Residual Stresses in Amorphous Polymers

Abstract

AbstractThe origin of internal stresses in a polymeric component, subjected to an arbitrary cooling, will be described. The differential volume relaxation arising as a result of the different thermal history suffered by each body point was considered as the primary source of stresses build up. A numerical routine was developed accounting for the simultaneous stress relaxation processes and implemented within an Ansys® environment. The volume relaxation kinetics was modelled by using the four‐parameter TNM (Tool‐Narayanaswamy‐Mohynian) phenomenological theory using the PVT (Pressure–Volume‐Temperature) data obtained on a polystyrene sample. The numerical algorithm translates the specific volume theoretical predictions at each body point as applied non‐mechanical loads acting on the component. Thermorheological complexity emerged due to coupling of volume and stress relaxation phenomena A linear dependence of Poisson's ratio on the tensile relaxation modulus was postulated. A quantitative predictions of time dependent stress distribution was realized for two specific test cases.