ＣＦＲＰ積層複合材料の熱残留応力と破壊強度

Abstract

Considering temperature dependency of the material properties of CFRP-UD composites, macroscopic thermal residual stresses of filament wound (FW) CFRP induced in the curing process are calculated as the first step. After evaluating these residual stresses, initial failure strengths of CFRP-FW materials are obtained based on three types of basic strength theories, i.e., Maximum stress theory, HOFFMAN theory and TSAI-WU theory. Curing conditions have considerable effect on the temperature dependency of the material properties and, as a result, on the thermal residual stresses. An important result is that proper combinations of loads and winding angles for helical FW-cylinder specimens are found in order to determine the key parameter in TSAI-WU theory, F12. From experimental results by others, it can be concluded that the minimum permissible F12 is suitable for this CFRP, contrary to the recommendation in the original paper by TSAI and WU. Thermal residual stresses have significant influence on the failure strengths. In most cases, failure strengths on the safest side are given by TSAI-WU theory using minimum F12.