Journal of Materials and Engineering Structures

209-221

Authors: Samia Khelifi, Hacene Ait Aider, Naceur Eddine Hannachi, El Mahdi Meghlat

The heterogeneous materials with fragile matrix behave in a softening manner after the elastic phase. This degradation can be modeled by the mechanics of the continuous damage by the introduction of a variable which measures the reduction of the resistant surface due to the initiation and the propagation of cracks. The Mazars model chosen for our study is isotropic and takes in account the asymmetrical behavior of concrete (traction-compression). The model is implemented in a finite element program working with GID interface, for the simulation of the real behavior of the material up to ruin. The application of the program to simple structures shows the complexity of the model to accurately describe the behavior of such a material. The main objective of our work is then, to highlight the limits of such a formulation by exploiting the results resulting from the simulation.

237-251

Authors: Amal Sinaceur, Ahmed Sahli, Sara Sahli

This paper deals with the development a finite element of laminated planar gantry based on the positional formulation whose kinematics enables independent turns and variation of slab thickness in an extension of the Layerwise theory. The objective is to verify the results obtained with the element proposed in this work and to compare its efficiency in relation to the two-dimensional finite elements. In addition, the analyzes are performed in order to verify the consistency, the efficiency and the robustness of the formulation with respect mainly to the correct representation of the stresses distributions. It is intended, therefore, to obtain an element capable of performing non-linear geometric analyzes in structures of plane porticoes composed of laminated composite materials with thin or thick cross-section. Thus, the results of strain distributions and stresses are expected to be more realistic along the thickness and interfaces, aiming at future modelling of the lamination failure process by delamination or sliding. The finite element proposed in this work presents a kinematics based on the Layerwise theory, but with positions intrinsically compatible by the positional mapping functions themselves. The formulation is geometric nonlinear with the possibility of large displacements and rotations and the proposed kinematics allows to represent the Zigzag effect and the transverse heterogeneity. In all examples, numerical analyzes are performed on the Ansys software using two-dimensional finite elements.

267-277

Authors: Djedjiga Boukhlef, Dalila Boughrara, Hassane Mohellebi

The objective of this work is to develop a digital model in order to envisage metal degradation on a microscopic scale. The reaction on the surface of the anodic considered as a degradation reaction when the surface forming the cathode remains unchanged. A one dimensional analytical solution representing the two mediums (anode and cathode), is introduced in the form of boundary conditions of Neumann type to the interface metal/electrolyte and thus the resolution was performed without mesh the analytical zone. Also, no re-meshing solving domain was need when simulating the border deformation.

289-304

Authors: Ahmed HAKEM

Tempering generates significant microstructural changes, usually hardening. In this study, we investigated the influence of the tempering treatments by temperature variation in increments of 10 and 20°C on the evolution of the main mechanical and structural characteristics of AlSi7Zn3Cu2Mg alloy. This is applied in the case cast in sand and shell gravitation both mechanically and manually. The pieces made from this alloy are part of the components of various achievements of S.N.V.I. Rouïba Algiers. To identify the alloy, four of the most used techniques were used: traction, indentation, resilience and microstructure.