scholarly journals An Analytical Model for Almost Conformal Spherical Contact Problems: Application to Total Hip Arthroplasty with UHMWPE Liner

2021 ◽  
Vol 11 (23) ◽  
pp. 11170
Author(s):  
Markus Heß ◽  
Fabian Forsbach
Keyword(s):  
Finite Element ◽  
Contact Problem ◽  
Closed Form ◽  
Wear Behavior ◽  
Analytical Models ◽  
Maximum Pressure ◽  
Winkler Foundation ◽  
Hip Implants ◽  
Normal Contact ◽  
Proposed Model

Due to its high relevance for designing ball joints in mechanical engineering and (artificial) hip joints in biomechanics, the almost conformal elastic contact between a sphere and a spherical cup represents an important contact problem of current research. As no closed-form analytical solution to the problem has been found to date, full computational methods such as the finite element method are needed for analysis. However, they often require incredibly long, unacceptable calculation times, making parameter studies hardly practicable. For this reason, approximate analytical and semi-analytical models are applied, capable of predicting quantities of interest with sufficient accuracy. In the present work, a very simple model based on a radially directed Winkler foundation is presented, which provides (approximate) closed-form analytical solutions for both the pressure distribution and the dependencies between macroscopic contact quantities such as normal force and indentation depth. To ensure an optimal mapping of a specific contact problem, only the foundation modulus must be defined in a suitable way. As an example, the proposed model has been successfully adapted to adequately simulate the frictionless normal contact for hard-on-soft hip implants. For this purpose, the foundation modulus was approximated with the aid of a finite element analysis instead of adopting it from already well-established models, as the latter produce clearly erroneous results for large liner thicknesses and large Poisson’s ratios. By a comparison with extensive parameter studies of finite element simulations, it is demonstrated that the proposed model provides acceptable results for all commonly used hard-on-soft hip implants. On this basis, the influence of geometrical changes of the femoral head and the acetabular cup on the maximum pressure as well as the half-contact angle is discussed, and consequences on the wear behavior are deduced.

Confined masonry walls subjected to combined axial loads and out-of-plane uniform pressures

2012 ◽  
Vol 39 (4) ◽  
pp. 439-447 ◽  
Author(s):  
Jorge Varela-Rivera ◽  
Manuel Polanco-May ◽  
Luis Fernandez-Baqueiro ◽  
Eric I. Moreno
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Axial Load ◽  
Analytical Models ◽  
Maximum Pressure ◽  
Masonry Walls ◽  
The Finite Element Method ◽  
Axial Loads ◽  
Confined Masonry ◽  
Out Of Plane

This paper presents the results of a study on the behavior of three full-scale confined masonry walls subjected to combined axial loads and out-of-plane uniform pressures. The variable studied was the wall axial load. Analytical models were developed to predict out-of-plane cracking and maximum pressures. The former was predicted using the finite element method and the latter using the spring-strut method. This last method was modified to include the effect of the wall axial load. Experimental cracking and maximum pressures were compared with those obtained from analytical models. Based on the experimental results, it was concluded that as the axial load increases, the out-of-plane maximum pressure also increases. However, this latter value is limited by crushing of the masonry. By comparing experimental and analytical results, it was concluded that the out-of-plane cracking and maximum pressures are in general well predicted by the analytical models developed in this work.

Nonlinear analysis of planar reinforced concrete structures

1987 ◽  
Vol 14 (6) ◽  
pp. 771-779
Author(s):  
Jihad B. Bahlis ◽  
M. Saeedmirza
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Nonlinear Analysis ◽  
Principal Stress ◽  
Monotonic Loading ◽  
Analytical Models ◽  
General State ◽  
Element Analysis ◽  
Constitutive Relationships ◽  
Proposed Model

A new, simple, hypoelastic, and anisotropic stress–strain relationship is proposed for modeling the behaviour of concrete subjected to a general state of monotonic loading. The proposed model reduces to an incremental orthotropic model if the direction of the principal stress axes remains constant. It also eliminates the inability of the orthotropic constitutive relationships to model the behaviour of concrete under a general state of monotonic loading when the principal stress axes rotate during the loading process.The capability and reliability of the proposed model for the analysis of structures in which the principal stress direction does not rotate is verified. A finite element computer program is formulated and used for the nonlinear analysis of planar concrete specimens tested by Kupfer, Hilsdorf, and Rusch and by Tasuji and reinforced concrete panels tested by Vecchio and Collins. The results obtained from the analytical models are in good agreement with the corresponding experimental results. Key words: biaxial stresses, constitutive relationships and failure criteria, cracking and postcracking response, finite element analysis, hypoelastic model, orthotropic model, plain and reinforced concrete.

Finite element analysis of frictionless contact problems using fuzzy control approach

2015 ◽  
Vol 32 (3) ◽  
pp. 585-606 ◽  
Author(s):  
F Massa ◽  
H Do ◽  
O Cazier ◽  
T Tison ◽  
B Lallemand
Keyword(s):  
Finite Element ◽  
Fuzzy Logic ◽  
Contact Problem ◽  
Fuzzy Logic Controller ◽  
Computational Time ◽  
Contact Method ◽  
Normal Contact ◽  
Content Type ◽  
Frictionless Contact ◽  
Non Linear

Purpose – The purpose of this paper is to present a new way to solve numerically a mechanical frictionless contact problem within a context of multiple sampling, frequently used to design robust structures. Design/methodology/approach – This paper proposes to integrate a control-based approach, currently used in automation domain, for the solving of non-linear mechanical problem. More precisely, a fuzzy logic controller is designed to create a link between the normal gaps identified between the bodies and the normal contact pressures applied at the interface. Findings – With this new strategy, the initial non-linear problem can be decomposed into a set of reduced linear problems solved using the finite element method. A projection built from the modal bases of each component in contact is considered to reduce computational time. Moreover, the proposed numerical applications highlight an interesting compromise between computation time and precision of contact data. Research limitations/implications – Currently, the proposed Fuzzy Logic Controller for Contact method has been developed for a frictionless contact problem in the case of 2D numerical applications. Therefore, as obtained results are very interesting, it will be possible to expand on these works in a future works for more complex problems including friction, 3D model and transient dynamic responses by adding other controllers. Originality/value – In conclusion, this paper highlights the interest of studying a contact problem by considering automation approaches and defines the basis of future multidisciplinary works.

A Simple Finite Element Based Model for a Constrained-Layer of Viscoelastic Material: Part 1 — Experimental Verification and Comparison With Analytical Models

1998 ◽  
Author(s):  
Carl Sisemore ◽  
Ahmad Smaili
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Viscoelastic Material ◽  
Damping Ratio ◽  
Base Material ◽  
Analytical Models ◽  
Proposed Model ◽  
Experimental Values ◽  
Lumped Masses ◽  
Stiffness And Damping

Abstract In this article, a simple, finite element based model for a constrained layer of viscoelastic damping for beams is developed and implemented. The proposed model uses a series of discrete springs and dampers to model the stiffness and damping, and lumped masses to account for the mass of the viscoelastic material while the base material and constraining layers are modeled with a five-node Timoshenko beam element. The accuracy of the model is verified experimentally by testing damped beams with various damping treatment configurations. The results from the proposed model and the experiments are then compared with the Mead-Markus analytical model. Concerns over the accuracy of the Mead-Markus analytical model are raised and discussed. The results demonstrate that the proposed model can predict the fundamental natural frequency of damped beams to within 3.5% or better of the experimentally determined values and that, with the exception of short and intermediate length constraining layers, the damping ratio can be predicted to within about 8% of the experimental values under most circumstances.

scholarly journals Limits of applicability of the Hertz solution for contact problem.

2015 ◽  
Vol 2015 (2) ◽  
pp. 66-70
Author(s):  
Владимир Сакало ◽  
Vladimir Sakalo ◽  
Алексей Сакало ◽  
Aleksey Sakalo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Contact Problem ◽  
Maximum Pressure ◽  
Correction Factors ◽  
Contact Patch ◽  
Element Method

Possibility of applying of the Hertz solution at close values of the radii of curvature of the pro-files of bodies is analyzed. Research is carried out on the example of contact problem for wheel and rail in case when the contact patch is located on the fillet parts of the wheel and rail. The same problem is solved by using finite element method. The correction factors for specifying parameters such as the size of the contact patch and the maximum pressure obtained by an ana-lytical method are proposed.

Performance enhancement of normal contact ratio gearing system through correction factor

2019 ◽  
Vol 13 (3) ◽  
pp. 5242-5258
Author(s):  
R. Ravivarman ◽  
K. Palaniradja ◽  
R. Prabhu Sekar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Correction Factor ◽  
Bending Strength ◽  
Performance Enhancement ◽  
Transmission Ratio ◽  
Contact Ratio ◽  
Element Analysis ◽  
Normal Contact ◽  
Root Region

As lined, higher transmission ratio drives system will have uneven stresses in the root region of the pinion and wheel. To enrich this agility of uneven stresses in normal-contact ratio (NCR) gearing system, an enhanced system is desirable to be industrialized. To attain this objective, it is proposed to put on the idea of modifying the correction factor in such a manner that the bending strength of the gearing system is improved. In this work, the correction factor is modified in such a way that the stress in the root region is equalized between the pinion and wheel. This equalization of stresses is carried out by providing a correction factor in three circumstances: in pinion; wheel and both the pinion and the wheel. Henceforth performances of this S+, S0 and S- drives are evaluated in finite element analysis (FEA) and compared for balanced root stresses in parallel shaft spur gearing systems. It is seen that the outcomes gained from the modified drive have enhanced performance than the standard drive.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

scholarly journals Development of Simulation Based p-Multipliers for Laterally Loaded Pile Groups in Granular Soil Using 3D Nonlinear Finite Element Model

2020 ◽  
Vol 11 (1) ◽  
pp. 26
Author(s):  
Muhammad Bilal Adeel ◽  
Muhammad Asad Jan ◽  
Muhammad Aaqib ◽  
Duhee Park
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Design Guidelines ◽  
American Petroleum Institute ◽  
Winkler Foundation ◽  
Group Effect ◽  
Pile Groups ◽  
Element Analysis ◽  
Laterally Loaded Pile ◽  
Laterally Loaded

The behavior of laterally loaded pile groups is usually accessed by beam-on-nonlinear-Winkler-foundation (BNWF) approach employing various forms of empirically derived p-y curves and p-multipliers. Averaged p-multiplier for a particular pile group is termed as the group effect parameter. In practice, the p-y curve presented by the American Petroleum Institute (API) is most often utilized for piles in granular soils, although its shortcomings are recognized. In this study, we performed 3D finite element analysis to develop p-multipliers and group effect parameters for 3 × 3 to 5 × 5 vertically squared pile groups. The effect of the ratio of spacing to pile diameter (S/D), number of group piles, varying friction angle (φ), and pile fixity conditions on p-multipliers and group effect parameters are evaluated and quantified. Based on the simulation outcomes, a new functional form to calculate p-multipliers is proposed for pile groups. Extensive comparisons with the experimental measurements reveal that the calculated p-multipliers and group effect parameters are within the recorded range. Comparisons with two design guidelines which do not account for the pile fixity condition demonstrate that they overestimate the p-multipliers for fixed-head condition.

scholarly journals Inlay-Retained Dental Bridges—A Finite Element Analysis

2021 ◽  
Vol 11 (9) ◽  
pp. 3770
Author(s):  
Monica Tatarciuc ◽  
George Alexandru Maftei ◽  
Anca Vitalariu ◽  
Ionut Luchian ◽  
Ioana Martu ◽  
...  
Keyword(s):  
Finite Element ◽  
Young Patients ◽  
Maximum Pressure ◽  
Class Iii ◽  
Element Analysis ◽  
Dental Prostheses ◽  
Abutment Teeth ◽  
Fixed Dental Prostheses ◽  
Implant Therapy ◽  
The Stability

Inlay-retained dental bridges can be a viable minimally invasive alternative when patients reject the idea of implant therapy or conventional retained full-coverage fixed dental prostheses, which require more tooth preparation. Inlay-retained dental bridges are indicated in patients with good oral hygiene, low susceptibility to caries, and a minimum coronal tooth height of 5 mm. The present study aims to evaluate, through the finite element method (FEM), the stability of these types of dental bridges and the stresses on the supporting teeth, under the action of masticatory forces. The analysis revealed the distribution of the load on the bridge elements and on the retainers, highlighting the areas of maximum pressure. The results of our study demonstrate that the stress determined by the loading force cannot cause damage to the prosthetic device or to abutment teeth. Thus, it can be considered an optimal economical solution for treating class III Kennedy edentation in young patients or as a provisional pre-implant rehabilitation option. However, special attention must be paid to its design, especially in the connection area between the bridge elements, because the connectors and the retainers represent the weakest parts.

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