Free vibration analysis of delaminated beams using mixed finite element model

Free vibration analysis of laminated beams with delamination has been presented in this paper. A 2-D plane stress mixed finite element model developed by the authors [G.S. Ramtekkar, Y.M. Desai, A.H. Shah, Natural vibrations of laminated composite beams by using mixed finite element modeling, Journal of Sound and Vibration 257(4) (2002) 635–641.] has been employed. Two models, namely the unconstrained-interface model and the contact-interface model have been proposed for the computation of frequencies and the mode shapes of delaminated beams. Laminated beams with mid-plane delamination as well as off-mid-plane delamination have been considered and the results have been compared with various theoretical and experimental results available in the literature. It has been concluded that the contact-interface model presents a realistic behaviour of the dynamics of delaminated beams whereas the unconstrained-interface model under-predicts the frequencies, particularly at the higher modes