Time-dependent strain distribution in polymers under complex stress history: Experimental study by Moire fringe method and finite element predictions

A combination of experimental and computational methods are developed, for predictions of nonlinear viscoelastic creep of polymers in sheet form, subj ected to inhomogeneous stress states and stress history. A recently propose d multiaxial constitutive model for glassy polymers was implemented in a co mmercial finite element (FE) package. The model was tested by means of cree p experiments on PMMA at elevated temperature, using specimens with a centr al circular hole. The experiments were performed using a tensile creep mach ine, and the geometric Moire fringe method was employed for measuring strai n distribution. The results obtained from the experiment and FE analysis we re compared.