Using Force and Kinematic Driven Finite Element Models to Analyze Contact Pressure Distributions on the Tibial Plateau

2007 ◽  
Author(s):  
Kristen R. Hovinga ◽  
Jiang Yao ◽  
Amy L. Lerner
Keyword(s):  
Finite Element ◽  
Articular Cartilage ◽  
Soft Tissue ◽  
Mr Imaging ◽  
Load Distribution ◽  
Tibial Plateau ◽  
Fe Analysis ◽  
Implant Design ◽  
Finite Element Models ◽  
Pressure Distributions

Finite element (FE) models have become an effective tool in studying soft tissue behavior in the knee joint, including meniscal translation and deformation, as well as articular cartilage contact [1–2]. These models are also useful in osteoarthritis research and implant design [3–4]. Our group has previously used a kinematic-driven FE analysis to study the effect of weightbearing on the load distribution of tibio-menisco-femoral contact using MR imaging [5].

MR Imaging of Tibial Plateau Fractures: Evaluation of Fracture Types and Associated Soft Tissue Injuries

1997 ◽  
Vol 36 (5) ◽  
pp. 867
Author(s):  
Geon Lee ◽  
Chan Heo ◽  
Yong Jo Kim ◽  
Hyeok Po Kwon ◽  
Jung Hyeok Kwon ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Mr Imaging ◽  
Tibial Plateau ◽  
Soft Tissue Injuries ◽  
Tibial Plateau Fractures ◽  
Tissue Injuries ◽  
Fracture Types

Viscoelastic characterization of soft tissue from dynamic finite element models

2008 ◽  
Vol 53 (22) ◽  
pp. 6569-6590 ◽  
Author(s):  
Hani Eskandari ◽  
Septimiu E Salcudean ◽  
Robert Rohling ◽  
Jacques Ohayon
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Models ◽  
Dynamic Finite Element

scholarly journals Biaxial estimation of biomechanical constitutive parameters of passive porcine sclera soft tissue

2021 ◽  
Author(s):  
Zwelihle Ndlovu ◽  
Dawood Desai ◽  
Thanyani Pandelani ◽  
Harry Ngwangwa ◽  
Fulufhelo Nemavhola
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Finite Element Model ◽  
Test Data ◽  
Element Model ◽  
Finite Element Models ◽  
Anisotropic Model ◽  
Material Models ◽  
Material Parameters ◽  
Constitutive Parameters

This study assesses the modelling capabilities of four constitutive hyperplastic material models to fit the experimental data of the porcine sclera soft tissue. It further estimates the material parameters and discusses their applicability to a finite element model by examining the statistical dispersion measured through the standard deviation. Fifteen sclera tissues were harvested from porcine’ slaughtered at an abattoir and were subjected to equi-biaxial testing. The results show that all the four material models yielded very good correlations at correlations above 96 %. The polynomial (anisotropic) model gave the best correlation of 98 %. However, the estimated material parameters varied widely from one test to another such that there would be needed to normalise the test data to avoid long optimisation processes after applying the average material parameters to finite element models. However, for application of the estimated material parameters to finite element models, there would be needed to consider normalising the test data to reduce the search region for the optimisation algorithms. Although the polynomial (anisotropic) model yielded the best correlation, it was found that the Choi-Vito had the least variation in the estimated material parameters thereby making it an easier option for application of its material parameters to a finite element model and also requiring minimum effort in the optimisation procedure. For the porcine sclera tissue, it was found that the anisotropy more influenced by the fiber-related properties than the background material matrix related properties.

Wing-Fuselage Lug Stress Prediction Using Finite Element Method

2013 ◽  
Vol 393 ◽  
pp. 317-322
Author(s):  
Abdul Malik Hussein Abdul Jalil ◽  
Wahyu Kuntjoro
Keyword(s):  
Finite Element ◽  
Load Distribution ◽  
Applied Load ◽  
Maximum Stress ◽  
Finite Element Models ◽  
Finite Element Analyses ◽  
Finite Element Software ◽  
Stress Prediction ◽  
Reaction Forces ◽  
The Individual

This paper describes the methodology to predict the stress level that occurs at the wing-fuselage lugs (joints). The finite element models of the wing, the wing lugs and the fuselage lugs were developed. Finite Element Analyses were performed using NASTRAN finite element software. CQUAD4 and BAR2 elements were used to represent the individual structures of the wing such as the ribs and stringers. The applied load was based on the symmetrical level flight condition. Once the load distribution acting at the wing had been calculated and applied, reaction forces at the nodes representing the wing lugs were obtained and these values applied to the lug models where the maximum stress value acting at the lugs was obtained.

Cartilage Thickness Distribution Affects Computational Model Predictions of Cervical Spine Facet Contact Parameters

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Wesley Womack ◽  
Ugur M. Ayturk ◽  
Christian M. Puttlitz
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Articular Cartilage ◽  
Cartilage Thickness ◽  
Implant Design ◽  
Lower Cervical Spine ◽  
Model Predictions ◽  
Geometric Representations ◽  
Spatially Varying ◽  
The Impact

With motion-sparing disk replacement implants gaining popularity as an alternative to anterior cervical discectomy and fusion (ACDF) for the treatment of certain spinal degenerative disorders, recent laboratory investigations have studied the effects of disk replacement and implant design on spinal kinematics and kinetics. Particularly relevant to cervical disk replacement implant design are any postoperative changes in solid stresses or contact conditions in the articular cartilage of the posterior facets, which are hypothesized to lead to adjacent-level degeneration. Such changes are commonly investigated using finite element methods, but significant simplification of the articular geometry is generally employed. The impact of such geometric representations has not been thoroughly investigated. In order to assess the effects of different models of cartilage geometry on load transfer and contact pressures in the lower cervical spine, a finite element model was generated using cadaver-based computed tomography imagery. Mesh resolution was varied in order to establish model convergence, and cadaveric testing was undertaken to validate model predictions. The validated model was altered to include four different geometric representations of the articular cartilage. Model predictions indicate that the two most common representations of articular cartilage geometry result in significant reductions in the predictive accuracy of the models. The two anatomically based geometric models exhibited less computational artifact, and relatively minor differences between them indicate that contact condition predictions of spatially varying thickness models are robust to anatomic variations in cartilage thickness and articular curvature. The results of this work indicate that finite element modeling efforts in the lower cervical spine should include anatomically based and spatially varying articular cartilage thickness models. Failure to do so may result in loss of fidelity of model predictions relevant to investigations of physiological import.

Multiphase Poroelastic Finite Element Models for Soft Tissue Structures

1992 ◽  
Vol 45 (6) ◽  
pp. 191-218 ◽  
Author(s):  
Bruce R. Simon
Keyword(s):  
Finite Element ◽  
Soft Tissue ◽  
Material Behavior ◽  
Constitutive Law ◽  
Finite Strains ◽  
Finite Element Models ◽  
Tissue Fluid ◽  
Biomechanical Models ◽  
Highly Nonlinear ◽  
Tissue Structures

During the last two decades, biological structures with soft tissue components have been modeled using poroelastic or mixture-based constitutive laws, i.e., the material is viewed as a deformable (porous) solid matrix that is saturated by mobile tissue fluid. These structures exhibit a highly nonlinear, history-dependent material behavior; undergo finite strains; and may swell or shrink when tissue ionic concentrations are altered. Given the geometric and material complexity of soft tissue structures and that they are subjected to complicated initial and boundary conditions, finite element models (FEMs) have been very useful for quantitative structural analyses. This paper surveys recent applications of poroelastic and mixture-based theories and the associated FEMs for the study of the biomechanics of soft tissues, and indicates future directions for research in this area. Equivalent finite-strain poroelastic and mixture continuum biomechanical models are presented. Special attention is given to the identification of material properties using a porohyperelastic constitutive law and a total Lagrangian view for the formulation. The associated FEMs are then formulated to include this porohyperelastic material response and finite strains. Extensions of the theory are suggested in order to include inherent viscoelasticity, transport phenomena, and swelling in soft tissue structures. A number of biomechanical research areas are identified, and possible applications of the porohyperelastic and mixture-based FEMs are suggested.

scholarly journals Structural Design Issues For Integral Abutment Bridges

2021 ◽  
Author(s):  
Navid Nikravan
Keyword(s):  
Finite Element ◽  
Load Distribution ◽  
Finite Element Models ◽  
Live Load ◽  
Skew Angle ◽  
Temperature Variations ◽  
Integral Bridges ◽  
Live Load Distribution Factors ◽  
Live Load Distribution ◽  
Load Distribution Factors

In recent years, integral abutment bridges have been increasingly used in Canada due to their low maintenance costs. Whereas a rational guideline to determine the maximum length and skew angle limits for integral bridges due to temperature variations do not exist in bridge codes. As such, structural behavior of integral bridges subjected to temperature variation was investigated through a numerical modeling. First, detailed 3D finite-element models were developed. The accuracy of finite-element models was validated against data collected from filed testing available in the literature on integral bridges subjected to the seasonal temperature variations and truck loading. Then, a parametric study was carried out to study the effects of key parameters on the performance of integral bridges when subjected to temperature variations. The numerical results indicated that number of design lanes, bridge length, abutment height, abutment-pile connection, pile size and skew angle had a significant impact on the behavior of integral bridges. Based on the data generated from the parametric study, new limits for the maximum length and skew angle of integral bridges based on displacement-ductility limit state of piles were established. Literature review revealed that live load distribution among girders in integral bridges due to truck loading conditions is as yet unavailable. This study is extended to develop new equations to estimate girder live load distribution factors for integral bridges. First, 2D and 3D finite-element models (FEMs) of integral bridges were developed. Then, a parametric study was performed to study the effects of parameters such as abutment height, abutment thickness, wingwall length, wingwall orientation, number of design lanes, span length, girder spacing and number of intermediate diaphragms. The results indicated that the live load distribution factors obtained from the FEMs were lower than those obtained from current CHBDC equations. Consequently, sets of empirical expressions were developed in the form of reduction factors that can be applied to CHBDC live load distribution factors to accurately calculate the girder distribution factors. Also, other set of equations for the live load distribution factors were developed in a similar form as that specified in CHBDC for possible inclusion in the bridge code.

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