In this paper, free vibration of laminated composite cylindrical shells reinforced with circumferential rings, are investigated with experimental, analytical and finite element methods and natural frequencies are obtained. The analysis is carried out for clamp-free and clamp-clamp boundary conditions and the results are compared with each other. To solve the problem, the equilibrium Equations of motions are written according to the classical shells theory and after simplification, the structural stiffness and mass matrices and the frequency Equation are derived using Galerkin method. The results obtained in this paper, are compared with the results available in the literatures, and the results of experimental and finite element methods and good agreement is observed. Manuscript profile

This study aims to the investigation of the effect of grid geometry on the modal response and buckling strength of a composite conical lattice structure under static axial loading by Finite Element Method (FEM). For this purpose, four structures with similar geometry have been designed through four grid structures. Abaqus finite element software has been used for modeling and analyzing the structures. The experimental results of Zamani and Ahmadifar study [1] have been used to validate the results of FEM. Given the results of numerical and experimental analysis, there is an accordance between the results and the FEM efficiency. The results show the contiguous natural frequency of the structures so that their negligible difference is due to the variations of structures’ weight and stiffness. Changing the grid does not affect the shape of the modes. The isogrid bears a higher buckling loading than the anisogrid. Reducing the rib angle is an effective parameter, which increases the buckling loading on the structure. Although peripheral ribs play a role in load bearing, adding their numbers increases the total weight of the structure, therefore, it has no significant effect on increasing the stability of the structure. Manuscript profile