Étude du comportement dynamique des composites stratifiés et sandwichs.

Abstract

Nowadays, the use of composite materials has taken a large place in civilian industries as well as in military and aerospace industries. In particular, composite structures with one or more attachments, such as different types of sensors, are often encountered in engineering applications. These attached masses affect the dynamic responses of the main structures. Therefore, the present thesis addresses the effect of attached mass on dynamic properties of composite laminate and sandwich plates, under flexural vibration, for clamped-free-free-free boundary conditions. Furthermore, factors influencing the effect of attached mass on the natural frequencies of laminate composite are studied using the Taguchi method. The considered factor parameters are: attached mass weight, attached mass locations from the clamped edge, staking sequences, and number of layers. In addition, the effects of the attached mass on the natural frequencies of sandwich plate according to several factors , these factors are the positions of the attached mass, the mechanical characteristics of the core, the ratios of thickness of core/ thickness the plate (hc / h), and the length / width ratios of the plate (a / b)). So, the study carried out is based on a model of calculation by the use of the finite element method. The results of this study indicate that the dynamic characteristics of the laminate composite and sandwich plates are sensitive to the attached mass, where the natural frequencies are found to be inversely proportional to the mass weight. The results were found that the locations of the attached mass are the most important factors affecting the natural frequencies of laminate plate, where the location of the masses fell into the antinodes area of vibration.