Conventional Constrained Layer Damping Research Articles

Damping ratio maximization in thickness direction using viscoelastic and structural materials based on constrained layer damping

Constrained layer damping (CLD) is a typical application known to exhibit high damping. However, the damping ratio generally attains its maximum value when the applied surface is fully covered with the damping material. In this study, a method is proposed of topology optimization in the thickness direction using viscoelastic and constrained materials based on CLD in order to obtain a higher damping ratio. A mathematical formulation is proposed of the material interpolation functions of the store elastic modulus, loss elastic modulus, Poisson's ratio and density. As a result of the optimization using a cantilever beam, the damping ratio obtained in the optimal layout is 1.44 times higher than that in conventional CLD. The higher damping in the optimal layout can be attributed to compression of the viscoelastic material by the slits, and a decrease in the flexural rigidity caused by the taper and the longitudinally extending part of the slits.

Application of the Electromechanical Surface Damping to the Vibration Control of a Cantilever Plate

The electromechanical surface damping technique (EMSD) is applied to suppress the bending and twisting (torsional) peak vibration amplitudes of a cantilever plate. The technique is a combination of the constrained layer damping (CLD) and the shunted piezoelectric methods in which the constraining layer of the CLD is replaced by a shunted piezoelectric ceramic. The frequency responses, to a white noise random base excitation, of the EMSD-treated plate at the vicinity of the first and second bending and twisting resonant frequencies are determined and compared with the corresponding responses of the CLD treatment. It is shown that, in general, the EMSD treatment provides more suppression of the bending and twisting peak vibration amplitudes than the conventional CLD treatment. The EMSD treatment, however, is more effective at higher frequencies and lower temperatures, which suggests that the EMSD method can be applied to extend the effective range of frequencies and/ or temperatures of the conventional CLD method. The work presented is primarily analytical; however, a crude and preliminary experimental work is presented to demonstrate the feasibility of the EMSD technique.