Optimum tuning of a vibration neutralizer for global vibration control

2001 ◽  
Vol 215 (8) ◽  
pp. 933-942 ◽  
Author(s):  
J Dayou ◽  
M. J. Brennan
Keyword(s):  
Resonance Frequency ◽  
Vibration Control ◽  
Dynamic Stiffness ◽  
Control Device ◽  
Single Frequency ◽  
Active Device ◽  
Low Frequencies ◽  
Quadratic Minimization ◽  
Minimization Technique ◽  
Insight Into

This paper is concerned with optimization of the natural frequency of a vibration neutralizer to minimize the global vibration of a structure at a single frequency. The optimization is carried out using a quadratic minimization technique to determine the dynamic stiffness of the control device that is required, and then the optimum resonance frequency of the neutralizer is determined. It is shown that, with the exception of very low frequencies, an optimally adjusted vibration neutralizer can be as effective as an active device at a single frequency. Simulations are presented with a single neutralizer on a beam to facilitate insight into the mechanisms of control.

Realization of Resonance of a Diaphragm at Any Desired Frequency

2015 ◽  
Vol 34 (1) ◽  
pp. 29-34
Author(s):  
Y. Zhang ◽  
L. Huang
Keyword(s):  
Mechanical Property ◽  
Resonance Frequency ◽  
Vibration Control ◽  
Mechanical System ◽  
Electromechanical Coupling ◽  
Mass System ◽  
Low Frequencies ◽  
Control Applications ◽  
Noise And Vibration ◽  
Lc Circuit

AbstractIn noise control, the reactance of a mechanical system needs to be minimized while the resistance is chosen suitably. This work illustrates the possibility of and the ease at which such design tasks may be accomplished by utilizing strong electromechanical coupling. Moving-coil loudspeaker is chosen as the vehicle of illustration and it is considered as a simple spring-mass system when operated below its first diaphragm mode. It is shown that the system mechanical property may be tuned easily by a simple R-LC circuit. In addition to the assigned resonance frequency, there can be a maximum of two other resonances. It is argued that the ability to tune the system mechanical resonance to any frequency, such as the ones at very low frequencies, can be very useful for noise and vibration control applications.

Seismic Control Effect for Nonlinear Benchmark Building Using Passive or Semi-Active Damper

2002 ◽  
Author(s):  
Akira Fukukita ◽  
Tomoo Saito ◽  
Keiji Shiba
Keyword(s):  
Active Control ◽  
Passive Control ◽  
Feedforward Control ◽  
Electrical Power ◽  
Control Device ◽  
Control Effect ◽  
Damping Force ◽  
Active Device ◽  
Seismic Control ◽  
Control Forces

We study the control effect for a 20-story benchmark building and apply passive or semi-active control devices to the building. First, the viscous damping wall is selected as a passive control device which consists of two outer plates and one inner plate, facing each other with a small gap filled with viscous fluid. The damping force depends on the interstory velocity, temperature and the shearing area. Next, the variable oil damper is selected as a semi-active control device which can produce the control forces by little electrical power. We propose a damper model in which the damping coefficient changes according to both the response of the damper and control forces based on an LQG feedback and feedforward control theory. It is demonstrated from the results of a series of simulations that the both passive device and semi-active device can effectively reduce the response of the structure in various earthquake motions.

Simultaneous Optimal Design of the Lyapunov-Based Semi-Active Control and the Semi-Active Vibration Control Device: Inverse Lyapunov Approach

2010 ◽  
Author(s):  
Kazuhiko Hiramoto ◽  
Taichi Matsuoka ◽  
Akira Fukukita ◽  
Katsuaki Sunakoda
Keyword(s):  
Optimal Design ◽  
Lyapunov Function ◽  
Vibration Control ◽  
Active Control ◽  
Control Device ◽  
Ball Screw ◽  
Design Parameters ◽  
Resistance Force ◽  
Control Law ◽  
Lyapunov Approach

We address a simultaneous optimal design problem of a semi-active control law and design parameters in a vibration control device for civil structures. The Vibration Control Device (VCD) that is being developed by authors is used as the semi-active control device in the present paper. The VCD is composed of a mechanism of a ball screw with a flywheel for the inertial resistance force and an electric motor with an electric circuit for the damping resistance force. A new bang-bang type semi-active control law referred to as Inverse Lyapunov Approach is proposed as the semi-active control law. In the Inverse Lyapunov Approach the Lyapunov function is searched so that performance measures in structural vibration control are optimized in the premise of the bang-bang type semi-active control based on the Lyapunov function. The design parameters to determine the Lyapunov function and the design parameters of the VCD are optimized for the good performance of the semi-active control system. The Genetic Algorithm is employed for the optimal design.

An Analytical Model for the Interaction of Mass Inclusions in Heterogeneous (HG) Blankets

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
A. Wagner ◽  
M. E. Johnson ◽  
K. Idrisi ◽  
D. P. Bartylla
Keyword(s):  
Elastic Layer ◽  
Analytical Approach ◽  
Low Frequency ◽  
Control Device ◽  
Effective Stiffness ◽  
Special Focus ◽  
Dynamic Vibration Absorber ◽  
Low Frequencies ◽  
Dynamic Vibration ◽  
The Masses

The heterogeneous (HG) blanket is a passive treatment used to reduce the low frequency transmission of sound through partitions. HG blankets, glued onto a structure, consist of an elastic medium with embedded mass inhomogeneities that mechanically replicate a mass-spring-damper system to reduce efficient radiating structural modes at low frequencies. The elastic layer typically used has sound absorption properties to create a noise control device with a wide bandwidth of performance. The natural frequency of an embedded dynamic vibration absorber is determined by the mass of the inhomogeneity as well as by its effective stiffness due to the interaction of the mass inclusion with the elastic layer. A novel analytical approach has been developed to describe in detail the interaction of the mass inclusions with the elastic layer and the interaction between the masses by evaluating special elastomechanical concepts. The effective stiffness is predicted by the analytical approach based on the shape of the mass inclusions as well as on the thickness and material properties of the layer. The experimental validation is included and a simplified direct equation to calculate the effective stiffness of a HG blanket is proposed. Furthermore, the stress field inside the elastic material will be evaluated with focus on the stresses at the base to assess the modeling of one or more masses placed on top of the elastic layer as dynamic vibration absorbers. Finally, the interaction between two (or more) masses placed onto the same layer is studied with special focus on the coupling of the masses at low distances between them.

The Detection And Mapping Of Defects In Organic Coatings Using Local Electrochemical Impedance Methods

1995 ◽  
Vol 411 ◽  
Author(s):  
S. R. Taylor ◽  
M. W. Wittmann
Keyword(s):  
Electrochemical Impedance ◽  
Organic Coatings ◽  
Single Frequency ◽  
Probe Design ◽  
Coating Failure ◽  
Local Electrochemical Impedance Spectroscopy ◽  
Physical Defects ◽  
Steel Substrates ◽  
Insight Into

ABSTRACTCoating failure initiates as a local event at defects which can result from chemical heterogeneities in the resin or physical defects such as bubbles, underfilm deposits, or pinholes. The ability to detect, map the location, as well as make quantitative in-situ measurements of coating heterogeneities will help identify the source of failure (i.e. coating chemistry, method of application, cure schedule, etc.) and provide insight into the mechanisms of coating degradation. This study used a 5 electrode arrangement to perform local electrochemical impedance spectroscopy (LEIS) on coated steel substrates. Using single frequency measurements, LEIS could successfully detect and map both intentional chemical heterogeneities and physical defects such as subsurface bubbles, underfilm deposits, and pinholes. Efforts to optimize probe design and instrumentation are ongoing.

Research on Vibration Control of Thin Plate Based on Pre-Stressing

2018 ◽  
Author(s):  
Cheng Zhang ◽  
Jian-run Zhang ◽  
Xi Lu
Keyword(s):  
Differential Equation ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Vibration Control ◽  
Thin Plate ◽  
Natural Frequencies ◽  
Control Method ◽  
Dynamic Stiffness ◽  
Thin Plates ◽  
Shape Functions

The weak dynamic stiffness of thin plate is one of the important factors that limit the use of thin plate. Improving the dynamic stiffness of thin plate is one of the effective methods for the vibration control of thin plate. In this paper, the influence of pre-stress on the vibration characteristics of thin plate is studied. A vibration control method of thin plate based on pre-stress is proposed. The vibration differential equation of quadrate thin plate under pre-stressing is established. Using the Galerkin principle, the natural frequencies corresponding to the shape functions of the quadrate thin plates under pre-stressing in different distribution forms are obtained. By comparison, it is found that pre-stressing on the thin plate can change the dynamic stiffness of thin plate. In particular, tensile stress can increase the dynamic stiffness of thin plate while compressive stress can reduce the dynamic stiffness of the thin plate. The greater the pre-stress, the more obvious the effect. In the end, the requirements of the pre-stress distribution which can improve the dynamic stiffness of thin plate effectively are derived.

scholarly journals Study on Multi-Degree of Freedom Dynamic Vibration Absorber of the Carbody of High-Speed Trains

2021 ◽  
Author(s):  
Yu SUN ◽  
Jinsong Zhou ◽  
Dao Gong ◽  
Yuanjin Ji
Keyword(s):  
Vibration Control ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
High Speed Train ◽  
Dynamic Vibration Absorber ◽  
Multiple Degrees Of Freedom ◽  
Dynamic Vibration

Abstract To absorb the vibration of the carbody of the high-speed train in multiple degrees of freedom, a multi-degree of freedom dynamic vibration absorber (MDOF DVA) is proposed. Installed under the carbody, the natural vibration frequency of the MDOF DVA from each DOF can be designed as a DVA for each single degree of freedom of the carbody. Hence, a 12-DOF model including the main vibration system and a MDOF DVA is established, and the principle of Multi-DOF dynamic vibration absorption is analyzed by combining the design method of single DVA and genetic algorithm. Based on a high-speed train dynamics model including an under-carbody MDOF DVA, the vibration control effect on each DOF of the MDOF DVA is analyzed by the virtual excitation method. Moreover, a high static and low dynamic stiffness (HSLDS) mount is proposed based on a cam–roller–spring mechanism for the installation of the MDOF DVA due to the requirement of the low vertical dynamic stiffness. From the dynamic simulation of a non-linear model in time-domain, the vibration control performance of the MDOF DVA installed with nonlinear HSLDS mount on the carbody is analyzed. The results show that the MDOF DVA can absorb the vibration of the carbody in multiple degrees of freedom effectively, and improve the running ride quality of the vehicle.

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