پرویز ملک زاده

As a first attempt, the vibrational behaviors of point supported truncated conical sandwich shells with circumferential stiffeners, graphene platelets reinforced composite porous core and face sheets (GPLRC-PC-FS) are investigated. The point supports are simulated using the conventional elastic translational and rotational springs, which can be easily converted to the classical boundary conditions. The face sheets, porous core and the circumferential stiffeners are co-axially and perfectly bonded, and each of these components are reinforced by uniformly distributed and randomly oriented graphene platelets (GPLs). The motion equations are derived using a zigzag shell theory based on the first-order shear deformation theory (FSDT) in conjunction with the Chebyshev-Ritz method. The results are validated by carrying out the convergence study and performing the comparison studies with existing solutions in the literature. After that, the influences of porosity and its structures, the GPLs weight fraction and geometric dimensions, face sheets, geometric parameters of the shell, boundary conditions, and the stiffener parameters on the results are investigated. The results show that the number of point supports plays an important role on the fundamental frequency of the considered shells. Moreover, it is found that the porosity and its distribution pattern and circumferential stiffeners have considerable effects on the natural frequencies. Also, the results reveal that by adding a very small amount of GPLs, the frequencies increase significantly.