Damping Characteristics Analysis Of CLD Structure And Marine Transmission Box

It has been a long time for the engineering application of CLD (constrainedlayer damping) and the research method is mature. With the development of newmaterials, damping materials with better characteristics are made in recent years,which contribute to the continuous research of CLD structure. That ships poweredby gas turbine needs complicated transmission and the requirement of seamen for aquiet working environment force technicians to take action to reduce the vibrationsand noises produced by the transmission. The CLD structure applying to box ofthe transmission is a good option. The loss factor is a core parameter of LCDstructure, which is still a very important parameter for a structure dynamic analysis.So this research is meaningful for engineering application.Finite element method is a useful tool to study CLD structures, such ascomplex eigenvalue method, direct frequency response method, and modal strainenergy method (MSE). The MSE method is a mature method and is widely used. Animproved method was brought out to reduce the error of the traditional MSE methodin this paper. Elasticity modulus was piecewise averaged and the loss factor ofviscoelastic material used in MSE method was the frequency-depend loss factor.Theoretically, any viscoelastic CLD can be analyzed by MSE method. Butcurrent objects are relatively simple, mostly3-layer and5-layer plates or beams.Whether these methods are suitable for complicated structures is still needed to betested. More complicated CLD plate with tendons was designed in the paper, whichis more common in the engineering application field. And a conclusion abouttendons affecting on loss factor of the CLD structure was gained. There’re a fewresearches about applying CLD structures to the marine transmission box. But thefrequent-dependent property of damping material and the loss factor of marinetransmission box was seldom considered. The loss factor of the marine transmissionbox with CLD structure was calculated and the damping property was provedquantitatively. And an effect of mode shapes on the loss factor of the dampedtransmission box had been discovered.Experiment measurement for dynamic parameters of CLD structure is a methodparalleled with numerical calculation and finite element simulation, which is similarto a modal experiment, in which the corresponding parameter is obtained by fittingparameters.4kinds of CLD structures were designed in this paper,3of them withdifferent thickness of5mm,10mm,15mm damping, and a none damping structurewas a control group. The loss factor of the4CLD structures under two boundaries was obtained by using the LMS vibration measuring and analysis system. Andcomparison of test data and simulation data was carried out in the paper.