Evaluation of fatigue damage in CFRP laminates based on periodic heating method using lock-in thermography

Abstract

Carbon fiber reinforced composite material (CFRP) is widely used for structural members of aircraft and automobiles because of its advantages such as high specific strength, corrosion resistance, and fatigue resistance. On the other hand, it is required to clarify the fatigue / deterioration generation mechanism to extend the design life. In this report, a new method was proposed for evaluating fatigue damage of CFRP laminates by the lock-in thermography. The results of verifying its validity with tensile test pieces with different fatigue processes was reported. A significant decrease in the in-plane thermal diffusivity was confirmed. However, it was suggested that it should be corrected by the amount of change of the fiber orientation angle. Out-of-plane thermal diffusivity results showed that the amount of decrease was small compared to the in-plane direction. Although it was suggested that it may have captured the occurrence of local fatigue damage. In the future, it will be necessary to investigate the effect of local fatigue damage on the thermal diffusivity using a numerical analysis model.