Fiber Break Evolution and Fatigue Life Prediction of CFRP with Random Fiber Distribution

Abstract A new method on fatigue life prediction of unidirectional (UD) carbon fiber reinforced plastic (CFRP) is proposed based on fatigue characteristic of single fiber and expansion of broken fiber clusters. Both of statistical fatigue strength of single fiber and non-uniform fiber distribution are considered to assess the fiber break evolution characteristic and the fatigue life of CFRP. A stress redistribution coefficient (SRC) model is proposed to calculate the magnitude of stress overload in intact fibres after nearby fibre break. The SRC depends on not only the distance between broken and intact fibers but also the number of fibers adjacent to the broken fiber. A flowchart is established to predict fatigue life of UD CFRP based on the proposed SRC model. The proposed SRC model predicts clear defection point on the curve of fiber breaking number and stiffness degradation as increase of loading cycles, which agrees well with experimental phenomena in available literatures.