抄録
Fatigue tests of Sheet Molding Compounds (SMC) are carried out for the purpose to investigate the diminution of the stiffness due to cyclic loading, the change of crack situation dependent of the number of cyclic loading and the relation of the current stiffness to the crack length. A linear relationship between the stiffness and the density of surface crack in fatigue process is recognized although the dependence of this relation on the applied stress level clearly exist. From further observation on the crack behavior inside of the specimens, it is found that the applied stress dependence of the relation is caused by the difference of crack behavior due to cyclic loading.
