Evaluation of thermal degradation of unidirectional CFRP rings

We have studied the thermal degradation of unidirectional carbon-FRP (CFRP) rings. First, we developed a method based on the ring tensile test for evaluating hoop directional strength. And we calculated the distribution of hoop stress by a finiteelement method considering friction. Then, we measured the thermal reduction of fatigue strength of unidirectional CFRP rings. To evaluate the degradation of fatigue strength, we applied the Arrhenius equation to confirm the relation between temperature and time. Using this evaluation method, we predicted the thermal reduction of fatigue strength under high temperature and long exposure time