RESPONSE OF RESIN TRANSFER MOLDED (RTM) COMPOSITES UNDER REVERSED CYCLIC LOADING

Compressive behavior and the tension-compression fatigue response of r esin transfer molded IM7 PW/PR 500 composite laminate with a circular notch have been studied. Fatigue damage characteristics have been inve stigated through the changes in the laminate strength and stiffness by gradually incrementing the fatigue cycles at a preselect ed load leve l. Progressive damage in the surface of the laminate during fatigue ha s been investigated using cellulose replicas. Failure mechanisms durin g static and cyclic tests have been identified and presented in detail . Extensive debonding of filaments and complete fiber bundle fracture accompanied by delamination were found to be responsible for fatigue f ailures, while fiber buckling, partial fiber fracture and delamination were characterized as the failure modes during static tests. Weibull analysis of the static, cyclic and residual tests have been performed and described in detail. Fractured as well as untested specimens were C-scanned, and the progressive damage growth during fatigue is present ed. Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) for the fractured specimen were also performed and the analysis of the fa ilure behavior is presented.