جستجوی مقالات مرتبط با کلیدواژه « double-curved shell » در نشریات گروه « مکانیک »

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.

In this research, the buckling of moderately thick double-curved composite sandwich panel with grid-stiffened core and carbon nanotubes reinforced surface layers under axial static loading has been studied analytically for the first time. The panel core is consisted of irregular hexagonal cells. The mechanical properties of the carbon nanotubes reinforced layers with different distributions are determined by the improved rule of mixtures. The buckling equations are obtained by using of the minimum total potential energy principle and Reddy's third-order theory and solved via the Navier method for different boundary conditions .The results show that the effect of carbon nanotubes on buckling load is in the way that the buckling performance in each case depends on the geometric parameters of the grid core. By assigning the appropriate value for grid core characteristics, the maximum buckling load can be obtained by the minimum amount of carbon nanotubes. It is observed that in the FG-V distribution mode, for the smaller amount of carbon nanotubes (0.05 volume fraction), the maximum buckling load is obtained. Also, for Rx/Ry=2 and FG-V distribution mode, the maximum buckling load gains in simply support boundary condition. For Rx/Ry=2 and UD distribution mode, the maximum buckling load obtained from Simple-Clamped boundary condition. It can be noticed that, in this shell type, the maximum buckling load doesn’t belong to fully clamped boundary conditions