Elastic properties of a novel cellular structure with trapezoidal beams

Cellular structures are potential candidates for cores of flexible sandwich skins that are required of low in-plane stiffness for morphing and high out-of-plane stiffness for load-bearing, as well as zero Poisson's ratio for one-dimensional morphing. In this paper a novel cellular structure of close-to-zero Poisson's ratio with trapezoidal beams is proposed to meet these requirements. The elastic properties of the structure were investigated through a combination of theoretical analysis and finite element validations. Then the effects of geometric parameters on the properties of the structure were studied and analyzed. Finally comparisons on the properties with a classical accordion cellular honeycomb were carried out. Results show that the analytical results are well matched with results of the finite element validations and the proposed structure is of a better in-plane morphing property than the conventional cellular structure. Small value of thickness-to-length ratio, large values of horizontal sub-beam proportion ratio along x-direction and vertical to trapezoidal beam thickness ratio are recommended for balancing the in-plane and out-of-plane properties.