Vibrational behavior investigation of composite conical shells reinforced by an anisogrid lattice structure using differential quadrature method

The present study aims to investigate the vibrational behavior of composite conical shells reinforced by an anisogrid lattice structure, using the analytical method. For this purpose, the smeared method was employed to determine the equivalent stiffness contribution of the stiffeners. In this approach, the smeared method was used to superimpose the stiffness contribution of the stiffeners with those of the shell to obtain the equivalent stiffness of the whole structure. The stiffeners were modeled as beams that can support shear forces and bending moments along with the axial forces. The governing partial differential equations of the problem are derived by applying Hamilton's principle and based on the first-order shear deformation theory, and then they are converted into a group of algebraic equations by using the differential quadrature method. Then, eigenvalue problem, and as a result, natural frequencies are calculated. In order to validate the results, comparisons of the present results with those of other studies are performed. Then. the effect of different parameters such as semi-vertex angle, circumferential wave number and the effect of different boundary conditions on the natural frequencies of the system has been evaluated.