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.

INDIVIDUALLY COMPUTED FINITE ELEMENT ANALYSIS OF THE NON-STEMMED ANATOMICAL TOTAL HIP PROSTHESIS

2005 ◽  
Vol 09 (01) ◽  
pp. 21-33
Author(s):  
Poon-Ung Chieng ◽  
Ching-I Chen ◽  
Chi-Chang Lin ◽  
Ching-Lin Tsai ◽  
Po-Quang Chen
Keyword(s):  
Finite Element ◽  
Femoral Neck ◽  
Stress Analysis ◽  
Hip Prosthesis ◽  
Element Model ◽  
Main Body ◽  
Total Hip Prosthesis ◽  
Level Of Evidence ◽  
Element Analysis ◽  
Total Hip

Background: Current total hip prosthesis lack an accurate individualized finite element model to assure an accurate fit, and further require amputation of a possibly healthy femoral neck. Methods: This research presents a new methodology for performing an automated three-dimensional finite element meshing for a new type of total hip prosthesis. The stress analysis for this new design, known as Non-stemmed Anatomical Total Hip Prosthesis, is based on the methodology proposed here. The merit of this method is that the automated meshing process can be produced by using ANSYS software alone, without the need for a complicated, self-developed meshing interface program. Results: This new methodology provides a smooth boundary around the contour of the femur and the interface between the femur and the Non-stemmed Anatomical Total Hip Prosthesis, as well as avoiding additional complications. This newly designed prosthesis involves minimal modification of the intact femoral neck alignment after total hip replacement, provided that the femoral neck is still healthy. The main body of this new prosthesis is a conical-shaped mask that tightly embraces the femoral neck. The bottom skirt of this mask contacts the greater and lesser trochanter in such a way that maintains the mask in the desired position using a screw through the axis of the femoral neck. Finite element stress analysis is performed to compare the stress distribution of the intact femur and the femur after implantation of the Non-stemmed Anatomical Total Hip Prosthesis. Conclusions: Hopefully, this new prosthesis will be the method of choice for patients who have healthy femoral necks, but sick femoral heads. Further research can focus on applying this new methodology to other bone structures. Level of Evidence: Therapeutic study, Level IV.

Optimal Design of a Hip Joint Implant With Hollow Stem Using Finite Element Method

2006 ◽  
Author(s):  
Nasser Zakeri ◽  
Farzam Farahmand ◽  
Hamid Katoozian
Keyword(s):  
Finite Element ◽  
Optimal Design ◽  
Bone Cement ◽  
Hip Joint ◽  
Cylindrical Cavity ◽  
Hip Prosthesis ◽  
Element Model ◽  
Optimization Criterion ◽  
Design Parameters ◽  
Joint Implant

Complication of artificial joint replacement is often attributed to the distribution of mechanical stresses over the bone-cement, and cement-implant interfaces. This study represents the analysis and optimization of a hollow-stem hip prosthesis to reduce the micro-motion and maintain uniformity of stress distribution over the interface regions. A three-dimensional finite element model of the proximal femur was constructed in ANSYS, including the cortical bone, the cancellous bone, the bone cement and the femoral component of hip joint implant. Three design parameters were considered for the implant stem, including the length of the stem and the length and radius of the distal cylindrical cavity. The optimization criterion was defined as a linear combination of the standard deviations of the equivalent Von-Mises stresses and the total displacements at the cement-implant interface nodes. The Response Surface Method and sensitivity analysis indicated that the length of the stem has a major impact on the optimization criterion and the length and the radius of the cavity stand as the minor factors. The optimal design was obtained to have a 10.5 cm length stem with a cylindrical cavity of 23.4 mm length and 1.3 mm radius. The assumed optimization criterion reduced substantially from 3.1 in the initial design to 2.52 in the optimal deign.

Finite-element analysis of stress in the canine diaphragm

1994 ◽  
Vol 76 (5) ◽  
pp. 2070-2075 ◽  
Author(s):  
S. S. Margulies ◽  
G. T. Lei ◽  
G. A. Farkas ◽  
J. R. Rodarte
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Model ◽  
Biaxial Stress ◽  
Principal Stresses ◽  
Element Analysis ◽  
Transdiaphragmatic Pressure ◽  
Sigma 1

Stress in the diaphragm, transdiaphragmatic pressure, and diaphragm shape are interrelated by a balance of forces. Using precise in vivo measurements of diaphragm shape and transdiaphragmatic pressure distribution in combination with finite-element analysis (ANSYS), we determined the direction and magnitude of stress in the passive diaphragm at relaxation volume. Lead spheres sutured along muscle bundles identified muscle bundle location and orientation in vivo. The x, y, and z coordinates of the lead spheres and entire surface of the diaphragm, excluding the zone of apposition, were determined to within 1.4 mm. Thin shell elements were used to construct a finite-element model of the diaphragm with a 2.1- to 4.2-mm internodal spacing. The diaphragm was assumed to have a uniform thickness of 2.5 mm, and magnitude and direction of the principal stresses were computed. The results show that 1) diaphragm stress is nonuniform and anisotropic (i.e., varies both with location on diaphragm surface and direction examined), 2) largest stress (sigma 1) is aligned with muscle bundles and is two to four times larger than sigma 2 (perpendicular to sigma 1 in diaphragm plane), and 3) stress along the muscle bundles is larger in vivo under conditions of biaxial stress than at same length in vitro under uniaxial stress. Although diaphragm stress and tension have often been assumed to be uniform, our finding that stress is oriented primarily along the muscle fibers should be considered in future models of the diaphragm.(ABSTRACT TRUNCATED AT 250 WORDS)

Numerical and Experimental Study of Elastic Interaction in Bolted Flange Joints

2016 ◽  
Author(s):  
Linbo Zhu ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Elastic Interaction ◽  
Element Model ◽  
Pressure Vessels ◽  
Nonlinear Finite Element ◽  
Elastic Behavior ◽  
Element Analysis ◽  
Bolted Flange

Bolted flange joints are widely used to connect pressure vessels and piping equipment together and facilitate their disassembly. Initial tightening of their bolts is a delicate operation because it is extremely difficult to achieve the target load and uniformity due to elastic interaction. The risk of failure due to leakage and fatigue under service loading is consequently increased. This paper presents a study on the effect of elastic interaction that is present during the tightening of a bolted flange joints using three-dimensional nonlinear finite element modeling and experimentation. The nonlinear non-elastic behavior of the gasket is taken into account in the numerical simulation. The scatter in bolt preload produced during the tightening sequence is evaluated. Based on the elastic interaction coefficient method, the initial target tightening load in each bolt for every pass are determined by using the nonlinear finite element model to obtain a uniform preload after the final tightening pass. The validity of the FEA (Finite Element Analysis) is supported by experimental tests conducted on a NPS 4 class 900 weld neck bolted flange joints using fiber and flexible graphite gaskets. This study provides guidance and enhances the safety and reliability of bolted flange joints by minimizing bolt scatter due to elastic interaction.

GAIT ANALYSIS DRIVEN 2D FINITE ELEMENT MODEL OF THE NEUROPATHIC HINDFOOT

2016 ◽  
Vol 16 (02) ◽  
pp. 1650012
Author(s):  
ANNAMARIA GUIOTTO ◽  
ALESSANDRA SCARTON ◽  
ZIMI SAWACHA ◽  
GABRIELLA GUARNERI ◽  
ANGELO AVOGARO ◽  
...  
Keyword(s):  
Finite Element ◽  
Gait Analysis ◽  
Element Model ◽  
Magnetic Resonance Images ◽  
Finite Elements Analysis ◽  
Element Analysis ◽  
Anatomical Structures ◽  
Plantar Pressures ◽  
Subject Specific

The diabetic foot is one of the most serious complications of diabetes mellitus and it can lead to foot ulcerations and amputations. Finite element analysis quantifies the loads developed in the different anatomical structures and describes how these affect foot tissue during foot–floor interaction. This approach for the diabetic subjects’ foot could provide valuable information in the process of plantar orthosis fabrication and fit. The purpose of this study was to develop two finite element models of the hindfoot, of healthy and diabetic neuropathic subjects. These models accounts for in vivo kinematics, kinetics, plantar pressure (PP) data and magnetic resonance images. These were acquired during gait analysis on 10 diabetic neuropathics and 10 healthy subjects. Validity of the models has been assessed through comparison between the peak PPs of simulated and experimental data: root mean square error (RMSE) in percentage of the experimental peak value was evaluated. Two different finite elements analysis were performed: subject-specific simulations in terms of both geometry and gait analysis, and by adopting the complete gait analysis dataset as boundary conditions. Model predicted plantar pressures were in good agreement with those experimentally measured. Best agreement was obtained in the subject-specific case (RMSE of 13%).

EVALUATING THE EFFECTS OF EXPERIMENTAL SETTINGS DURING ISO 7206-4 ENDURANCE AND PERFORMACE TESTS: A FINITE ELEMENT ANALYSIS

2020 ◽  
Vol 20 (03) ◽  
pp. 2050006
Author(s):  
SILVIA PIANIGIANI ◽  
FABIO ALEMANI
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Experimental Test ◽  
Hip Prosthesis ◽  
Numerical Models ◽  
Frontal Plane ◽  
Element Model ◽  
Element Analysis ◽  
Cement Block ◽  
And Performance

ISO 7206-4:2010 is used to determine the endurance properties and performance of stemmed femoral components of hip prosthesis. Experimental set-ups are allowed for tolerances with respect to the desired settings. The effects of the acceptable accuracies are not known nowadays. For this reason, this study aims at evaluating how and how much the precision of the experimental settings can affect the outputs under ISO 7206-4:2010 boundaries. Thus, a finite element model was first defined and verified against experimental test. Then, a sensitivity analysis involving accepted variations for potting level, angle in the frontal plane, angle in the lateral plane and material in use for the cement block, was performed. The results of sensitivity analysis show that both stress and deformation outputs were affected up to 100[Formula: see text]MPa and 0.5[Formula: see text]mm, respectively, for varus configurations. The material properties of the cement block had a main effect on the displacement of the head. The collected information through the performed sensitivity analysis on the verified model against experimental test has a double benefit. It supports the understanding of the potential effects during the experimental set-ups and it is also helpful in case of determining ranges for verification of developed numerical models.

The Construction of Finite Element Model of Invisible Appliance of Inhomogeneous Thickness by Reverse Engineering Technology

2015 ◽  
Vol 741 ◽  
pp. 254-257
Author(s):  
Yan Fang Yue ◽  
Yang Wang ◽  
Yong Di Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Reverse Engineering ◽  
Laser Scanning ◽  
Element Model ◽  
Real Surface ◽  
Element Analysis ◽  
Engineering Technology ◽  
Dental Model ◽  
The Ideal

Reverse engineering technology and Laser scanning technology was used to obtain and establish the ideal digital dental mode and dental model with invisible appliance. To complete the Boolean subtraction between the dental model with invisible appliance and the ideal dental mode by the alignment marks designed in the guml, so that got the digital model of invisible appliance. Then the finite element model was established by the finite element analysis platform ANSYS. A more precise dentition finite element model of invisible appliance is established, which can reflect the real surface geometrical morphology of invisible appliance and its inhomogeneous thickness characteristics.

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