Papers by Author: Mehdi Bayat

Abstract: The present work studies the crack behavior along the surface of the friction stir welded (FSW) joint of 2024-T351 aluminum alloy. The surface engineering of shot peening and skimming are used to enhance the fracture characteristics of the joint. Then multiple crack initiation is detected within FSW zones by scanning electron microscopy, while plastic replication technique is used to monitor the crack propagation. The variation of residual stress is measured (using hole drilling technique) as well as hardness characteristic (using standard method of Vicker) to study the fatigue life of the FSW by two models of Pearson and Nicholls, incorporating crack closure and stress relaxation.

Abstract: The work presents a summary of previous studies on fatigue crack propagation within various Aluminum alloys. The effective characteristics on crack growth are first highlighted and the influence of surface engineering such as polishing, shot peening and skimming to enhance the failure resistance are discussed. Several different existing developed models for predicting the rate of crack propagation are compared in terms of incorporated effective parameters. Finally numerical and computational analyses as the accurate, fast and cheap methods which have attracted the Engineers’ interest are reviewed and compared with other methods.

Abstract: In this study a subroutine was developed and added in the pre-processing module of the frame work of commercial package of ANSYS to distribute the extra masses according to specific assigned centre of gravity (COG). The work further calculate the first bending and torsional natural frequencies of the simplified body in white (BIW) model of automotive in order to maximize these frequencies with final mass constraint. It is found that adding the extra masses symmetrically about longitudinal axis helps to improve the first bending and torsion natural frequencies. However, removing the mass along this axis leads to have higher values in the case of first bending and natural frequencies.