Hui- Shen

Postbuckling analysis of axially loaded functionally graded cylindrical panels in thermal environments

Abstract A postbuckling analysis is presented for a functionally graded cylindrical panel of finite length subjected to axial compression in thermal environments. Material properties are assumed to be temperature dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of a functionally graded cylindrical panel are based on Reddy’s higher order shear deformation shell theory with a von Karman–Donnell-type of kinematic nonlinearity and including thermal effects. Two cases of the in-plane boundary conditions are considered. The nonlinear prebuckling deformations and initial geometric imperfections of the panel are both taken into account. A boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, large deflections in the postbuckling range, and initial geometric imperfections of the shell, is extended to the case of functionally graded cylindrical panels under axial compression. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behavior of axially loaded, perfect and imperfect, functional graded cylindrical panels with two constituent materials and under different sets of thermal environments. The influences played by temperature rise, volume fraction distributions, the character of in-plane boundary conditions, transverse shear deformation, panel geometric parameters, as well as initial geometric imperfections are studied.

Thermomechanical postbuckling of shear deformable laminated cylindrical shells with local geometric imperfections

Abstract The effect of local geometric imperfections on the buckling and postbuckling of shear deformable laminated cylindrical shells subjected to combined axial compression and uniform temperature loading is investigated. Two cases of compressive postbuckling of initially heated shells and of thermal postbuckling of initially compressed shells are considered. The governing equations are based on Reddys higher order shear deformation shell theory with a von Karman–Donnell-type of kinematic nonlinearity and including thermal effects. The material properties are assumed to be independent of the temperature. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A boundary layer theory of shell buckling is extended to the case of shear deformable cross-ply laminated cylindrical shells and a singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the compressive or thermal postbuckling behavior of moderately thick, cross-ply laminated cylindrical shells with local or modal geometric imperfections. The results show that, for the same value of amplitude, the local geometric imperfection has a small effect on the buckling load as well as postubuckling response of the shell than a modal imperfection does.

Postbuckling of shear deformable laminated plates with piezoelectric actuators under complex loading conditions

Abstract Postbuckling analysis is presented for a simply supported, shear deformable laminated plate with piezoelectric actuators subjected to the combined action of mechanical, electric and thermal loads. The temperature field considered is assumed to be a uniform distribution over the plate surface and through the plate thickness and the electric field is assumed to be the transverse component E Z only. The material properties are assumed to be independent of the temperature and the electric field. The governing equations of a laminated plate are based on Reddys higher order shear deformation plate theory that includes thermo-piezoelectric effects. The initial geometric imperfection of the plate is taken into account. Two cases of the in-plane boundary conditions are considered. A perturbation technique is employed to determine buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behavior of perfect and imperfect, symmetric cross-ply and antisymmetric angle-ply laminated plates with fully covered or embedded piezoelectric actuators under different sets of thermal and electric loading conditions. The effects played by temperature rise, applied voltage, the character of in-plane boundary conditions, transverse shear deformation, plate aspect ratio, fiber orientation and stacking sequence as well as initial geometric imperfections are studied.

The effects of hygrothermal conditions on the postbuckling of shear deformable laminated cylindrical shells

Abstract The effect of hygrothermal conditions on the buckling and postbuckling of shear deformable laminated cylindrical shells subjected to combined loading of axial compression and external pressure is investigated using a micro-to-macro-mechanical analytical model. The material properties of the composite are affected by the variation of temperature and moisture, and are based on a micro-mechanical model of a laminate. The governing equations are based on Reddys higher order shear deformation shell theory with von Karman–Donnell-type of kinematic nonlinearity and including hygrothermal effects. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A boundary layer theory of shell buckling is extended to the case of shear deformable laminated cylindrical shells under hygrothermal environments and a singular perturbation technique is employed to determine the interactive buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behaviour of perfect and imperfect, moderately thick, cross-ply laminated cylindrical shells under different sets of environmental conditions. The results show that the hygrothermal environment has a significant effect on the interactive buckling load as well as postbuckling response of the shell. In contrast, it has a small effect on the imperfection sensitivity of the shell with a very small geometric imperfection.

Postbuckling of laminated cylindrical shells with piezoelectric actuators under combined external pressure and heating

Abstract A postbuckling analysis is presented for a cross-ply laminated cylindrical shell with piezoelectric actuators subjected to the combined action of external pressure and heating and under electric loading cases. The temperature rise considered is assumed to be a uniform distribution over the shell surface and through the shell thickness and the electric field is assumed to be the transverse component E Z only. The material properties are assumed to be independent of the temperature and the electric field. The governing equations are based on the classical shell theory with von Karman–Donnell type of kinematic nonlinearity. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, large deflections in the postbuckling range, and initial geometric imperfections of the shell, is extended to the case of hybrid laminated cylindrical shells. A singular perturbation technique is employed to determine the interactive buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behavior of perfect and imperfect, cross-ply laminated cylindrical thin shells with fully covered or embedded piezoelectric actuators subjected to combined action of external pressure and heating and under different sets of electric loading cases. The effects played by applied voltage, shell geometric parameter, stacking sequence, as well as initial geometric imperfections are studied.

Thermomechanical postbuckling of composite laminated cylindrical shells with local geometric imperfections

Abstract The effect of local geometric imperfections on the buckling and postbuckling of composite laminated cylindrical shells subjected to combined axial compression and uniform temperature loading was investigated. The two cases of compressive postbuckling of initially heated shells and of thermal postbuckling of initially compressed shells are considered. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of the nonlinear prebuckling deformation, the nonlinear large deflection in the postbuckling range and the initial geometric imperfection of the shell. The analysis uses a singular perturbation technique to determine buckling loads and postbuckling equilibrium paths. Numerical examples are presented that relate to the performances of cross-ply laminated cylindrical shells with or without initial local imperfections, from which results for isotropic cylindrical shells follow as a limiting case. Typical results are presented in dimensionless graphical form for different parameters and loading conditions.