Abstract
Recently, fatigue limit estimation based on the dissipated energy measurement using infrared thermography has attracted attention in various industries. In this study, dissipated energy measurement was applied to the evaluation of fatigue properties for composite material. The short glass fiber reinforced plastics, which is called BMC (Bulk Molding Compound) was used. In a staircase-like stress level test, dissipated energy increased with increase of stress level and there was a liner relationship between dissipated energy and energy loss caused by viscoelastic deformation. In constant stress level fatigue test, dissipated energy and thermoelastic temperature change showed the constant value in initial period of fatigue test, and then slightly decreased. On the other hand, energy loss increased with increase of loading cycles. It was considered that this deference between the change of dissipated energy and energy loss were due to the initiation of crack and fiber/matrix delamination. Therefore it was found that dissipated energy for BMC could evaluate plastic deformation of matrix and the condition of fiber/matrix interface.
