Effects of surface contact on the dynamic responses of delaminated composite plates

This paper investigates the modal parameters such as the damping ratio, frequency and shape of delaminated composite plates with contact properties. The contact damping is analyzed using a viscoelastic Coulomb friction model with sliding phase, which combines energy dissipation of sliding friction and sticky friction. Finite element method (FEM) based models simulate the dynamic responses of delaminated composite plates, in which the constant normal contact stiffness and contact damping are introduced via penalty stiffness method and equivalent viscous damping, respectively. Relevant vibration experiments are set up to obtain the modal parameters of delaminated composite plates. The results show that the modal damping ratio of the composite laminated plates increases significantly with increase in the delamination percentage, and the contact damping plays a major role in the increase of the modal damping ratio. Furthermore, the contact stiffness also has a minor influence on the modal frequency and shape of delaminated composite plates. The experimental data is consistent with simulations, thereby establishing the accuracy of the FEM model.