show that increasing β-stabilizer concentration destabilizes the ω-phase, in agreement with experiments. The Young’s modulus of ω-phase also decreased at larger concentration of β-stabilizers. Within the region of ω-phase stability, addition of Nb, Ta, and V (Group-V elements) decreased Young’s modulus more steeply compared to Mo and W (Group-VI elements) additions. The higher values of Young’s modulus of Ti–W and Ti–Mo binaries is related to the stronger stabilization of ω-phase due to the higher number of valence electrons. Density of states (DOS) calculations also revealed a stronger covalent bonding in the ω-phase compared to a metallic bonding in β-phase, and indicate that alloying is a promising route to enhance the ω-phase’s ductility. Overall, the mechanical properties of ω-phase predicted by our calculations agree well with the available experiments. Importantly, our study reveals that ω precipitates are not intrinsically embrittling and detrimental, and that we can create Ti-alloys with both good ductility and strength by tailoring ω precipitates' composition instead of completely eliminating them.

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Tailoring a Low Young Modulus for a Beta Titanium Alloy by Combining Severe Plastic Deformation with Solution Treatment

Materials ◽

10.3390/ma14133467 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3467

Author(s):

Anna Nocivin ◽

Doina Raducanu ◽

Bogdan Vasile ◽

Corneliu Trisca-Rusu ◽

Elisabeta Mirela Cojocaru ◽

...

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Plastic Deformation ◽

Severe Plastic Deformation ◽

Young’S Modulus ◽

Young's Modulus ◽

Solution Treatment ◽

Young Modulus ◽

Orthopedic Implants ◽

Beta Titanium Alloy

The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of etot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.

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Phase Formation, Microstructure and Mechanical Properties of Mg67Ag33 as Potential Biomaterial

Metals ◽

10.3390/met11030461 ◽

2021 ◽

Vol 11 (3) ◽

pp. 461

Author(s):

Konrad Kosiba ◽

Konda Gokuldoss Prashanth ◽

Sergio Scudino

Keyword(s):

Mechanical Properties ◽

Young’S Modulus ◽

Young's Modulus ◽

Equilibrium Phase ◽

Antibacterial Properties ◽

Equilibrium Phase Diagram ◽

Compressive Yield Strength ◽

X Ray ◽

Fine Grained ◽

Equilibrium Phases

The phase and microstructure formation as well as mechanical properties of the rapidly solidified Mg67Ag33 (at. %) alloy were investigated. Owing to kinetic constraints effective during rapid cooling, the formation of equilibrium phases is suppressed. Instead, the microstructure is mainly composed of oversaturated hexagonal closest packed Mg-based dendrites surrounded by a mixture of phases, as probed by X-ray diffraction, electron microscopy and energy dispersive X-ray spectroscopy. A possible non-equilibrium phase diagram is suggested. Mainly because of the fine-grained dendritic and interdendritic microstructure, the material shows appreciable mechanical properties, such as a compressive yield strength and Young’s modulus of 245 ± 5 MPa and 63 ± 2 GPa, respectively. Due to this low Young’s modulus, the Mg67Ag33 alloy has potential for usage as biomaterial and challenges ahead, such as biomechanical compatibility, biodegradability and antibacterial properties are outlined.

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Effect of Nanopores on Mechanical Properties of the Shape Memory Alloy

Micromachines ◽

10.3390/mi12050529 ◽

2021 ◽

Vol 12 (5) ◽

pp. 529

Author(s):

Chunzhi Du ◽

Zhifan Li ◽

Bingfei Liu

Keyword(s):

Mechanical Properties ◽

Constitutive Model ◽

Shape Memory ◽

Young’S Modulus ◽

Residual Strain ◽

Surface Effect ◽

Young's Modulus ◽

Strain Curve ◽

Stress Strain ◽

Strength Limit

Nanoporous Shape Memory Alloys (SMA) are widely used in aerospace, military industry, medical and health and other fields. More and more attention has been paid to its mechanical properties. In particular, when the size of the pores is reduced to the nanometer level, the effect of the surface effect of the nanoporous material on the mechanical properties of the SMA will increase sharply, and the residual strain of the SMA material will change with the nanoporosity. In this work, the expression of Young’s modulus of nanopore SMA considering surface effects is first derived, which is a function of nanoporosity and nanopore size. Based on the obtained Young’s modulus, a constitutive model of nanoporous SMA considering residual strain is established. Then, the stress–strain curve of dense SMA based on the new constitutive model is drawn by numerical method. The results are in good agreement with the simulation results in the published literature. Finally, the stress-strain curves of SMA with different nanoporosities are drawn, and it is concluded that the Young’s modulus and strength limit decrease with the increase of nanoporosity.

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