Characteristics of CFRP/PU foam and GFRP/PU sandwich beams having initial debond between facesheet and core

Abstract

In the present investigation, we present, the flexural characteristics of carbon fiber reinforced polymer/polyurethane foam and glass fiber reinforced polymer/polyurethane foam sandwich beams having partial debonding between facesheet and core that acts interfacial degradation and hinders the load transfer between facesheets and core. An initial pre-crack between core and face sheet is created by placing a Teflon sheet at the interface on one end of the beams during the manufacturing of sandwich beams. A comparative analysis is carried out to study the effect of using CFRP and Eglass prepregs as face sheet material on such sandwich beams. The flexural behavior of GFRP/PU sandwich beams having initial debond is characterized and analyzed under both three- and four-point loadings. Lastly, the effect of varying the support span length on the flexural response of CFRP/PU sandwich beam having initial debond is also investigated. It was found that the degraded sandwich beams having woven CFRP facesheets have slightly higher stiffness and peak load level as compared to the sandwich beam having cross ply GFRP facesheets. GFRP/PU foam sandwich beam showed higher ductile behavior prior to progressive failure of the sandwich beam. It was observed that the crack tip of the implanted interfacial debond acts as a medium to trigger the interfacial damage followed by the shear failure of the core due to the progression of the initial crack into the core.