The effect of visco-elastic core thickness on modal loss factors of a thick three-layer cylinder

Free vibration of damped three-layer sandwich cylinders with thick layers is considered. In particular, the effect of the different thicknesses for the middle layer on the overall natural frequencies and modal damping factors are studied. The constrained layer damping is accomplished by sandwiching a linear visco-elastic material between two isotropic elastic cylinders with the same properties. The governing equations are derived using the theory of elasto-dynamic, by employing complex elastic moduli for the sandwiched layer. Dimensionless natural frequencies and modal loss-factors for the first three thickness modes associated with wave numbers of n = 0, 1, 2, 3, and 4 are tabulated for a range of thicknesses for the middle visco-elastic layer while keeping the thicknesses of inner and outer layers unchanged.