Effects of Cut-out On The Natural Frequency of Glass Fibre –Epoxy Composite Plates

Abstract

Excellent mechanical properties of composite laminates combined with high stiffness and light weight have been an active field of research for decades. Industry now a day is also promoting the use of composites over other conventional materials for structural purposes. Keeping that in mind, it is utmost important to determine the static and vibrational characteristics of composite plates. Composite plates used as structural elements are generally subjected to various shapes, sizes and design of cut-outs. These cut-out servers for various practical uses for the designers. In this study basically the study of the modal characteristics of the glass fibre epoxy composite plates in the presence of different cut-outs was taken up. The study was a combination of experiments and analytical modelling. Parameters such as size of cut-out, different thickness of plate with same size of cut-out, distance of cut-out from support and relative position of the cut-out was studied. The variation in the mode frequencies and mode shapes were investigated for all the above cases.
For modal analysis, a Fast Fourier Transform Analyzer, Pulse lab shop software, Accelerometer was used. From this we obtained the frequencies of the first four modes. The results obtained by the Pulse were then compared with the data obtained from the Ansys modelling. Detail mode shapes for various conditions were retrieved from Ansys. First the analysis of the composite plates without cut-outs was done. Then cut-outs were introduced in the plates. Results from the modal analysis and Ansys were found to have very less variation. The Variations of natural frequency with different parameters are presented.