Low-velocity impact resistance of ATH/epoxy core sandwich composite panels: Experimental and numerical analyses

In this study, a new composite sandwich was investigated as a solution for the rehabilitation of existing hydraulic turbine. The innovative sandwich construction with an ATH/epoxy core (i.e. epoxy resin filled with alumina tri-hydrate (ATH) particles) and non-crimp glass fabric fiber-reinforced epoxy face sheets was subjected to low-velocity impact at various energy levels. A 3D progressive damage model was developed to predict the damage characteristics in the face sheets in combination with a viscoplastic-damage model to simulate the nonlinear response of the core. The obtained numerical results were compared with the test data to assess the effectiveness of the proposed model. Good correlation with respect to the contact force and energy-time relationships, permanent deformation, and impact-induced damage was achieved. The performance of the sandwich panel with an ATH/epoxy core was evaluated in term of impact damage resistance and energy dissipation capacity. Microscopic observations were performed to determine the damage and failure modes in the impact zone. The important role of the core material for enhancing the face-sheet damage tolerance was also identified. The various energy dissipation components were also quantified during an impact loading, and the energy dissipated in the sandwich core was approximately 50% of the initial impact energy.