A PREDICTION METHOD OF NONLINEAR CREEP BEHAVIOR OF PVC COATED FABRIC MEMBRANE AT DIFFERENT STRESSES

The uniaxial tension creep tests for PVC (polyvinylchloride) coated fabric membranes of 2/2 plain weave were carried out along the warp and weft directions at five different stresses states. By mean of the generalized Kelvin-Voigt linear viscoelastic creep model with seven parameters (four compliance components and three retarded time), the experimental data were analyzed. The results revealed that there had been good fitting effect for the linear model at single stress and three retarded time had been maintained at multiple stresses. On these bases, the linear viscoelastic model was modified into a nonlinear viscoelastic model with seven parameters (four compliance components and three retarded time) and a nonlinear visco-elastic-plastic model with fourteen parameters (eight compliance components and six retarded time). The latter was amalgamated into a nonlinear model with seven parameters(four compliance components and three retarded time). Considering that the three retarded time of the nonlinear models were the same as the linear model, that the nonlinear factors were come from four compliance components, the experiment data was analyzed with the aid of 4th degree polynomial. The result showed that the method could give better prediction at other stresses.