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The linear 3D piezoelasticity theory along with active damping control (ADC) strategy are applied for non-stationary vibroacoustic response suppression of a doubly fluid-loaded functionally graded piezolaminated (FGPM) composite hollow cylinder of infinite length under general time-varying excitations. The control gain parameters are identified and tuned using Genetic Algorithm (GA) with a multi-objective performance index that constrains the key elasto-acoustic system parameters and control voltage. The uncontrolled and controlled time response histories due to a pair of equal and opposite impulsive external point loads are calculated by means of Durbin’s numerical inverse Laplace transform algorithm. Numerical simulations demonstrate the superior (good) performance of the GA-optimized distributed active damping control system in effective attenuation of sound pressure transients radiated into the internal (external) acoustic space for two basic control configurations. Also, some interesting features of the transient fluid-structure interaction control problem are illustrated via proper 2D time domain images and animations of the 3D sound field. Limiting cases are considered and accuracy of the formulation is established with the aid of a commercial finite element package as well as comparisons with the current literature.

Openings in plate structures are essential in various engineering applications, particularly in vibro-acoustic systems where airflow is required. This paper investigates noise control in vibro-acoustic systems with noise barriers incorporating structural openings, focusing on active noise control and Active Structural Acoustic Control (ASAC). It also introduces a novel approach, Dual-Actuator-Type Active Noise Control (DATANC), which combines loudspeakers and inertial actuators into the same barrier to address the challenges of noise reduction. A sound power estimation method is proposed to account for sound transmission through the opening and is integrated into an analytical model for optimizing actuator placement; predictions show strong agreement with observed behavior. Among the ASAC configurations, experimental analysis shows that actuators placed near the edge of the opening achieve the greatest noise reduction in the 100–200 Hz range, where acoustic leakage is dominant. DATANC consistently outperformed all single-actuator configurations, delivering superior attenuation of dominant vibro-acoustic resonances while maintaining reasonable computational complexity. The analysis is extended to a plate with a transparent lid over the opening to evaluate the contribution of acoustic leakage to the system performance. The findings of this study demonstrate that optimized actuator placement, combined with DATANC, provides a practical solution for noise control in systems where structural openings are required.

The use of inertial actuators to control the radiated sound pressure of a steel ship model at a lake measurement facility is examined. Therefore, methods of active vibration control as well as active control of target sound fields are applied using a fixed configuration of twelve accelerometers, eight control actuators, and five hydrophones. A narrowband feedforward active control system is used to manipulate the sound pressure at hydrophone positions, focusing not only on reducing but also on adding spectral lines in the radiated signature. The performance is assessed using measured data by additional accelerometers inside the ship model as well as by hydrophones surrounding the measurement facility. It is found that less control effort is necessary for the generation of additional tones compared to the control of a present disturbance at hydrophones. In the frequency range considered (below 500 Hz), the actively induced change in the mean structural velocity is not necessarily proportional to the change in the radiated sound pressure. In contrast to the vibration velocity, no unwanted amplification of the sound pressure is found for the frequencies observed.

The active casing approach is a technique to reduce noise emission of devices and machinery by controlling vibrations of their casings. This method was successfully validated by the authors for a single-panel casing in previous publications. However, if even higher noise reduction is required, a dedicated double-panel structure can be employed. In this paper, the sound insulation efficiency of a double-panel active casing is evaluated and compared with a single-panel structure by performing a series of laboratory experiments. The least mean squares algorithm is used to adaptively update control filter parameters. A low-frequency noise in the range up to 500 Hz is considered. Advantages and limits of the proposed approach are pointed out and discussed, and conclusions for future research are given.

Linear quadratic Gaussian optimal control is one of the techniques used for active noise control. In practical implementation of this technique, one of the key difficulties faced is the estimation of the states of the plant. A state observer that accurately estimates these states can be used in this regard. Studies reported make use of analytically or experimentally derived models to build observers. This paper proposes a method for active noise control in the framework of active structural-acoustic control incorporating system identification for the development of the linear quadratic Gaussian controller. Kalman filter is used as a stochastic state observer of the plant states. System identification is carried out using modal testing and finite element model updating to obtain an accurate model of the plant for building up the Kalman filter. The objective of the proposed method is to actively reduce the noise inside the cavity due to disturbances acting on the cavity structure. The active control is achieved by controlling the structural vibrations by taking into account the degree of coupling between the various structural and the acoustic modes. The effectiveness of the proposed method is evaluated experimentally on a 3D rectangular box cavity with a flexible plate.

Passive noise reduction means are commonly used to reduce noise in the industry but, unfortunately, their effectiveness is poor in the low frequency range. By applying active structural acoustic control to the enclosure walls significant improvement of the insulating properties in this frequency range can be achieved. In this paper a model of double panel structure with ASAC is presented. The structure consists of two aluminium plates separated by an air gap. Two inertial magnetoelectric actuators and two piezoceramic MFC sensors were used for controlling the structure. A multichannel FxLMS algorithm with virtual error microphone technique is used as a control algorithm. The signal of a virtual error microphone is extrapolated basing on signals from MFC sensors. Performance of this actively controlled structure for tonal signals at selected frequencies is presented in the article. During the study, a double panel structure was mounted on one wall of sound insulating enclosure located in an acoustic chamber. During the measurements local and global reduction of noise test signal was investigated.

High acoustic insulation windows are common mean to decrease sound transmission to closed spaces. Hence, the improvement of sound insulation of windows is very important research issue. In this paper partial results of research project aimed at synthesis of the window panel with actively controlled sound transmission are presented. Recent stage of the project is focused on the development of multichannel Active Structural Acoustic Control algorithm. High amplitude excitation produces nonlinear vibration effects. Using feedforward control strategy it is convenient to control not only the reference signal spectrum, but also additional frequencies generated as the cause of nonlinearity. Therefore neural network based algorithm is considered. To lower the computational burden of the algorithm, round robin based error backpropagation learning is employed. The results of numerical simulations are presented. Major conclusion of presented part of the research is that the algorithm is capable of controlling a wide-band noise efficiently. Reduction of the computational complexity leads to increased convergence time, not influencing the final value of mean square error.

It is possible to enhance acoustic isolation of the device from the environment by appropriately controlling vibration of a device casing. Sound insulation efficiency of this technique for a rigid casing was confirmed by the authors in previous publications. In this paper, a light-weight casing is investigated, where vibrational couplings between walls are much greater due to lack of a rigid frame. A laboratory setup is described in details. The influence of the cross-paths on successful global noise reduction is considered. Multiple vibration actuators are installed on each of the casing walls. An adaptive control strategy based on the Least Mean Square (LMS) algorithm is used to update control filter parameters. Obtained results are reported, discussed, and conclusions for future research are drawn.

The active noise-reducing casing developed and promoted by the authors in recent publications have multiple advantages over other active noise control methods. When compared to classical solutions, it allows for obtaining global reduction of noise generated by a device enclosed in the casing. Moreover, the system does not require loudspeakers, and much smaller actuators attached to the casing walls are used instead. In turn, when compared to passive casings, the walls can be made thinner, lighter and with much better thermal transfer than sound-absorbing materials. For active noise control a feedforward structure is usually used. However, it requires an in-advance reference signal, which can be difficult to be acquired for some applications. Fortunately, usually the dominant noise components are due to rotational operations of the enclosed device parts, and thus they are tonal and multitonal. Therefore, it can be adequately predicted and the Internal Model Control structure can be used to benefit from algorithms well developed for feedforward systems. The authors have already tested that approach for a rigid casing, where interaction of the walls was significantly reduced. In this paper the idea is further explored and applied for a light-weight casing, more frequently met in practice, where each vibrating wall of the casing influences all the other walls. The system is verified in laboratory experiments.

A multi-objective mixed H 2 / H ∞ robust output feedback control synthesis with regional pole placement constraints in a linear matrix inequalities framework is adopted for active low-frequency sound radiation control of an arbitrarily thick, rigidly baffled, simply supported, multi-layered piezo-composite circular panel. The adopted control system concurrently captures the benefits of both H 2 transient control performance and H ∞ robust stability in the face of external disturbances and system uncertainties. Also, the implemented volumetric sensing/actuation configuration avoids the typical problems associated with conventional (spatially discrete) piezoelectric sensor/actuator patches, where the total volume velocity can be effectively cancelled with the main contribution being to the long wavelength acoustic power emission. The elasto-acoustic analysis is based on the spatial state-space method in the context of exact 3D elasticity theory along with the Rayleigh integral formula where Neumann’s addition theorem is incorporated in the associated Hankel transform representation to arrive at a computationally efficient expression for the nonaxisymmetric pressure field within the acoustic half-space, valid in both near and far fields. Subspace system identification of the fully coupled structure–fluid interaction problem is performed, and the truncated modes are considered as multiplicative uncertainties in synthesis of the mixed-norm controller. Numerical simulations establish the ability of the implemented volumetric sensing/actuation methodology in cooperation with the multi-objective robust active control scheme for restraining low-frequency sound radiation from a Ba 2 NaNb 5 O 15 /steel/PZT4 circular piezo-laminated plate, without provoking instability of the closed-loop system. Also, superior bandwidth frequency and tracking performance in comparison to the H 2 and H ∞ controllers are observed. This work is believed to be the first such attempt to exactly model (and actively control) the 3D nonaxisymmetric acousto-elastodynamic frequency response of an arbitrarily thick, smart piezo-laminated circular plate in heavy fluid loading condition (i.e. without using any kind of far-field, low-frequency, and/or light fluid coupling approximations), with straightforward extensibility for any arbitrary through-thickness variation of distributed material properties.