Effect of Physical Aging and Variable Stress History on the Creep Response of Polymeric Composites

In this project the effect of physical aging on the creep of IM7/K3B (a high temperature thermoplastic polyimide resin based composite) is being studied. The effect of physical aging on the creep behavior of IM7/K3B is studied by conducting tensile creep tests on unidirectional and multiangle specimens. The testing program for this study is currently underway and results will be forthcoming. In an earlier paper a model capable of modeling the effect of physical aging on the creep response with frequently changing stress level was proposed based on the Boltzmann superposition integral. This linear model is now extended to the nonlinear region through the use of Schapery’s theory. In these models the effect of physical aging is incorporated through the use of effective time theory proposed by Struik. The proposed analytical model is verified by comparing, predictions with data from literature.