scholarly journals Finite Element Prediction of Transchondral Stress and Strain in the Human Hip

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Corinne R. Henak ◽  
Gerard A. Ateshian ◽  
Jeffrey A. Weiss
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Tensile Strain ◽  
Maximum Shear Stress ◽  
Cartilage Damage ◽  
Constitutive Models ◽  
Hip Osteoarthritis ◽  
Principal Strain ◽  
Stress And Strain ◽  
Fiber Distribution

Cartilage fissures, surface fibrillation, and delamination represent early signs of hip osteoarthritis (OA). This damage may be caused by elevated first principal (most tensile) strain and maximum shear stress. The objectives of this study were to use a population of validated finite element (FE) models of normal human hips to evaluate the required mesh for converged predictions of cartilage tensile strain and shear stress, to assess the sensitivity to cartilage constitutive assumptions, and to determine the patterns of transchondral stress and strain that occur during activities of daily living. Five specimen-specific FE models were evaluated using three constitutive models for articular cartilage: quasilinear neo-Hookean, nonlinear Veronda Westmann, and tension-compression nonlinear ellipsoidal fiber distribution (EFD). Transchondral predictions of maximum shear stress and first principal strain were determined. Mesh convergence analysis demonstrated that five trilinear elements were adequate through the depth of the cartilage for precise predictions. The EFD model had the stiffest response with increasing strains, predicting the largest peak stresses and smallest peak strains. Conversely, the neo-Hookean model predicted the smallest peak stresses and largest peak strains. Models with neo-Hookean cartilage predicted smaller transchondral gradients of maximum shear stress than those with Veronda Westmann and EFD models. For FE models with EFD cartilage, the anterolateral region of the acetabulum had larger peak maximum shear stress and first principal strain than all other anatomical regions, consistent with observations of cartilage damage in disease. Results demonstrate that tension-compression nonlinearity of a continuous fiber distribution exhibiting strain induced anisotropy incorporates important features that have large effects on predictions of transchondral stress and strain. This population of normal hips provides baseline data for future comparisons to pathomorphologic hips. This approach can be used to evaluate these and other mechanical variables in the human hip and their potential role in the pathogenesis of osteoarthritis (OA).

Effects of Cartilage Constitutive Model on Specimen-Specific Validation and Predictions of Cartilage Mechanics in the Human Hip

2013 ◽  
Author(s):  
Corinne R. Henak ◽  
Ashley L. Kapron ◽  
Andrew E. Anderson ◽  
Gerard A. Ateshian ◽  
Benjamin J. Ellis ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Articular Surface ◽  
Maximum Shear Stress ◽  
Hip Osteoarthritis ◽  
Experimental Measurements ◽  
Cartilage Mechanics ◽  
Model Predictions ◽  
Mechanical Factors

The initiation and progression of hip osteoarthritis (OA) may be predicted by mechanical factors [1]. Contact stress (CS), maximum shear stress (MSS) at the osteochondral interface and first principal strain (FPS) at the articular surface have been identified as parameters that alter the physical integrity and metabolism of cartilage [1]. Although these parameters are difficult to measure in-vivo, they can be predicted using finite element (FE) models. However, the reliability of model predictions and the effects of model assumptions are largely unknown. Direct validation of FE models against experimental measurements for a series of specimens shows the reliability of predictions across specimen geometry [1], although to date this has only been performed for a single hip [2].

Finite Element Aided Design Evolution of Composite Leaf Spring

2006 ◽  
Vol 3-4 ◽  
pp. 429-434 ◽  
Author(s):  
J. Hou ◽  
George Jeronimidis
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Maximum Shear Stress ◽  
Leaf Spring ◽  
Original Design ◽  
Virtual Production ◽  
Glass Fibre Reinforced ◽  
Spring System ◽  
Interlaminar Shear ◽  
Aided Design

This paper shows the process of the virtual production development of the mechanical connection between the top leaf of a dual composite leaf spring system to a shackle using finite element methods. The commercial FEA package MSC/MARC has been used for the analysis. In the original design the joint was based on a closed eye-end. Full scale testing results showed that this configuration achieved the vertical proof load of 150 kN and 1 million cycles of fatigue load. However, a problem with delamination occurred at the interface between the fibres going around the eye and the main leaf body. To overcome this problem, a second design was tried using transverse bandages of woven glass fibre reinforced tape to wrap the section that is prone to delaminate. In this case, the maximum interlaminar shear stress was reduced by a certain amount but it was still higher than the material’s shear strength. Based on the fact that, even with delamination, the top leaf spring still sustained the maximum static and fatigue loads required, the third design was proposed with an open eye-end, eliminating altogether the interface where the maximum shear stress occurs. The maximum shear stress predicted by FEA is reduced significantly and a safety factor of around 2 has been obtained. Thus, a successful and safe design has been achieved.

Investigation of Design Parameters and Failure Criteria of O-Ring Seal Structure

2005 ◽  
Author(s):  
Dianyin Hu ◽  
Rongqiao Wang ◽  
Quanbin Ren ◽  
Jie Hong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shear Stress ◽  
Normal Stress ◽  
Maximum Shear Stress ◽  
Design Parameters ◽  
Element Analysis ◽  
Axisymmetric Model ◽  
Sealing Performance ◽  
Maximum Contact

First, this paper established the seal structural 2D axisymmetric model of a certain Solid Rocket Booster (SRB) and calculated the deformation and stresses at ignition through a large displacement, incompressible, contact finite element analysis. The results show that the maximum contact stress appears at the contact area and the maximum shear stress at groove notch. Then, some typical parameters of the seal structure which might have the impact on the sealing performance, such as the gap breadth, initial compressibility, fillets of the groove notch and bottom, groove width, were analyzed. We can find that the gap breadth and initial compressibility do great contributions to the maximum contact normal stress, and the groove notch and bottom fillets act upon the maximum shear stress obviously. In order to verify the validity of the 2D axisymmetric model, 3D structural finite element analysis of the structure was conducted, and the results indicate that in service, the upper flange is inclined relative to the nether flange, which seems to mean that the gap breadth can not be considered as a constant during the 2D axisymmetric analysis. However further calculations say that if using the minimum gap breadth gotten in 3D analysis as its constant gap value, the above 2D axisymmetric model can rationally take the place of 3D model to analyze the sealing performance. Finally, the failure modes & criteria of the O-ring seals based on the maximum contact normal stress and shear stress were determined to ensure the reliability of this structure.

Mechanism Analysis of Rutting at Urban Intersections Based on Numerical Simulation of Moving Loads

2010 ◽  
Vol 152-153 ◽  
pp. 1192-1198 ◽  
Author(s):  
Ze Jiao Dong ◽  
Zong Jie Sun ◽  
Xiang Bing Gong ◽  
Hao Liu
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Asphalt Pavement ◽  
Moving Load ◽  
Maximum Shear Stress ◽  
Uniform Motion ◽  
Dynamic Mode ◽  
Mechanism Analysis ◽  
Horizontal Shear ◽  
Pavement Structure

Frequent starting and braking of vehicles causes rutting of asphalt pavement at urban intersection. As a result, dynamic response of pavement subjected to these kinds of vehicle loadings can be used to analyze rutting mechanism. At first, vehicle loading at urban intersection was described by a vertical and horizontal combined moving pressure with variable speeds. Then, three-dimensional finite element model in transient dynamic mode is developed based on the practical pavement structure. And the moving load, boundary conditions and material parameters were briefly introduced. Finally, through the comparison of time histories and spatial distribution among accelerating, decelerating and uniform motion, mechanism of rutting of asphalt pavement at urban intersections was illustrated according to the finite element simulation. It shows that frequent starting and braking of vehicle at urban intersections, obviously change the stress distribution within pavement structure compared with uniform motion case. The distribution and amplitude of maximum shear stress and horizontal shear stress was observed during the passage of the loading, which will result in shear flow deformation. Pavement structure subjected to moving load exhibits an alternative characteristic which will accelerate the rutting damage of pavement.

Research on the Shear Nails on the Arch Foot of an Oblique Cross Steel Box Arch Bridge

2013 ◽  
Vol 663 ◽  
pp. 49-54
Author(s):  
Xin Huang ◽  
Z.Z. Bai ◽  
De Wei Chen
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Maximum Shear Stress ◽  
Element Model ◽  
Bottom Up ◽  
Arch Bridge ◽  
Distribution Rules

In order to find the distribution rules on the shear nails on the steel-concrete composite segment of arch foot of an oblique cross steel box arch bridge, it established a space finite element model through the engineering of Wenzhou Weiwulu oblique cross steel box arch bridge, analyzing the maximum shear stress of the shear nails under normal using stage. The result shows that the welding nails in different position have a great difference in their shear stress. The welding nails which welded in a place that has a greater stiffness bear a bigger shear stress. So their mechanical performance of steel-concrete segment is better. In addition, the maximum shear stress becomes bigger from the bottom up to the top of the steel box.

An Evaluation of Chip Separation Criteria for the FEM Simulation of Machining

1996 ◽  
Vol 118 (4) ◽  
pp. 545-554 ◽  
Author(s):  
J. M. Huang ◽  
J. T. Black
Keyword(s):  
Shear Stress ◽  
Maximum Shear Stress ◽  
Fem Simulation ◽  
Shear Plane ◽  
Machining Process ◽  
Stress And Strain ◽  
Machined Surface ◽  
Average Maximum ◽  
Chip Separation ◽  
Chip Geometry

Different chip separation criteria for the FEM simulation of machining were examined. Criterion based on distance between the tool tip and the node located immediately ahead, criterion based on maximum shear stress in the element ahead of the tool tip, criterion based on average maximum shear stress in the shear plane, and criterion based on a combination of distance and stress were investigated. Under conditions of smooth separation of chip from workpiece, simulation results showed that, during steady-state cutting, the type of chip separation criteria did not greatly affect chip geometry, nor distributions of stress and strain. The magnitude of the chip separation criteria also did not significantly affect chip geometry and distributions of stress in the chip but it did affect the chip separation process, distributions of stress in the machined surface, and distributions of effective plastic strain both in the chip and in the machined surface. During the initiation of cutting, neither the geometrical nor physical criteria simulate the machining process correctly. A combination of geometric and physical criteria was also recommended in this study.

Research on Anti-Rutting Performance of Reconstruct Pavement

2012 ◽  
Vol 178-181 ◽  
pp. 1601-1604
Author(s):  
Lian Yu Wei ◽  
Fei Gao ◽  
Shi Bin Ma ◽  
Qing Zhou Wang
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Finite Element Model ◽  
Asphalt Pavement ◽  
Maximum Shear Stress ◽  
Element Model ◽  
The State ◽  
Longitudinal Slope ◽  
The Finite Element Model

Based on the overhaul structure of actual asphalt pavement, establishes the finite element model and analyses the shear stress in the state of overload, longitudinal slope and contact coefficient. The result is that the load and the gradient of longitudinal slope larger, the influence of rutting more seriously. The growth of shear stress is larger which brought by adding load on steep longitudinal slope than that of adding on longitudinal slope. The contact coefficient of interlayer α larger the maximum shear stress larger, on the contrary, the contact coefficient of interlayer α smaller the maximum shear stress smaller.

The Effect of the Frontal Plane Tibiofemoral Angle and Varus Knee Moment on the Contact Stress and Strain at the Knee Cartilage

2010 ◽  
Vol 26 (4) ◽  
pp. 432-443 ◽  
Author(s):  
Nicholas H. Yang ◽  
Paul K. Canavan ◽  
Hamid Nayeb-Hashemi
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Normal Stress ◽  
Frontal Plane ◽  
Stress And Strain ◽  
Normal Strain ◽  
Knee Cartilage ◽  
Element Analysis ◽  
Tibiofemoral Angle ◽  
The Individual

Subject-specific models were developed and finite element analysis was performed to observe the effect of the frontal plane tibiofemoral angle on the normal stress, Tresca shear stress and normal strain at the surface of the knee cartilage. Finite element models were created for three subjects with different tibiofemoral angle and physiological loading conditions were defined from motion analysis and muscle force mathematical models to simulate static single-leg stance. The results showed that the greatest magnitude of the normal stress, Tresca shear stress and normal strain at the medial compartment was for the varus aligned individual. Considering the lateral knee compartment, the individual with valgus alignment had the largest stress and strain at the cartilage. The present investigation is the first known attempt to analyze the effects of tibiofemoral alignment during single-leg support on the contact variables of the cartilage at the knee joint. The method could be potentially used to help identify individuals most susceptible to osteoarthritis and to prescribe preventive measures.

scholarly journals Finite Model Analysis and Practical Design Equations of Circular Concrete-Filled Steel Tube Columns Subjected to Compression-Torsion Load

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5564
Author(s):  
Yongzhi Gong ◽  
Faxing Ding ◽  
Liping Wang ◽  
Borong Huang ◽  
Yingjie Shan ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Axial Force ◽  
Maximum Shear Stress ◽  
Steel Tube ◽  
Steel Tubes ◽  
Concrete Filled Steel Tube ◽  
Composite Action ◽  
Practical Design ◽  
Cfst Columns

The objective of this study is to investigate the mechanical properties and the composite action of circular concrete-filled steel tube (CFST) columns subjected to compression-torsion load using finite element model analysis. Load–strain (T–γ) curves, normal stress, shear stress, and the composite action between the steel tubes and the interior concrete were analyzed based on the verified 3D finite element models. The results indicate that with the increase of axial force, the maximum shear stress at the core concrete increased significantly, and the maximum shear stress of the steel tubes gradually decreased. Meanwhile, the torsional bearing capacity of the column increased at first and then decreased. The torque share in the columns changed from the tube-sharing domain to the concrete-sharing domain, while the axial force of the steel tube remained unchanged. Practical design equations for the torsional capacity of axially loaded circular CFST columns were proposed based on the parametric analysis. The accuracy and validity of the proposed equations were verified against the collected experimental results.

Runners With Patellofemoral Pain Exhibit Greater Peak Patella Cartilage Stress Compared With Pain-Free Runners

2018 ◽  
Vol 34 (4) ◽  
pp. 298-305 ◽  
Author(s):  
Tzu-Chieh Liao ◽  
Joyce H. Keyak ◽  
Christopher M. Powers
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Hydrostatic Pressure ◽  
External Rotation ◽  
Maximum Shear Stress ◽  
Knee Extensor ◽  
Peak Stress ◽  
Patellofemoral Pain ◽  
Subject Specific ◽  
Recreational Runners

The primary purpose of this study is to determine whether recreational runners with patellofemoral pain (PFP) exhibit greater peak patella cartilage stress compared with pain-free runners. A secondary purpose was to determine the kinematic and/or kinetic predictors of peak patella cartilage stress during running. A total of 22 female recreational runners (12 with PFP and 10 pain-free controls) participated in this study. Patella cartilage stress profiles were quantified using subject-specific finite element models simulating the maximum knee flexion angle during the stance phase of running. Input parameters to the finite element model included subject-specific patellofemoral joint geometry, quadriceps muscle forces, and lower-extremity kinematics in the frontal and transverse planes. Tibiofemoral joint kinematics and kinetics were quantified to determine the best predictor of stress using stepwise regression analysis. Compared with the pain-free runners, those with PFP exhibited greater peak hydrostatic pressure (PFP vs control: 21.2 [5.6] MPa vs 16.5 [4.6] MPa) and maximum shear stress (PFP vs control: 11.3 [4.6] MPa vs 8.7 [2.3] MPa). Knee external rotation was the best predictor of peak hydrostatic pressure and peak maximum shear stress (38% and 25% of variances, respectively), followed by the knee extensor moment (21% and 25% of variances, respectively). Runners with PFP exhibit greater peak patella cartilage stress during running compared with pain-free individuals. The combination of knee external rotation and a high knee extensor moment best predicted the elevated peak stress during running.

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