Fatigue characterization study of CFRP under hygrothermal environment based on continuum damage mechanics model

Abstract

Carbon fibre-reinforced polymers (CFRPs) are now widely used for highperformance fields such as aircraft structures. On average, these structural components are subjected with more than 10 8 cycles during their lifetime. To make full use of the mechanical performance of CFRP, the fatigue behaviour needs to be well studied. Nevertheless, at present, fatigue behaviour and failure mechanisms of CFRP under hygrothermal environment are not sufficiently investigated. To obtain comprehensive knowledge about fatigue behaviour and failure mechanisms of CFRP, hygrothermal tests and ultrasonic three-point bending fatigue experiments are designed. Besides, a damage variable is proposed as the function of stiffness to evaluate the fatigue degradation of the composite. A nonlinear continuum damage mechanics (CDM) model is compared with three models and employed for fatigue damage evolution under cyclic loading. Compared with the other three models, the experimental results show a better consistency between the result of the CDM model and the measured damage. Meanwhile, the damage variable expresses the damage state of the composite effectively. The damage variable and the CDM model provide a reference for fatigue characterization analysis and further life prediction of CFRP.

Influence of pulse duration on the fatigue behavior of a carbon‐fiber‐reinforced composite under cyclic three‐point bending at 20 kHz

“…Yoshi et al, 12 Gude et al, 13 Koch et al, 14 and Ueki et al 15 used shakerbased test systems to apply cyclic bending loads on CFRP and GFRP materials at loading frequencies between 60 and 230 Hz. Backe et al, 16,17 Weibel et al, 18 Cui et al, 19 Li et al, 20 Premanand and Balle, 21 and Premanand et al 22 investigated the VHCF and GCF of CFRP at ultrasonic cyclic frequencies. With an ultrasonic fatigue test (UFT) system, Wang et al 23 were able to investigate the HCF and VHCF properties of a honeycomb sandwich structure under three-point bending loads.…”

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

“…Thus, adhesive degradation of the calcium silicate hydrate and epoxy interface is a dominant failure mechanism of the CFRP/concrete composite. Although there have been numerous previous studies on concrete reinforced with CFRP sheets under harsh environments, ,− these investigations are mostly based on macroexperiments. There is limited insight into the micromechanism of adhesive degradation of the epoxy/C-S-H interface affected by hygrothermal conditions.…”