Etude du comportement mécanique de structures sandwiches à differents materiaux de revetements

Abstract

The sandwich material, present a certain interest in term of rigidity and specific resistance for the aeronautic structure design. The study of this material meets always the choice problem of their constituants (coating and heart) in order to load the optimal mechanical characteristics. The aim of our work is to do a comparative study of the mechanical behaviour of the sandwich plates with various materials of coatings charged in cylindrical bending and compression by taking into account of transverse shearning. For this reason, the coatings are considered at the base of wood (plywood) or composite laminates ( glass/ epoxy, graphite/epoxy or kevlar /epoxy) of stacking sequence [- θ /+ θ ] 5s and [90 ° /0 ° ] 5s and the heart is in balsa, aluminium honeycomb, moss herex, or plast honeycomb .The mechanical behaviour of the sandwich plates was determinated by the use of the mathematical approaches based on the formulation of the equilibrium equations, and the development of the classical theory of thin laminated plates .The change of the nature constituent material as well as the research of the effect of the plate dimensions and the orientation of fibers reinforcing the composite coatings permit to determine the evolution of the plates resistance and their deformations, and to calculate the stress in each layer composing the coatings superior and inferior. The obtained different results were shaw that the sandwich material with coating in graphite /epoxy and with heart in aluminium honeycomb resist in buckling and cylindrical bending better .In return the material at the base of wood (plywood/balsa),is characterized by a low mechanical resistance. The adequate choice of the coating material thus ensures a better behaviour of all the sandwich plate.