The main objective of the research was to examine wrinkling behavior of blanks during deep drawing of pressure vessel end closures. This research was conducted, in part, to provide technical support to a local industry, C. E. McPherson Ltd. at Kingston, Ontario, which is a division of Conrex Steel Ltd. at Toronto. The finite element method was utilized as the major method of investigation to simulate the forming operation. In addition, experimental tests were carried out under similar conditions to assess the finite element results. Manufacturing processes at C. E. MacPherson Ltd. were also studied to give an understanding of the complexity of the operation.

A large body of literature describing theoretical, numerical and experimental studies of wrinkling was reviewed. Based on this review, important factors affecting the onset and growth of wrinkles were identified. One such factor, in the context of finite element modeling of the process, was the introduction of material imperfections to the model in its initial state.

In the current research, the effects of these “initial imperfections” are systematically investigated. Finite element models of the deep drawing of pressure vessel end closures are developed which include various types and magnitudes of imperfections. The results are validated against experimental data gathered at C. E. MacPherson.

The general trends of the model results and those obtained from experiments were in good agreement. It was shown that initial imperfections in material and tooling, play a key role in the initiation of wrinkling in finite element modeling of a deep drawing process. More specifically, it was shown that tooling imperfections are a critical factor while material imperfections have little impact on the formation and growth of wrinkles.