Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"Vibro-Acoustic"”.
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Vibro-acoustic optimization of panel with curvilinear stiffeners
… stiffened panels with predefined structural and acoustic response is the focus of this dissertation. Researchers have dealt with sizing optimization of panels with straight/curvilinear stiffeners for many years and it has been proven that in some cases the mass of a panel with curvilinear …
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Vibro-acoustic dynamics in the presence of uncertainty and nonlinearity
The statistics of the vibro-acoustic response for an ensemble of systems with uncertain properties, such as those arising from manufacturing and material imperfections, is critical in the design of built-up structures. This is particularly important in the mid-frequency range, where sensitivity to …
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The vibro-acoustic modelling and analysis of damage mechanisms in paper
This thesis investigates the use of the acoustic emission (AE) monitoring technique for use in identifying the damage mechanisms present in paper associated with its production process. The microscopic structure of paper consists of a random mesh of paper fibres connected by hydrogen bonds. This …
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Statistical Vibro-Acoustic Modelling of Nonlinear Systems with Applications in Vehicles
… techniques can be employed to improve the acoustic comfort without compromising the vehicle performance. At the design stage of a noise control system, the estimation of the structure-borne sound pressure levels in the car cabin is a challenging problem, as uncertainties in a physical …
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On in-situ methodologies for the characterisation and simulation of vibro-acoustic assemblies
… the same cannot be said in the realm of acoustics. Although numerical methods, such as finite and boundary element analysis, are able to predict, with some accuracy, the passive properties of simple assembly components, they currently lack the ability to accurately model more complex …
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Structure Borne Noise Analysis Using Helmholtz Equation Least Squares Based Forced Vibro Acoustic Components
… equation least squares (HELS) based nearfield acoustic holography method. In this study, the HELS formulations derived in spherical co-ordinates using spherical wave expansion functions utilize the input data of acoustic pressures measured in the nearfield of a vibrating object to reconstruct …
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Diesel-cng dual fuel combustion characterization using vibro-acoustic analysis and response surface methodology
… a statistical method was proposed to analyse the vibro-acoustic signal generated by a knock sensor installed at the outer cylinder wall of the engine. The frequency distribution analysis was applied to interpret the high variability of the vibro-acoustic signal. The results were used as the input …
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The influence of structural-acoustic coupling on the dynamic behaviour of a one-dimensional vibro-acoustic system
… of this thesis is to investigate the structural-acoustic coupling effects on the dynamic behaviour of a vibro-acoustic system under passive/active control. The simplest model of a vibro-acoustic system one can consider is a one-dimensional acoustic cavity driven by a single-degree-of-freedom …
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Numerical and analytical vibro-acoustic modelling of porous materials: the Cell Method for poroelasticity and the case of inclusions
… dei materiali porori per applicazioni vibro-acustiche rapprensenta un aspetto di una certa complessità. Le simulazioni numeriche sono spesso problematiche quando siano coinvolte geometrie di pezzi reali, in particolare riguardo i tempi computazionali e la convergenza. Allo stesso tempo, …
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Comfort studies on aircraft interior sound and vibration
… the effects of combined sound and vibration (vibro-acoustics) on comfort sensation in aircraft. In the first study, seven cruising situations were presented in an aircraft mock-up and rated by 117 subjects using 15 polarities of a semantic differential. Principal component analyses proved that …
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Linear iron-core permanent magnet motor with high force and low acoustic noise
Acoustic noise and associated vibration are potentially troubling characteristics of electric machines including variable-reluctance motors, induction machines, and permanent magnet synchronous motors. The severity of this problem depends on the types of motors and their applications. One exemplary …
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Sound Radiation Responses and Acoustic Behvior of Sandwich Panel
… construction engineering. Investigations on the acoustic behavior of sandwich structures is of practical importance, not only for engineers but to researchers in the field. A numerical study of the vibro-acoustic and sound transmission loss (STL) of an aluminum honeycomb core sandwich panel with …
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Investigation and improvment of noise, vibration and harshness(nvh) properties of automotive panels
… accomplishments have been logged in the work. Vibro-acoustic responses of PCMS materials, and newly-constructed generally periodic materials are explored, and some computer procedures are generated. The results give some suggestions for design directions to follow in order to achieve better …
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Radiated Noise Assessment of Shipboard Systems Using Vibration Analysis
Since the emergence of acoustic warfare, especially in modern times, noise regulation of ships has become a concern, leading to ships being built and tested with rigorous and periodical measures to ensure their noise signatures are minimal. Simultaneously, other predictive maintenance and load …
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Extreme energy absorption : the design, modeling, and testing of negative stiffness metamaterial inclusions
… elements capable of passively suppressing vibro-acoustic energy. Relevant recent research has shown that it is possible to produce composite materials whose macroscopic mechanical stiffness and loss properties surpass those of conventional composites through the addition of trace amounts of …
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The prediction of industrial noise and its transmission through metal cladding systems
… analysis of structuralvibrations. Complex vibro-acoustic models are forwarded to predict the properties ofsuch materials. Much effort is spent simplifying these predictions, thus yieldingaccurate engineering methods. Finally the results are applied to commercial double-leafcladding. This …
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Design and development of advanced vibration and noise control devices using finite element analysis
… absorbers coupled to the structural and acoustics domains were validated . Parametric studies were performed on these fully coupled 3D-FE models in order to understand the effect of the variation in the material properties and geometrical configuration of these vibration absorbers on …
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Computational Modal Analysis of Prestressed Half Scale Generic Business Jet Substructures
… modal parameters are crucial inputs for vibro-acoustic finite element analyses and require accurate modal models. The work presented here aims to provide insight into the techniques necessary to model business jet fuselages with prestressed skin panels through computational modal analysis …
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Fast transfer path analysis using controlled electric motors as in-situ blocked force vibration sources
… and troubleshoot steering noise in vehicles. For acoustic development and refinement, test-based methodologies such as Transfer Path Analysis (TPA) are used to analyse noise and vibration propagation in complex systems. In response to the evolving demands in acoustic engineering, TPA approaches …
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