Dynamic instability analysis of porous FGM conical shells subjected to parametric excitation in thermal environment within FSDT

摘要

The conical shell structure is prone to dynamic instability when subjected to time dependent periodic axial loads and it can cause structural damage. Based on that this paper presents an accurate and semi-analytical method for investigation the dynamic instability of porous functionally graded material (PFGM) conical shell in thermal environment. In the analysis, three common types of PFGM conical shells, namely, uniform, symmetric and asymmetric distribution are considered assuming that material properties are related to temperature. The governing equations of conical shell subjected to parametric excitation are established by the Hamilton's principle considering first order shear deformation theory. Then the Mathieu-Hill equations describing the parametric stability of conical shell are obtained by generalized differential quadrature (GDQ) method, and the Bolotin's method is utilized to obtain the first-order approximations of principal instability regions of shell structure. By comparing the numerical results with the existing solutions in open literature, the validity of the proposed theoretical model is verified. Finally, the influences of porosity distribution type, gradient index, radius-to-thickness ratio, porosity volume fraction and temperature fields on the dynamic stability of PFGM conical shell have been investigated, wherein for different porosity distribution types, the UPD type is more sensitive to gradient index as compared to other three types, while the SPD has the minimum relative width.