マルコフ過程による炭素繊維束の強度信頼性解析

抄録

The reuse of carbon fibers (rCFs) recovered from waste carbon fiber reinforced plastics (CFRPs), which volume is expected to increase, is becoming increasingly important. When rCFs are used to reproduce CFRPs, it is essential to evaluate the tensile strength reliability at the fiber bundle (FB) level. This study aims to clarify the effects of frictional stress on the FB tensile strength reliability. A stochastic model based on a Markov process was proposed to describe the tensile fracture behavior of FBs. The key advantage of employing the Markov process lies in its ability to discretize the fracture process into multiple states, each representing FBs with varying number of broken fibers as a function of applied stress. Furthermore, each state is characterized by a probability, enabling the analysis of FB strength reliability. The proposed model was applied to stress–strain curves obtained from tensile tests of FBs consisting of 12,000 CFs. The model exhibited good agreement with the experimental results and enabled estimation of both the Weibull parameters for CF strength and the friction coefficient. Finally, the effect of frictional stress on strength reliability was analyzed. The results found that frictional stress improves the overall strength reliability of FB.