Abstract
The following conclusions were obtained as a result of examining the fatigue strength characteristic from observation of fatigue testing and a fracture paying attention to damage to the resin / fiber interface in GFRP which denatured resin. 1) The damage mechanism was the same although Young's modulus fell PDMS compared with PC. 2) In fatigue testing, the life difference in a high stress region is based on the difference in a damage mechanism. 3) It generates with early elongation and damage results in destruction through the rigid fall by the crack progress following it.