This book is a companion text to Active Control of Sound by P.A. Nelson and S.J. Elliott, also published by Academic Press. It summarizes the principles underlying active vibration control and its practical applications by combining material from vibrations, mechanics, signal processing, acoustics, and control theory. The emphasis of the book is on the active control of waves in structures, the active isolation of vibrations, the use of distributed strain actuators and sensors, and the active control of structurally radiated sound. The feedforward control of deterministic disturbances, the active control of structural waves and the active isolation of vibrations are covered in detail, as well as the more conventional work on modal feedback. The principles of the transducers used as actuateors and sensors for such control strategies are also given an in-depth description. The reader will find particularly interesting the two chapters on the active control of sound radiation from structures: active structural acoustic control. The reason for controlling high frequency vibration is often to prevent sound radiation, and the principles and practical application of such techniques are presented here for both plates and cylinders. The volume is written in textbook style and is aimed at students, practicing engineers, and researchers.

Active control of vibration, 1st edition

Magnetic Field–Suppressed Lithium Dendrite Growth for Stable Lithium-Metal Batteries

Nonlinear vibration isolation for fluid-conveying pipes using quasi-zero stiffness characteristics

A novel quasi-zero-stiffness strut and its applications in six-degree-of-freedom vibration isolation platform

Vibration and noise control using shunted piezoelectric transducers: A review

Nonlinear self-defined truss element based on the plane truss structure with flexible connector

A quasi-zero stiffness coupling comprises a shell and an inner shaft arranged in the shell. One end of the inner shaft is connected with the bottom of the shell through a rubber spring, and the rubber spring is a tooth-type rubber spring. The inner ring of the rubber spring and teeth at the end of the inner shaft are clamped to each other closely, and the outer ring of the rubber spring and teeth on the inner wall of the shell are clamped to each other closely, so that it is guaranteed that the shell drives the inner shaft to rotate together when twisting. An outer magnetic ring is fixed to the inner wall of the shell, an inner magnetic ring is fixed to the outer circumferential ring of the inner shaft, and the outer magnetic ring and the inner magnetic ring constitute a magnetic spring. The outer ring of the bearing is matched with the shell, the inner ring of the bearing and the inner shaft are matched to restrain the inner shaft from making axial movement and radial movement relative to the shell. The negative stiffness of the outer magnetic ring and the inner magnetic ring are made approximate to the positive stiffness of the rubber spring by selecting geometrical parameters of the outer magnetic ring and the inner magnetic ring, so that the total stiffness is made to reach a quasi-zero state. The quasi-zero stiffness coupling can effectively transmit driving torque, also can isolate disturbance torque, has a wide vibration isolation frequency band, and has a good isolation effect on low-frequency disturbance. The quasi-zero stiffness coupling can be used for solving the torsional vibration problem of a rotor system, and is particularly suitable for precise rotor systems.

Quasi-zero stiffness coupling

In this study, large-sized Al–Zn–Mg–Cu alloy billets were prepared by direct chill casting imposed with annular electromagnetic stirring and intercooling; a process named uniform direct chill casting The effects of uniform direct chill casting on grain size and the alloying element distribution of the billets were investigated and compared with those of the normal direct chill casting method The results show that the microstructures were refined and the homogeneity of the alloying elements distribution was greatly improved by imposing the annular electromagnetic stirring and intercooling In uniform direct chill casting, explosive nucleation can be triggered, originating from the mold wall and dendrite fragments for grain refinement The effects of electromagnetic stirring on macrosegregation are discussed with consideration of the centrifugal force that drives the movement of melt from the central part towards the upper-periphery part, which could suppress the macrosegregation of alloying elements The refined grain can reduce the permeability of the melt in the mushy zone that can restrain macrosegregation

Microstructures and Macrosegregation of Al-Zn-Mg-Cu Alloy Billet Prepared by Uniform Direct Chill Casting.

With the increase in the diameter of antenna, it easily leads to low natural frequency. Besides, on account of the characteristics of lightweight, great flexibility, weak damping and large size, external excitation can dramatically bring vibration. Therefore, this paper investigates the vibration control for a hoop flexible structure of antenna by using a piezoelectric stack actuator. At first, a multi-body dynamics equation is established and solved to illustrate the influence of external excitation. Meanwhile, proportional derivative algorithm, fuzzy algorithm, and least mean square adaptive filtering algorithm are applied to derive the vibration control theory. Then, a 3D model of the hoop flexible structure is built by finite element software. The frequency and mode are calculated by modal analysis. Finally, based on a designed piezoelectric actuator, the simulation is established to suppress the vibration. The result illustrates that the amplitude of response is decreased significantly after adopting the actuator and intelligent control algorithm.

The multi-body analysis and vibration control of the second-order mode of a hoop flexible structure

An active vibration control scheme was proposed based on Macro Fiber Composite (MFC) actuators for the bending and torsional vibration control of large flexible lightweight wing structures. Firstly, a finite element modeling and modal analysis of a flexible wing are carried out. Further, the number, type, and location distribution of the MFC actuators bonded on the supported beam of the wing are designed. Then, the actuated characteristics of the two kinds of MFC actuators required for bending and torsional vibration controls was theoretically analyzed. The simulation model of the overall vibration control system was also finally obtained. Finally, through ANSYS simulation analysis, the vibration control effect of the current control system on the first two-order low-frequency modal response of the wing structure is given. The simulation results show that the proposed active vibration control scheme has specific feasibility and effectiveness.

Yajun Luo

Papers

Nonlinear self-defined truss element based on the plane truss structure with flexible connector

Quasi-zero stiffness coupling

Microstructures and Macrosegregation of Al-Zn-Mg-Cu Alloy Billet Prepared by Uniform Direct Chill Casting.

The multi-body analysis and vibration control of the second-order mode of a hoop flexible structure

Research on active vibration control of flexible wing based on MFC actuator