Free vibration analysis of sandwich plates

Abstract

Laminated sandwich plates consisting of a soft core bounded by two relatively thin and stiff faces exhibit excellent strength to weight and stiffness to weight ratios. This makes them very suitable for applications where weight saving is a major concern, such as in aerospace and automotive structures. Piezoelectric layers or patches, due to their simple electro-mechanical properties, can easily be integrated with sandwich composites. The objective of integrating piezoelectric patches is to use them as sensors and actuators in order to control the excessive deformations and vibrations of the structure. Such a structure will have self-correcting capabilities against external loads and is called a smart structure. This further reduces the weight of the structure without compromising on strength or stiffness and becomes a very suitable choice for aerospace applications. Since these structures are often subjected to high dynamic loadings, it becomes important to have an insight of their free vibration characteristics. The work presented includes a study of the free vibration response of laminated sandwich plates using different core materials. From the study it was found that the material of the core significantly influences the free vibration behaviour of the plate, the natural frequency increases with the increase in density of the core material and also with an increase in mode number. The investigation will help in acquiring a better insight of the dynamic behaviour of sandwich plates with surface bonded piezoelectric patches. The efficiency and accuracy of the used elements is established by validation of the results with the published literature.