A Stress/Strain-Driven Homogenization Approach for the Uniaxial Analysis of Fibrous Soft Tissues

2019 ◽  
Author(s):  
Mauricio Lazzari ◽  
Thiago André Carniel ◽  
Eduardo Fancello
Keyword(s):  
Soft Tissues ◽  
Stress Strain ◽  
Homogenization Approach

Hyperelastic Muscle Simulation

2007 ◽  
Vol 345-346 ◽  
pp. 1241-1244 ◽  
Author(s):  
Mohd. Zahid Ansari ◽  
Sang Kyo Lee ◽  
Chong Du Cho
Keyword(s):  
Skeletal Muscle ◽  
Silicone Rubber ◽  
Soft Tissues ◽  
Material Model ◽  
Incompressible Material ◽  
Material Behavior ◽  
Rubber Tube ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and nearly incompressible. The incompressible material behavior may lead to some difficulties in numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations can be used to overcome incompressible material problems. The hyperelastic materials can be used to describe the biological skeletal muscle behavior. In this study, experiments are conducted to obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can be used to successfully simulate the muscle material behavior. Such an analysis can be used to simulate and analyze other soft tissues that show similar behavior.

TEMPERATURE-DEPENDENT THERMOMECHANICAL MODELING OF SOFT TISSUE DEFORMATION

2018 ◽  
Vol 18 (08) ◽  
pp. 1840021 ◽  
Author(s):  
JINAO ZHANG ◽  
JEREMY HILLS ◽  
YONGMIN ZHONG ◽  
BIJAN SHIRINZADEH ◽  
JULIAN SMITH ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Soft Tissue ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Soft Tissues ◽  
Thermal Parameters ◽  
Temperature Dependent ◽  
Stress Strain ◽  
Thermomechanical Modeling

Modeling of thermomechanical behavior of soft tissues is vitally important for the development of surgical simulation of hyperthermia procedures. Currently, most literature considers only temperature-independent thermal parameters, such as the temperature-independent tissue specific heat capacity, thermal conductivity and stress–strain relationships for soft tissue thermomechanical modeling; however, these thermal parameters vary with temperatures as shown in the literature. This paper investigates the effect of temperature-dependent thermal parameters for soft tissue thermomechanical modeling. It establishes formulations for specific heat capacity, thermal conductivity and stress–strain relationships of soft tissues, all of which are temperature-dependent parameters. Simulations and comparison analyses are conducted, showing a different thermal-induced stress distribution of lower magnitudes when considering temperature-dependent thermal parameters of soft tissues.

A Nonlinear Anisotropic Viscoelastic Model for the Tensile Behavior of the Corneal Stroma

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
T. D. Nguyen ◽  
R. E. Jones ◽  
B. L. Boyce
Keyword(s):  
Soft Tissues ◽  
Viscoelastic Model ◽  
Corneal Stroma ◽  
Viscoelastic Behavior ◽  
Cyclic Stress ◽  
Uniaxial Tensile ◽  
Nonlinear Creep ◽  
Stress Strain ◽  
Highly Nonlinear ◽  
Tensile Strip

Tensile strip experiments of bovine corneas have shown that the tissue exhibits a nonlinear rate-dependent stress-strain response and a highly nonlinear creep response that depends on the applied hold stress. In this paper, we present a constitutive model for the finite deformation, anisotropic, nonlinear viscoelastic behavior of the corneal stroma. The model formulates the elastic and viscous response of the stroma as the average of the elastic and viscous response of the individual lamellae weighted by a probability density function of the preferred in-plane lamellar orientations. The result is a microstructure-based model that incorporates the viscoelastic properties of the matrix and lamellae and the lamellar architecture in the response of the stroma. In addition, the model includes a fully nonlinear description of the viscoelastic response of the lamellar(fiber) level. This is in contrast to previous microstructure-based models of fibrous soft tissues, which relied on quasilinear viscoelastic formulations of the fiber viscoelasticity. Simulations of recent tensile strip experiments show that the model is able to predict, well within the bounds of experimental error and natural variations, the cyclic stress-strain behavior and nonlinear creep behavior observed in uniaxial tensile experiments of excised strips of bovine cornea.

Measurement of Mechanical Characteristics of Tibial Periosteum and Evaluation of Local Differences

1998 ◽  
Vol 120 (1) ◽  
pp. 85-91 ◽  
Author(s):  
E. Uchiyama ◽  
K. Yamakoshi ◽  
T. Sasaki
Keyword(s):  
Transverse Direction ◽  
Mechanical Characteristics ◽  
Soft Tissues ◽  
Experimental System ◽  
Longitudinal Direction ◽  
The Other ◽  
Connective Tissues ◽  
Stress Strain ◽  
Linear Region ◽  
Strain Pattern

Stress–strain relationships of bovine tibial periosteum, harvested from anterior, medial, lateral, and posterior aspects of tibia, were successfully measured using a newly developed experimental system. Results showed a curvilinear stress–strain pattern having three regions, i.e., toe, almost linear, and rupture regions, which resembled those of biological soft tissues like ligaments, skin, etc. Tensile moduli in the toe region (Ee) and in the linear region (Ec) were obtained by linear regressional analyses. These values and the tensile strength (σt) showed clear local differences. The values of Ee, Ec, and σt, in the longitudinal direction in the metaphyseal regions where ligaments or connective tissues attach were approximately two times larger than those in the diaphysis, where muscles or connective tissues attach. However, these properties in the metaphyseal and diaphyseal regions with muscle attachments were almost the same. In the transverse direction, these properties in the anterior proximal metaphysis were approximately two times larger than those in the diaphysis and in the distal metaphysis. In the other regions, these properties appeared not to be significantly different. These results clearly demonstrate that the mechanical properties of periosteum are strongly influenced by the ligament and muscle attachments.

Interpretation of Experimental Data is Substantial for Constitutive Characterization of Arterial Tissue

2021 ◽  
Author(s):  
Ondrej Lisický ◽  
Anna Hrubanová ◽  
Jiri Bursa
Keyword(s):  
Experimental Data ◽  
Soft Tissues ◽  
Constitutive Models ◽  
Uniaxial Stress ◽  
Mechanical Tests ◽  
Data Sets ◽  
Stress Strain ◽  
Rigorous Approach ◽  
Carotid Wall

Abstract The paper aims at evaluation of mechanical tests of soft tissues and creation of their representative stress-strain responses and respective constitutive models. Interpretation of sets of experimental results depends highly on the approach to the data analysis. Their common representation through mean and standard deviation may be misleading and give non-realistic results. In the paper, raw data of 7 studies consisting of 11 experimental data sets (concerning carotid wall and atheroma tissues) are re-analysed to show the importance of their rigorous analysis. The sets of individual uniaxial stress-strain curves are evaluated using three different protocols: stress-based, stretch-based and constant-based, and the population-representative response is created by their mean or median values. Except for nearly linear responses, there are substantial differences between the resulting curves, being mostly the highest for constant-based evaluation. But also the stretch-based evaluation may change the character of the response significantly. Finally, medians of the stress-based responses are recommended as the most rigorous approach for arterial and other soft tissues with significant strain stiffening.

scholarly journals Digital image correlation-based point-wise inverse characterization of heterogeneous material properties of gallbladder in vitro

2014 ◽  
Vol 470 (2167) ◽  
pp. 20140152 ◽  
Author(s):  
Katia Genovese ◽  
Luciana Casaletto ◽  
Jay D. Humphrey ◽  
Jia Lu
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Material Properties ◽  
Soft Tissues ◽  
Applied Pressure ◽  
Heterogeneous Material ◽  
Image Correlation ◽  
Surface Geometry ◽  
Stress Strain ◽  
Full Field

Continuing advances in mechanobiology reveal more and more that many cell types, especially those responsible for establishing, maintaining, remodelling or repairing extracellular matrix, are extremely sensitive to their local mechanical environment. Indeed, it appears that they fashion the extracellular matrix so as to promote a ‘mechanical homeostasis’. A natural corollary, therefore, is that cells will try to offset complexities in geometry and applied loads with heterogeneous material properties in order to render their local environment mechanobiologically favourable. There is a pressing need, therefore, for hybrid experimental–computational methods in biomechanics that can quantify such heterogeneities. In this paper, we present an approach that combines experimental information on full-field surface geometry and deformations with a membrane-based point-wise inverse method to infer full-field mechanical properties for soft tissues that exhibit nonlinear behaviours under finite deformations. To illustrate the potential utility of this new approach, we present the first quantification of regional mechanical properties of an excised but intact gallbladder, a thin-walled, sac-like organ that plays a fundamental role in normal digestion. The gallbladder was inflated to a maximum local stretch of 120% in eight pressure increments; at each pressure pause, the entire three-dimensional surface was optically extracted, and from which the surface strains were computed. Wall stresses in each state were predicted from the deformed geometry and the applied pressure using an inverse elastostatic method. The elastic properties of the gallbladder tissue were then characterized locally using point-wise stress–strain data. The gallbladder was found to be highly heterogeneous, with drastically different stiffness between the hepatic and the serosal sides. The identified material model was validated through forward finite-element analysis; both the configurations and the local stress–strain patterns were well reproduced.

Viscoelastic Homogenization Approach for Damping Properties of Polymer Composites Using Fractional Calculus

2011 ◽  
Author(s):  
Yotsugi Shibuya
Keyword(s):  
Fractional Calculus ◽  
Polymer Composites ◽  
Polymer Matrix ◽  
Maxwell Model ◽  
Inverse Laplace Transform ◽  
Material System ◽  
Damping Properties ◽  
Stress Strain ◽  
Homogenization Approach ◽  
Fractional Maxwell Model

Polymer composites are attractive material system with damping ability to reduce vibration of mechanical structures and improve controllability of mechanical system. To understand effect of constituents and microstructure on damping properties of polymer composites, a detailed micromechanical study is needed to develop the method of analysis for microscopic viscoelastic deformation and macroscopic damping properties. Viscoelastic homogenization approach with fractional calculus is developed to evaluate effective damping properties of polymer composites. The microstructure of the composite is supposed to be periodic and polymer matrix is viscoelastic medium. Damping properties of the composite are evaluated from the stress strain diagram and associated energy dissipation during cyclic loading. Viscoelastic properties of the polymer matrix are identified using a generalized fractional Maxwell model with spring and fractional elements. Coefficients of elements in the generalized fractional Maxwell model are determined to be fitting into experimental data in frequency domain. The homogenized stress strain relation in time domain given by inverse Laplace transform is derived and numerical calculations are carried out.

EFFECTS OF CULTURE PERIODS AND LOADING ON BIOMECHANICAL PROPERTIES OF SHEEP COLLAGEN FASCICLES

2014 ◽  
Vol 14 (06) ◽  
pp. 1440010
Author(s):  
AHMET C. CILINGIR
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Soft Tissues ◽  
Culture Media ◽  
Experimental Studies ◽  
Biomechanical Properties ◽  
Collagen Fibrils ◽  
Tangent Modulus ◽  
Control Group ◽  
Stress Strain

Soft tissues (e.g., tendon, skin, cartilage) change their dimensions and properties in response to applied mechanical stress/strain, which is called remodeling. Experimental studies using tissue cultures were performed to understand the biomechanical properties of collagen fascicles under mechanical loads. Collagen fascicles were dissected from sheep Achilles tendons and loaded under 1, 2, and 3 kg for 2, 4, and 6 days under culture. The mechanical properties of collagen fascicles after being loaded into the culture media were determined using tensile tester, and resultant stress–strain curves, tangent modulus, tensile strength, and strain at failure values were compared with those in a non-loaded and non-cultured control group of fascicles. The tangent modulus and tensile strength of the collagen fascicles increased with the increasing remodeling load after two days of culture. However, these values gradually decreased with the increasing culture period compared with the control group. According to the results obtained in this study, the mechanical properties of collagen fascicles were improved by loading at two days of culture, most likely due to the remodeling of collagen fibers. However, after a period of remodeling, local strains on the collagen fibrils increased, and finally, the collagen fibrils broke down, decreasing the mechanical properties of the tissue.

Real-time cutting simulation in virtual reality systems based on the measurement of porcine organs

SIMULATION ◽  
2017 ◽  
Vol 93 (12) ◽  
pp. 1073-1085 ◽  
Author(s):  
YiDong Bao ◽  
DongMei Wu
Keyword(s):  
Stress Relaxation ◽  
Soft Tissues ◽  
Organ Specificity ◽  
Relaxation Data ◽  
Stress Strain ◽  
Pig Liver ◽  
Cutting Simulation ◽  
Virtual Operation ◽  
Liver And Kidney ◽  
Cutting Model

A virtual soft tissues cutting model consistent with the organ specificity of real soft tissues was established in this paper, which was applied to the virtual operation training system. A measurement platform of soft tissue organ was designed and built, and the stress–strain and stress–relaxation data of pig liver and kidney were experimentally measured. Then, using the viscoelasticity mathematical formula, an improved virtual cutting model of the meshless classified balls-filling was constructed through VC++ and OpenGL. The cutting performance of the virtual soft tissues was further increased by leveraging the improved cutting classification algorithm. Finally, the extrusion and cutting simulation was enabled through the force feedback device, and the accuracy and effectiveness of this cutting model were validated by a comparative study of the virtual soft tissues cutting model and the stress–strain and stress–relaxation data of pig liver and kidney.

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