HYGROSCOPIC EFFECT ON THE BUCKLING BEHAVIOUR. OF COMPOSITE LAMINATED PLATES

Abstract

The present work deals with the study of effect of moisture absorption on the buckling of composite laminated plates. Composite materials are being used in many critical application where they are subjected to adverse environmental condition. As such, a knowledge of the deterioration in the performance of these structures is a subject of great importance. In the present work the composite laminate has been modelled as a thin plate. Moisture diffusion in the plate is assumed to be governed by Fick's law. The hygroscopic stress resultant due to moisture absorption is incorporated in the formulation of the plate buckling problem. A finite element formulation with three noded triangular element is carried out to form the governing equation. Results have been presented for simply supported and clamped square plate of T 300/5208 graphite epoxy laminate. Stacking sequences are taken to be (0 /± 45/90)4s, (0/90)8s and (± 45)8s. Variation of buckling load of the laminate with moisture absorption time has been plotted for different equilibrium moisture concentration in the laminate. Results presented in this work indicate that the effect of moisture absorption on buckling load of laminates is quite significant. For low values of moisture concentration a steady state value of buckling load is obtained whereas for higher values of moisture concentration required buckling load drops to zero, indicating plate buckling due to hygroscopic stress resultants alone. From the work presented, it is concluded that with moisture diffusion, performance of composite plates subjected to buckling loads deteriorates and there is a need for accounting the hygroscopic effect in a realistic design of composite structures subjected to adverse environmental condition. (