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Parametric optimization of dental implants

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

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 4

1061--1076

EN

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.

2

Effect of residual stresses on the stress intensity factor of cracks in a metal matrix composite: numerical analysis

Ramdoum S., Bouafia F., Serier B., Fekirini H.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 1

119--131

EN

In this work, the finite element method was used to determine the stress intensity factors as a function of crack propagation in metal matrix composite structure, A threedimensional numerical model was developed to analyze the effect of the residual stresses induced in the fiber and in the matrix during cooling from the elaboration temperature at room temperature on the behavior out of the composite. Added to commissioning constraints, these internal stresses can lead to interfacial decohesion (debonding) or damage the matrix. This study falls within this context and allows cracks behavioral analysis initiated in a metal matrix composite reinforced by unidirectional fibers in ceramic. To do this, a three-dimensional numerical model was analyzed by method of finite element (FEM). This analysis is made according to several parameters such as the size of the cracking defects, its propagation, its interaction with the interface, the volume fraction of the fibers (the fiber-fiber interdistance), orientation of the crack and the temperature.

3

3D FE analysis of the behavior of elliptical cracks on orthopedic cement of the total hip prosthesis

Benouis A., Zagane M. S., Boulenouar A., Serier B., Belgherras M. E.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 3

803--813

EN

An explicit analysis conducted on the crack behavior in chirurgical cement (Polymethylmethacrylate – PMMA) used for Total Hip Prosthesis (THP) is of great importance in collecting information about the nature of the phenomenon of loosening of the cement application. The rupture of the orthopedic cement is practically the main cause of this loosening. Understanding diﬀerent rupture mechanisms give a great value in advancing the durability of the cemented total prosthesis. The purpose of this study is to analyse cracks behavior, initiated in the cement that links the femoral-stem with the bone, using the Finite Element Analysis Method (FEM). The present study brings into focus the variation of the stress intensity factor in modes I, II and III. This rupture criterion is used according to the nature of crack, its orientation and its location in the orthopedic cement. At ﬁrst, the level and distribution of the equivalent von Mises stress is analysed, which is induced in the medial, proximal and distal parts of the bone cement. Then, the behavior of diﬀerent geometric forms of an elliptical crack is evaluated which are located and initiated within the body of these three parts.

4

Prediction of crack propagation direction in the cemented total hip prosthesis

Charef D., Serier B.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 3

703--716

EN

The major inconvenient of the Poly methyl methacrylate (PMMA) is the crack formation; this phenomenon takes place during the polymerization process which is the result of an exothermic chemical reaction. In this context, this study aims to predict the behavior of macros cracks situated in the most heavily loaded sites in newly used bone cement. In fact, the prediction of crack propagation directions in bone cement during exercising the most practiced activity by patients allows determination of the most favorable cracking directions and subsequently provides orientations for the studies aiming to fight against this phenomenon.

5

Numerical analysis of the foods nature effect on the mechanical behavior of dental implants

Sifi M., Serier B., Merdji A., Benaissa A, Mootanah R.

Mechanics and Mechanical Engineering

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2017

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Vol. 21, nr 4

1021--1032

EN

This study focuses on a three-dimensional numerical analysis by the finite element method, the mechanical behavior of the dental prosthesis implant composed of a single implant. The effect of the nature of food on the level and distribution of the Von Mises equivalent stress generated in the bone and the elements that constitute this prosthesis have been highlighted. It has been shown that this level is particularly important that the Crushed masticated foods are rigid. This work was carried out to answer questions whose purpose was to analyze the risk of overload in the mandibular region. Loads transfer mechanisms and the possible failure of osseointegrated implants, the shape of the implant, the geometrical and mechanical properties of the placement site and bone resorption of the crest. A proper estimation of these effects allows the correct design of the implant.

6

Finite element analysis of the behaviour of a crack in the orthopedic cement

Benouis A., Boulenouar A., Serier B.

Journal of Theoretical and Applied Mechanics

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2016

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Vol. 54 nr 1

277--284

EN

In this paper, the finite element method is used to analyse the crack behaviour in the orthopedic cement of the total hip replacement by computing the stress intensity factors (SIFs) arround the crack tip. In this work, three cases are studied: crack emanating from a cavity, interaction effect of the crack emanating from a cavity with another cavity and the interaction effect of two cracks emanatingfrom two cavities. The stress intensity factors under mixed mode problems at the crack tip are computed for three zones of prosthesis: proximal, median and distal. The obtained results show that the crack initiated from a micro-cavity in the distal zone of cement can be propagated at the same time by opening and shearing of its lips. It is contrary to that initiated in the proximal zone which cannot be propagated. The mechanical behaviour of cracks in the medial zone depends of the crack initiation position.

7

The mechanical behaviour of dental implant with stress barrier

Merdji A., Aminallah L., Bachir Bouiadjra B., Serier B., Mootanah R., Ould Chikh E.B., Moslih A.M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2011

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z. 99

36-37

EN

It has been well known that the success of dental implant is heavily dependent on initial stability and long-term osseo-integration due to optimal stress distribution in the surrounding bones. For this reason, the search of the rational solutions to reduce these stresses has become an important issue in this field. Alternatives to reduce the forces transmitted to implants have been studied, including variations in implant positioning, implant design, prosthesis shape, occlusal requirements, prosthetic components and prosthetic materials. Thus, a new concept of adding a bio-elastomer to the prosthetic components of implant system was interposed between the abutment and the framework crown in order to damp the occlusive shocks and to attenuate the stress concentrated at the implant/bone interface. The new implant system design was assessed by the three dimensional finite element techniques using ABAQUS program to study the effect of elastomer material under an occlusal load on the induced equivalent von Mises interface stresses. These stresses were compared with those provoked by the standardized implant. The von Mises stress distribution indicated that stress was maximal around the top of the implant with varying intensities in the different loading cases. The stress was highest in the cortical bone at the neck of implant and lowest in the cancellous bone. Overall, the novel implant provoked lower interface stresses only in the cortical bone due to the stress shielding effect of the elastomeric stress barrier.

8

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

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2011

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z. 99

13-13

EN

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.