Thermo-viscoelastic responses of multilayered polymer composites: Experimental and numerical studies

This study presents experimental works and finite element (FE) analyses of nonlinear thermo-viscoelastic behaviors of multilayered (pultruded) composites under tension. Creep tests are conducted on E-glass/polyester composites having 0°, 45° and 90° off-axis fiber orientations at various temperatures and stresses. Isochronous creep curves show that the nonlinear stress–strain responses increase with time and temperature for composites tested at higher temperatures (75–125 °F) while there is no particular trend seen at lower temperatures (0–50 °F). A convolution integral model is used for the time–stress–temperature dependent responses. The nonlinear viscoelastic model is implemented in FE framework for analyzing responses of viscoelastic pultruded structures. Sensitivity analysis is conducted to examine error in measuring strains during experiments by simulating the creep tests using FE.