International Journal of Materials Engineering 2012, 2(6): 90-104 DOI: 10.5923/j.ijme.20120206.04 Fracture Behavior of the Cement Mantle of Reconstructed Acetabulum in the Presence of a Microcrack Emanating from a Microvoid D. Ouinas 1,* , A.Flliti 1 , M. Sahnoun 1 , S. Be nbare k 2 , N. Taghezout 3 1 Laboratoire de modélisation numérique et expérimentale des phénomènes mécaniques, Department of Mechanical Engineering, University Abdelhamid Ibn Badis, Mostaganem, 27000, Algeria 2 LECM, Department of Mechanics, Faculty of Engineering, University of Sidi-BelAbbes, 22000, Algeria 3 Department of Computer Science, University of Es-Senia Oran, BP 1524, El-M' Naouer, 31000, Oran, Algeria Abstract In this work, the finite element method is used to analyze the behavior of the crack emanating from a microvoid in acetabular cement mantle by computing the stress intensity factor. A simple 2D multilayer model developed by Benbarek et al.[1] to reproduce the stress distributions in the cement mantle has been used. To provide the place of birth of the crack, the stress distribution around the microvoid is determined in several positions for three different loads. The effect of axial and radial displacement of the microvoid in the cement is highlighted. The results indicate that the stress distribution , xx  yy  and xy  induced in the cement around the microvoid are not homogeneous and this, whatever its position. In addition, there is a large birth risk of cracks in several radial directions depending on the position of the microvoid in the cement mantle. The crack can be triggered in several directions in mode I or mode II, while the mixed mode is dominant. The K I and K II SIF varies according to the position of the microcrack and the microvoid in the cement. They increase proportionally with the increase of the weight of the patient. It should be noted that the K I SIF are two times higher than the SIF K II . The maxima of the K I SIF are obtained for the position of the microvoid α = 100° and θ = 45° of the microcrack and the risk of the propagation of the microcrack is very important for this orientation. Keywords Bone cement, Acetabulum, Microvoid, Microcracks, Stress Intensity Factors, Finite Element Analysis 1. Introduction Although the Polymethylmethacrylate has long been known as a fixative in orthopedics dental prostheses, its first use in hip arthroplasty in 1962[2]. Despite the various disadvantages of PMMA, improved techniques of preparation and implementation of cement and implementation methods contributes to the survival of cemented arthroplasties. In addition, the function of fixing the implant, the bone cement is responsible for transferring the loads of the joint to the bone. Face loads transmitted, which can reach in some circumstances eight times the weight of the patient[3,4], bio-competence cement must be good[5]. Thus, the mechanical and physical properties of cement are determining in the service life of the implant[6,7]. These properties are strongly affected by the size and number of pores in cement[8]. Indeed, the porosity can cause crack * Corresponding author: douinas@netcourrier.com (D. Ouinas) Published online at http://journal.sapub.org/ijme Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved initiation by fatigue, by creating irregular areas[9,10]. Thus, surgeons tend to reduce the porosity to ensure greater resistance to fatigue. Gold, that this trend is directly related to the chosen method of mixing during the preparation of cement[11]. For example, the conventional method of mixing leads to a porosity ranging from 5 to 16% depending on the type of cement, while the method of "vacuum mixing" generates a porosity of 0.1 to 1%[12,13]. Some authors assume that the latter method, increases the mechanical properties largely due to the decrease in micropores and macropores[14, 15], thus improving the life of the cement[16,17]. The effect of the position and orientation of a crack in the cement in three loads using the finite element method has been studied by Serier et al.[18] and Bachir Bouiadjra et al.[19]. They indicate that, for the third case load, the risk of crack propagation is higher when the crack is in the horizontal position for both failure modes. Achour et al.[20] presented a study on the mechanical behavior of the damage (failure) of the interface between the cement / bone and cement / stem in total hip prosthesis. They conclude that interfacial crack (cement / bone) in the distal region can spread by opening and shear; it can cause a risk of brutal