Structural design of pyramidal truss core sandwich beams loaded in 3-point bending

The dimensions of pyramidal lattice truss core sandwich beams loaded in 3-point bending are designed to achieve the most weight-efficient structure. The bending stiffness and strength of the sandwich beam is predicted theoretically, and the identified failure modes include core member buckling, core member crushing, face wrinkling, and face crushing. To predict the relevant limit loads of the four failure modes, a force analysis is carried out based on structural mechanics. The inclined angle of the core member is determined by maximizing the bending stiffness-to-weight ratio. The length and radius of the core member, the thickness of the face, and the length of the sandwich beam are determined by maximizing the bending strength-to-weight ratio for the given height of the core. The effectiveness of the design method is validated by experiments, and the specimen with optimal geometric parameters possesses the largest weight efficiency. The useful results are extended to give an available design tool for sandwich beam manufacturers.