Debonding dynamics in FRP plated beams: high order cohesive FE formulation and parametric sensitivity

This paper studies the dynamic characteristics of the debonding mechanism in beams strengthened with FRP. The paper formulates a special finite element for the dynamic analysis of the layered beam and looks into the parameters that govern the dynamic phenomenon. The finite element is based on an extended high order theory that incorporates a rich 2D elasticity based stress and displacement fields in the adhesive layer and allows to consider debonding at the two physical interfaces of that layer through cohesive interfaces. These concepts are combined with the basic form of inertial forces to formulate a multi-layered finite element that utilizes the versatility of the FE method and avoids the need to mesh through the thickness of each layer. The computational framework is then used to study the dynamic debonding process and to examine the impact of a series of geometrical, elastic, mechanical, and physical parameters. Among other findings, the investigation reveals the potentially negative impact of stiffening the FRP layer on the dynamic failure, the sensitivity to the properties of the adhesive, and the interesting insensitivity to the loading rate (within the examined range). Finally, the sensitivity of the response to the properties of the cohesive interfaces and the idea of characterizing those interfaces based on dynamic observations are discussed.