Dynamic edge debonding in FRP strengthened beams

The debonding failure in beams strengthened with externally bonded composite materials, as well as in many other layered and adhesively bonded structural elements, is a dynamic process. This paper studies the dynamics of the edge debonding process in beams strengthened with Fiber Reinforced Polymer (FRP) composite materials and derives an analytical model for the dynamic debonding process. The model adopts an extended high order approach, incorporates the dynamic inertial effects, and considers the high order displacement, acceleration, and stress fields in the adhesive layer. The model uses two cohesive interfaces for the consideration of independent debonding mechanisms at the two physical interfaces of the adhesive layer. It also accounts for the inelastic accumulation of damage at the interfaces and for their degradation under the effect of the dynamic and cyclic response. Along with the derivation of the model and its validation through comparison with 2D dynamic finite element analysis, the paper studies the dynamics of the edge debonding mechanism under two loading conditions. In the first case, the load is applied statically but the debonding mechanism drives the structure into the dynamic regime. In the second case, the dynamic debonding mechanism is triggered by an impulse load. In both cases, the results reveal and quantify the critical dynamic features of the edge debonding mechanism, its time and velocity scales, and its impact on the performance and resilience of the strengthened beam.