Fracture toughness and crack growth resistance of sandwich panels with grooved cores

The delamination phenomenon in sandwich panels occurs in the form of face/core debonding. The grooved foams are usually employed in curved sandwich structures for easier formability and better adhesion. In this research, the debonding toughness of facesheet to the core in a sandwich beam with grooved core is investigated using numerical and experimental methods. The sandwich beam consisted of two Kevlar 49/polyester facesheets and a polyurethane foam core. To obtain the values of strain energy release rate, the Cracked Sandwich Beam (CSB) specimen along with the Modified Beam Theory (MBT) method was used for the data reduction of the test results. In the numerical part, a model based on the cohesive zone theory was employed to simulate the crack growth in the specimens. Comparison of the numerical and experimental load–displacement curves indicated that the proposed model can reasonably predict the behavior of the structure under similar loading conditions. The effect of foam-related parameters such as the number and width of core grooves on crack growth resistance was examined numerically. The results showed that increasing the number and width of the grooves enhanced the resistance of the sandwich beams against the growth of interfacial cracks.