Non-Destructive Fatigue Evaluation through Thermophysical Properties Using Lock-In Thermography

Abstract

In this study, we proposed a non-destructive testing and evaluation (NDT&E) method for assessing the micro-scale fatigue damage of carbon-fiber-reinforced plastic (CFRP) structures. The process involves evaluating the thermophysical properties of the material, specifically the thermal diffusivity D and specific heat capacity Cp. To measure these properties, we employed the laser-induced periodic heating method using lock-in thermography, which is suitable for anisotropic composite materials. Our fatigue experiments revealed that the thermal diffusivity D decreased and the specific heat capacity Cp increased with the increase in fatigue cycles. We attribute these trends to the thermal resistance caused by the change in composite microstructure and the degradation of the matrix resin. These findings are discussed in detail, with implications for assessing CFRP structures and potential future research directions.

Keywords

• CFRP
• fatigue damage
• lock-in thermography
• specific heat capacity
• thermal diffusivity