Uniform Temperature Loading Research Articles

Thermal postbuckling analysis of imperfect laminated plates on softening non-linear elastic foundations

A thermal postbuckling analysis is presented for a simply supported, composite laminated plate subjected to uniform or non-uniform parabolic temperature loading and resting on a softening non-linear elastic foundation. The formulation is based on the classical laminated plate theory and includes the plate-foundation interaction and thermal effects. The analysis uses a mixed Galerkin-perturbation technique to determine thermal buckling loads and postbuckling equilibrium paths, taking initial geometrical imperfections into account. Numerical examples cover the performance of perfect and imperfect, antisymmetric angle-ply and symmetric cross-ply laminated plates. Typical results are presented in dimensionless graphical form for different parameters and exhibit interesting imperfection sensitivity, e.g. the thermal postbuckling equilibrium path can be unstable.

Thermomechanical postbuckling of imperfect moderately thick plates on two-parameter elastic foundations

A postbuckling analysis is presented for a simply supported, moderately thick rectangular plate subjected to combined axial compression and uniform temperature loading and resting on a two-parameter elastic foundation. The two cases of thermal postbuckling of initially compressed plates and of compressive postbuckling of initially heated plates are considered. The initial geometrical imperfection of the plate is taken into account. The formulations are based on the Reissner-Mindlin plate theory considering the first order shear deformation effect, and including the plate-foundation interaction and thermal effect. The analysis uses a deflection-type perturbation technique to determine the buckling loads and postbuckling equilibrium paths. Numerical examples cover the performances of perfect and imperfect, moderately thick plates resting on Winkler or Pasternak-type elastic foundations. Typical results are presented in dimensionless graphical form.

Thermomechanical postbuckling analysis of imperfect laminated plates on two-parameter elastic foundations

A postbuckling analysis is presented for a simply supported, composite laminated plate subjected to combined axial compression and uniform temperature loading and resting on a two-parameter elastic foundation. The two cases of thermal postbuckling of initially compressed plates and of compressive postbuckling of initially heated plates are considered. The initial geometrical imperfection of the plate is taken into account. The analysis uses a perturbation technique to determine the buckling loads and the postbuckling equilibrium paths. Numerical examples cover the performances of perfect and imperfect, antisymmetrically angle-ply and symmetrically cross-ply laminated plates. Typical results are presented in dimensionless graphical form.

Post-buckling analysis of imperfect laminated plates under combined axial and thermal loads

A post-buckling analysis of composite laminated plates subjected to combined axial compression and uniform temperature loading is presented. The two cases of thermal post-buckling of initially compressed plates and of compression post-buckling of initially heated plates are considered. The initial geometrical imperfection of the plates is taken into account. The analysis uses a perturbation technique to determine buckling loads and post-buckling equilibrium paths. Numerical examples are presented that relate to the performances of perfect and imperfect, antisymmetrically angle-ply and symmetrically cross-ply laminated plates. Typical results are presented in dimensionless graphical form.

Thermomechanical Postbuckling of Imperfect Moderately Thick Plates on Nonlinear Elastic Foundations*

A postbuckling analysis is presented for a moderately thick rectangular plate subjected to combined axial compression and uniform temperature loading, and resting on a softening nonlinear elastic foundation. The cases of (1) thermal postbuckling of initially compressed plates and (2) compressive post-buckling of initially heated plates are considered. The initial geometrical imperfections of the plates are taken into account. Formulations are based on Reissner-Mindlin plate theory, considering first-order shear deformation effects, and including plate-foundation interaction and thermal effects. The analysis uses a deflection-type perturbation technique to determine buckling loads and postbuckling equilibrium paths. Numerical examples include the performance of perfect and imperfect, moderately thick plates resting on softening nonlinear elastic foundations. Typical results are presented in dimensionless graphical form.

Thermal post-buckling analysis of imperfect laminated plates

A thermal post-buckling analysis of composite laminated plates subjected to uniform or nonuniform (parabolic) temperature loading is presented. The initial geometrical imperfection of the plate is taken into account. The analysis uses a mixed Galerkin-perturbation technique to determine the thermal buckling loads and post-buckling equilibrium paths. Numerical examples are presented that relate to the performances of perfect and imperfect, antisymmetrically angle-ply and symmetrically cross-ply laminated plates. Typical results are presented in nondimensional graphical form.

Refined theory for non-linear buckling of heated composite shallow spherical shells

The present study deals with static buckling and postbuckling behavior of clamped shallow laminated spherical shell with polar-orthotropic layers subjected to a conservative uniform external pressure and temperature load. The physical properties of the material are assumed to be temperature independent. The variational principle of minimum potential energy of the system is used to obtain the static governing equations in terms of displacements. Five Mindlin-type displacement variables are utilized to take into account a thickness shear. A tenth order system of non-linear differential equations is obtained and its numerical solution is shown for the case of axisymmetric deformation and constant temperature field. A method of solution, including finite difference discretization and modified relaxation procedure, is proposed. Some specific effects inherent to composite shells are found and discussed.

Thermal postbuckling analysis of moderately thick plates

A thermal postbuckling analysis is presented for a moderately thick rectangular plate subjected to (1) uniform and non-uniform tent-like temperature loading; and (2) combined axial compression and uniform temperature loading. The initial geometrical imperfection of plate is taken into account. The formulations are based on the Reissner-Mindlin plate theory considering the effects of rotary inertia and transverse shear deformation. The analysis uses a deflection-type perturbation technique to determine the thermal buckling loads and postbuckling equilibrium paths. Numerical examples are presented that relate to the performances of perfect and imperfect, moderately thick rectangular plates and are compared with the results predicted by the thin plate theory.

THERMAL POSTBUCKLING OF METAL MATRIX LAMINATED PLATES

The postbuckling response of metal matrix laminated plates that are subjected to thermal loading is investigated A micromechanical analysis, which accounts the thermo-viscoplastic behavior of the metallic matrix and its interaction with the elastic fibers and provides the overall constitutive response of metal matrix composite (MMC), is performed. This is further employed in a structural analysis to obtain the thermal postbuckling behavior of MMC laminated plates. Results are presented for unidirectional and angle-ply graphite / aluminum and boron /aluminum geometrically imperfect plates that are subjected to uniform temperature loadings. The influences of the amplitude of initial geometrical imperfections, the lamination angle, the length-to-thickness ratio, and the effect of heating followed by a subsequent cooling are investigated. Comparisons with the corresponding elastic solutions, which are obtained by neglecting the inelastic effects in the metallic matrix, are presented

Boundary Element Heat Conduction and Thermoelastic Analyses of Interface Crack in LSI Package in Consideration of Contact Between Crack Surfaces.

The interface crack initiated between the die pad (lead frame) and the resin encapsulant in the LSI package sometimes leads to package cracking and becomes critical to package fracture design. On the other hand, the property of thermal diffusion has become a main concern for recent package design of power semiconductor devices. To simulate these problems, we developed the boundary element heat conduction and thermoelastic analysis code, which can deal with thermoelastic contact of the interface crack. The stress intensity factors for an interface crack are calculated by the extrapolation method which is proposed by one of the authors. Using the above technique, the interface crack initiated in a plastic-molded LSI package is analyzed under conditions of uniform temperature loading and heat generation in the Si-chip. Calculated interfacial stress intensity factor Ki shows a decreasing trend against the interface crack length in all the above cases. Taking into account the contact of the crack surface, the results of the disturbance in temperature distribution are outstanding. However, the normalized stress intensity factor Ki/|ΔTmax| Shows almost identical behavior against with the crack length and is less dependent on the contact region length and the amount of heat generation.

Postbuckling response of antisymmetric angle-ply laminates to uniform temperature loading

The postbuckling behavior of antisymmetric angle-ply plates, resting on simple supports and subjected to a gradually increasing uniform temperature field is investigated. Stable equilibrium configurations are determined through a direct application of the principle of minimum potential energy. Since nonunique equilibrium states may exist, a method of incremental loading is employed to identify the particular state associated with a given thermal loading path. Numerical results for fiber-reinforced laminates illustrate the effects of ply orientation, number of layers and aspect ratio on the postbuckling behavior. The phenomena of secondary buckling is examined in detail.