Experimental determination of the fracture forming limits in metal forming

Abstract

AbstractThis paper revisits the determination of the fracture forming limits in metal forming with the purpose of providing readers understanding on the experimental procedures and identification of their pitfalls and sources of error. The presentation covers fracture in sheet and bulk metal forming under three different crack opening modes: by tension (mode I of fracture mechanics), by in-plane shear (mode II), and by out-of-plane shear (mode III). It is shown that the determination of the fracture forming limits must account for the specificities of sheet forming, which is fundamentally based on material flow under plane stress conditions, and of bulk forming, which essentially features material flow under three-dimensional conditions. The content of the paper is an attempt to merge previous work of the authors in the determination of the fracture forming limits, which is scattered through various publications, so that a comprehensive view of their accumulated experience in sheet and bulk forming can be provided in a single publication.