اثر نیروی محوری بر ارتعاشات آزاد پوسته استوانه ای کامپوزیتی

Nowadays, due to their desirable properties such as special strength and special stiffness, composite cylindrical shells have found many applications in various industries such as automotive, marine and aerospace. In most cases, this shell is under dynamic loads and may experience vibration, buckling and fatigue. For this reason, in this article, the free vibrations of multi-layered composite cylindrical shells and the effect of compressive axial load on their frequencies have been investigated. First, the equilibrium equations of the composite cylindrical shell are written based on the first-order shear deformation the theory of the shells. Strain-displacement and curvature-displacement relationships are considered based on the first Law approximation. The boundary conditions are simply supported. Then the analysis of buckling load and free vibrations of the composite cylindrical shell was performed and the buckling load and natural frequencies were extracted. Finally, the effect of compressive axial load and ratio of length-to-radius on the natural frequencies of the shell have been investigated. The results show that with the increase of the compressive axial load and the increase of the ratio of length to radius, the natural frequencies decrease. In a small circumferential waves number (n), increasing the longitudinal half-wave (m) has a great effect on the natural frequency, while in a large circumferential waves number, increasing the longitudinal half-wave has no effect on the natural frequency.