Study on damage failure for a new double-triangular truss core sandwich structure

In order to solve the inherent problems of low bonding strength between face and core, a new double triangular truss core sandwich structure with reinforced frame is proposed, and the face and core are melt connected by thermoplastic composite carbon fiber reinforced polyether ether ketone (CF/PEEK). The response of the new double-triangular truss core sandwich structure under three-point bending load is investigated by both theoretical and finite element methods. Firstly, the theoretical prediction equation of bending stiffness and strength of double-triangular truss core sandwich structure is established, and the failure mechanism diagram is constructed. A valid three-point bending finite element model is established by Abaqus to predict the damage pattern of the structure and obtain the results of damage initiation location, damage process, final failure modes and load-displacement curve. The effect of geometric parameters on the bending performance of the sandwich structure was investigated. The results show that the calculated theoretical deflection curves and the ones obtained by numerical simulation are in good agreement. The average error between the two is 7.94%, verifying the reasonableness of the theoretical prediction model. The effect of geometric parameters on the bending performance of the sandwich structure was investigated. The new sandwich structure has stronger bending resistance and better ultimate load capacity than traditional honeycomb and V-shaped structures. Failure modes such as panel crumpling and crushing, fracture of reinforcement frames, buckling and fracture of core rods occur in sandwich structures under bending loads.