A distribution model of ultra-high cycle fatigue property based on crack density for braided CFRP

The microscopic observation and statistical investigation of matrix cracks are carried out through the ultra-high cycle bending fatigue experiment of braided CFRP (Carbon Fiber Reinforced Plastic) in this paper, and the matrix crack development law of CFRP under ultra-high cycle fatigue load has been studied. It is found that there are two different forms of matrix cracks under the ultra-high cycle fatigue load, and a bimodal distribution model of matrix crack density is established based on the distribution law of matrix crack density. At the same time, the ultra-high cycle fatigue life distribution model of braided CFRP is established based on the matrix crack density distribution model. At last, the corresponding fatigue life of CDS (Characteristic damage state) is obtained through the crack density evolution curve, and the life distribution model is verified.