S0406-1-3 一方向CFRPのトランスバース疲労強度に及ぼす応力比と板厚の影響(プラスチック基複合材料の加工と評価(1))

Abstract

Effects of stress ratio and laminate thickness on the transverse fatigue behavior of unidirectional CFRP have been examined. First, constant-amplitude fatigue tests were performed at various stress ratios on two kinds of 90° specimens with different thickness. The transverse fatigue life under tension-tension fatigue loading became shorter with decreasing stress ratio or with increasing specimen thickness. Under compression-compression fatigue loading, on the other hand, both the stress ratio and laminate thickness had no significant influence on the transverse fatigue life. It was found that the fatigue life becomes the shortest at the critical stress ratio (i.e. the ratio of compressive strength to tensile one), regardless of the thickness of specimens. Then, an existing constant fatigue life (CFL) diagram based fatigue life prediction method was tested on the 90° laminates with different thickness. Results showed that it does not allow accurate prediction of the observed transverse fatigue behavior. Finally, a new CFL diagram based mode that consists of three segments has been developed, and evaluated by comparing with experimental results.