Mechanical properties and failure behavior of the sandwich structures with carbon fiber-reinforced X-type lattice truss core

As we known, composite sandwich structure with advantages of high specific strength/modulus, high temperature resistance, damping, etc., which is widely used in various fields. And there is more space in its core to supply for multi-functional filler, which provides the possibility for special engineering applications (such as heat insulation, wave absorption, etc.). In this paper, a new type of lightweight composite lattice structure (called X-type lattice structure) is proposed based on the stretching dominated idea of quadrilateral grid and lattice strut. The mechanical properties and failure behavior of X-type lattice structures are investigated based on theoretical and experimental methods. The experiment results show that the mechanical properties of the X-type lattice sandwich structure is more superior than those of other pyramidal lattice sandwich structures. In theoretical analysis, we found the fact that the shear equivalent stiffness of X-type lattice structure is independent of the loading direction, while the shear strength is related to the loading direction. Meanwhile, its minimum shear strength will be reached at the 0 degrees loading direction, and the maximum shear strength will be obtained when the loading direction is 45 degrees.