Numerical Analysis for Neck Propagation of Plastic Films (2)

Abstract

The analysis of large deformation behaviors for polymers is regarded as one of the most important subjects in the fields of film and fiber processing.We studied unique load-displacement behavior in neck formation and neck propagation of polymers, that is decrease of load just after the yield point, by use of finite element method (FEM). Especially, the relationship between the decrease of load and elastic-plastic constitutive law was investigated in detail.The following results were obtained;(1) The decrease of load just after the yield point could be reproduced in the results of numerical analysis.(2) Unloading occurs in the unnecked part simultaneously with neck formation, and the decrease of load after the yield point is originated by this unloading.(3) The decrease of load after the yield point, the increase of cross section at unloading part, and the magnitude of neck depend on the size of plastic deformation region before steep rise of tangent modulus.