DYNAMIC STABILITY OF STIFFENED LAMINATED COMPOSITE PLATES AND SHELLS SUBJECTED TO INPLANE PULSATING FORCES

The dynamic stability of laminated composite stiffened or non-stiffene d plates and shells due to periodic in-plane forces at boundaries is i nvestigated in this paper. A three-dimensional (3-D) degenerated shell element and a 3-D degenerated curved beam element are used to model p lates/shells and stiffeners, respectively. The characteristic equation s to find the natural frequencies, buckling loads and their correspond ing mode shapes are obtained from the finite element equation of motio n. Then, the method of Hill's infinite determinants or the method of m ultiple scales is applied to analyse the dynamic instability regions. Numerical results are presented to demonstrate the effects of various parameters, such as skew angle, lamination scheme, stiffened scheme, i n-plane force type and curvature of cylindrical shell, on the dynamic stability of stiffened and non-stiffened plates and shells subjected t o in-plane pulsating forces at boundaries.