Investigation of debonding growth between composite skins and corrugated foam-composite core in sandwich panels under bending loading

This study investigates experimentally and numerically the resistance to separation between composite skins and different complex geometries of the corrugated core filled with PVC foam. To this purpose, three different geometries including simple foam core without any corrugated composite, longitudinal trapezoid, and square cores are considered and manufactured as waved (corrugated) composite core. In each specimen, an artificial pre-crack is located between the skin and core and then the effect of the skin's thickness and the core shaped on the debonding growth are examined for the first time. Three-point bending tests are carried out using ENS (End Notch Shear) fixture. Furthermore, the nonlinear response due to separation initiation and propagation between the skins and the core is investigated by employing the cohesive zone model (CZM) using ABAQUS finite element software. In fact a finite element model has developed to simulate debonding in sandwiched structures, and experimentally validated the model with the aim to improve the performance of sandwiched structures. A good agreement is found between the experimental and numerical results. According to the results, between the longitudinal trapezoid, and square cores, for the same increased in the weight percentage of sandwich panel, the square core is suggested as an optimal design having the highest bonding strength.