Increasing the damping of flexural vibrations of laminated FPC structures by incorporation of soft intermediate plies with minimum reduction of stiffness

Abstract The flexural vibrations of laminated fiber-polymer composite structures (FPCs) can be damped as desired by the incorporation of a soft ply placed optimally in the zero line of longitudinal flexural stress. In the dimensioning of this ply with respect to maximal damping of the first mode, however, a simultaneous strong reduction of static stiffness results (factor about 4), as compared with a classic layered structure without damping ply. Through the choice of a higher shear-modulus for the damping ply, the loss of stiffness can be held down to about 20%, although a high modal loss-factor of the first mode of 0·3–0·5 of the maximal damping for this mode can be attained. An interesting side-effect which resulted for higher modes was greater modal loss-factors than with the choice of the shear-modulus for a maximal damping of the first mode.