Failure mechanisms of a sandwich beam with an ATH/epoxy core under static and dynamic three-point bending

In this work, mechanical response of a new sandwich beam with a hybrid core composed of epoxy resin and Alumina trihydrate (ATH) was investigated. Interactions between the indentation mode and the core shear failure mode, as well as the role of face/core debonding were evaluated as part of the failure mechanism. A digital image correlation technique (DIC) was used to capture the sequence of failure and the strain field during quasi-static loading. In addition, an explicit nonlinear finite element model was developed to predict the evolution of damage in the sandwich face sheet and core. The model includes a viscoplastic-damage model to simulate the strain rate-dependent behavior of the core material. The numerical results were compared with the impact data to demonstrate the ability of the model to follow the evolution of damage from onset to catastrophic failure. It was found that shear failure in the core plays the main role in the final failure of sandwich beams. For an impact energy below 60 J, indentation is the dominant failure mode, and its effect on the flexural response of the beam was demonstrated.