Viscous damping approximation of laminated anisotropic composite plates using the finite element method

The main source of mechanical damping in laminated composite materials arises from the inelastic nature of the matrix and the relative slipping at the fiber/matrix interfaces. Damping in laminated composite materials is usually a function of many parameters including the volume fraction of the fibers, fiber diameter and fiber orientation relative to the axis of loading. Also the magnitude and frequency of the applied load and many environmental factors should be mentioned. Since the complex phenomenon of damping is difficult to incorporate into the structural dynamic analysis of laminated plates, a viscous damping approximation is employed here. Experimental data on specific damping capacity (SDC) of unidirectional composite beams is used to define an average modal loss factor associated with each mode of vibration of a laminated plate. These loss factors are then employed with a finite element analysis and a multidimensional definition of critical damping to form a Rayleigh damping matrix [C] as a linear combination of the stiffness and mass matrices. Realistic examples illustrate the importance of several parameters in the vibration of laminated composite plates with damping. Such an analysis can be useful in the development of new composite materials where high damping is one of the primary objectives.