Impact of Interfacial Nonuniformity on the Dynamic Debonding in FRP-Plated Beams

The paper studies the effect of nonuniformity and localized degradation of the interfacial conditions on the dynamic debonding mechanism in layered structural elements. In particular, it looks into the effect of a periodic delamination pattern. Such a pattern is observed in masonry or periodically cracked concrete elements strengthened with fiber reinforced polymer (FRP) plates and in other periodic structural forms such as armor plates with ceramic tiles, sandwich plates, and coating for electronic devices. The study focuses on FRP plated beam specimens and combines analytical modeling using a high order multilayered theory with cohesive interfaces, numerical solutions using a specially tailored finite element formulation, and experimental, techniques that are based on high-speed photography and image processing. The combined methodologies reveal the impact of pre-existing periodically delaminated regions on the response of the examined beams. Specifically, it reveals the impact on the critical load and displacement where the dynamic process commences, on the kinematics of the process including the debonding front movement and velocity, on the duration of the process, and on its potential arrest. Altogether, the combined effort sheds more light on the dynamic nature of the debonding failure in layered structural elements and the role it plays in their structural behavior.