Time-Dependent Behavior of a Graphite/Thermoplastic Composite and the Effects of Stress and Physical Aging

Abstract

Experimental studies were performed to determine the effects of stress and physical aging on the matrix dominated time-dependent properties of IM7/8320 composite. Isothermal tensile creep/aging test techniques developed for polymers were adapted for testing of the composite material. Time-dependent transverse (S22) and shear (S66) compliance's for an orthotropic plate were found from short-term creep compliance measurements at constant, sub-Tg temperatures. These compliance terms were shown to be affected by physical aging. Aging time shift factors and shift rates were found to be a function of temperature and applied stress.