Random System Properties Research Articles

Post buckling response of laminated composite plate on elastic foundation with random system properties

This paper deals with second order statistics of post buckling load of shear deformable laminated composite plates resting on linear elastic foundation with random system properties. The formulation is based on higher order shear deformation plate theory in general von Karman sense, which includes foundation effect using two-parameter Pasternak model. The random system equations are derived using the principal of virtual work. A finite element method is used for spatial descretization of the laminate with a reasonable accuracy. A perturbation technique has been the first time successfully combined with direct iterative technique by neglecting the changes in nonlinear stiffness matrix due to random variation of transverse displacements during iteration. The numerical results for the second order statistics of post buckling loads are obtained. A detailed study is carried out to highlight the characteristics of the random response and its sensitivity to different foundation parameters, the plate thickness ratio, the plate aspect ratio, the support condition, the stacking sequence and the lamination angle on the post buckling response of the laminate. The results have been compared with existing results and an independent Monte Carlo simulation.

Non-linear stochastic dynamics of systems with random properties: A spectral approach combined with statistical linearization

The goal of the paper is to include into statistical linearization random system properties, which may be important in the case of a narrow-band excitation. Random properties of the system are described by a Karhunen-Loeve-expansion, and for the response of a linear system with random properties subjected to a stochastic loading a spectral approach introducing Hermitian polynomials for the random response quantities is used according to a proposal of Ghanem and Spanos. Whereas for a deterministic non-linear contribution to a random linear system the procedure is rather similar to the well-established linearization for deterministic systems, some additional operations are necessary to take into account the randomness of the non-linear contributions.