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Parametric optimization of dental implants

Bensmain W., Benlebna M., Serier B., Abbes B., Bouiadjra B.

Mechanics and Mechanical Engineering

2018

Vol. 22, nr 4

1061--1076

Osseointegration is a fundamental phenomenon of dental implantology. It ensures the stability, the safety and the durability of dental implants and predictable clinical success in long-term. The geometric form of the implant is a defining parameter of osseointegration and implant-bone charge transfer. This is the essential constitutes of this study. In fact, we demonstrate using the finite elements method with tridimensional numerical computations, that the geometrical parameters of the implant conditionate the level and the repartition of the stresses, induced in the cortical bone and the spongy bone during the masticatory process, simulated here by dynamic charging. The effect of several parameters [size and conicity of the implant neck, size and radius of curvature of the implant apex] and the shape of the implant corps on the biomechanical behavior of the bone. The latest was analyzed in terms of variation of the equivalent stress induced in the bone. The purpose of this analysis was the developing of an implant form allowing stress relaxation, during the mastication process, in the living tissue.

Effects of Interaction between Two Cavities on the Bone Cement Damage of the Total Hip Prothesis

Sahli A., Benbarek S., Bouiadjra B., Mokhtar B. M.

Mechanics and Mechanical Engineering

2014

Vol. 18, nr 2

107--120

In orthopedic surgery and more particularly in total hip arthroplasty, the fixation of implants is usually done with surgical cement consisting essentially of polymer (PMMA). Fractures and loosening appear after a high stress gradient. The origin of this phenomenon is the presence of micro–cavity located in the volume of PMMA. The aim of this study is to investigate the effect of the interaction between two cavities on the cement damage where the external conditions (loads and geometric forms) can cause the fracture of the cement and therefore aseptic loosening of the prosthesis. A numerical model is generated using finite element method to analyze the damage of orthopedic cement around the microcavity and estimate the length of the crack emanating from microcavity for each position of the human body. Result show that the damaged area is influenced by the cavity shape (only elliptical cavity shape can initiate damage). The most dangerous cavity position is located in the middle of the cement socket, on the axis of the loading. The distance between two cavities has an effect if it is less than 100 μm. One can estimate the initiation of a crack of maximum length of 16μm.

Numerical analysis of the effect of thermal residual stresses on the performances of bonded composite repairs in aircraft structures

Aminallah L., Benhamena A., Aid A., Merdji A., Bouiadjra B., Serier B., Benseddio N.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2011

z. 99

13-13

In this study the finite element method is used to analyse the effect of the thermal residual stresses resulting from adhesive curing on the performances of the bonded composite repair in aircraft structures. The stress-intensity factor at the crack tip is chosen as fracture criterion in order to estimate the repair performances. The obtained results show that the presence of the thermal residual stresses reduces considerably the repair performances and consequently decreases the fatigue life of cracked structures. The effects of the curing temperature, the adhesive properties and the adhesive thickness on the stress intensity factor (SIF) variation with thermal stresses are also analysed.