Dynamic instability analysis of functionally graded multiphase polymer–CNT–GPL composite conical shells under thermal environments

This study investigates the dynamic behavior of functionally graded hybrid composite conical shells (FG-HCCSs) reinforced with graphene platelets (GPLs) and carbon nanotubes (CNTs) under periodically varying compressive loads in a thermal environment. Multiple functionally graded (FG) schemes are used to represent the variation of CNT and GPL content through the thickness of the hybrid composite conical shells. The composite’s effective mechanical properties are calculated through a coupled application of the modified Halpin–Tsai model and the rule of mixtures. The formulation of the governing equations for parametrically excited hybrid composite conical shells is carried out within the framework of Hamilton’s principle and first-order shear deformation shell theory (FSDT). The transformation of the governing equations into the Mathieu–Hill form is carried out using the generalized differential quadrature method (GDQM), followed by the application of Bolotin’s method to predict the principal dynamic instability region (PDIR) of the FG-GPL/CNT-reinforced conical shells in a thermal environment. Validation of the theoretical model is achieved by matching the computed results with previously published findings. In this work, the dynamic behavior of FG multilayer hybrid composite conical shells reinforced with GPLs and CNTs is investigated by examining the effects of several parameters on the PDIRs of FG-GPL/CNTRC conical shells under different thermal environments, including the reinforcement weight fraction and distribution, the semi-vertex angle, the inner radius-to-thickness ratio, the circumferential mode number, the static load factors, and the boundary conditions.