Approximation of the critical buckling factor for composite panels

This article is concerned with the approximation of the critical buckling factor for thin composite plates. A new method to improve the approximation of this critical factor is applied based on its behavior with respect to lamination parameters and loading conditions. This method allows accurate approximation of the critical buckling factor for non-orthotropic laminates under complex combined loadings (including shear loading). The influence of the stacking sequence and loading conditions is extensively studied as well as properties of the critical buckling factor behavior (e.g concavity over tensor D or out-of-plane lamination parameters). Moreover, the critical buckling factor is numerically shown to be piecewise linear for orthotropic laminates under combined loading whenever shear remains low and it is also shown to be piecewise continuous in the general case. Based on the numerically observed behavior, a new scheme for the approximation is applied that separates each buckling mode and builds linear, polynomial or rational regressions for each mode. Results of this approach and applications to structural optimization are presented

Perturbed rotational motions of a spheroid with cavity filled with a viscous fluid

We consider a motion about the center of mass of a spheroid with a cavity filled with a viscous fluid. It is assumed that the velocity of the fluid is sufficiently high, so the corresponding Reynolds number is small. The torque of forces acting on the body by the viscous fluid in the cavity is determined by the method developed in the works of F.L. Chernousko. Asymptotic approach permits to obtain some qualitative results and to describe nonlinear evolution of angular motion using simplified averaged equations and numerical solution. </jats:p