Microstructural damage based modeling of thermal conductivity of cyclically loaded CFRP

Thermography is widely used in the damage characterization of the composite materials. Effective thermal conductivity of the damaged composite can be predicted based on the temperature distribution obtained using pulse thermography. In this work, a new equivalent circuit model (ECM), based on thermal resistance of the constituents, was developed to compute longitudinal and transverse thermal conductivity of carbon fiber reinforced polymer (CFRP) composite for given microstructural damage state. The damage state, in terms of fiber breakage and interface debonding, was obtained from fatigue loading of CFRP composite. The thermal conductivity of the composite obtained using ECM was in excellent agreement with finite element simulations. Finally, the transverse conductivity obtained from ECM was linearly proportional to the mean grey scale obtained from IR thermography. This is for the first time that an observed thermal property (IR thermography) was correlated to an independently modeled thermal property (transverse conductivity) based on microstructural attributes.