Experimental and analytical study of the dynamic debonding in FRP plated beams

This paper presents an experimental study of the dynamic debonding failure mechanism in FRP plated beams. The experimental study is accompanied by an analytical/numerical study. The focus in the experimental investigation is on the dynamic aspects of the brittle, rapid, and abrupt failure mechanism and on its characterization and quantification. The experimental technique is based on four point bending tests of FRP plated steel beam specimens. The main dynamic monitoring technique uses high-speed digital photography with rate of 88,050 frames per second. The analytical and numerical aspects of the investigation use an extended high order layered beam theory with a physical modeling resolution that considers nucleation and evolution of the debonding mechanism in each physical interface. This is achieved by using cohesive interfaces and a specially tailored finite element formulation that is based on the theory. Digital image processing of the experimental results reveals and quantifies the dynamics of the interfacial failure with propagation velocities in the order of 100–1000 m/s and duration of less than 0.2 ms. The results reveal the dynamic nature of the failure process and provide an experimental benchmark for its consideration. They also provide direct experimental data for supporting and validating the theory and for determining the fracture energy and length scale parameters of the cohesive interfaces. With that, the combined experimental and theoretical study further explores the dynamic features of the failure mechanism.