Analysis of the puncture of a bisphenol‐a polycarbonate disc

Abstract

Abstract The finite element technique is applied to analytically predict the response of a disc made of BPA‐polycarbonate during a displacement‐controlled puncture test with a hemispherical indenter. The analysis includes effects of contact load, large displacements and rotations, and large strains and material yielding. Two general topics are addressed with this analysis. First, it is shown that the load‐displacement behavior of impacted, BPA‐polycarbonate plates can be accurately predicted over a wide range of engineering interest (strains up to 30 percent) using a bilinear representation of the stress‐strain curve and flow theory of plasticity. For this purpose, the von Mises criterion is applied to define yielding in a generalized biaxial stress state, and strain rate effects are incorporated through the use of a yield stress consistent with the initial strain rate during the test. Second, in order to broaden the understanding of results associated with this widely used test, a number of mechanical and material effects are discussed, including large displacements, friction at the clamped support and indenter head, and clamping pressure at the support. Lack of agreement between the present analysis and experimental results with regard to ultimate load at puncture suggests that strain hardening and strain rate hardening of the material during the high‐strain portion of the test (30 percent‐60 percent) must be more accurately modeled for improved predictive capability.