The natural frequencies of acoustic—structure systems can be approximated by a closed-form expression that accounts for the interaction between two uncoupled component modes: a given structural mode and the acoustic mode with which it couples most strongly. In this greatly expanded and extensively revised edition, the authors have retained most of the analytically based material that forms the pedagogical content of the first edition, and have expanded it to present the theoretical foundations of modern numerical analysis. The analysis of the vibrational response of thin-plate and shell structures to incident sound, acoustic-coupling between structures and enclosed volumes of fluid, and analyses of fluid-structure interaction are examined. With consideration of the interaction between the shaft and hull structure, the dynamic response and the radiated sound pressure of the system are presented. This paper has proposed a scheme for estimating high-frequency damping of a beam through electro-mechanical signatures of piezoelectric wafers mounted on the beam. The accuracy of this method is checked on an aluminum plate with and without a cutout. Fuselage stiffness properties are modelled using lamination parameters and their effect on the vibro-acoustic performance is investigated using two different approaches.
However, discrepancy between the models and the measurement was found to arise with the decrease of the cross-sectional area and the increase of the hole thickness since the viscosity effect is substantial for small and long holes. The number of examples of experimental data that relate to the theoretical content, and illustrate important features of vibroacoustic interaction, has been augmented by the inclusion of a selection from the vast amount of material published during the past twenty five years. Acoustically Induced Vibration of Structures 7. This work seeks to identify and validate different mathematical and computational methods for predicting the results of horizontal impact tests. Acoustically Induced Vibration of Structures; 5. At off-resonance frequencies, the way in which energy flows into the hole is found to depend upon whether the coupled system is stiffness-like or mass-like.
Active structural acoustic control commonly aims at the suppression of the far—field radiated sound power. Transmission of Sound Through Partitions Chapter 6. This paper presents a closed form solution for the vibration and acoustic problem of orthotropic plates under a thermal environment. The frequency equations and mode functions obtained for the orthotropic heated plates with at least two adjacent edges clamped are much simpler than those by the conventional methods. Summary The first edition of Sound and Structural Vibration was written in the early 1980s. Contrary to the acoustic potential energy, the mean velocity is not necessarily reduced in order to achieve a reduction in sound radiation.
Considering damping effect while resonance of a beam evolves, wave perspective is adopted to formulate the electro-mechanical signatures of piezoelectric wafers. Application of the latter is illustrated by examples that have been chosen to complement the analytical approaches to solving fairly simple problems of sound radiation, transmission and fluid-structural coupling that are presented in the first edition. For the acoustic cavities in the vibro-acoustic analysis, the spectra of the averaged quadratic sound pressure of both the left and right trapezoidal cavity, P 2 L and P 2 R , are plotted in Fig. Based on the equations derived, an analytical solution to the static deformation problem for single-layer rectangular plate hinge-supported along its contour and subjected of a uniformly distributed pressure applied to one of its boundary planes is obtained. Thus, it is fundamental for the aerospace industry to be able to correctly simulate composite materials vibroacoustic behavior in order to allow a low weight-low cost design including the acoustic effects. Then, it is shown that the proposed method has a greater control effect with a small number of actuators and it needs less control energy. Acoustically Induced Vibration of Structures Chapter 7.
They may be characterized by parameters like added mass, added damping and added stiffness describing fluid and flow effects on structure motion. A survey made by Morfey 1969 of the low-frequency acoustic properties of circular, rectangular and elliptic holes demonstrated also the weak dependence of the acoustic response on the hope shape. Limitations were found for all of the methods, and caution is advised when using these to design to horizontal impact noise criteria. In this study, the methods used to excite a panel with point force actuators for active sound transmission control are investigated by simulations. The theoretical model of the considered vibro-acoustic system is developed by using the modal superposition method in conjunction with envelope rectangular technique.
The first edition of Sound and Structural Vibration was written in the early 1980s. Results of simulations on plate coupled with a cavity filled with water are presented. The idea is by installing a partition to effectively block the sound energy and transmitting only few of the rest. During the last years it has been observed a growing interest in the characterization of the acoustical performances of building elements at low frequencies. It can be shown, that the adaptive circuit allows a tighter adjustment to the edge of stability resulting in higher damping or, in the case of too high vibration amplitudes, prevents the output voltage from saturating.
This is the reason why the infinite extent theories under-predict the sound insulation. The model was then improved Gompeters, 1965 by combining with the viscosity formula developed by Ingerslev and Nielsen 1944 , yielding better accuracy for ka up to 0. The core of different thickness was used to study its effect on acoustic insulation. In contrast, the sound transmissionproperties are adversely influenced by the low effective mass. In this paper, to develop a leak location detection system for a compressible fluid such as gas, the conventional detection methods have been studied, improved, and verified through the experiment using the compressed air. Usually it is built from analog electronic components, such as operational amplifiers, resistors and capacitors. The partition nowadays has been widely developed in terms of design and applications.