Buckling Finite Element Analysis of Moderately Thick Spherical Sandwich Panel with Grid Stiffened Core and SMA Reinforced Layers

In the present study, the buckling behavior of moderately thick spherical sandwich panels with grid stiffened core and shape-memory wires (SMA) reinforced layer is studied for the first time. The core of the panel is a grid structure and its cells are tetrahedral, and the outer layers are reinforced by SMA wires with a uniform, one-way distribution. The finite element method is used to perform the simulations. The Brinson model is used for SMA super-elastic behavior definition and fuzzy transformations are applied using the UMAT subroutine in ABAQUS software. The effect of effective geometric and mechanical parameters such as the radius of curvature of the shell, the volume fraction of SMA wires, and their prestressing on the buckling loads of the shell are verified. The results show that SMA wires cause recycled stresses that are applied as a tensile force on the upper layers of the shell. This characteristic increases the stiffness of the shell and leads the buckling load growth. If α =0.1, Increasing the volume fraction of SMA wires from 0 to 0.6% leads to the buckling load growth by 325%. In addition, the buckling load per unit volume of the shell with grid core and without grid core is 0.71 and 0.79, respectively, which indicates that the presence of grid core increases the specific buckling load by 11%. This increase, along with the reduction in the weight of the structure, highlights the importance of using sandwich structures with grid cores.