Analysis for Neck Propagation of Plastic Molding (1) : Neck Propagation Behavior of Polybutylene Terephthalate Molding

摘要

The neck formation and neck propagation behavior of plastic moldings are very complicated and one of the most important subjects in the field of polymer processing. In this paper, we report our results on the necking and neck propagation behavior for Polybutylene terephthalate (PBT) in uniaxial tension tests. In addition, a numerical model for PBT molding has been developed, and the neck propagation behavior under tensile load has been analyzed by the finite element method (FEM). By comparing numerical results with experimental ones, it could be confirmed that necking initiates and propagates after the specimen undergoes uniform plastic deformation. The effect of strain rate on load-displacement behavior has also been studied in uniaxial tensile tests. Furthermore, a constitutive relationship at low strain rates, which can be used to estimate the actual load-displacement behavior, could be obtained by FEM.