Bending strength and failure of single-layer and double-layer sandwich structure with graded truss core

The influence of the gradient of a sandwich structure with graded truss core on bending behavior are investigated in this paper. The single-layer and double-layer composite sandwich structures are formed by alternating width of core bars and stiffening plate. Three different types of sandwich structure with graded truss core are designed and manufactured. The gradient of a sandwich structure is characterized by introducing a gradient ratio g. A continuum damage model based on Hashin criteria is developed to predict the strength of these structures. The results from three-point bending tests are used to verify the FE model. Good agreements can be achieved between experimental and numerical results. The numerical model is subsequently used to investigate the influence of gradient ratio g on bending strength, stiffness and damage distribution of these sandwich structures. The results indicate that the gradient ratio g can prominently influence the failure mode of the double-layer sandwich structure. An appropriate gradient ratio g of truss core can promote the sandwich structure with higher strength and stiffness. The stiffening plate can significantly enhance the strength and stiffness of the double-layer sandwich structure.