Effect of Delamination Size on the Natural Frequency of Twintex and Natural Fibre/Poly-Propylene Hybrid Composite Cantilever Beam

A variety of defects exist in a laminated composite structure. Some are due to defective manufacturing conditions and processes, while some are created as a consequence of in-service loading conditions. Delamination is a defect which can arise due to either poor manufacturing processes or due to in-service loading. A delamination marks a physical separation between two adjacent layers of the composite and it has significant effects on the mechanical behaviour of the composite structure. In this work, we focus on quantifying the effects of delamination situated at the free end of a rectangular composite cantilever beam on the beam natural frequencies. Twintex and natural fibre/poly-propylene materials are considered as the individual phases. FEA is carried out by considering the contact model. The results reveal that the presence of a delamination has a huge impact on the natural frequency and so does the size of the delamination, in that the natural frequency reduces and new opening modes of vibration and introduced.