Finite Element Analysis of the Hydro-mechanical Hole Punching Process

Abstract

This paper describes the characteristics of the hydro-mechanical punching processs on developing. The process is inverstigated with the finite element analysis uting the commercial code(ABAQUS). The hydro-mechanical punching process is divided by two stages. The First stage is the mechanical half piercing in which a upper punch goes down until the initial crack is not occurred. The next stage is the hydro punching stage where a lower punch goes up until the final fracture is occurred. In order to evaluate the fracture of material, the ductile fracture criteria such as the Cockcroft, Brozzo and Oyane are adopted. The valud of ductile fracture criteria is calculated with VUMAT in ABAQUS Explicit. The hydro-pressure retards the initial crack on a blank and induces the another crack under a blank during the punching process. Then, the fianl fracture zone is placed on the middle surface of a blank to thickness direction. Therefore, the more clear shearing surface can be obtained with the process of hydro-mechanical punching than with the conventional one.