Wear Characteristics of Conventional and Squeeze-Film Artificial Hip Joints

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
S. Boedo ◽  
S. A. Coots
Keyword(s):  
Implant Design ◽  
Squeeze Film ◽  
Linear Wear ◽  
Wear Depth ◽  
Element Analysis ◽  
Wear Characteristics ◽  
Wear Rates ◽  
Cycle Loading ◽  
Artificial Hip Joints ◽  
Elastic Elements

This paper investigates the wear characteristics of a novel squeeze-film hip implant design. Key features of the design are elastic elements attached to the cup which provide a mechanical means for ball separation during the swing phase of the gait loading cycle. An Archard-based wear formulation was implemented utilizing the ansys finite element analysis program which relates contact pressure and sliding distance to linear wear depth. It is found that low-modulus elastic elements with bonded high-modulus metal coatings offer significant predicted improvement in linear and volumetric wear rates when compared with conventional implant geometries for gait cycle loading and kinematic conditions found in practice.

scholarly journals New Dental Implant with 3D Shock Absorbers and Tooth-Like Mobility—Prototype Development, Finite Element Analysis (FEA), and Mechanical Testing

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3444
Author(s):  
Avram Manea ◽  
Grigore Baciut ◽  
Mihaela Baciut ◽  
Dumitru Pop ◽  
Dan Sorin Comsa ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Testing ◽  
Alveolar Bone ◽  
Mechanical Performance ◽  
Implant Design ◽  
Element Analysis ◽  
Prototype Development ◽  
Second Stage ◽  
Testing Protocol

Background: Once inserted and osseointegrated, dental implants become ankylosed, which makes them immobile with respect to the alveolar bone. The present paper describes the development of a new and original implant design which replicates the 3D physiological mobility of natural teeth. The first phase of the test followed the resistance of the implant to mechanical stress as well as the behavior of the surrounding bone. Modifications to the design were made after the first set of results. In the second stage, mechanical tests in conjunction with finite element analysis were performed to test the improved implant design. Methods: In order to test the new concept, 6 titanium alloy (Ti6Al4V) implants were produced (milling). The implants were fitted into the dynamic testing device. The initial mobility was measured for each implant as well as their mobility after several test cycles. In the second stage, 10 implants with the modified design were produced. The testing protocol included mechanical testing and finite element analysis. Results: The initial testing protocol was applied almost entirely successfully. Premature fracturing of some implants and fitting blocks occurred and the testing protocol was readjusted. The issues in the initial test helped design the final testing protocol and the new implants with improved mechanical performance. Conclusion: The new prototype proved the efficiency of the concept. The initial tests pointed out the need for design improvement and the following tests validated the concept.

FE Modeling of Stress Distribution in MAO Coating on TC4 Substrate under Thermal Shock Cyclic Loading

2014 ◽  
Vol 941-944 ◽  
pp. 1629-1632 ◽  
Author(s):  
Ye Sheng Zhong ◽  
Li Ping Shi ◽  
Ming Wei Li ◽  
Jia Yu ◽  
Jian Han Liang ◽  
...  
Keyword(s):  
Shear Stress ◽  
Thermal Stress ◽  
Stress Distribution ◽  
Adhesive Strength ◽  
Thermal Cycle ◽  
Radial Stress ◽  
Numerical Study ◽  
Element Analysis ◽  
Solid Element ◽  
Cycle Loading

A numerical study using finite element analysis (FEA) was performed to investigate the thermal, shear and radial stresses developed in MAO coating on substrate of TC4 under thermal cycle loading. The four-node quadrilateral thermal solid element PLANE55 and four-node quadrilateral structural solid element PLANE42 with axisymmetric option was used to model the temperature distribution and thermal stress field of the MAO coating on TC4 substrates. The thermal stress, radial stress and shear stress along the thickness in film/substrate system are analyzed systematically under different thermal cycle loading. It is found that the thermal stress of MAO coating exhibits a linear relationship with thickness of substrate, but it exhibit a parabolic relationship with the thickness of the coating. The radial stress and shear stress distribution of the coating–substrate combination are also calculated. It is observed that high tensile shear stress of MAO coating on TC4 substrate reduces its adhesive strength but high-compressive shear stress improves its adhesive strength.

Finite Element Analysis as an Aid to Implant Design

1979 ◽  
Vol 7 (1) ◽  
pp. 169-175 ◽  
Author(s):  
A. M. Weinstein ◽  
J. J. Klawitter ◽  
S. D. Cook
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Implant Design ◽  
Element Analysis

scholarly journals New analytical formalisms used in finite element analysis of robots with elastic elements

2020 ◽  
Vol 14 (1) ◽  
pp. 1335-1341
Author(s):  
Sorin Vlase ◽  
Iuliu Negrean ◽  
Marin Marin ◽  
Maria Luminiţa Scutaru
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Analysis ◽  
Elastic Elements

Axisymmetric Finite Element Analysis of Hip Replacement with an Elastomeric Layer: The Effects of Layer Thickness

1994 ◽  
Vol 208 (3) ◽  
pp. 139-149 ◽  
Author(s):  
A Strozzi ◽  
A Unsworth
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Response ◽  
Maximum Shear Stress ◽  
Hydrodynamic Theory ◽  
Asymptotic Model ◽  
Hip Joints ◽  
Element Analysis ◽  
Contact Width ◽  
Artificial Hip Joints

Finite element analysis of compliant layered artificial hip joints has been used to study the mechanical response of four different layer thicknesses from 0.5 to 3 mm. The results have been compared with a classical asymptotic model in terms of maximum contact pressure and contact width, and of maximum shear stress at the layer-backing interface and its location. The surface deformations and load capacities have also been compared. The best thickness was found to be 2 mm; though a marginal reduction in stresses would be found in the 3 mm layer, the penetrations would be greater and these might have implications for the fatigue life of the material. A formula for the thickness of the fluid film has been derived on the basis of the inverse hydrodynamic theory and the results show good correlation with existing theories.

Improvement of FAC Maintenance Program Issued From BRT-CICERO™ via CFD Calculations

2016 ◽  
Author(s):  
Elodie Gipon
Keyword(s):  
Mass Transfer ◽  
Nuclear Power ◽  
Power Plants ◽  
Specific Effect ◽  
Piping System ◽  
Element Analysis ◽  
Accelerated Corrosion ◽  
Wear Rates ◽  
Maintenance Program ◽  
Calculation Algorithms

Flow Accelerated Corrosion (FAC) is very effective for nuclear power plant. This generalized corrosion can lead to the rupture of pipe and in some dramatic cases to casualties. During the last 20 years Electricité de France (EDF) has developed software called BRT-CICERO™ for the surveillance of the carbon steel piping system of its Nuclear Power Plants (NPPs). This software enables the operator to calculate the FAC wear rates by taking into account all the influencing parameters such as pipe isometrics, alloy content, chemical conditioning, design and operating parameters of the steam water circuit (temperature, pressure, etc…). This is a major tool to help operators organize their maintenance and inspections plan. The algorithms implemented in BRT-CICERO™ are based on tests conducted by EDF R&D, empirical results (national and international feedback), literature reviews and on permanent adjustments based on the operating feedback, via statistical studies. However, for some piping components, from the turbine’s hall, flow dynamics are not optimized and calculated FAC kinetics may be too conservative. EDF is committed for optimizing and increasing reliability of its maintenance programs to prevent the risk of pipe rupture due to FAC. As in consequence EDF is leading continuous improvement in parameters and calculation algorithms for BRT-CICERO™. Furthermore studies on the geometric characteristics of the pipes were conducted. In BRT-CICERO™ geometric effect of a pipe component (elbow reduction, tees …) is taken into account by considering a factor called “Geo” in the calculation to tune the thickness loss rate according the component type, its characteristics and specific effect on flow mass transfer. EDF implements finite element analysis software to compute the mass transfer coefficient k and so ascertain the “Geo” coefficient. These computed “Geo” coefficients are compared to those used in BRT-CICERO™. If necessary, current “Geo” coefficients used in BRT-CICERO™ will be adjusted and optimized to improve maintenance programs issued from the software. The presentation deals with the calculation method used for these studies and some results will be shown on tube and elbows.

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