Concept for the numerical description of the true stress/strain behaviour of semi-crystalline thermoplastics

Abstract

In this paper a concept is presented to describe the true material behaviour of semi-crystalline thermoplastics. Investigations of the true material behaviour are needed because thermoplastics are being increasingly used as materials for components that are subject to plastic strains. In order to be able to describe these strains as exactly as possible, knowledge of the true stress/strain behaviour is of major importance. Therefore, in this paper a description formula for the true material behaviour is presented, which also defines the material behaviour in the viscoplastic area. The formula parameters are shifted to master curves at a definite reference temperature with the help of the time–temperature–shift principle (TTS-principle). By means of this the temperature and strain-dependent material behaviour can be described quickly and over a wide range. It is an efficient way of obtaining material input data for finite-element-analysis-programs without adopting large experimental investigations.