Static And Dynamic Analyses Of Graded Graphene-reinforced Porous Spinning Cylindrical Shells

Carbon-based materials,like carbon nanotubes(CNTs)and graphene platelets(GPLs)have attracted considerable attention and been used as reinforcement nanofillers for many years.Among these materials,the GPLs are preferred nanofillers to exhibit better reinforcement effects resulting from their higher Young's modulus,outstanding tensile strength,and larger specific surface area.Functionally graded graphene-reinforced porous composites can bring new market opportunities and facilitate the industrialization of high-tech smart materials,electromagnetic absorption components,and superior fuel cells,because they can maintain extremely high mechanical strength,lightweight properties and great energy absorption,simultaneously.Cylindrical shell is one of the existing gyration shell structures and always accompanied by spinning motion,such as the high-speed centrifugal separators and ballistic missiles.Although massive research work has been conducted on structural dynamics and stability of functionally graded graphene-reinforced composite structures,static and dynamic analyses of graded graphene-reinforced porous composite spinning cylindrical shell remain unknown despite of their significance in the practical engineering,also effects of centrifugal force,Coriolis force and initial hoop tension caused by the spinning motion on the shell's wave vibrations and amplitude-frequency relationship are not yet revealed in the published papers.This work investigates buckling behaviors,linear and nonlinear vibration characteristics and dynamics behaviors of graded graphene-reinforced porous composite spinning cylindrical shell under external loads.The main works are reported as follows:(1).Considering different types of GPL patterns and porosity distributions,a functionally graded graphene-reinforced porous composite cylindrical shell model with spinning motion is established.It is assumed that the graphene platelet nanofillers and internal pores are randomly oriented and uniformly dispersed in each concentric cylindrical shell,and both the GPL weight fraction and the porosity coefficient vary continuously along the thickness direction.Effective material properties of the composite are derived by employing the rule of mixture,the modified Halpin-Tsai model and closed-cell Gaussian random field model.Equations of motion of the shell are obtained based on the first-order shear deformation theory(FSDT)and Donnell shell theory,respectively.(2).An analytical solution for the axisymmetric pre-buckling deformation of the composite spinning cylindrical shell under external axial force and radial pressure is derived by using the power-law function about the deformation.Considering influence of the prebuckling deformation,critical buckling loads of the composite spinning cylindrical shell are obtained through the eigenvalue problem.(3).Natural frequencies of travelling waves for the composite spinning cylindrical shell under FSDT and Donnell theory are derived,respectively.Influence of inplane inertia on accuracy of calculation for the natural frequencies is analyzed.Parametric studies on the shell's natural frequency are carried out where effect of the initial hoop tension caused by the spinning motion on the natural frequencies of travelling waves are studied.(4).Nonlinear free and forced vibrations of the graded graphene-reinforced composite spinning cylindrical shell in thermal environment are studied.Nonlinear frequencies of the spinning cylindrical shell are derived by employing an assumed model.Nonlinear primary resonance and 1:3 subharmonic resonance are analyzed by using the multiply scale method.Parametric studies on the shell's nonlinear frequencies and harmonic resonance behaviors are conducted.Furthermore,the mechanism of how the spinning motion affects the amplitude–frequency curves of harmonic resonances of the cylindrical shell is revealed.(5).According to the Hertz contact theory,the time-dependent contact force between a foreign impactor and the cylindrical shell is calculated by adopting a single spring-mass model.Considering a simply-supported spinning cylindrical shell,on the base of a second-order differential equation,an analytical solution for time-dependent displacements and strains is obtained by using the Duhamel integration.A gratifying GPL distribution pattern for impact responses of the composite cylindrical shell is carried out.