HYGROTHERMALLY INDUCED POST BUCKLING RESPONSE OF LAMINATED COMPOSITE PLATES WITH UNCERTAIN SYSTEM PROPERTIES: STOCHASTIC FINITE ELEMENTAL MICROMECHANICALMODEL

摘要

The effects of moisture and temperature on the post buckling of laminated composite plate with temperature dependentproperties(T.D) subjected to uni-axial compression is investigated using micro-mechanical model.. The system properties such as hygrothermo-material properties, fiber volume fractions of respective fiber and matrix constituents are modeled as independent random variables. The temperature and moisture field considered to be uniform distributions over the plate surface and through the plate thickness. The material properties of the composite are affected by the variation of temperatures and moisture are based on micro-mechanical model The basic formulation is based on Reddy's higher order shear deformation plate theory and general von-Karman types of nonlinearity. A C~0 FEM in conjunction with first order perturbation technique (FOPT) in MATLAB programme will be employed to compute the mean and standard deviation of the hygrothermally induced post buckling response of the laminated composite plate having random change in all input material variables, thermal expansion coefficients, coefficients of hygroscopic expansion and geometric parameters for micro mechanical model The deterministic dimensionless mean response result will be validated with available literature and for coefficient of variation of hygrothermally induced post buckling load with an independent Monte Carlo simulation. A C~0 finite element method in conjunction mean centered first order perturbation technique is out lined and solved the stochastic nonlinear generalized eigen value problem. The developed stochastic procedure is usefully used for hygrothermally induced post buckling problem based on micro-mechanical approach with a reasonable accuracy. Parametric studies are carried out to see the effect of volume fractions, amplitude ratios, temperature and moisture increments, geometric parameters, lay-ups, boundary conditions on the mean and variance of plate post buckling loads. The present outlined approach has been validated with those available results in literature's and independent Monte-Carlo simulation.