An Enhanced Discrete Element Model for Predicting Hip Contact Stresses

2012 ◽  
Author(s):  
Christine L. Abraham ◽  
Steve A. Maas ◽  
Jeffrey A. Weiss ◽  
Benjamin J. Ellis ◽  
Christopher L. Peters ◽  
...  
Keyword(s):  
Hip Joint ◽  
Contact Stress ◽  
Element Model ◽  
Discrete Element ◽  
Contact Stresses ◽  
Fe Method ◽  
Element Analysis ◽  
Dea Model ◽  
Subject Specific ◽  
And Cartilage

Chronic exposure to excessive stress on articular cartilage in the hip joint predicts the progression and onset of osteoarthritis (OA) [1]. Discrete element analysis (DEA) has been used to predict cartilage contact stresses [2, 3]. Because of its low computational expense and relative ease of application, DEA could be an effective alternative to the finite element (FE) method for the study of contact stresses in the hip. Previous DEA models have assumed concentric hip joint geometry and constant cartilage thickness. These assumptions lead to underestimates for cartilage contact stress and predict unrealistic, simplified contact patterns [2, 4]. It is possible that DEA could provide more realistic predictions of cartilage contact stress if subject-specific bone and cartilage geometry were used. The objectives of this study were to develop a DEA model that accommodates subject-specific bone and cartilage geometry, and to compare DEA model predictions of cartilage contact stresses with predictions from validated FE models.

scholarly journals Implementation of Discrete Element Analysis for Subject-Specific, Population-Wide Investigations of Habitual Contact Stress Exposure

2010 ◽  
Vol 26 (2) ◽  
pp. 215-223 ◽  
Author(s):  
Donald D. Anderson ◽  
Krishna S. Iyer ◽  
Neil A. Segal ◽  
John A. Lynch ◽  
Thomas D. Brown
Keyword(s):  
Contact Stress ◽  
Large Population ◽  
Discrete Element ◽  
Population Based ◽  
Contact Stresses ◽  
Stress Exposure ◽  
Element Analysis ◽  
Large Numbers ◽  
Subject Specific ◽  
In Series

There exist no large-series human data linking contact stress exposure to an articular joint’s propensity for developing osteoarthritis because contact stress analysis for large numbers of subjects remains impractical. The speed and simplicity of discrete element analysis (DEA) for estimating contact stresses makes its application to this problem highly attractive, but to date DEA has been used to study only a small numbers of cases. This is because substantial issues regarding its use in population-wide studies have not been addressed. Chief among them are developing fast and robust methods for model derivation and the selection of boundary conditions, establishing accuracy of computed contact stresses, and including capabilities for modeling in-series structural elements (e.g., a meniscus). This article describes an implementation of DEA that makes it feasible to perform subject-specific modeling in articular joints in large population-based studies.

scholarly journals A new discrete element analysis method for predicting hip joint contact stresses

2013 ◽  
Vol 46 (6) ◽  
pp. 1121-1127 ◽  
Author(s):  
Christine L. Abraham ◽  
Steve A. Maas ◽  
Jeffrey A. Weiss ◽  
Benjamin J. Ellis ◽  
Christopher L. Peters ◽  
...  
Keyword(s):  
Hip Joint ◽  
Discrete Element ◽  
Contact Stresses ◽  
Analysis Method ◽  
Element Analysis ◽  
Joint Contact

scholarly journals Validation of Finite Element Predictions of Cartilage Contact Pressure in the Human Hip Joint

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Andrew E. Anderson ◽  
Benjamin J. Ellis ◽  
Steve A. Maas ◽  
Christopher L. Peters ◽  
Jeffrey A. Weiss
Keyword(s):  
Finite Element ◽  
Hip Joint ◽  
Image Data ◽  
Contact Stresses ◽  
Stair Climbing ◽  
Patient Specific ◽  
Contact Areas ◽  
Subject Specific ◽  
Peak Pressures ◽  
And Cartilage

Methods to predict contact stresses in the hip can provide an improved understanding of load distribution in the normal and pathologic joint. The objectives of this study were to develop and validate a three-dimensional finite element (FE) model for predicting cartilage contact stresses in the human hip using subject-specific geometry from computed tomography image data, and to assess the sensitivity of model predictions to boundary conditions, cartilage geometry, and cartilage material properties. Loads based on in vivo data were applied to a cadaveric hip joint to simulate walking, descending stairs, and stair-climbing. Contact pressures and areas were measured using pressure sensitive film. CT image data were segmented and discretized into FE meshes of bone and cartilage. FE boundary and loading conditions mimicked the experimental testing. Fair to good qualitative correspondence was obtained between FE predictions and experimental measurements for simulated walking and descending stairs, while excellent agreement was obtained for stair-climbing. Experimental peak pressures, average pressures, and contact areas were 10.0MPa (limit of film detection), 4.4–5.0MPa, and 321.9–425.1mm2, respectively, while FE-predicted peak pressures, average pressures, and contact areas were 10.8–12.7MPa, 5.1–6.2MPa, and 304.2–366.1mm2, respectively. Misalignment errors, determined as the difference in root mean squared error before and after alignment of FE results, were less than 10%. Magnitude errors, determined as the residual error following alignment, were approximately 30% but decreased to 10–15% when the regions of highest pressure were compared. Alterations to the cartilage shear modulus, bulk modulus, or thickness resulted in ±25% change in peak pressures, while changes in average pressures and contact areas were minor (±10%). When the pelvis and proximal femur were represented as rigid, there were large changes, but the effect depended on the particular loading scenario. Overall, the subject-specific FE predictions compared favorably with pressure film measurements and were in good agreement with published experimental data. The validated modeling framework provides a foundation for development of patient-specific FE models to investigate the mechanics of normal and pathological hips.

A Finite Element Analysis of the Human Temporomandibular Joint

1994 ◽  
Vol 116 (4) ◽  
pp. 401-407 ◽  
Author(s):  
J. Chen ◽  
Liangfeng Xu
Keyword(s):  
Finite Element ◽  
Temporomandibular Joint ◽  
Reaction Force ◽  
Element Model ◽  
Contact Stresses ◽  
Element Analysis ◽  
Tensile Stresses ◽  
Reaction Forces ◽  
Von Mises ◽  
Von Mises Stresses

A 2-D finite element model of the human temporomandibular joint (TMJ) has been developed to investigate the stresses and reaction forces within the joint during normal sagittal jaw closure. The mechanical parameters analyzed were maximum principal and von Mises stresses in the disk, the contact stresses on the condylar and temporal surfaces, and the condylar reactions. The model bypassed the complexity of estimating muscle forces by using measured joint motion as input. The model was evaluated by several tests. The results demonstrated that the resultant condylar reaction force was directed toward the posterior side of the eminence. The contact stresses along the condylar and temporal surfaces were not evenly distributed. Separations were found at both upper and lower boundaries. High tensile stresses were found at the upper boundaries. High tensile stresses were found at the upper boundary of the middle portion of the disk.

Finite Element Analysis of the Effect of Surface Hardening Depth in Port Crane Wheel

2011 ◽  
Vol 291-294 ◽  
pp. 3282-3286 ◽  
Author(s):  
Jiang Wei Wu ◽  
Peng Wang
Keyword(s):  
Finite Element ◽  
Surface Hardening ◽  
Three Dimensional ◽  
Element Model ◽  
Contact Stresses ◽  
Numerical Results ◽  
Element Analysis ◽  
Finite Element Software ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In port crane industry, the surface hardening technique is widely used in order to improve the strength of wheel. But the hardening depth is chosen only by according to the experience, and the effect of different hardened depths is not studied theoretically. In this paper, the contact stresses in wheel with different hardening depth have been analyzed by applying three-dimensional finite element model. Based on this model, the ANSYS10.0 finite element software is used. The elastic wheel is used to verify the numerical results with the Hertz’s theory. Three different hardening depths, namely 10mm, 25mm and whole hardened wheel, under three different vertical loads were applied. The effect of hardening depth of a surface hardened wheel is discussed by comparing the contact stresses and contact areas from the numerical results.

Finite Element Analysis for Gear Contact Based on UG and ABAQUS

2013 ◽  
Vol 442 ◽  
pp. 229-232 ◽  
Author(s):  
Li Mei Wu ◽  
Fei Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Tooth Surface ◽  
Element Analysis ◽  
Tooth Width ◽  
Gear Contact ◽  
Maximum Contact

According to the cutting theory of involute tooth profile, established an exact three-dimensional parametric model by UG. Used ABAQUS to crate finite element model for gear meshing. After simulated the meshing process, discussed the periodicity of the tooth surface contact stress. Based on the result of finite element analysis, made a comparison of the maximum contact stress between finite element solution and Hertz theoretical solution, analyzed the contact stress distribution on tooth width, and researched the effect of friction factor on contact stress. All that provided some theoretical basis for gear contact strength design.

Biomechanical Modeling of Hip Joint Prosthesis

2005 ◽  
Author(s):  
M. C. Gaspar ◽  
A. Mateus ◽  
C. Pereira ◽  
F. V. Antunes
Keyword(s):  
Finite Element ◽  
Hip Joint ◽  
Laser Scanning ◽  
Hip Prosthesis ◽  
Element Model ◽  
Geometrical Model ◽  
Elastic Behavior ◽  
Joint Prosthesis ◽  
Element Analysis

In this work a Bombelli cementless isoelastic RM total hip prosthesis was considered. It was implanted over a course of 14 years on the patient and studied subsequently to its chirurgical replacement. Computed Tomography, radiographies and 3-D laser scanning were used to assess the prosthesis geometry, while the original femur anatomy was modeled based on 2-D radiographies taken at different stages of the in-vivo implant of the prosthesis. A finite element model was developed, based on the generated 3-D geometrical model, considering a linear elastic behavior and typical loading conditions. This analysis allowed determining stress and strain fields throughout bone-prosthesis contact surface and critical areas in terms of micromovements. The developed procedure, consisting of 3-D scanning, generation of geometrical 3-D models and finite element analysis, results in a powerful tool to follow-up and predict failure mechanisms in hip joint prosthesis.

scholarly journals Analysis and Control of Twist Defects of Aluminum Profiles with Large Z-Section in Roll Bending Process

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 31 ◽  
Author(s):  
Anheng Wang ◽  
Hongqian Xue ◽  
Emin Bayraktar ◽  
Yanli Yang ◽  
Shah Saud ◽  
...  
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Element Model ◽  
Effective Control ◽  
Curvature Radius ◽  
3D Fem ◽  
Fe Method ◽  
Element Analysis ◽  
Roll Bending ◽  
Bending Process

This paper focuses on the twist defects and the control strategy in the process of four-roll bending for aluminum alloy Z-section profiles with large cross-section. A 3D finite element model (3D-FEM) of roll bending process has been developed, on the premise of the curvature radius of the profile, the particularly pronounced twist defects characteristic of 7075-O aluminum alloy Z-section profiles were studied by FE method. The simulation results showed that the effective control of the twist defects of the profile could be realized by adjusting the side roller so that the exit guide roll was higher than the entrance one (the side rolls presented an asymmetric loading mode with respect to the main rolls) and increasing the radius of upper roll. Corresponding experimental tests were carried out to verify the accuracy of the numerical analysis. The experimental results indicated that control strategies based on finite element analysis (FEA) had a significant inhibitory function on twist defects in the actual roll bending process.

Femur Design Parameters and Contact Stresses at UHMWPE Hip Joint Cup

2011 ◽  
Vol 478 ◽  
pp. 93-102
Author(s):  
H. Fouad ◽  
S.M. Darwish
Keyword(s):  
Hip Joint ◽  
Contact Stress ◽  
Contact Stresses ◽  
Functionally Graded ◽  
Design Parameters ◽  
Slight Reduction ◽  
Metal Backing ◽  
Low Modulus ◽  
Long Term Performance ◽  
Term Performance

The contact stress that occurs in the ultra-high molecular weight polyethylene (UHMWPE) hip joint cup has been shown to be correlated with the implant wear rate. The wear of the hip joint is considered as one of the main factors that affect the long term performance of the implant. The contact stress that occurs in the UHMWPE hip joint cup is affected by the implant dimensions and materials. In this study, four different femur materials and geometries were used to investigate the effects of femur design parameters on the resultant contact stress on the UHMWPE cup. The results of the finite element (FE) simulation show that the contact stresses at the UHMWPE cup decreases dramatically with increasing the femur diameter. Also the results indicated that the contact stresses on the UHMWPE cup decrease significantly when using functionally graded (FG) femur with low modulus of elasticity. The presence of metal backing results in a slight reduction in the UHMWPE cup contact stresses especially for small femurs. Finally, the presence of a gap between the UHMWPE cup and the femur results in a remarkable increase in the cup stress especially for a small femur. The hip joint femur dimensions and materials are thought to play an important role in the transition of load in the implant and should be taken into consideration during the design of the hip joint.

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