Numerical analysis of the behavior of repaired cracks with composite patch in thick metallic structures (S06)

In this study, the behavior of repaired cracks with bonded composite patch is analyzed numerically. The stress-intensity factor at the crack tip is chosen as fracture criterion in order to estimate the repair performances. This factor at the crack front is computed using three-dimensional finite element method. The obtained results show that the stress intensity factor at the crack front is highly reduced by the presence of the patch repair. The increase of the thickness of the repaired structure has a negative effect on the repair efficiency. The effects of the geometrical parameters on the stress intensity factors were analyzed. These parameters must be optimized in order to improve the repair performances

The Spiny Lobster, Palinurus mauritanicus (Gruvel, 1911) from Algerian West Coasts: A Species to Protect.

The study of the biometric characteristics of the pink lobster, Palinurus mauritanicus allowed us to define some parameters related to reproduction and growth of a noble little-known species in the Mediterranean, which is not protected in Algeria, and tends to be scarce. To avoid future a pronounced decline in the fishable stock and allow a rational balance of specimens attending island fishing areas; our recommendations are based on observations made ??during sampling process that are resumed as follows: prohibit throughout the year capture of berried females, and returned them to water in case of accidental trawl capture, closing the lobster fishing during periods of reproduction and egg maturation (July, August an

L’écosysteme steppique face à la désertification : Cas de la région d’El Bayadh, Algérie

La steppe algérienne est un écosystème aride caractérisé par des ressources naturelles limitées, un sol pauvre, des formations végétales basses et ouvertes et des conditions climatiques sévères. Ce travail est une contribution à l'analyse de la désertification dans la région d’El Bayadh. Le travail est basé sur deux méthodes de suivi et de compréhension. Un diagnostic phyto-écologique et l’utilisation de la télédétection et SIG comme outils puissants de suivi et d'investigation. L’objectif est de mettre en évidence l’importance du phénomène et d’analyser les principaux facteurs discriminants dans l’évolution de ce problème écologique et ses conséquences socio-économiques sur l’équilibre du système de l’organisation pastorale traditionnelle.The algerian steppe is an arid ecosystem characterized by limited natural resources, a poor soil, and low and opened vegetable formations and severe climatic conditions.This work is a contribution of studying the problem of the desertification in El Bayadh region. It is based on two methods of follow-up and understanding, a phyto-ecological diagnosis and the use of remote sensing and SIG as powerful tool of follow-up and investigation. The objective of this paper is to highlight the importance of desertification phenomena in Algeria and to analyze the principal discriminating factors in the evolution of this ecological problem and its socio-economic consequences on the traditional system balance of the pastoral organization

3D Crack Behavior in the Orthopedic Cement Mantle of a Total Hip Replacement

The total hip replacement is an operation that replaces a diseased hip with a mechanical articulation. Both components of the mechanical articulation (stem and the cup) are bonded to bone using orthopedic cement, whose reliability determines the longevity of the implant. The cement around the metallic stem forms a mantle whose strength and toughness determine its resistance to fatigue and failure by fracture. Typical cements are acrylic polymers that often suffer from internal cracks and other defects created during polymerization. This study is a systematic analysis of preexisting 3D crack behavior in the orthopedic cement mantle when subjected to external body forces. Different crack orientations and angular positions around the mantle are studied to identify which locations will propagate the crack. This is accomplished by a global stress analysis of the mantle followed by a failure analysis. Amongst others, the existence of a crack in the proximal region of the orthopedic cement is identified as a critical area, especially in the lateral sides of the stem in the radial direction

Damage of the Bone-Cement Interface in Finite Element Analyses of Cemented Orthopaedic Implants

In orthopedic surgery and particularly in total hip arthroplasty, fixation of femoral implant is generally made by the surgical cement. Bone–cement interface has long been implicated in failure of cemented total hip replacement (THA), it is actually a critical site that affect the long-term stability and survival of prosthetic implants after implantation. The main purpose of this study is to investigate the effect of cement penetration into the bone on damage scenario at the interface. Previously most researchers have been performed to study damage accumulation in the cement mantle for different amount of cement penetration. In this work, bone–cement interface integrity has been studied for different mechanical properties. Cohesive traction separation law is used to detect contact damage between cement and bone. Results showed that a larger debonded area was predicted proximally and distally. Adhesion between bone and cement is affected mainly by cement penetration into the bone. Higher cement penetration into the bone leads to a good load transfer. A lower strength of the bone–cement interface due to a lower mechanical property results in faster interface damage. So we advise surgeons to well perpetrate the bone for long-term durability of cemented THA

Analyse par la méthode des éléments finis du comportement en rupture du ciment de l'implant femoral

La tenue mécanique de la prothèse totale de hanche dépend essentiellement de la nature du ciment utilisé. Le rôle principal du ciment est d'assurer une bonne adhésion implant–os et de minimiser le transfert de charge de l'implant à l'os. Sous l'effet des sollicitations mécaniques, le ciment doit pouvoir résister à l'initiation et à la propagation de fissure pouvant conduire à sa ruine et par conséquent au descellement de la prothèse. Notre travail s'inscrit dans ce contexte et a pour objectif l'analyse par la méthode des éléments finis du comportement en rupture du ciment fixant l'implant à l'os. Le champ de cette analyse s'étend sur différentes zones du ciment (proximale, médiane et distale) des côtés extérieur et intérieur du fémur. Nous montrons clairement l'effet de la position et de l'orientation de la fissure dans le ciment sur les variations du facteur d'intensité de contrainte en pointe de fissure