Vibration Analysis And Optimization Of Beam With Partial Constrained Viscoelastic Layer Damping Treatments

Vibration and noise on the hazards of life have been recognized by the people. In the early 1950s the passive control of the vibration have been applied, passive constrained layer damping treatment for vibration can be achieved by the shearing deformation of viscoelastic material which can dissipate mechanical energy of damping structure. But researches on it are mainly focused on the whole constrained layer damping treatment. The studies on the partial constrained layer damping treatment are rare.This paper mainly introduced the basic viscoelastic material characteristics, mathematical model, energy-consuming mechanism, indexes relating to viscoelastic material and viscoelastic material performance parameters. The elastic structure finite element dynamics model is researched, and then the elastic-viscoelastic composite structure in frequency domain were deduced. And some methods of viscoelastic layer damping treatment and several finite element methods in the calculation of damping structure are presented.Then an analysis of a simple-supported beam structure covered with partial constrained viscoelastic layer damping patches is performed. Taking use of energy method, Rayleigh-Ritz method, the finite element method and the Lagrange equations, the mathematical model is established. A Matlab program was developed using the equations developed above to find the frequency response and search how the loss factor changes with the location and length of damping patches. At the same time, in this paper, vibration analysis of beams covered with multiple standoff constrained layer damping patches is researched. A finite element model is established, and an application of Matlab program is developed to analyze the model again. From the numerical experiment, standoff constrained layer damping patches can enhance the loss factors more effectively while the stiffness of the beam decreases less.In the end, a further study for the structure is carried out. A beam structure with stand-off layer damping patches treatment of continuous constrained layer could make the shearing deformation of viscoelastic further increased and loss factors gain greater. By studying the beams of different damping layers, it can be found the length, space and division of the damping layers can change the loss factors more effectively. Then, the optimization is carried out. The optimal solutions which are gained after and before mass constraints are compared. At the same time, the effect of the weights in different working condition is apparently important. So under some working conditions, for the sake of reducing vibration, inductions of damping layer are necessary. But it must be restricted to avoid the extra mass. Some valuable conclusions for actual applications are drawn.