%0 Journal Article
%T Failure Prediction in Bulk Metal Forming Process
%A Ameen Topa
%A Qasim H. Shah
%J International Journal of Manufacturing Engineering
%D 2014
%R 10.1155/2014/385065
%X An important concern in metal forming is whether the desired deformation can be accomplished without defects in the final product. Various ductile fracture criteria have been developed and experimentally verified for a limited number of cases of metal forming processes. These criteria are highly dependent on the geometry of the workpiece and cannot be utilized for complicated shapes without experimental verification. However, experimental work is a resource hungry process. This paper proposes the ability of finite element analysis (FEA) software such as LS-DYNA to pinpoint the crack-like flaws in bulk metal forming products. Two different approaches named as arbitrary Lagrangian-Eulerian (ALE) and smooth particle hydrodynamics (SPH) formulations were adopted. The results of the simulations agree well with the experimental work and a comparison between the two formulations has been carried out. Both approximation methods successfully predicted the flow of workpiece material (plastic deformation). However ALE method was able to pinpoint the location of the flaws. 1. Introduction In metal forming processes, the term workability refers to the degree of deformation that can be achieved in the workpiece without the occurrence of a defect, that is, the appearance of surface or internal cracks. Failure usually occurs as ductile fracture in metalworking and rarely as brittle fracture. The propagation of the cracks is of little interest as the main objective is to avoid their initiation. These cracks usually appear within regions that are highly strained due to extensive plastic flow of the material during the metal forming process [1]. The initiation of ductile fracture is a multistep process consisting of microvoid nucleation, growth, and then their coalescence [2]. Microvoids usually nucleate due to the debonding of the matrix material followed by a stage of void growth in which the microvoids grow under the applied stress state. The final phase of the ductile fracture happens when neighbouring microvoids coalesce together into a crack [3]. The occurrence of ductile fracture in metal forming process is a major limiting factor [4]. The prediction of the initiation of the cracks is important as it allows prior modification of the forming process which can result in sound and reliable products [5]. Therefore, the prediction of ductile fracture in metal forming processes has attracted the attention of many researchers for more than five decades [6] and has been extensively studied in literature with contributions from both academic and industrial research
%U http://www.hindawi.com/journals/ijme/2014/385065/