Mechanics
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ISSN 1734-8927
e-ISSN: 2300-7060
Issue Date
2007
Volume
Vol. 26
Number
No. 2
Description
Journal Volume
Mechanics
Vol. 26 (2007)
Projects
Pages
Articles
Active noise and vibration control system design considerations
(Wydawnictwa AGH, 2007) Hansen, Colin H.; Qiu, Xiaojun; Petersen, Cornelis; Howard, Carl Q.; Singh, Sarabjeet
When designing active control systems to reduce noise radiated by vibrating surfaces, there are many variables that need to be optimised to achieve the maximum possible system performance. There are also a number of hardware and software aspects that must be considered and accounted for when a laboratory system is adapted for operation in an industrial or commercial environment. There needs to be some sort of hierarchy in the approach to optimising the many variables which include type, locations and numbers of control sources, quality of the reference signal for feedforward systems, software structure and algorithm considerations and hardware architecture considerations. This paper discuses a number of issues associated with the implementation of active noise and vibration control systems that have been the subject of investigation at The University of Adelaide.
The analysis of vibrations of control gyroscope as a driver in the target tracking unit of homing missile
(Wydawnictwa AGH, 2007) Koruba, Zbigniew; Krzysztofik, Izabela
In the contemporary detection and target tracking units of rocket missile (RM), the control gyroscope remains an essential element being the device used for changing the position of the target line of sight (LOS). Target tracking accuracy of a rocket missile depends on the gyroscope work precision. Thus, it is necessary to examine the impact of the external actions and disturbances - rapid manoeuvres in the initial stage of RM flight, deck vibrations or strong wind blows on the dynamics of the gyroscope. The paper discusses the research results of the dynamics of control gyroscope set on the RM deck while seeking, detecting and tracking a mobile target.
Remote visualization of the velocity distribution on vibrating structures using the wave field analysis
(Wydawnictwa AGH, 2007) Lewin, Peter A.; Berger, Andrew W.; Vecchio, Christopher J.; Schafer, Mark E.
Knowledge of vibrating pattern characteristics is of interest in many applications, including minimization of noise generation in different media and design and optimization of piezoelectric transducers used in diagnostic ultrasound imaging. A field expansion technique developed for analyzing the acoustic fields and vibrating structures is presented. The technique is based on the angular spectrum method of wave-field analysis, and is applicable to both continuous (CW) and wideband pulsed waves, and allows the effects of acoustic parameters such as absorption, dispersion, refraction, and phase distortion to be accounted for. Examples of remotely reconstructed surface velocity distributions of complex acoustic radiators are presented and the potential applications of the technique developed in the analysis of fields radiated by sources with arbitrary geometries, including arrays are also pointed out.
Experimental study of vibration control in a two-degree-of-freedom pitch-plane model of a magnetorheological vehicle suspension
(Wydawnictwa AGH, 2007) Martynowicz, Paweł; Sapiński, Bogdan
The paper concerns the vibration control in a two-degree-of-freedom model of vehicle suspension equipped with independently controlled MR dampers in front and rear sections. The suspension model was tested in open-loop and feedback system configurations under harmonic and square base excitations. The experiments were conducted on the specially designed laboratory setup with data acquisition and control system configured in MATLAB/Simulink environment. The obtained results reveal effectiveness of MR dampers in vibration isolation for a wide range of excitation frequencies.
Model - based active noise control of a piezoelectric structure
(Wydawnictwa AGH, 2007) Nestorović, Tamara; Lef?vre, Jean; Gabbert, Urlich
Methods of active noise and vibration control involve different techniques which combine electroacoustics with integration of active materials and controller into a complex active structural system in order to enable radiation of an anti-phased field for cancellation or attenuation of an original noise in a specific domain. This paper presents a model-based controller design procedure for the active noise attenuation of a piezoelectric structure surrounded by the acoustic fluid. Model development is based on a finite element method approach, which takes into consideration the electro-mechanical-acoustic effects. A FEM-based state-space model obtained after appropriate transformations and modal reduction is used for the controller design. The aim of the control, suppression of the acoustic fluid pressure in a prescribed point or field, is achieved using an optimal LQ controller designed based on a developed state-space model. The controller design involves also a novel approach, with included additional dynamics for the noise control in the presence of periodic excitations. The effects of the suggested method are tested on a smart acoustic box consisting of an aluminium plate with attached piezoelectric patches, surrounded by the acoustic fluid (air) inside the wooden box. The air pressure reduction at a selected point inside the box is observed in the controlled case.