Hygrothermal effects on mechanical behavior of scarf repaired carbon-epoxy laminates subject to axial compression loads: Experiment and numerical simulation

Experimental and numerical study are carried out to investigate hygrothermal effects on the mechanical behavior and damage propagation of scarf repaired carbon fiber reinforced plastic (CFRP) laminates. Experimental tests were carried out under four environment conditions: room temperature/dry, room temperature/wet, elevated temperature (95 degrees C)/dry and elevated temperature (95 degrees C)/wet. Results showed no decrease in compression strength after moisture absorption, whereas the reduction under elevated temperature were 15.5% and 17.2% for dry and wet specimens, respectively. Furthermore, a finite element model was developed to simulate the failure process and predict structural strength, in which moisture diffusion, hygrothermal stress analysis and progressive damage model were considered. Good agreement was achieved between the predicted compression strength and experimental results. It is revealed that the damage in the adhesive initiates adjacent to 0 degrees plies and propagates in circumferential direction. Water absorption causes initial damage in the edge of the adhesive layer, while it does not reduce the compression strength. And elevated temperature leads to earlier damage in adhesive. After large part of the adhesive layer damaged, damages in parent laminate occur and propagate transversely to the free edge sides until the final structural collapse, which is similar with the experimental phenomenon. POLYM. COMPOS., 39:904-914, 2018. (c) 2016 Society of Plastics Engineers