Two dimensional dynamic debonding in FRP strengthened plates

Abstract

Interfacial debonding is ever-present in structural failures of adhesively bonded layered structures in general, and of FRP strengthened plates in particular. Experimental observations repeatedly characterize debonding failures in FRP strengthened plates as sudden, brittle, and rapid. In contrast to numerous analytical and numerical studies that capture, quantify, and describe the dynamic nature of debonding in FRP strengthened beams, the analytical-computational handling and the understanding of the role of dynamics in 2D plate-type debonding in FRP strengthened plates is far from fully developed. The present paper aims to shed new light on- and gain new insights into the 2D and dynamic nature of debonding in FRP strengthened plates. A specially tailored dynamic and nonlinear analytical-computational platform, comprising a multilayered plate theory and its corresponding in-house finite element counterpart, is developed to face the multiple modeling, analytical, and numerical challenges. The capacity of the analytical-computational platform to capture the high rate dynamic evolution of debonding is validated in the context of an FRP strengthened beam by comparison to experimental results and observations reported in the literature. Then, a novel numerical study looks into the dynamic evolution of debonding in an FPP strengthened two-way slab specimen. The study focuses on the geometrically irregular, 2D, and dynamic evolution of the debonding area, on the impact of the debonding and debonding rate on the structural stability, on the debonding velocities and their dependence on the loading rate, on the impact of inertial forces and significance of a dynamic vs. static analysis. The study reveals that, contrary to the assumptions of static conditions frequently made in the literature, the 2D debonding phenomenon in FRP strengthened plates is inherently rapid, unstable, and dynamic by nature, and points at the strong link between the 2D irregularity of the debonding evolution in plates and this fundamental dynamic nature.