ON THE FREE VIBRATION ANALYSIS OF LAMINATED COMPOSITE AND SANDWICH PLATES: A LAYERWISE FINITE ELEMENT FORMULATION

Abstract

IN THIS PAPER, A NEW HIGHER-ORDER LAYERWISE FINITE ELEMENT MODEL, DEVELOPED EARLIER BY THE PRESENT AUTHORS FOR THE STATIC ANALYSIS OF LAMINATED COMPOSITE AND SANDWICH PLATES, IS EXTENDED TO STUDY THE FREE VIBRATION BEHAVIOR OF MULTILAYER SANDWICH PLATES. IN THE PRESENT LAYERWISE MODEL, A FIRST-ORDER DISPLACEMENT FIELD IS ASSUMED FOR THE FACE SHEETS, WHEREAS A HIGHER-ORDER DISPLACEMENT FIELD IS ASSUMED FOR THE CORE. THANKS FOR ENFORCING THE CONTINUITY OF THE INTERLAMINAR DISPLACEMENT, THE NUMBER OF VARIABLES IS INDEPENDENT OF THE NUMBER OF LAYERS. IN ORDER TO REDUCE THE COMPUTATION EFFORT, A SIMPLY FOUR-NODED C0 CONTINUOUS ISOPARAMETRIC ELEMENT IS DEVELOPED BASED ON THE PROPOSED MODEL. IN ORDER TO STUDY THE FREE VIBRATION, A CONSISTENT MASS MATRIX IS ADOPTED IN THE PRESENT FORMULATION. SEVERAL EXAMPLES OF LAMINATED COMPOSITE AND SANDWICH PLATE WITH DIFFERENT MATERIAL COMBINATIONS, ASPECT RATIOS, BOUNDARY CONDITIONS, NUMBER OF LAYERS, GEOMETRY AND PLY ORIENTATIONS ARE CONSIDERED FOR THE ANALYSIS. THE PERFORMANCE AND RELIABILITY OF THE PROPOSED FORMULATION ARE DEMONSTRATED BY COMPARING THE AUTHORÂS RESULTS WITH THOSE OBTAINED USING THE THREE-DIMENSIONAL ELASTICITY THEORY, ANALYTICAL SOLUTIONS AND OTHER ADVANCED FINITE ELEMENT MODELS. FROM THE OBTAINED RESULTS, IT CAN BE CONCLUDED THAT THE PROPOSED FINITE ELEMENT MODEL IS SIMPLE AND ACCURATE IN SOLVING THE FREE VIBRATION PROBLEMS OF LAMINATED COMPOSITE AND SANDWICH PLATES.