Vibration Analysis And Active Vibration Control Of Open Cylindrical Shells

Thin-wall open cylindrical shells are widely used in aerospace,automobile,railway vehicles,ships,submarines and other industrial fields,due to the thin wall,the panel often appears vibration when subjected to external loads,which easily leads to serious vibration and noise problems of the structures.In order to effectively reduce the vibration of the open cylindrical shells,the Active Constrained Layer Damping(ACLD)is applied to reduce vibration.In this paper,a dynamic model of open cylindrical shell with ACLD is established.The influence of ACLD parameters on response characteristics is analyzed,and a multiple objective optimization method is used to optimize the ACLD structure.Last,an adaptive vibration control algorithm for ACLD open cylindrical shell is proposed.The main content of paper are as follows:(1)Based on Lagrange equation and Sanders shell theory,the dynamic equation of ACLD open cylindrical shell structure is established.The vibration responses of piezoelectric layer and damping layer are studied.The results show,thickness of piezoelectric layer,thickness of damping layer,numbers of damping layer section,duty ratio of damping element,laying angle of constrained layer have significant effect on the first three natural frequency and loss factors.The applicability of local applying ACLD vibration reduction method is studied under different lengths,radio and opening angles of cylindrical shells,which provided a reference for vibration and noise reduction of open shell.(2)In order to improve the efficiency of vibration reduction,the non-dominated sorting genetic algorithm with the elitist strategy(NSGA-II)is proposed.The optimization objective is to maximize the loss factors and minimize the structure mass ratio,and the structure parameters of ACLD which affect the vibration characteristics are taken as design variables.The optimization and simulation of open cylindrical shell with ACLD are carried out.the results of optimization indicate that the NSGA-?can effectively reduce the complexity of calculation.The results show that the amplitude of the first third order frequencies domain are reduced under the condition of less quality of ACLD structure.(3)According to the optimization results of partly applying ACLD open cylindrical shell,an adaptive feed-forward control controller based on LMS algorithm is designed to reduce the vibration of ACLD open cylindrical shell.The loss factors and modal frequency characteristics of open cylindrical shell under different control voltage are analyzed,the effects of different sampling frequency,initial weighting factors and orders of filter on the control system are investigated.The results show that the adaptive feed-forward controller based on LMS algorithm can effectively suppress the vibration of the open cylindrical shells by selecting appropriate sampling frequency,initial weighting factors and orders of filter.