Free Vibration Study of Annular Laminated Composite Circular Plates with Holes

Abstract

A composite laminate is layers of fibres of composite materials which are assembled to provide desired engineering properties. These have a wide range of application, especially in weight sensitive structures like aircraft, spacecraft. Laminated plates used in these structures are subjected to dynamic loads. These plates with numerous circular cut outs are either used to lessen the mass of the whole structure or to expand the inspection. The presence of cut outs in the plates changes the stress distribution of the plates and makes the analysis complex. When an external system vibrates has exactly the same natural frequency as the internal system, resonance follows producing considerable deflections. Specific plans can minimise these unnecessary failures. Hence the analysis of the modal characteristics of these plates is significant. First an isotropic circular plate’s behaviour is studied and then a circular orthotropic plate has been considered for this study. The material properties have been fixed. The natural frequencies have been computed for different boundary condition, hole-radius ratio, and thickness to radius ratio, and fibre orientation, asymmetric and symmetric holes. The effects of these variables on the nature of vibration have been analysed and discussed. ANSYS 13.0 is used for the computation of natural frequencies.