Based on the linear theories of thin cylindrical shells and viscoelastic materials, a governing equation describing vibration of a sandwich circular cylindrical shell with a viscoelastic core under harmonic excitation is derived. The equation can be written as a matrix differential equation of the first order, and is obtained by considering the energy dissipation due to the shear deformation of the viscoelastic core layer and the interaction between all layers. A new matrix method for solving the governing equation is then presented with an extended homogeneous capacity precision integration approach. Having obtained these, vibration characteristics and damping effect of the sandwich cylindrical shell can be studied. The method differs from a recently published work as the state vector in the governing equation is composed of displacements and internal forces of the sandwich shell rather than displacements and their derivatives. So the present method can be applied to solve dynamic problems of the kind of sandwich shells with various boundary conditions and partially constrained layer damping. Numerical examples show that the proposed approach is effective and reliable compared with the existing methods.

To enhance the generality and flexibility of active constrained layer damped (ACLD) forms used in vibration control for circular cylindrical shells, the piezoelectric layer of the ACLD form is divided into several sub-blocks by thin insulated layers, and the sub-blocks are integrated on the viscoelastic layer continuously in the circumferential direction. In addition, on the basis of the authors' recent research on passive constrained layer damped (PCLD) circular cylindrical shells, the piezoelectric effects of the constrained layer (made of piezoelectric material) are further considered. Then, the integrated first-order differential equation for such an ACLD (partially treated in the axial direction) circular cylindrical shell is derived by reformulating the integrated first-order differential equation for the PCLD circular cylindrical shell. Next, employing the extended homogeneous capacity precision integration approach and the superposition principle, a high precision semi-analytical method is developed for solving the dynamic problem for such ACLD circular cylindrical shells. Subsequently, several kinds of circumferential modal control strategy are compared by the method presented. Furthermore, the concept of a circumferential dominant modal control strategy is proposed, which is different from the traditional modal control method. The numerical results show that, on applying the circumferential dominant modal control strategy, the ACLD cylindrical shell attenuates the vibration better. Lastly, some influence factors for the circumferential dominant modal control strategy affecting the damping effect of ACLD circular cylindrical shells are also investigated.

No abstract

No abstract

No abstract