A generalized model of modal parameters of glass reinforced plastic structures (GRP) is presented. The extensive analysis of the fitted experimental results proves that the quasi uniform mass damping is the main feature of vibratory GRP structures. Consistent with the analysis it is stated that the number of boundary degrees of freedom, code number, volume fraction and typical order of natural mode have significant effects respectively on controlling the type of each set of quasi rectangular hyperbolic relations associated with the vibration damping of GRP structures.The close agreement between the numerical results of the finite element model and the fitted experimental results shows the efficiency and applicability of the present modelling techniques, resulting in significant simplifications in solutions of idiosyncratic composite systems with lowest residual errors.

An improved model of modal parameters of glass reinforced plastic structures (GRP) is presented.T h e extensive analysis of :he fitted experimental results proves that the quasi uniform mass damping is the main feature of vibratory G R P structures.Consistent with the analysis it is stated that the number of boi~ndary degrees of freedom, code number, volume fraction and typical order of natural mode have significant effects respectively on controlling the type of each set of quasi rectangular hyperbolic relations associated with the vibration d a m p i n g of G R P structures.The close agreement between the numerical results of-' the finite element model and the fitted experimental results s h o w s the efficiency and applicability of the present modelling techniques, resulting in s i g n i f i c a n t s i m p l i f i c a t i o n s in s o l u t i o n s o f idiosyncratic composite systems with lowest residual errors.

An improved dynamical model for vibration damping in composite structures is introduced to investigate the stacking sequence and the degree of anisotropy as a function of the vibration modes. Extensive investigation has been carried out from the fitting of modal measurements with lowest residual errors to establish quasi-uniform mass damping models in terms of normal coordinates system. The analysis of the obtained results proves not only the efficiency of the proposed model but also its applicability in any wide range of frequency spectrum of composites.