Study on the shear strength degradation of ACA joints induced by different hygrothermal aging conditions

The effect of the different hygrothermal conditions on the shear strength degradation of ACA joints and the difference among them are studied in this paper using experiments and numerical simulations. First of all, several hygrothermal aging tests with different accelerating levels are carried out to explore the hygrothermal environment induced degradation paths of interfacial strength of ACA joints. It is found that the shear strength degradation paths differ from each other when the ACA joints are tested under different hygrothermal conditions, while they are similar to each other. For each case, the shear strength firstly decreases rapidly and then slowly approximates to a fixed value, and the shear strength difference between each other goes to an approximate constant after certain early test hours. After that, to understand the degradation mechanism better, finite element modeling is achieved to study the relationship of moisture concentration in ACA layer and shear strength of the ACA joints, and it is found that moisture saturation and diffusion rate are considered to be the main causes of the shear strength degradation.