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.

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.

Nonlinear Finite Element Analysis for Thermoplastic Pipes

1998 ◽  
Vol 1624 (1) ◽  
pp. 225-230 ◽  
Author(s):  
Chuntao Zhang ◽  
Ian D. Moore
Keyword(s):  
Finite Element ◽  
Geometrical Nonlinearity ◽  
Constitutive Models ◽  
Material Behavior ◽  
Pipe Material ◽  
Limit States ◽  
Element Analysis ◽  
Finite Element Program ◽  
Highly Nonlinear ◽  
Nonlinear Constitutive Models

Thermoplastic pipes are being used increasingly for water supply lines, storm sewers, and leachate collection systems in landfills. To facilitate limit states design for buried polymer pipes, nonlinear constitutive models have recently been developed to characterize the highly nonlinear and time-dependent material behavior of high-density polyethylene (HDPE). These models have been implemented in a finite element program to permit structural analysis for buried HDPE pipes and to provide information regarding performance limits of the structures. Predictions of HDPE pipe response under parallel plate loading and hoop compression in a soil cell are reported and compared with pipe response measured in laboratory tests. Effects on the structural performance of pipe material nonlinearity, geometrical nonlinearity, and backfill soil properties were investigated. Good correlations were found between the finite element predictions and the experimental measurements. The models can be used to predict pipe response under many different load histories (not just relaxation or creep). Work is ongoing to develop nonlinear constitutive models for polyvinylchloride and polypropylene to extend the predictive capability of the finite element model to these materials.

Development of Constitutive Equation for Infinite Body of Impact Problem

2007 ◽  
Vol 353-358 ◽  
pp. 611-614
Author(s):  
Seung Yong Yang
Keyword(s):  
Finite Element ◽  
Constitutive Equation ◽  
Plane Waves ◽  
Shear Plane ◽  
Material Behavior ◽  
Infinite Body ◽  
Wave Impact ◽  
Finite Element Software ◽  
Impact Simulations ◽  
Impact Problem

A constitutive equation was developed for an infinite body in plane wave impact problem, and implemented using the finite element software ABAQUS user subroutine. Bilinear material behavior under monotonically increasing loading was considered for the constitutive equation. The finite element governed by this type of material behavior can be used as an infinite body transmitting longitudinal and shear plane waves, so that the number of finite elements can be reduced in impact simulations. To test the developed method, results of a plate impact experiment were examined. The numerical results show the accuracy of the developed constitutive equation.

Bodner-Partom Constitutive Model and Nonlinear Finite Element Analysis

1990 ◽  
Vol 112 (3) ◽  
pp. 287-291 ◽  
Author(s):  
F. A. Kolkailah ◽  
A. J. McPhate
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Plastic Strain ◽  
Constitutive Model ◽  
Finite Element Model ◽  
Numerical Technique ◽  
Element Model ◽  
Material Behavior ◽  
Model Parameters ◽  
Elastic Plastic

In this paper, results from an elastic-plastic finite-element model incorporating the Bodner-Partom model of nonlinear time-dependent material behavior are presented. The parameters in the constitutive model are computed from a leastsquare fit to experimental data obtained from uniaxial stress-strain and creep tests at 650°C. The finite element model of a double-notched specimen is employed to determine the value of the elastic-plastic strain and is compared to experimental data. The constitutive model parameters evaluated in this paper are found to be in good agreement with those obtained by the other investigators. However, the parameters determined by the numerical technique tend to give response that agree with the data better than do graphically determined parameters previously used. The calculated elastic-plastic strain from the model agreed well with the experimental strain.

Development of a Flow Evolution Network Model for the Stress–Strain Behavior of Poly(L-lactide)

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Maureen L. Dreher ◽  
Srinidhi Nagaraja ◽  
Jorgen Bergstrom ◽  
Danika Hayman
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Computational Modeling ◽  
Medical Devices ◽  
Constitutive Models ◽  
Constitutive Relationship ◽  
Displacement Curve ◽  
Stress Strain ◽  
Strain Behavior ◽  
Flow Evolution

Computational modeling is critical to medical device development and has grown in its utility for predicting device performance. Additionally, there is an increasing trend to use absorbable polymers for the manufacturing of medical devices. However, computational modeling of absorbable devices is hampered by a lack of appropriate constitutive models that capture their viscoelasticity and postyield behavior. The objective of this study was to develop a constitutive model that incorporated viscoplasticity for a common medical absorbable polymer. Microtensile bars of poly(L-lactide) (PLLA) were studied experimentally to evaluate their monotonic, cyclic, unloading, and relaxation behavior as well as rate dependencies under physiological conditions. The data were then fit to a viscoplastic flow evolution network (FEN) constitutive model. PLLA exhibited rate-dependent stress–strain behavior with significant postyield softening and stress relaxation. The FEN model was able to capture these relevant mechanical behaviors well with high accuracy. In addition, the suitability of the FEN model for predicting the stress–strain behavior of PLLA medical devices was investigated using finite element (FE) simulations of nonstandard geometries. The nonstandard geometries chosen were representative of generic PLLA cardiovascular stent subunits. These finite element simulations demonstrated that modeling PLLA using the FEN constitutive relationship accurately reproduced the specimen’s force–displacement curve, and therefore, is a suitable relationship to use when simulating stress distribution in PLLA medical devices. This study demonstrates the utility of an advanced constitutive model that incorporates viscoplasticity for simulating PLLA mechanical behavior.

INFLUENCE OF THE CONSTITUTIVE MATERIAL BEHAVIOR MODEL ASSIGNED TO THE ANNULUS FIBROSUS AND THE NUCLEUS PULPOSUS ON THE BIOMECHANICAL PERFORMANCE OF A MODEL OF THE CERVICAL SPINE: A FINITE ELEMENT ANALYSIS STUDY

2010 ◽  
Vol 10 (01) ◽  
pp. 151-166 ◽  
Author(s):  
YUAN LI ◽  
GLADIUS LEWIS
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cervical Spine ◽  
Annulus Fibrosus ◽  
Constitutive Models ◽  
Material Behavior ◽  
Elastic Behavior ◽  
Behavior Model ◽  
Element Analysis ◽  
Constitutive Material

One feature of the literature on finite element analysis of models of cervical spine segment(s) is that an assortment of constitutive models has been used for the elastic behavior of the annulus fibrosus (AF) and the nucleus pulposus (NF). The extent to which the model assigned to each of these tissues affects the values of the biomechanical parameters of interest of the model is lacking. This issue was the subject of the present study. We used a three-dimensional solid model of the C4–C6 motion segment units (which comprised the vertebral bodies, the bony posterior elements (transverse processes, pedicles, laminae, spinous processes, and facet joints), the intervertebral discs (IVDs), the endplates, and the five major ligaments) and eight combinations of constitutive models. It was found that (1) the influence of the constitutive material models used depended on the tissue considered, with some, such as the posterior endplate of C5 and the cancellous bone of C6, showing marked sensitivity, while others, such as the cancellous bone of C4 and the cortical bone of C5, were moderately affected; and (2) the biomechanical performance of the spine model is more sensitive to the material behavior model used for the AF than it is to that used for the NF. These results suggest that experimental and computational efforts expended in obtaining the most appropriate constitutive model for the elastic behavior of the two parts of the IVD, in particular the AF, are justified.

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.

Thermomechanical Finite Element Analysis of Problems in Electronic Packaging Using the Disturbed State Concept: Part 1—Theory and Formulation

1998 ◽  
Vol 120 (1) ◽  
pp. 41-47 ◽  
Author(s):  
C. Basaran ◽  
C. S. Desai ◽  
T. Kundu
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Electronic Packaging ◽  
Constitutive Models ◽  
Cyclic Behavior ◽  
Element Analysis ◽  
Theoretical Formulation ◽  
Finite Element Procedure ◽  
Reliable Design ◽  
Number Of Cycles

Accurate prediction of the thermomechanical cyclic behavior of joints and interfaces in semiconductor devices is essential for their reliable design. In order to understand and predict the behavior of such interfaces there is a need for improved and unified constitutive models that can include elastic, inelastic, viscous, and temperature dependent microstructural behavior. Furthermore, such unified material models should be implemented in finite element procedures so as to yield accurate and reliable predictions of stresses, strains, deformations, microcracking, damage, and number of cycles to failure due to thermomechanical loading. The main objective of this paper is to present implementation of such an unified constitutive model in a finite element procedure and its application to typical problems in electronic packaging; details of the constitutive model are given by Desai et al. (1995). Details of the theoretical formulation is presented in this Part 1, while its applications and validations are presented in Part 2, Basaran et al. (1998).

A New Framework for Myocardium Constitutive Parameters Estimation

2018 ◽  
Vol 876 ◽  
pp. 128-132
Author(s):  
Yi Qiang Li ◽  
Zhi Qiang Huang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Left Ventricle ◽  
Constitutive Model ◽  
Optimization Algorithm ◽  
Left Ventricular ◽  
Parameters Estimation ◽  
Material Behavior ◽  
Element Analysis ◽  
Constitutive Parameters

In this study, a new inverse analysis framework for estimation of myocardium constitutive parameters is established. In this framework, by using cardiac magnetic resonance image of realistic human left ventricular, a more realistic, finite element analysis model for analyzing the deformation of left ventricle during diastole is introduced. The anisotropic nonlinear Holzapfel-Ogden constitutive model is used to describe the material behavior of myocardium. Estimating the parameters as for the inverse problem of left ventricle deformation, a novel hybrid simplex and particle swarm optimization algorithm is proposed to estimate the parameters of myocardium’s constitutive model. Numerical examples presents that finite element analysis results and the estimated parameters are in good agreement with the experimental data reported in literature, comparing with current optimization algorithm, the presented hybrid optimal algorithm can estimate the constitutive parameters more efficient. The efficiency and validity of the proposed parameter estimation framework is demonstrated.

scholarly journals Dynamic testing and simulation of 9 mm full metal jacket ammunition

2021 ◽  
Vol 250 ◽  
pp. 05002
Author(s):  
Yann Coget ◽  
Josip Novak ◽  
Georg Gütter ◽  
Yaël Demarty ◽  
Alexis Rusinek
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
High Speed ◽  
Dynamic Testing ◽  
Real Life ◽  
Constitutive Models ◽  
Armed Forces ◽  
Ballistic Impacts ◽  
High Degree ◽  
The Impact

Ballistic protection for armed forces requires a continuous performance improvement to successfully face ever evolving threats and scenarios. Ballistic tests are conventionally carried out in order to assess and validate the levels of protection to a high degree of accuracy. Although very effective, those tests are often time consuming and lack the necessary flexibility. A better approach would be to set up a numerical protocol for a number of simulations and only carry out final real life validation tests. Unquestionably, the main advantage of finite element modelling is the possibility to simultaneously evaluate a wide variety of configurations and their interactions (materials, geometry, architecture, etc.). For reliability, it is necessary to use sufficiently precise material behaviour models to accurately transcribe the phenomena observed during the impact. Our study focuses on the mechanical behaviour of 9 mm ammunition materials, namely a lead alloy core and a steel alloy jacket. For this purpose, a preliminary study (not presented here), was carried out on both the lead core and the steel jacket separately and the parameters for each constitutive model were determined. Lead-steel cylindrical samples, extracted from the ammunition, have been used for the validation of the entire constitutive model. By utilizing those samples, a high degree of the ammunitions material properties have been retained. SHPB tests have been carried out in multiple conditions, varying the striker speeds and temperatures. Additionally, the tests were recorded with an ultra-high speed camera. Strain gages were used to record signals along the input and output bars. Those measurements have been compared to numerical results using Finite Element code (ABAQUS® Explicit). A very satisfying correlation between the experimental data and the simulation has been reached, thus validating the jacket and core constitutive models and interactions for subsequent studies of ballistic impacts.

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