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Prediction of Number of Cycles from Fatigue Test Conditions and Transverse Crack Density of CFRP Cross-Ply Laminates

YOUZOU KITAGAWA, KOTARO HIRAIWA, MASAHIRO ARAI, AKINORI YOSHIMURA, KEITZ GOTO

Abstract


In the present paper, we proposed a methodology that can predict the number of applied load cycles in tension-tension fatigue test of CFRP laminates from microscopic damages and test conditions. It is difficult to predict the fracture of CFRP laminates and to estimate the remaining life of CFRP laminates for ensuring the long-term reliability of the CFRP components because the fracture process of CFRP laminates is quite complex. The damage process of CFRP consists of various microscopic damage such as matrix cracks, fiber/matrix interfacial debondings, delamination and so on. In order to quantitatively estimate the remaining life of CFRPs, we focused on the degree of the microscopic damages and relate that to the remaining life of them. The tension-tension fatigue tests of CFRP cross-ply laminates were carried out, and we suspended the tests at arbitrary cycles. When the tests were suspended, we counted the number of transverse cracks occurred on the specimens by a replica method, and measured the stiffness degradation of the specimens. We formulated an equation that can predict the stiffness degradation using fatigue test conditions. The predicted stiffness degradation to the number of cycles using the formula agreed well with the experimental results. The result demonstrated that the formula can predict the number of subjected cycles from fatigue test conditions and transverse crack density.


DOI
10.12783/asc36/35918

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References


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