Finite element prediction of damping of composite GFRP and CFRP laminates – a hybrid formulation – vibration damping experiments and Rayleigh damping

The work reported in this paper describes the development of a hybrid methodology for the prediction of damping properties of vibrating composite laminates; this method could also be applied to homogeneous materials. This hybrid methodology consists of experimental identification of damping, using vibration damping testing methods, and utilization of FEA. The experimentally identified damping property is that of specific damping capacity (SDC), a measure of damping during the first mode of resonant vibration of beams. The finite element (FE) approach utilizes the concept of Rayleigh damping, and in particular mass proportional damping for the modeling of the damped response of vibrating systems. It is shown that by using such a methodology, damping data can be extracted for cases, where application of continuum mechanics analytical solutions cannot provide reliable information. Furthermore, the development of the finite element models is described. The association of damping properties with material reinforcement is highlighted. A series of continuous and woven, cross ply and quasi isotropic GFRP and CFRP coupons were vibrated. The FE damped response prediction was in very good agreement with laboratory observations.