Thermal cycling effects on the mode-I delamination of multilayer laminated composites: An experimental-numerical approach

In this research, the influence of thermal cycling on the fracture toughness and maximum load in the mode-I delamination of polymer matrix composites (PMCs) was investigated. To reduce the effect of the remote ply orientation on the fracture toughness during initiation and propagation delamination, double cantilever beam (DCB) specimens with a stacking sequence of unidirectional [0] 16 were considered. The specimens were subjected to thermal-cycled loading between 15 degrees C and 65 degrees C for 50-150 number cycles. One group of un-cycled specimens was examined at the commencement of the research as a control group to determine the effects of thermal cycling loading on mechanical characteristics of the second group specimens. During the DCB experiment, the specimens were inspected by 2 real-time cameras to record the delamination length and initial crack tip opening displacement (ICTOD). The strain energy release rate (SERR) approach was used for obtaining the critical fracture toughness from the experimental data. By employing the digital image correlation (DIC) method, the initial crack tip separation profile was obtained. The measured bridging laws with the cohesive zone elements model are used to accurately simulate the delamination propagation in DCB specimens. Investigation of load variations revealed that critical fracture toughness in the mode-I of delamination is firmly affected by the thermal cycling process.