Flattened Brazilian disc and modified ring test methods are attractive methods being simpler compared to the other mode I fracture toughness testing methods on rock cores. The aim of this study is to improve these simple methods to yield fracture toughness values that are close to the ones determined by the suggested methods. ABAQUS finite element program was used to determine stress intensity factors of models with various dimensions. Comparing fracture toughness to the results obtained by semicircular bending method tests (0.94 MPa&amp / #8730 / m for andesite and 0.56 MPa&amp / #8730 / m for marble) and the cracked chevron notched Brazilian disc method tests (1.45 MPa&amp / #8730 / m for andesite and 1.08 MPa&amp / #8730 / m for marble), proper geometrical parameters were investigated by changing diameter, central-hole diameter, and loading angle of Ankara andesite and Afyon marble specimens. Semicircular bending method results were lower than the cracked chevron notched Brazilian disc method results. With flattened Brazilian disc method, the closest results (1.45 MPa&amp / #8730 / m for andesite and 1.12 MPa&amp / #8730 / m for marble) to the suggested method was obtained by 54 mm diameter discs with loading angles between 32.5&deg / and 38.0&deg / and with thicknesses between 19 mm and 34 mm. With modified ring test on andesite, the closest results to the suggested method was obtained by 75 mm diameter discs with 8 mm central-hole diameter and 25&deg / loading angle (1.47 MPa&amp / #8730 / m for andesite and 1.07 MPa&amp / #8730 / m for marble), and with 14 mm central-hole diameter and 16&deg / loading angle (1.50 MPa&amp / #8730 / m for andesite and 1.05 MPa&amp / #8730 / m for marble).

This thesis endeavors towards developing various concepts employed in analysis and design of acoustic filters for varied applications ranging from combination mufflers for automobiles to complex networks of gas carrying ducts to multiply connected complex automotive silencing devices to the noise control coatings for underwater applications. A two-dimensional wave modeling approach has been proposed to evaluate sound attenuation characteristics of dissipative mufflers of finite length with/without extended inlet and outlet tubes including very large mufflers. The correctness of the method has been validated through comparison with experimental results from literature. Two other frequently used approximate schemes have been discussed briefly with reference to the available literature. These three approaches have then been weighed against each other to show the effectiveness and limitations of each one. A thorough comparison study has been performed to investigate each one’s extent of applicability. A parametric study with different parameters suggests some useful design guidelines that can be put to use while designing such mufflers. Benefits and drawbacks of reactive and dissipative mufflers have been discussed with an intention of striking a compromise between them to achieve a better transmission quality over a broad frequency range. This has been accomplished by combining these two types of mufflers/filters explicitly. These combination mufflers are analyzed using a transfer matrix based approach by extending the aforesaid concept of two-dimensional wave modeling for finite dissipative ducts. The present approach has been used to analyze axi-symmetric circular lined plenum chambers also. The effectiveness of the bulk reaction assumption to model absorptive lining is illustrated. A parametric study has been carried out to investigate the effects of different thicknesses and placements of the absorptive lining. The contributions of reflective and absorptive portion of the combination mufflerto overall attenuation performance have been investigated from the designer’s point of view A generalized algorithm has been developed for studying the plane sound wave propa- gation in a system of interconnected rigid-walled acoustic filter elements. Interconnection between various elements is represented by a connectivity matrix. Equations of volume velocity continuity and pressure equilibrium at the interconnections are generated using this connectivity matrix and are solved using the Gauss-Jordan elimination scheme to get the overall transfer matrix of the system. The algorithm used for generalized labeling of the network and computation of Transmission Loss has also been discussed. The algorithm has been applied to investigate a multiply connected automobile mufflers as a network of acoustic elements which guides the way to a specialized application discussed next. Results for some configurations have been compared with those from the FEM analysis and experiments. A parametric study with respect to some geometric variables is carried out. The acoustical similarity between apparently different networks is discussed. The approach is flexible to incorporate any other acoustic elements, provided the acoustic variables at the junctions of the element can be related by a transfer matrix a priori. Commercial automotive mufflers are often too complex to be broken into a cascade of one dimensional elements with predetermined transfer matrices. The one dimensional (1-D) scheme presented here is based on an algorithm that uses user friendly visual volume elements to generate the system equations which are then solved using a Gauss-Jordan elimination scheme to derive the overall transfer matrix of the muffler. This work attempts and succeeds to a great extent in exploiting the speed of the one dimensional analysis with the flexibility, generality and user friendliness of three dimensional analysis using geometric modeling. A code based on the developed algorithm has been employed to demonstrate the generality of the proposed method in analyzing commercial muffers by considering three very diverse classes of mufflers with different kinds of combinations of reactive, perforated and absorptive elements. Though the examples presented in the thesis are not very complex for they are meant to be just representative cases of certain classes of mufflers, yet the algorithm can handle a large domain of commercial mufflers of high degree of complexity. Results from the present algorithm have been validated through comparisons with both the analytical and the more general, three-dimensional FEM based results. The forte of the proposed method is its power to construct the system matrix consistent with the boundary conditions from the geometrical model to evaluate the four pole parameters of the entire muffer and thence its transmission loss,etc. Thus, the algorithm can be used in conjunction with the transfer matrix based muffler programs to analyze the entire exhaust system of an automobile. A different kind of acoustic filter than the above mentioned cases is then taken up for investigation. These refer to the specialized underwater acoustic filters laid as linings on submerged bodies. These kind of underwater noise control linings have three different types of objectives, namely, Echo Reduction, Transmission Reduction (TL maximization) and a combination thereof. These coatings have been shown to be behaving very differently with different shape, size and number of air channels present in the layer. In this regard, a finite element model based methodology has been followed. An hybrid type finite element based on the Pian and Tong formulation has been modified and used so as to make the computational efforts less demanding as compared to the original one. The developed finite element has been shown to be immune to the difficulties that arise due to the near incompressible characteristics of the viscoelastic materials used and the high distortion of the elements of the FE mesh. The adequacy of this formulation has been shown by comparing its results with the analytical, FE based, and experimental results. Then, this methodology has been used to analyze and generate design curves to control various geometrical parameters for proper designing of these linings. Different unit cell representations for different types of distributions of air cavities on the linings have been discussed. Four different types of layers have been introduced and analyzed to address different objectives mentioned above. They have been termed as the Anechoic layer, Insulation layer and Combination Layer of coupled and decoupled type in this thesis. The first two layers have been designed to achieve very dissimilar characteristics and the next two layers have been designed to balance their disparities. A thorough parametric study has been carried out on the geometrical parameters of all the layers to come up with the design guidelines. For anechoic and the insulation layers, different distributions have been analyzed with different unit cell geometries and their usability in specific situations has been outlined. Effect of static pressure has also been studied by using an approximate finite element method. This method can be used to simulate deep-sea testing environment.

Noise control in the heating, ventilation and air-conditioning (HVAC) systems is one of the critical design parameters in measuring the occupant comfort. The noise generated by air-handling units propagates through the ducts in the axial as well as transverse direction. Noise radiated in the transverse direction from the duct walls excited by the internal sound field is called the breakout noise. An analytical formulation has been developed in this thesis in order to predict the breakout noise by incorporating three-dimensional effects along with the acoustical and structural wave coupling phenomena. The first step in the breakout noise prediction is to calculate the interior acoustic response and flexural vibration displacement of the compliant walls. Dynamic interaction between the internal acoustic subsystem and flexible structural subsystem has been expressed in terms of the modal characteristics of the uncoupled response of the acoustic and structural sub-systems. Solutions of the inhomogeneous wave equation are rearranged in terms of impedance and mobility, and the equations describing the complete system are expressed in terms of matrices, which result in a compact matrix formulation. Examples of the formulation are a rectangular cavity with one flexible wall and a rectangular cavity with four-flexible walls. The formulation is modified to incorporate complex boundary conditions by means of appropriate Green’s functions. It is implemented for flexible wall duct using the modified cavity Green’s function. Another objective of the present investigation is to understand the coupling phenomenon and its effect on the compliant wall vibration displacement. The developed three-dimensional analytical analysis of the breakout noise is convenient to implement on the computer, and also to extend the sub-system level model to the system level model in order to analyze a complex acoustic-structural system for the breakout noise problem. The extent of coupling is calculated using a transfer factor based on the uncoupled natural frequencies of the acoustic and structural subsystems. It is observed from the free vibration analysis that a coupling between the cavity and the flexible panel exists in the vicinity of an uncoupled acoustic natural frequency. If a strong coupling occurs between an acoustic mode and a panel mode, then damping of structural subsystem would control it. The cavity volume changes stiffness of the panel, which in turn affects noise radiation in the stiffness-controlled region. The second step is to calculate the sound power radiated from complaint wall. The wall vibration velocity is a linear combination of the uncoupled flexural modes of the structural subsystem. It is substituted into the Rayleigh integral and Kirchhoff– Helmholtz (KH) integral formulation to predict the sound pressure radiated by the vibrating duct wall. The radiated sound power can be obtained by integrating the acoustic intensity over the surface of the flexible duct wall making use of appropriate expressions for radiation impedance. The radiation impedance terms involve a quadruple integral. Evaluation of this integral is quite complex and poses formidable computational challenges. These have been overcome by means of a co-ordinate transformation. Sound power radiation from flexible walls of the plenum and duct walls has been calculated using an equivalent plate model. Analytical results are corroborated with numerical models. The second part of thesis deals with a one-dimensional model to predict the breakout noise from a thin rectangular duct with different end conditions like anechoic termination, rigid-end termination, and the open-end termination. This model incorporates acoustic reflection effects in the duct internal sound field by using standing wave pattern by means of the transfer matrix approach. A one-dimensional prediction method based on the four-pole parameters has been developed to evaluate the lagged duct performance in terms of the breakout noise reduction. Radiation impedance of a duct is calculated by three different methods: (i) finite line source model (ii) finite cylinder model, and (iii) equivalent plate model based on fundamental bending mode of the duct. It is observed that the proposed model that uses the equivalent plate model for the lagged duct and the line source model for the bare duct is appropriate to predict the transverse insertion loss of the lagging, particularly at the lower frequencies that are of primary interest for reducing the breakout noise of rectangular ducts. The bare duct breakout noise results are compared with those of the corresponding 3-D analytical models. It shows that the one-dimensional model captures the overall mean pattern of breakout noise very well. The third part of the thesis examines the internal acoustic field and thence the transmission loss (TL) of a rectangular expansion chamber, the inlet and outlet of which are situated at arbitrary locations of the chamber; i.e., the sidewall or the face of the chamber. The four-pole parameters have been expressed in terms of an appropriate Green’s function of a rectangular cavity with homogeneous boundary conditions. A transfer matrix formulation has been developed for the yielding-wall rectangular chambers by considering structural-acoustic coupling. It may be combined readily with the transfer matrices of the other constituent elements upstream and downstream in order to compute the overall transmission loss or insertion loss. Wherever applicable, parametric studies have been conducted to evolve the design guidelines for minimizing the breakout noise from the HVAC ducts, plenums and cavities.

The objective of this research is to presents new acoustic echo cancellation design methods that can effectively work in the nonlinear environment. Acoustic echo is an annoying issue for voice communication systems. Because of room acoustics and delay in the transmission path, echoes affect the sound quality and may hamper communications. Acoustic echo cancellers (AECs) are employed to remove the acoustic echo while keeping full-duplex communications. AEC designs face a variety of challenges, including long room impulse response, acoustic path nonlinearity, ambient noise, and double-talk situation. We investigate two parts of echo canceller design: echo cancellation algorithm design and control logic algorithm design. In the first part, our work focuses on the nonlinear adaptive and fast-convergence algorithms. We investigate three different structures: predistortion linearization, cascade structure, and nonlinear residual echo suppressor. Specifically, we are interested in the coherence function, since it provides a means for quantifying linear association between two stationary random processes. By using the coherence as a criterion to design the nonlinear echo canceller in the system, our method guarantees the algorithm stability and leads to a faster convergence rate. In the second part, our work focuses on the robustness of AECs in the presence of interference. With regard to the near-end speech, we investigate the double-talk detector (DTD) design in conjunction with nonlinear AECs. Specifically, we propose to design a DTD based on the mutual information (MI). We show that the advantage of the MI-based method, when compared with the existing methods, is that it is applicable to both the linear and nonlinear scenarios. With respect to the background noise, we propose a variable step-size and variable tap-length least mean square (LMS) algorithm. Based on the fact that the room impulse response usually exhibits an exponential decay power profile in acoustic echo cancellation applications, the proposed method finds optimal step size and tap length at each iteration. Thus, it achieves faster convergence rate and better steady-state performance. We show a number of experimental results to illustrate the performance of the proposed algorithms.

[Truncated abstract] This thesis presents three different methods to investigate flexural wave propagation and scattering, power flow and transmission efficiencies, and dynamic stress concentration and fatigue failures in structural dynamics. The first method is based on the acoustical wave propagator (AWP) technique, which is the main part described in this thesis. Through the numerical implementation of the AWP, the complete information of the vibrating structure can be obtained including displacement, velocity, acceleration, bending moments, strain and stresses. The AWP technique has been applied to systems consisting of a one-dimensional stepped beam, a two-dimensional thin plate, a thin plate with a sharp change of section, a heterogeneous plate with multiple cylindrical patches, and a Mindlin?s plate with a reinforced rib. For this Mindlin?s plate structure, through the comparison of the results obtained by Mindlin?s thick plate theory and Kirchhoff?s classical thin plate theory, the difference of theoretical predicted results is investigated. As part of these investigations, reflection and transmission coefficients, power flow and transmission efficiencies in a onedimensional stepped beam, and power flow in a two-dimensional circular plate structure, are studied. In particular, this technique has been successfully extended to investigate wave propagation and scattering, and dynamic stress concentration at discontinuities. Potential applications are fatigue failure prediction and damage detection in complex structures. The second method is based on experimental techniques to investigate the structural response under impact loads, which consist of the waveform measuring technique in the time domain by using the WAVEVIEW software, and steady-state measurements by using the Polytec Laser Scanning Vibrometer (PLSV) in the frequency domain. The waveform measuring technique is introduced to obtain the waveform at different locations in the time domain. These experimental results can be used to verify the validity of predicted results obtained by the AWP technique. Furthermore, distributions of dynamic strain and stress in both near-field (close to discontinuities) and far-field regions are investigated for the study of the effects of the discontinuities on reflection and transmission coefficients in a one-dimensional stepped beam structure. Experimental results in the time domain can be easily transferred into those in the frequency domain by the fast Fourier transformation, and compared with those obtained by other researchers. This PLSV technique provides an accurate and efficient tool to investigate mode shape and power flow in some coupled structures, such as a ribbed plate. Through the finite differencing technique, autospectral and spatial of dynamic strain can be obtained. The third method considered uses the travelling wave solution method to solve reflection and transmission coefficients in a one-dimensional stepped beam structure in the time domain. In particular, analytical exact solutions of reflection and transmission coefficients under the given initial-value problem are derived. These analytical solutions together with experimental results can be used to compare with those obtained by the AWP technique.

Afin de réduire les bruits rayonnés en sortie de guide d’onde, des traitements acoustiques localement réactifs, comme les structures « Plaque perforée/Nid d’abeilles », peuvent être appliqués en liner. La conception de ces liners devient alors un challenge important avec l’apparition de nouvelles normes sur le bruit et impose de posséder une très bonne connaissance du comportement de ces traitements, en particulier leur impédance de surface. Néanmoins, la caractérisation de cette impédance n’est pas une chose facile et est généralement réalisée via des modèles semi-empiriques comme ceux de Guess, Elnady, Allam ou expérimentalement par des méthodes de mesures directes ou inverses. Ces approches inverses permettent, par la confrontation d’une modélisation du problème avec des observations expérimentales, de retourner, au travers d’une fonction coût, l’impédance du traitement. Ces méthodes ont l’avantage de réaliser une observation dans les conditions réelles d’utilisation du traitement. En effet, de nombreux paramètres influencent l’impédance de surface comme la présence d’un écoulement, l’incidence de l’onde… Dans cette thèse, une méthode d’identification de l’impédance est proposée. A partir de l’impédance de surface d’un traitement « Plaque perforée/Nid d’abeille » prédite par un modèle empirique via ses paramètres géométriques (épaisseur de la plaque, diamètre des perforations…), une méthode basée sur l’approche Bayésienne est implémentée afin de remonter à l’impédance réelle du traitement. Le problème étudié consiste en la propagation d’une onde dans un tronçon rectangulaire traité sur sa face supérieure et la mesure des pressions acoustiques est réalisée sur le banc d’essai de l’Université Technologique de Compiègne avec un écoulement rasant. Un modèle de propagation d’ondes dans le conduit est développé via la technique du raccordement modal, afin de prédire la pression aux positions des microphones pour n’importe quelle valeur d’impédance. A partir de la mesure et de la simulation, la règle de Bayes peut être appliquée afin de construire la densité de probabilité a posteriori. Cette densité de probabilité est alors échantillonnée au travers d’un algorithme Évolutionnaire de Monte Carlo par Chaîne de Markov (EMCMC). L’intérêt principale de cette méthode, est d’obtenir de nombreuses d’informations statistiques sur les paramètres caractérisant l’impédance de surface comme leur distribution et leur corrélation. / Locally reactive acoustic liners such as honeycomb structures with perforated panels can be modeled with a surface impedance in standard numerical models. However, the characterization of this impedance is not always straightforward. Empirical models or standing wave tube measurements are generally used to get the behavior of these acoustic treatments. Unfortunately, these methods provide only an evaluation of the impedance under specific conditions. Moreover, the conditions of use can change significantly the acoustic liners behavior as grazing flow conditions or oblique incident waves. A characterization of locally reactive acoustic liners is presented here. Starting from a set of parameters and represents a surface impedance using empirical model, an inverse method based on Bayesian approach is used to return the surface impedance taking in consideration the real conditions of use. A rectangular duct treated by a liner on its upper face is considered and these conditions are similar to the experiment present at the Université de Technologie de Compiègne. This inverse method requires a direct model to predict the pressure at some microphone positions with any surface impedance. The model used in the following is based on the Mode-Matching method. From the direct analytical model, the Bayes'rule is then used to get the posterior probability density function of the estimated impedance. An Evolutionary Monte Carlo by Markov chain (EMCMC) method is used to sample this posterior probability density. This method provides not only the best set of parameters but also some statistical information for each parameter.

We are seeing a revolution in computing and artificial intelligence; intelligent machines have become ingrained in and improved every aspect of our lives. Despite the increasing number of intelligent devices and breakthroughs in artificial intelligence, we have yet to achieve truly intelligent environments. Audio is one of the most common sensing and actuation modalities used in intelligent devices. In this thesis, we focus on how we can more robustly integrate audio intelligence into a wide array of resource-constrained platforms that enable more intelligent environments. We present systems and methods for adaptive audio filtering that enables us to more robustly embed acoustic intelligence into a wide range of real time and resource-constrained mobile, embedded, and cyber-physical systems that are adaptable to a wide range of different applications, environments, and scenarios. First, we introduce methods for embedding audio intelligence into wearables, like headsets and helmets, to improve pedestrian safety in urban environments by using sound to detect vehicles, localize vehicles, and alert pedestrians well in advance to give them enough time to avoid a collision. We create a segmented architecture and data processing pipeline that partitions computation between embedded front-end platform and the smartphone platform. The embedded front-end hardware platform consists of a microcontroller and commercial-off-the shelf (COTS) components embedded into a headset and samples audio from an array of four MEMS microphones. Our embedded front-end platform computes a series of spatiotemporal features used to localize vehicles: relative delay, relative power, and zero crossing rate. These features are computed in the embedded front-end headset platform and transmitted wirelessly to the smartphone platform because there is not enough bandwidth to transmit more than two channels of raw audio with low latency using standard wireless communication protocols, like Bluetooth Low-Energy. The smartphone platform runs machine learning algorithms to detect vehicles, localize vehicles, and alert pedestrians. To help reduce power consumption, we integrate an application specific integrated circuit into our embedded front-end platform and create a new localization algorithm called angle via polygonal regression (AvPR) that combines the physics of audio waves, the geometry of a microphone array, and a data driven training and calibration process that enables us to estimate the high resolution direction of the vehicle while being robust to noise resulting from movements in the microphone array as we walk the streets. Second, we explore the challenges in adapting our platforms for pedestrian safety to more general and noisier scenarios, namely construction worker safety sounds of nearby power tools and machinery that are orders of magnitude greater than that of a distant vehicle. We introduce an adaptive noise filtering architecture that allows workers to filter out construction tool sounds and reveal low-energy vehicle sounds to better detect them. Our architecture combines the strengths of both the physics of audio waves and data-driven methods to more robustly filter out construction sounds while being able to run on a resource-limited mobile and embedded platform. In our adaptive filtering architecture, we introduce and incorporate a data-driven filtering algorithm, called probabilistic template matching (PTM), that leverages pre-trained statistical models of construction tools to perform content-based filtering. We demonstrate improvements that our adaptive filtering architecture brings to our audio-based urban safety wearable in real construction site scenarios and against state-of-art audio filtering algorithms, while having a minimal impact on the power consumption and latency of the overall system. We also explore how these methods can be used to improve audio privacy and remove privacy-sensitive speech from applications that have no need to detect and analyze speech. Finally, we introduce a common selective audio filtering platform that builds upon our adaptive filtering architecture for a wide range of real-time mobile, embedded, and cyber-physical applications. Our architecture can account for a wide range of different sounds, model types, and signal representations by integrating an algorithm we present called content-informed beamforming (CIBF). CIBF combines traditional beamforming (spatial filtering using the physics of audio waves) with data driven machine learning sound detectors and models that developers may already create for their own applications to enhance and filter out specified sounds and noises. Alternatively, developers can also select sounds and models from a library we provide. We demonstrate how our selective filtering architecture can improve the detection of specific target sounds and filter out noises in a wide range of application scenarios. Additionally, through two case studies, we demonstrate how our selective filtering architecture can easily integrate into and improve the performance of real mobile and embedded applications over existing state-of-art solutions, while having minimal impact on latency and power consumption. Ultimately, this selective filtering architecture enables developers and engineers to more easily embed robust audio intelligence into common objects found around us and resource-constrained systems to create more intelligent environments.

Indiana University-Purdue University Indianapolis (IUPUI) / In order to conform to pollutant-control regulations and minimize NOx emissions, modern household boilers and central heating systems are moving toward premixed combustors. These combustors have been successful with regards to emissions along with efficiency. However, their implementation has been associated with acoustical instability problems that could be solved through precise optimization in design rather than trial and error experimentation. This thesis introduces an experimental apparatus, which is designed to investigate the acoustic instability problem at the flame level. The goal is an experimental determination of the flame transfer function and comparison of the experimental data with a theoretical model of the flame. An experimental procedure is designed to diagnose the origins of the combustion instabilities by measurement of the flame transfer function. This research is carried out in three steps. The first step is to understand the acoustic instability problem through study of the theoretical models of the flame transfer function and selection of a model, which is most functional in industrial applications. A xiii measurement technique for the flame transfer function is developed according to the required accuracy in measurements, repeatability, and configurability for a wide range of operating conditions. Subsequently, an experimental apparatus is designed to accommodate the flame transfer function measurement technique. The components of the acoustic system are carefully sized to achieve precise measurement of the system parameters such as flows, pressures, and acoustic responses, and the apparatus is built. The apparatus is operated to measure the flame transfer function at several operating conditions. The experimentally measured flame transfer function is compared with a theoretical model for further verification. The experimental apparatus provides an improved assessment of the acoustic instability problem for industrial applications.

La prédiction du bruit de roulement ferroviaire est en enjeu majeur pour la maitrise des nuisances sonores. Au point de contact roue/rail, la roue et la voie sont excités de manière dynamique, ce qui enclenche le rayonnement du bruit de roulement. Les réponses vibratoires au point de contact ainsi que les taux de décroissance des ondes sont des données primordiales pour simuler de manière précise le bruit de roulement. Or, la dimension infinie de la voie ferrée conduit bien souvent à des modèles éléments finis coûteux et non adaptés à la recherche de solutions innovantes. La thèse a pour objectifs de proposer un modèle vibratoire de voie en éléments finis qui prenne en compte la dimension infinie périodique de la voie, mais aussi d’inclure une portion de voie non-périodique sur laquelle des solutions anti-vibratiles peuvent être testées. La propagation des vibrations est exprimée sous la forme d’une décomposition en ondes par la méthode WFE (Wave Finite Element). Le calcul de la réponse vibratoire de la voie périodique infinie est obtenu à partir du déplacement d’une cellule physique longue d’environ 0.6 m. Pour réduire les temps de calcul nécessaires à sa condensation dynamique, une méthode de bi-périodisation est proposée. Le couplage entre les méthodes éléments finis et WFE est développé pour prendre en considération les supports élastiques dans cette cellule. Les comparaisons avec des mobilités expérimentales ainsi que des taux de décroissance montrent un très bon accord calculs-mesures. Enfin, le modèle développé dans cette thèse a permis de tester l’efficacité d’une solution anti-vibratile innovante développée au sein du projet CERVIFER. Celle-ci offre un comportement bi-mode, elle assouplit les supports autour de la roue préservant ainsi l’infrastructure, mais elle rigidifie les supports loin de la roue pour augmenter les taux de décroissance. Les résultats numériques se révèlent prometteurs en termes d’efficacité du dispositif et entrevoient une poursuite du développement de cette solution anti-vibratile. / Railway noise is a critical issue concerning environmental noise. At the wheel/rail contact point, both the wheel and the track are dynamically excited and vibrate together to emit the well known rolling noise. The point receptance of the rail and the track decay rates are important quantities to accurately predict wheel-rail noise emission. However, the infinite dimension of the track leads to cumbersome numerical finite-element (FE) models and not adapted to assist the research of innovative solutions. The goals of this thesis are to build an efficient numerical model for calculating the vibration from an infinite railway track, but also to include a central non-periodic part with the aim of testing anti-vibration solutions. The vibration propagation along the track is expressed as a sum of different waves using the WFEM (Wave Finite Element Method). The displacements of a 0.6 m unit cell lead to the computation of the whole track. To reduce the dynamic condensation of this cell, a bi-periodic method is proposed in this thesis. The FEM - WFEM coupling is proposed to easily include elastic supports inside the unit cell. Results show a good correlation between test and calculation. Finally, the model proposed in this thesis was used to test the efficiency of an innovative anti-vibration solution developed within the CERVIFER project. It is a dual mode device which makes the supports softer around the wheel to protect the infrastructure, and stiffer away from the wheel to increase the track decay rates. The numerical results revealed to be really promising, and they will permit to pursue the development of this anti-vibration solution.

Modular construction of housing is an industry on the rise. The prefabrication of construction modules gives a greater control over material consumption, promotes standardization, and lessens the disturbance during the construction time in the field. Lindbäcks Bygg AB prefabricates housing modules in their factory at Haraholmen, Piteå. The modules are then transported to construction sites all over the country and assembled. Lindbäcks Bygg AB has made the design choice to focus on lightweight wooden constructions for their modules, which comes with its own set of challenges. The urban densification of our city regions has led to more and more residential building being planned and constructed in areas that are submitted to high noise levels from surrounding traffic. This puts a great strain on the sound reduction of the building’s façade wall construction, something that has proven to be a problem with lightweight wooden walls. The aim of this master thesis project has been to test different solutions for lightweight façade wall constructions, and to ultimately find one or more solution that meet the requirements of the Swedish standards and regulations, as well as the needs of the tenants, and that can be implemented by Lindbäcks Bygg AB for manufacturing and assembly. The project has therefore been carried out in two parts, one theoretical and one practical. The theoretical part has verified the problem with traffic noise levels in residential buildings and identified the critical areas of the current façade construction. The theoretical work led to a list of defining factors for the sound reduction, which in turn worked as a basis for the ideation process.  As a result, the theoretical part led to a number of different construction concepts for façade walls. The concepts were first tested theoretically through modelling and calculation, and verified with the acousticians at Tyréns Sverige AB and the engineers of Lindbäcks Bygg AB. The most promising concepts were sent on to be manufactured. The practical part of this master thesis project was carried out mainly as acoustical measurements and the subsequent analysis, where the manufactured façade wall constructions were mounted on a free-standing module. The result of the practical part, and of the master thesis project, were four different façade wall constructions that met the requirements for noise reduction, which were presented to Lindbäcks Bygg AB and Tyréns Sverige AB. The construction most easily implemented is a construction with an airgap between the wall panels, and this construction will now have to be structurally verified and adapted for the factory, before being utilized in future building projects. / Modulärt byggande av bostäder är en bransch på frammarsch. Prefabricering av byggnadsmoduler ger en större kontroll över materialåtgången, främjar standardisering och minskar störningarna under byggtiden i fält. Lindbäcks Bygg AB prefabricerar bostadsmoduler i sin fabrik på Haraholmen, Piteå. Modulerna transporteras sedan till byggarbetsplatser över hela landet och monteras till bostadskomplex. Lindbäcks Bygg AB har gjort designvalet att fokusera på lätta träkonstruktioner för sina moduler, vilket kommer med sin egen uppsättning utmaningar. Förtätningen av våra stadsregioner har lett till att allt mer bostadsbyggande planeras och uppförs i områden som utsätts för höga bullernivåer från omgivande trafik. Detta utsätter byggnadens fasadväggskonstruktion för en stor akustisk belastning, något som har visat sig vara ett problem med lätta träväggar. Syftet med detta examensarbete har varit att testa olika lösningar för lätta fasadväggskonstruktioner, och att i slutändan hitta en eller flera lösningar som uppfyller kraven i svenska standarder och föreskrifter samt hyresgästernas behov, och som kan implementeras av Lindbäcks Bygg AB för tillverkning och montering. Projektet har därför genomförts i två delar, en teoretisk och en praktisk. Den teoretiska delen har verifierat problemet med trafikbullernivåer i bostadshus och identifierat kritiska områden i den nuvarande fasadkonstruktionen. Det teoretiska arbetet ledde fram till en lista med kritiska faktorer för ljudreduktionen, som i sin tur fungerade som grund för designprocessen. Som ett resultat ledde den teoretiska delen till en rad olika konstruktionskoncept för fasadväggar. Koncepten testades först teoretiskt genom modellering och beräkning, och verifierades av akustikerna på Tyréns Sverige AB och ingenjörerna på Lindbäcks Bygg AB. De mest lovande koncepten skickades vidare för tillverkning. Den praktiska delen av detta examensarbete genomfördes främst som akustiska mätningar och efterföljande analys, där de tillverkade fasadväggkonstruktionerna monterades på en fristående modul. Resultatet av den praktiska delen, och av examensarbetet, blev fyra olika fasadväggskonstruktioner som uppfyller kraven för ljudreduktion, vilka presenterades för Lindbäcks Bygg AB och Tyréns Sverige AB. Den konstruktion som är enklast att implementera är en konstruktion med luftspalt mellan väggpanelerna, och denna konstruktion kommer nu att behöva verifieras med avseende på ex. hållfasthet och anpassas för fabriken, innan den kan användas i framtida byggprojekt.