Delamination analysis of carbon fiber composites under hygrothermal environment using acoustic emission

Non-destructive test technique for monitoring delamination failure under complex load and environments is still not mature until now. The purpose of this paper is to study mixed-mode delamination failure properties of carbon fiber/epoxy composite laminates under hygrothermal environment using acoustic emission. Different water-saturated composite specimens with initial intralaminar and interlaminar defects are tested. Two loading modes including single-leg and over-leg three-point bending are applied under hygrothermal environment. By analyzing the responses of acoustic emission parameters including amplitude and energy, the effects of the hygrothermal environment, layup pattern and initial defect on the delamination behaviors of composite specimens are studied. Besides, different failure modes are observed through scanning electron microscope. Quantitative acoustic emission results show hygrothermal environment and load mode affect the delamination properties of composites remarkably.