Vibration analysis of multiple delaminated composite beams

In this study, the effects of location, size and number of delaminations, boundary conditions, orientation angles and stacking sequences on the natural frequency of laminated composite beams are investigated experimentally, analytically and numerically. Two-dimensional finite element models of the delaminated beams are obtained using ANSYS (Finite ElementMethod Code). The analytical method is developed using Euler-Bernoulli beam theory. Then, analytical results are compared with the results available in the literature and the numerical and experimental results in the present study. It has been seen that all results obtained are very close to each other. It is shown that the natural frequencies decrease when sizes and numbers of edge and middle delaminations in the beam increase, and the location of the delamination is also very important. The first natural frequency value of beam of [0° /90°] 8 is found to be the highest as compared to the beams with angles [30°] 16 and [60°] 16. However, the natural frequency values in the beams that have the angle-ply of [θ] 16 are lower than those of [θ/?θ] 8, [(θ/?θ) 4] s and [(θ/?θ) s] 4. © 2012 Koninklijke Brill NV, Leiden