Vibration Analysis And Research On Control For Spherical-cylindrical Shell With Active Constrained Layer Damping

The spherical-cylindrical shell structure is widely used in railway,aviation,navigation,and other engineering fields due to its excellent volume ratio,load-bearing capacity,and good aerodynamic performance,such as the transition structure of the cab shell of the EMU,the shape structure of the missile head and Submarine hull structure.The working environment of these structures is very complicated,and they are often subjected to various dynamic excitations,and there are serious vibration and noise problems.In response to this problem,this paper adopts the method of laying Active Constrained Layer Damping(ACLD)to study effective ways to reduce the vibration of the spherical-cylindrical shell structure.The main work is as follows:(1)Using the Donnell thin shell theory and Lagrange equation,the dynamic equation of the ACLD rotating thin shell is established.This equation provides a theoretical foundation for the subsequent analysis of the ACLD cylindrical shell and spherical shell.(2)Based on the established dynamic equations of the ACLD rotating thin shell,the dynamic models of the ACLD cylindrical shell and spherical shell are derived,and the effects of structural parameters of ACLD base layer,viscoelastic layer,and piezoelectric layer,as well as the voltage on the vibration characteristics of cylindrical and spherical shells,are studied respectively.The results show that by setting the ACLD structural parameters reasonably and applying a specific excitation voltage,the vibration displacement of the cylindrical and spherical shell structures can be effectively reduced.(3)Using the mechanical and displacement matching relationship between the cylindrical shell and the spherical shell,a dynamic model of the spherical-cylindrical combined shell is established and the influence of the main parameters of the ACLD viscoelastic layer and the piezoelectric layer on the vibration characteristics of the spherical-cylindrical shell is analyzed.The results show that the laying of the active constrained damping structure has little effect on the working frequency of the sphere-cylindrical shell structure.In the allowable range of volume and mass,increasing the thickness of the viscoelastic layer,the thickness of the piezoelectric layer,the number of viscoelastic sections of the cylindrical shell part,and the laying angle of the spherical shell and the cylindrical shell part constraining layer can effectively increase the damping performance of the spherical-cylindrical shell.(4)Based on inverse piezoelectric effect of the piezoelectric layer structure,using linear quadratic Gaussian(LQG)control algorithm and normalized least mean square error(NLMS)adaptive control algorithm,a vibration control algorithm for a spherical-cylindrical composite shell structure is designed to realize active vibration control.The effects of different filter orders,adaptive step lengths,and other parameters on the system's vibration reduction control effect are compared and analyzed.The results show that the LQG/NLMS compound control method can guarantee the effectiveness of damping the spherical-cylindrical shell under different filter orders and adaptive step lengths.Increasing the adaptive step length and filter order can effectively improve the response rate of vibration damping control.However,if the adaptive step size is too large,it will easily lead to voltage runaway.