Numerical Analysis of Heat Conduction Effect Corresponding to Infrared Stress Measurements in Multi-Lamina CFRP Plates

In an infrared stress measurement for multi-lamina CFRP, it is important to evaluate the effect of heat conduction from inner layers induced by the thermoelastic effect. Although a temperature amplitude at a specimen surface is measured in the infrared stress graphic system, the heat flux from the inner layers influences the surface temperature state because it has the same frequency as the applied loads. As a preliminary step of analysis, thermoelastic coefficients of unidirectional CFRP were investigated first. Then, the effects of heat conduction were evaluated numerically for two stacking sequences of CFRP laminates based on an analytical equation and finite element analysis. These calculated results were compared with the experimental results. Two kinds of theoretical results, analytical and finite element analysis, agreed well with experimental results. It was clearly indicated that the thermal conduction must be considered for the infrared stress measurement of multi-lamina CFRP.