Carbon/Epoxy複合材料の応力比ランダム疲労試験法と寿命予測法の提案

抄録

Effects of random R-ratio loading on fatigue life of a quasi-isotropic woven fabric CFRP laminate have been studied. A new methodology for generating random R-ratio loading is first developed with the help of the anisomorphic constant fatigue life diagram approach. In the random fatigue testing, different R-ratio waveforms of different stress levels are randomly generated for two constant values of life, respectively, and they are alternately sequenced to form a block that is repeatedly applied to specimens of the composite. Random loading test results suggest a strong interaction between the waveforms consecutively applied. It is demonstrated that the Miner life based on the controlled original waveforms in the random R-ratio loading is excessively optimistic. In contrast, the use of the Miner rule in conjunction with the rain flow method allows much better prediction of fatigue life with an accuracy of a factor of two.