Effects of Joint Congruency on the Response of a Tension-Compression Nonlinear Constitutive Model for Cartilage

2008 ◽  
Author(s):  
Benjamin J. Ellis ◽  
Gerard A. Ateshian ◽  
Andrew E. Anderson ◽  
Clare Canal ◽  
Steve A. Maas ◽  
...  
Keyword(s):  
Constitutive Model ◽  
Solid Phase ◽  
Constitutive Models ◽  
Incompressible Material ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Similar Response ◽  
Joint Congruency ◽  
Nonlinear Constitutive Model ◽  
Rate Dependent

Articular cartilage exhibits inhomogeneous, rate-dependent and tension-compression (TC) nonlinear material properties. It is a biphasic material (solid and fluid phases) and its solid phase is stiffer in tension than compression [1]. Despite this complex material behavior, elastic, incompressible material models can be used to predict the short-time loading response of cartilage [2]. To our knowledge, the use of an anisotropic incompressible material to represent cartilage in a finite element (FE) joint model has not been investigated and thus the importance of the TC nonlinearity in the analysis of 3D articular contact models is limited [3]. We have been investigating a TC nonlinear incompressible constitutive model to represent hip cartilage. The objective of this study was to assess the influence of TC nonlinearity on FE predictions of stress and strain as a function of congruency between two spherical cartilage layers. It was hypothesized that the TC nonlinear and neo-Hookean constitutive models would yield a similar response when the cartilage layers were nearly congruent, but as the congruency of the cartilage layers decreased the predicted response from the two materials would be different.

scholarly journals A nonlinear strain-rate dependent constitutive model for uncured rubber materials under large deformation

2020 ◽  
Vol 37 ◽  
pp. 118-125
Author(s):  
Weihua Zhou ◽  
Changqing Fang ◽  
Huifeng Tan ◽  
Huiyu Sun
Keyword(s):  
Constitutive Model ◽  
Large Deformation ◽  
Mechanical Response ◽  
Uniaxial Tensile ◽  
Hysteresis Phenomenon ◽  
Mechanical Behaviors ◽  
Nonlinear Constitutive Model ◽  
Rate Dependent ◽  
Parallel Networks ◽  
Non Gaussian

Abstract Uncured rubber possesses remarkable hyperelastic and viscoelastic properties while it undergoes large deformation; therefore, it has wide application prospects and attracts great research interests from academia and industry. In this paper, a nonlinear constitutive model with two parallel networks is developed to describe the mechanical response of uncured rubber. The constitutive model is incorporated with the Eying model to describe the hysteresis phenomenon and viscous flow criterion, and the hyperelastic properties under large deformation are captured by a non-Gaussian chain molecular network model. Based on the model, the mechanical behaviors of hyperelasticity, viscoelasticity and hysteresis under different strain rates are investigated. Furthermore, the constitutive model is employed to estimate uniaxial tensile, cyclic loading–unloading and multistep tensile relaxation mechanical behaviors of uncured rubber, and the prediction results show good agreement with the test data. The nonlinear mechanical constitutive model provides an efficient method for predicting the mechanical response of uncured rubber materials.

Experimental and Numerical Study of Soft Tissue Surrogate Behavior Under Ballistic Loading

2012 ◽  
Author(s):  
Ericka K. Amborn ◽  
Karim H. Muci-Küchler ◽  
Brandon J. Hinz
Keyword(s):  
Soft Tissue ◽  
Constitutive Model ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Constitutive Models ◽  
Material Behavior ◽  
Good Representation

Studying the high strain rate behavior of soft tissues and soft tissue surrogates is of interest to improve the understanding of injury mechanisms during blast and impact events. Tests such as the split Hopkinson pressure bar have been successfully used to characterize material behavior at high strain rates under simple loading conditions. However, experiments involving more complex stress states are needed for the validation of constitutive models and numerical simulation techniques for fast transient events. In particular, for the case of ballistic injuries, controlled tests that can better reflect the effects induced by a penetrating projectile are of interest. This paper presents an experiment that tries to achieve that goal. The experimental setup involves a cylindrical test sample made of a translucent soft tissue surrogate that has a small pre-made cylindrical channel along its axis. A small caliber projectile is fired through the pre-made channel at representative speeds using an air rifle. High speed video is used in conjunction with specialized software to generate data for model validation. A Lagrangian Finite Element Method (FEM) model was prepared in ABAQUS/Explicit to simulate the experiments. Different hyperelastic constitutive models were explored to represent the behavior of the soft tissue surrogate and the required material properties were obtained from high strain rate test data reported in the open literature. The simulation results corresponding to each constitutive model considered were qualitatively compared against the experimental data for a single projectile speed. The constitutive model that provided the closest match was then used to perform an additional simulation at a different projectile velocity and quantitative comparisons between numerical and experimental results were made. The comparisons showed that the Marlow hyperelastic model available in ABAQUS/Explicit was able to produce a good representation of the soft tissue surrogate behavior observed experimentally at the two projectile speeds considered.

scholarly journals Energy-based constitutive modelling of local material properties of canine aortas

2016 ◽  
Vol 3 (9) ◽  
pp. 160365 ◽  
Author(s):  
Kaveh Laksari ◽  
Danial Shahmirzadi ◽  
Camilo J. Acosta ◽  
Elisa Konofagou
Keyword(s):  
Constitutive Model ◽  
Mechanical Behaviour ◽  
Computational Models ◽  
Constitutive Models ◽  
Constitutive Modelling ◽  
Axial Position ◽  
Aortic Tissue ◽  
Nonlinear Constitutive Model ◽  
Local Material Properties

This study aims at determining the in vitro anisotropic mechanical behaviour of canine aortic tissue. We specifically focused on spatial variations of these properties along the axis of the vessel. We performed uniaxial stretch tests on canine aortic samples in both circumferential and longitudinal directions, as well as histological examinations to derive the tissue's fibre orientations. We subsequently characterized a constitutive model that incorporates both phenomenological and structural elements to account for macroscopic and microstructural behaviour of the tissue. We showed the two fibre families were oriented at similar angles with respect to the aorta's axis. We also found significant changes in mechanical behaviour of the tissue as a function of axial position from proximal to distal direction: the fibres become more aligned with the aortic axis from 46° to 30°. Also, the linear shear modulus of media decreased as we moved distally along the aortic axis from 139 to 64 kPa. These changes derived from the parameters in the nonlinear constitutive model agreed well with the changes in tissue structure. In addition, we showed that isotropic contribution, carried by elastic lamellae, to the total stress induced in the tissue decreases at higher stretch ratios, whereas anisotropic stress, carried by collagen fibres, increases. The constitutive models can be readily used to design computational models of tissue deformation during physiological loading cycles. The findings of this study extend the understanding of local mechanical properties that could lead to region-specific diagnostics and treatment of arterial diseases.

A Second Generation of Numerical Implementation of Nonlinear Piezoelectric Models in Commercially Available Tools

2008 ◽  
Author(s):  
M. A. Siddiq Qidwai ◽  
V. G. DeGiorgi
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Domain Switching ◽  
Piezoelectric Materials ◽  
Nonlinear Behavior ◽  
Material Behavior ◽  
Device Performance ◽  
Performance Improvements ◽  
Rate Dependent ◽  
Theoretical Developments

Domain switching based nonlinear behavior is characteristic of relaxor-type piezoelectric material such as PMN-PT single crystals. These materials offer significant device performance improvements over traditional polycrystalline piezoelectric materials such as PZT-5A. The promise of increased performance of these materials has led to work in development of constitutive characterizations so that material behavior under load and material failure mechanisms can be understood and predicted. However, there is a gap between development of such theoretical developments and in workable manifestations available as part of commercial finite element codes for use in device design. In the current work, the authors extend previously documented implementation of a macro-mechanical constitutive model which addresses domain switching, into a commercially available finite element code. A rate dependent version of the constitutive model has been successfully realized and used to reproduce a variety of piezoelectric constitutive behaviors.

Simulation of Impact and Fragmentation With the Meshless Methods

2010 ◽  
Author(s):  
Namık Kılıc¸ ◽  
Atıl Erdik ◽  
Bu¨lent Ekici
Keyword(s):  
High Performance ◽  
Split Hopkinson Pressure Bar ◽  
Meshless Methods ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Hopkinson Pressure Bar ◽  
Material Interfaces ◽  
Explicit Finite Element ◽  
Rate Dependent ◽  
Impact Problems

High velocity impact and penetration problems include large deformation, erosion, high strain rate dependent nonlinear material behavior and fragmentation. Therefore, meshless methods seem to be ideally suited for the modeling of penetration events as they allow unrestricted deformation and easy tracking of material interfaces and loading histories. In the first part of this study, a brief overview about meshless methods is given. Also the most important features of meshless methods with respect to mesh based approaches are compared. In the second part, numerical model is developed using one of the most frequently used meshless method, Smoothed Particle Hydrodynamics (SPH). 3D numerical simulations are performed on a high performance computer using MPP version of the explicit finite element code LS-Dyna. For reasonable behavior of material response under dynamic loading, Johnson Cook material models for armor steel target and 7,62 armor piercing projectile are derived using SHPB (Split Hopkinson Pressure Bar) test data. SPH computational investigation is compared with available experimental data such as penetration depth and impact crater diameter. For the future work, other potential meshless methods for ballistic impact problems are identified.

Preliminary Study on the Deformation of Yuxi Basin under Gravity Action by Nonlinear Finite Element Simulation

2012 ◽  
Vol 170-173 ◽  
pp. 1097-1106
Author(s):  
Tie Fei Li ◽  
Xue Liang Chen ◽  
Meng Tan Gao
Keyword(s):  
Constitutive Model ◽  
Great Influence ◽  
Constitutive Models ◽  
Secondary Development ◽  
Modified Model ◽  
Nonlinear Constitutive Model ◽  
Element Simulation ◽  
Calculation Results ◽  
Nonlinear Elastic ◽  
Nonlinear Finite Element Simulation

Abstract. A secondary development of the ADINA software for Duncan-Chang E-B nonlinear elastic constitutive model was conducted in this paper, and the veracity of calculation results was verified. To contrast linear constitutive model and Duncan-Chang nonlinear constitutive model, the deformation of YuXi basin profile model under gravity action was calculated by both of the constitutive models. The results show that the subsidence in the linear results is about 12% larger than the nonlinear results, and the nonlinear model has advantages in parameter choosing. Meanwhile, a modified model of YuXi basin which depends on the latest data from our recent work in YuXi area was built to compare with the original model, the calculation results show that the changes in the basin basement structure and basin depth have great influence on the distribution and maximums of the deformation results, when the changes in the internal structure and sequence influence relatively little.

The Effect of the Variation in ACL Constitutive Model on Joint Kinematics and Biomechanics Under Different Loads: A Finite Element Study

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Chao Wan ◽  
Zhixiu Hao ◽  
Shizhu Wen
Keyword(s):  
Finite Element ◽  
Constitutive Equation ◽  
Constitutive Model ◽  
Constitutive Models ◽  
Transversely Isotropic ◽  
Joint Kinematics ◽  
Material Behavior ◽  
Ground Substance ◽  
Anterior Tibial ◽  
Hyperelastic Model

The biomechanics and function of the anterior cruciate ligament (ACL) have been widely studied using both experimental and simulation methods. It is known that a constitutive model of joint tissue is a critical factor in the numerical simulation. Some different ligament constitutive models have been presented to describe the ACL material behavior. However, the effect of the variation in the ligament constitutive model on joint kinematics and biomechanics has still not been studied. In this paper, a three-dimensional finite element model of an intact tibiofemoral joint was reconstructed. Three ACL constitutive models were compared under different joint loads (such as anterior tibial force, varus tibial torque, and valgus tibial torque) to investigate the effect of the change of the ACL constitutive model. The three constitutive models corresponded to an isotropic hyperelasticity model, a transversely isotropic hyperelasticity model with neo-Hookean ground substance description, and a transversely isotropic hyperelastic model with nonlinear ground substance description. Although the material properties of these constitutive equations were fitted on the same uniaxial tension stress-strain curve, the change of the ACL material constitutive model was found to induce altered joint kinematics and biomechanics. The effect of different ACL constitutive equations on joint kinematics depended on both deformation direction and load type. The variation in the ACL constitutive models would influence the joint kinematic results greatly in both the anterior and internal directions under anterior tibial force as well as some other deformations such as the anterior and medial tibial translations under valgus tibial torque, and the medial tibial translation and internal rotation under varus torque. It was revealed that the transversely isotropic hyperelastic model with nonlinear ground substance description (FE model III) was the best representation of the realistic ACL property by a linear regression between the simulated and the experiment deformation results. But the comparison of the predicted and experiment force of ligaments showed that all the three ACL constitutive models represented similar force results. The stress value and distribution of ACL were also altered by the change in the constitutive equation. In brief, although different ACL constitutive models have been fitted using the same uniaxial tension curve and have the similar longitudinal material property, the ACL constitutive equation should still be carefully chosen to investigate joint kinematics and biomechanics due to the different transverse material behavior.

scholarly journals Investigation of Density- and Strain Rate-dependent Strain Hardening-softening-coupled material Behavior of Polyurethane Foams using Elasto-viscoplastic Constitutive Model

2020 ◽  
Vol 58 (5) ◽  
pp. 357-367
Author(s):  
Tae-Rim Kim ◽  
Chi-Seung Lee
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Strain Hardening ◽  
Material Behavior ◽  
Implicit Time ◽  
Stress Strain ◽  
Integration Algorithm ◽  
Material Response ◽  
Material Parameters ◽  
Rate Dependent

Polyurethane foam (PUF) is one of the most well-known cellular materials and is widely employed in various industrial and biomedical fields thanks to its many advantages. These include mechanical and material characteristics such as low density and thermal conductivity, and high specific elastic modulus and strength. Despite of these advantages, the PUF has extremely complex material nonlinearity, with changes in density and strain rate, which is a major obstacle to material design and the application of PUF-based structures. PUF has elasto-viscoplastic behavior including three stages of material features, linear elasticity, softening/plateau with stress drop and densification. These phenomena depend strongly on strain rate and density. Therefore, in this study, a phenomenological constitutive model, namely, an elasto-viscoplastic model, was proposed to describe the density- and strain rate-dependent material nonlinear behavior of PUF. The yield surface-independent plastic multiplier, and the hardening- and softening-associated internal state variables proposed by Frank and Brockman, and Zairi et al. were adopted in the constitutive model, respectively. The proposed constitutive model was discretized using the implicit time integration algorithm and was implemented into a user-defined subroutine of the commercial finite element analysis program, ABAQUS. At the same time, a deterministic identification method for material parameters of the constitutive model was introduced to predict the precise material response of PUF under arbitrary densities and strain rates. To do this, the three-dimensional constitutive model was contracted to a one-dimensional equation, and the explicit equation for each material parameter was derived. Then, the strain hardening- and softeningdependent material parameters were calculated using experimental results, such as the work hardening ratestress curve and the yield stress-strain rate curve. After analyzing the obtained material parameters, it was found that the material parameters were strongly dependent on the density and the strain rate. Consequently, the macroscopic material response of PUF, such as a uniaxial compressive stress-strain curve, can be predicted based on the proposed method in this study.

scholarly journals Calibration of Finn Model and UBCSAND Model for Simplified Liquefaction Analysis Procedures

2021 ◽  
Vol 11 (11) ◽  
pp. 5283
Author(s):  
Jui-Ching Chou ◽  
Hsueh-Tusng Yang ◽  
Der-Guey Lin
Keyword(s):  
Numerical Simulation ◽  
Constitutive Model ◽  
Structural Damage ◽  
Simulation Analysis ◽  
Constitutive Models ◽  
Soil Liquefaction ◽  
Analysis Procedure ◽  
Liquefaction Resistance ◽  
Simplified Procedure ◽  
Liquefaction Analysis

Soil-liquefaction-related hazards can damage structures or lead to an extensive loss of life and property. Therefore, the stability and safety of structures against soil liquefaction are essential for evaluation in earthquake design. In practice, the simplified liquefaction analysis procedure associated with numerical simulation analysis is the most used approach for evaluating the behavior of structures or the effectiveness of mitigation plans. First, the occurrence of soil liquefaction is evaluated using the simplified procedure. If soil liquefaction occurs, the resulting structural damage or the following mitigation plan is evaluated using the numerical simulation analysis. Rational and comparable evaluation results between the simplified liquefaction analysis procedure and the numerical simulation analysis are achieved by ensuring that the liquefaction constitutive model used in the numerical simulation has a consistent liquefaction resistance with the simplified liquefaction analysis procedure. In this study, two frequently used liquefaction constitutive models (Finn model and UBCSAND model) were calibrated by fitting the liquefaction triggering curves of most used simplified liquefaction analysis procedures (NCEER, HBF, JRA96, and T-Y procedures) in Taiwan via FLAC program. In addition, the responses of two calibrated models were compared and discussed to provide guidelines for selecting an appropriate liquefaction constitutive model in future projects.

Sign in / Sign up

Export Citation Format

Share Document