Rosalin Sahoo

Dynamic Instability of Laminated Composite and Sandwich Plates Using a New Inverse Hyperbolic Zigzag Theory

AbstractThe present study deals with the dynamic stability behavior of laminated composite and sandwich plates subjected to in-plane static and periodic compressive loads based on a recently developed inverse hyperbolic zigzag theory by the authors. The present model satisfies the traction-free boundary conditions on the surfaces of the plate and interlaminar continuity conditions at the layer interfaces, thus obviating the need for a shear correction factor. An efficient C0 continuous isoparametric serendipity element with seven field variables is employed for the usual discretization of the plate structure. The effect of span-thickness ratio, modular ratio, boundary conditions, static load factor, and thickness ratios are examined by solving a variety of numerical problems on laminated composite and sandwich structures. The principal instability regions of plate structures are obtained using Bolotin’s approach and are represented either in the nondimensional load amplitude-excitation frequency plane or ...

Dynamic Instability of Laminated-Composite and Sandwich Plates Using a New Inverse Trigonometric Zigzag Theory

A structure with periodic dynamic load may lead to dynamic instability due to parametric resonance. In the present work, the dynamic stability analysis of laminated composite and sandwich plate due to in-plane periodic loads is studied based on recently developed inverse trigonometric zigzag theory (ITZZT). Transverse shear stress continuity at layer interfaces along with traction-free boundary conditions on the plate surfaces is satisfied by the model obviating the need of shear correction factor. An efficient C0 continuous, eight noded isoparametric element with seven field variable is employed for the dynamic stability analysis of laminated composite and sandwich plates. The boundaries of instability regions are determined using Bolotins approach and the first instability zone is presented either in the nondimensional load amplitude–excitation frequency plane or load amplitude–load frequency plane. The influences of various parameters such as degrees of orthotropy, span-thickness ratios, boundary conditions, static load factors, and thickness ratios on the dynamic instability regions (DIRs) are studied by solving a number of problems. The evaluated results are validated with the available results in the literature based on different deformation theories. The efficiency of the present model is ascertained by the improved accuracy of predicted results at the cost of less computational involvement.