CONSTITUTIVE MODELING OF POLYMER-FILMS FROM VISCOELASTICITY TO VISCOPLASTICITY

A unified constitutive model for polymer films is proposed with viscoe lastic characterization at small deformation and viscoplastic characte rization at large deformation based on molecular chain deformation mec hanisms. The evolution equations and the temperature dependence of dra g stress and back stress are established from molecular network theori es in this paper. The material constants are then determined by master curves and a consistent procedure. A good agreement between the exper imental data of polycarbonate film tests and model predictions is achi eved.