Microstructurally Motivated Constitutive Models for Mouse Arteries

2009 ◽  
Author(s):  
Laura Hansen ◽  
William Wan ◽  
Rudolph Gleason
Keyword(s):  
Vascular Remodeling ◽  
Carotid Arteries ◽  
Constitutive Models ◽  
Axial Loading ◽  
Local Environment ◽  
Stress And Strain ◽  
Biaxial Testing ◽  
Material Parameters ◽  
Local Stresses ◽  
Testing Data

Vascular remodeling occurs as cells sense changes in their mechanical environment. Thus, quantifying the cells’ local environment in terms of stress and strain distributions is an important aspect in studies of vascular remodeling. Knowledge of the constitutive behavior of vessel will allow the local stresses and strains to be calculated given applied loads and geometry. The goal of this study is to determine material parameters for several constitutive models by fitting biaxial testing data from mouse carotid arteries cultured under different axial loading conditions [1].

scholarly journals An Investigation of Uniaxial Mechanical Properties of Excised Sheep Heart Muscle Fibre – Fitting of Different Hyperelastic Constitutive Models

2021 ◽  
Author(s):  
Fulufhelo Nemavhola ◽  
Harry M Ngwangwa ◽  
Thanyani Pandelani
Keyword(s):  
Experimental Data ◽  
Soft Tissues ◽  
Constitutive Models ◽  
Finite Element Models ◽  
Predictive Capability ◽  
Material Parameters ◽  
Linear Finite Element ◽  
Fitting Algorithm ◽  
Testing Data

Abstract : This paper presents the investigation of biomechanical behaviour of sheep heart fibre using uniaxial tests in various samples. Non-linear Finite Element models (FEA) that are utilised in understanding mechanisms of different diseases may not be developed without the accurate material properties. This paper presents uniaxial mechanical testing data of the sheep heart fibre. The mechanical uniaxial data of the heart fibre was then used in fitting four constitutive models including the Fung model, Polynomial (Anisotropic), Holzapfel (2005) model, Holzapfel (2000) model and the Four-fibre Family model. Even though the constitutive models for soft tissues including heart myocardium have been presented over several decades, there is still a need for accurate material parameters from reliable hyperelastic constitutive models. Therefore, the aim of this research paper is to select five hyperelastic constitutive models and fit experimental data in the uniaxial experimental data of the sheep heart fibre. A fitting algorithm was made used to optimally fitting and determination of the material parameters based on selected hyperelastic constitutive model. In this study, the evaluation index (EI) was used to measure the performance and capability of each selected anisotropic hyperelatic model. It was observed that the best predictive capability of the mechanical behaviour of sheep heart fibre the Polynomial (anisotropic) model has the EI of 100 and this means that it is the best performance when compared to all the other models.

Uncertainty Quantification in Predicting Behaviour of Rubber-Like Materials in Uni-Axial Loading

2020 ◽  
Author(s):  
Aref Ghaderi ◽  
Vahid Morovati ◽  
Pouyan Nasiri ◽  
Roozbeh Dargazany
Keyword(s):  
Uncertainty Quantification ◽  
Mechanical Response ◽  
Pure Shear ◽  
Constitutive Models ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Deterministic Models ◽  
Data Set ◽  
Material Parameters ◽  
Axial Extension

Abstract Material parameters related to deterministic models can have different values due to variation of experiments outcome. From a mathematical point of view, probabilistic modeling can improve this problem. It means that material parameters of constitutive models can be characterized as random variables with a probability distribution. To this end, we propose a constitutive models of rubber-like materials based on uncertainty quantification (UQ) approach. UQ reduces uncertainties in both computational and real-world applications. Constitutive models in elastomers play a crucial role in both science and industry due to their unique hyper-elastic behavior under different loading conditions (uni-axial extension, biaxial, or pure shear). Here our goal is to model the uncertainty in constitutive models of elastomers, and accordingly, identify sensitive parameters that we highly contribute to model uncertainty and error. Modern UQ models can be implemented to use the physics of the problem compared to black-box machine learning approaches that uses data only. In this research, we propagate uncertainty through the model, characterize sensitivity of material behavior to show the importance of each parameter for uncertainty reduction. To this end, we utilized Bayesian rules to develop a model considering uncertainty in the mechanical response of elastomers. As an important assumption, we believe that our measurements are around the model prediction, but it is contaminated by Gaussian noise. We can make the noise by maximizing the posterior. The uni-axial extension experimental data set is used to calibrate the model and propagate uncertainty in this research.

scholarly journals Identification of orthotropic material parameters for acute, necrotic, fibrotic and remodelling myocardial infarcts in the rat

2019 ◽  
Author(s):  
Mazin S. Sirry ◽  
Laura Dubuis ◽  
Neil H. Davies ◽  
Jun Liao ◽  
Thomas Franz
Keyword(s):  
Constitutive Model ◽  
Orthotropic Material ◽  
Constitutive Models ◽  
Biaxial Stress ◽  
Percentage Error ◽  
Fe Model ◽  
Stress Strain ◽  
Material Parameters ◽  
Strain Data ◽  
Tensile Experiment

AbstractFinite element (FE) models have been effectively utilized in studying biomechanical aspects of myocardial infarction (MI). Although the rat is a widely used animal model for MI, there is a lack of material parameters based on anisotropic constitutive models for rat myocardial infarcts in literature. This study aimed at employing inverse methods to identify the parameters of an orthotropic constitutive model for myocardial infarcts in the acute, necrotic, fibrotic and remodelling phases utilizing the biaxial mechanical data developed in a previous study. FE model was developed mimicking the setup of the biaxial tensile experiment. The orthotropic case of the generalized Fung constitutive model was utilized to model the material properties of the infarct. The parameters of Fung model were optimized so that the FE solution best fitted the biaxial experimental stress-strain data. A genetic algorithm was used to minimize the objective function. Fung orthotropic material parameters for different infarct stages were identified. The FE model predictions best approximated the experimental data of the 28 days infarct stage with 3.0% mean absolute percentage error. The worst approximation was for the 7 days stage with 3.6% error. This study demonstrated that the experimental biaxial stress-strain data of healing rat infarcts could be successfully approximated using inverse FE methods and genetic algorithms. The material parameters identified in this study will provide an essential platform for FE investigations of biomechanical aspects of MI and the development of therapies.

Influence of service ageing on polyester-reinforced polyvinyl chloride-coated fabrics reported through mathematical material models

2018 ◽  
Vol 89 (8) ◽  
pp. 1472-1487
Author(s):  
Krzysztof Zerdzicki ◽  
Pawel Klosowski ◽  
Krzysztof Woznica
Keyword(s):  
Polyvinyl Chloride ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Material Models ◽  
Material Parameters ◽  
Coated Fabric ◽  
Coated Fabrics ◽  
Term Creep

In this paper the coupled service (constructional tension) and environmental (sunlight, rainfalls, temperature variations) ageing influence on the polyester-reinforced polyvinyl chloride (PVC)-coated fabric VALMEX is studied. Two cases of the same fabric have been analyzed: one USED for 20 years on the real construction of the Forest Opera in Sopot (Poland), and one kept as a spare material (NOT USED). The following tests have been conducted: uniaxial tensile, biaxial tensile and long-term creep tests. The obtained results have been used for the parameter identification of the piecewise non-linear, Burgers and Bodner–Partom models. Next, the analysis of the influence of environmental conditions on the parameters of these models has been made. It has been concluded that some parameters are more and the others are less sensitive to the exposure to environmental and mechanical conditions. The change of material parameters for fill threads (due to larger deformation) is higher. The obtained results may be useful in the durability evaluation of the textile membranes reinforced with polyester threads and PVC coated. All the constitutive models with the identified parameters may be used for the numerical analysis of structures made of fabrics at the service beginning and after long-term usage.

Study of the Creep Deformation of Sanicro 25 Austenitic Steel by Computer Simulations

2019 ◽  
Vol 961 ◽  
pp. 156-162
Author(s):  
Tri Widodo Besar Riyadi ◽  
Fakhri Hasamulhaq Ahmad ◽  
Ibham Veza ◽  
Agung Setyo Darmawan ◽  
Agus Dwi Anggono ◽  
...  
Keyword(s):  
Experimental Data ◽  
Austenitic Steel ◽  
Power Law ◽  
Tube Wall ◽  
Cylindrical Tube ◽  
Stress And Strain ◽  
Uniform Temperature ◽  
Material Parameters ◽  
Simulation Input ◽  
Abaqus Software

The Abaqus software was used to simulate the creep behavior of a cylindrical tube of Sanicro-25 austenitic steel under an internal pressure of 11.3 MPa at a uniform temperature at 750 °C. The data used for the simulation input were obtained from the experimental data of a previous work. The hidden information of material parameters was estimated from the shape of creep strain versus time plots obtained from the experimental data. The validated results between the simulation and the experimental data produced the material parameter of the creep power law which were set at 2.6 x 10-22 for the power law constant and 9 for the stress exponent. The parameters were further used to explore the stress and strain inside and outside of the tube wall and the thickness changes of the tube wall.

UNDERSTANDING THE VISCOELASTIC PROPERTIES OF RABBIT CORNEA BASED ON STRESS RELAXATION TESTS AND CYCLIC UNIAXIAL TESTS

2017 ◽  
Vol 17 (07) ◽  
pp. 1740035 ◽  
Author(s):  
HAIXIA ZHANG ◽  
XIUQING QIAN ◽  
LIN LI ◽  
ZHICHENG LIU
Keyword(s):  
Stress Relaxation ◽  
Test Data ◽  
Viscoelastic Properties ◽  
Linear Optimization ◽  
Constitutive Models ◽  
Optimization Techniques ◽  
Rabbit Cornea ◽  
Uniaxial Test ◽  
Material Parameters ◽  
Biomechanical Behavior

Background: Determining the viscoelastic properties of cornea is important in the fields of understanding of the tissue’s response to mechanical actions and the accurate numerical simulation of corneal biomechanical behavior under the effects of keratoconus and refractive surgery. To address this need, we present an approach to model the viscoelastic response of rabbit cornea from uniaxial test data. Methods: The corneal strip samples from six rabbits were obtained to perform cyclic uniaxial tension tests and stress relaxation tests. We investigated the suitability of six constitutive models, including empirical models and hyperelastic models, by a quasi-linear viscoelastic law. Applying non-linear optimization techniques, we found material parameters for each different strip sample. Results and conclusions: The model gave a better fit to loading data with [Formula: see text], and predicted the unloading data in the cyclic uniaxial tests with errors-of-fit ranging from 0.03 to 0.06. The results indicate that the best model is the power of the first invariant of strain with Prony form relaxation model, and that the method to identify the material parameters are valid for modeling the visoelastic response of cornea from uniaxial test data.

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