Paper number 1136

AN EXAMINATION OF HEAT CONDUCTION EFFECT IN INFRARED STRESS MEASUREMENT OF CFRP LAMINATES

Sunao Sugimoto¹ and Takashi Ishikawa¹

1 Composite Structure Section, Structures Division, National Aerospace Laboratory
6-13-1, Ohsawa, Mitaka, Tokyo 181-0015, Japan

Summary

In an infrared stress measurement for multi-lamina CFRP, it is important to evaluate the effect of heat conduction from inner layers induced by 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 gives an influence to the surface temperature state because it has the same frequency as the applied loads. As the 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, were 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.

Keywords

thermoelastic constant, thermal expansion, infrared stress measurement, unsteady heat conduction, carbon-epoxy.