“…16,17 Moreover, Spagnoli studied the different modes of instability in stringer-stiffened cones under axial compression through finite element. 18 For vibration of unstiffened conical shell, many papers discuss the frequency characteristics based on CLT, particularly the works done by Sivadas and Ganesan, 19 Thambiratnam and Zhuge, 20 Tong, 21,22 and Sofiyev et al 23,24 Additionally, Najafov et al derived the governing equations for non-linear free vibration of truncated, thin, laminated, orthotropic conical shells using the theory of large deformations. 25 This theory cannot be used for thick shells and even thin shells when the number of circumferential waves increases as a result of neglecting shear deformation and rotary inertia effects in CLT.…”