Skidding contributes to up to 35% of wet pavement accidents. Pavement surface friction therefore is an important component of highway safety. The skid resistance also varies seasonally and reduces over time due to surface polishing. These leave the pavement in a state of increased risk of skidding accidents. An adequate surface friction that accommodates the seasonal and long term variations is essential for safety over the pavement surface service life. The resistance to skidding, however, depends on surface microtexture and macrotexture. Alternatively, increased texture aimed at increased and durable surface friction may affect the noise generated on the road. In fact, traffic noise is a growing problem throughout the world. Noise barriers, traditionally used for noise reduction, are expensive and inefficient in some cases. As the pavement surface characteristics play a key role in noise generation and propagation, it provides a window for noise reduction by altering the pavement surface. The challenge, however, is to provide a smooth, quiet, long-lasting, and economic pavement with adequate and durable surface friction. This research has been directed to address this challenge and to provide a realistic guideline. The tire-pavement noise, sound absorption, and skid resistance performances of various flexible and rigid pavement surfaces have been examined using the field and laboratory test data. Models for the prediction of pavement skid resistance including the seasonal and long term variations have also been developed correlating the influencing factors. A value engineering approach has been proposed to accommodate the construction and maintenance costs, longevity, smoothness, safety and noise in the selection of pavement surfaces.

Skidding contributes to up to 35% of wet pavement accidents. Pavement surface friction therefore is an important component of highway safety. The skid resistance also varies seasonally and reduces over time due to surface polishing. These leave the pavement in a state of increased risk of skidding accidents. An adequate surface friction that accommodates the seasonal and long term variations is essential for safety over the pavement surface service life. The resistance to skidding, however, depends on surface microtexture and macrotexture. Alternatively, increased texture aimed at increased and durable surface friction may affect the noise generated on the road. In fact, traffic noise is a growing problem throughout the world. Noise barriers, traditionally used for noise reduction, are expensive and inefficient in some cases. As the pavement surface characteristics play a key role in noise generation and propagation, it provides a window for noise reduction by altering the pavement surface. The challenge, however, is to provide a smooth, quiet, long-lasting, and economic pavement with adequate and durable surface friction. This research has been directed to address this challenge and to provide a realistic guideline. The tire-pavement noise, sound absorption, and skid resistance performances of various flexible and rigid pavement surfaces have been examined using the field and laboratory test data. Models for the prediction of pavement skid resistance including the seasonal and long term variations have also been developed correlating the influencing factors. A value engineering approach has been proposed to accommodate the construction and maintenance costs, longevity, smoothness, safety and noise in the selection of pavement surfaces.

Syfte: När städerna växer i allt snabbare takt behövs nya platser att bygga bostäder på. De kommuner som växer väljer allt oftare att bebygga platser som tidigare ratats på grund av bland annat buller. Från statens sida finns det krav på hur stor bullernivån får vara. Kraven har sitt ursprung i att över två miljoner svenskar utsätts för buller dagligen. Buller kan leda till hälsoproblematik, i form av sömnstörningar och hjärt- och kärlsjukdomar. För att minska hälsoproblemen görs bullerutredningar, där förslag hur bullernivåerna kan minskas ges. Syftet med arbetet är att ge läsaren kunskap i vilka faktorer som påverkar bullerutredningar och tillvägagångssättet vid valet av bullerreducerande åtgärder så att byggnation närmare trafikerad väg kan möjliggöras. Metod: De metoder som använts i arbetet är litteraturstudie, dokumentanalys och intervjuer. Den litteratur som samlats in består av vetenskapliga artiklar. Dokumenten består av bullerutredningar genomförda av olika företag på olika platser i Sverige. Utifrån bullerutredningarna har personer att intervjua valts. De personer som intervjuats har utfört några av de bullerutredningar som använts i dokumentanalysen. Resultat: För att besvara rapportens syfte ställdes tre frågeställningar upp. Den första frågeställningen behandlar bullerreducerande tekniker, vilka tekniker som används idag. I rapporten framkom det att det finns ett flertal sätt att reducera buller. I följande ordning rangordnas de som mest frekvent använda: tyst sida, bullerskärm, hastighetsminskning, avstånd mellan hus och väg, vegetation, flytt av väg och tyst asfalt. I rapportens andra frågeställning behandlas vilka faktorer som påverkar valet av bullerreducerande åtgärd. Från litteraturstudien framkom absorption, reflektion och reduktion som viktiga faktorer. I dokumentanalysen framkom omgivning, trafik och hastighet som viktiga faktorer. I intervjuerna framkom estetik och pris som viktiga vid val av reducerande åtgärd. I den tredje frågeställningen behandlas frågan om hur byggnation närmare väg kan möjliggöras. I resultatet framkommer det att alla lösningar som tidigare nämnts har förmåga att reducera buller, men hur effektiva de är och hur bra de reducerar buller varierar från fall till fall. Omgivning och trafikmängd har stor betydelse. Konsekvenser: Att utnyttja de tekniska lösningar som tidigare beskrivits ger en minskad bullernivå och således kan byggnation nära trafikerad väg möjliggöras. Att utföra en bullerutredning i ett tidigt skede medför att senare och dyrare ändringar kan undvikas, vilket gör att byggnationen kan ske snabbare. Rapporten föreslår att bullerproblematiken ska beaktas tidigt i projekt, detta för att skapa en lösning som alla i projektet kan acceptera. Begränsningar: Rapportens resultat är begränsat till ett mindre urval av bullerutredningar och intervjuer. Fler utredningar och intervjuer hade bidragit till ett större spektrum. Rapporten tar enbart hänsyn till buller utomhus och vilka möjligheter till bullerreduktion det finns. / Purpose: When cities grow at a faster rate, new places are needed to build housing.The municipalities that are growing tends to choose build sites that previously wererejected due to noise pollution. There are requirements from the state that the noise maynot exceed certain values. The requirements originate from the fact that over twomillion swedes are exposed to noise daily. Noise can lead to health problems, in theform of sleep disorders and cardiovascular disease. To reduce health problems noiseinvestigations are made, where suggestions are made in how noise levels can bereduced. The purpose of the work is to provide the reader with knowledge of whichfactors influence noise investigations and the approach to the choice of noise reductionmeasures so that construction can be made closer to trafficked roads. Method: The methods used are literature studies, document analysis and interviews.The literature gathered consists of scientific articles. The documents consist of noiseinvestigations conducted by different companies all over Sweden. Persons to interviewwere chosen from the conductors of the noise investigations documents. Findings: To answer the report's purpose, three questions were raised. The firstquestion deals with noise-reducing technologies and which technologies are used today.The report found that there are several ways to reduce noise. In the following order, themost frequently used are: silent facade, noise screen, speed reduction, distance betweenhouse and roads, vegetation, road moving and quiet asphalt. The second question of thereport addresses the factors that influence the choice of noise reduction measure. Fromthe literature study, absorption, reflection and reduction were found to be importantfactors. In the document analysis, surroundings, traffic and speed emerged as importantfactors. In the interviews, aesthetics and price emerged as important in the choice ofwhich reducing action should be taken. The third question deals with the question ofhow construction can be made closer to the road. In the result it appears that all of thesolutions mentioned earlier have the ability to reduce noise, but how effective they areand how well they reduce noise varies from case to case. Surroundings and trafficvolume are of great importance. Implications: Making use of the technical solutions previously described, results in areduced noise level and there for construction near road can be made possible.Executing a noise investigation at an early stage means that later and more expensivechanges can be avoided, which means that construction can take place sooner. Thereport suggests therefore that noise issues should be considered early in projects. It isalso important to get a solution that everyone can accept. Limitations: The report's results are limited to a smaller selection of noiseinvestigations and interviews. More investigations and interviews could hadcontributed to a larger spectrum. The report does only consider noise outdoors and whatopportunities for noise reduction there are.

Made available in DSpace on 2014-12-17T14:58:02Z (GMT). No. of bitstreams: 1 MariaCRO_DISSERT.pdf: 2657350 bytes, checksum: 6329dc6423194c512c4121d699e43fa5 (MD5) Previous issue date: 2010-07-26 / This work proposes the development of an innovative material made from a vegetable polyurethane matrix and load of industrial waste, from retread tires, for thermal insulation and environmental comfort. Experimental procedures are presented, as well as the results of the thermal and acoustic performance of this composite material, made from an expansive foam derived from the castor seed oil and fiber of scrap tires. The residue was treated superficially with sodium hydroxide, to eliminate contaminants, and characterized macroscopically and microscopically. Samples were produced with addition of residues at levels of 5%, 10%, 15% and 20% by weight, for determination of thermal properties: conductivity, heat capacity and thermal diffusivity, sound absortion index and density. The results were compared to commercially available thermal insulation and sound absorbing products. According to the analysis of results, it was concluded that the developed composite presents characteristics that qualify it as a thermal insulation with superior performance, compared to commercial available insulation, and sound absorption capacity greater than the castor oil polyurethane s, without addition of the residue / Neste trabalho tratou-se do desenvolvimento de um material inovador constitu?do de matriz poliuret?nica vegetal e carga de res?duo industrial, proveniente de recauchutagem de pneus, para fins de isola??o t?rmica e conforto ambiental. Para tanto, s?o apresentados procedimentos e resultados experimentais obtidos da an?lise do desempenho t?rmico e ac?stico desse material comp?sito produzido a partir de resina expansiva derivada do ?leo da semente de mamona e fibras de pneus inserv?veis. O res?duo foi tratado superficialmente com hidr?xido de s?dio, para a elimina??o de impurezas, e caracterizados macrosc?pica e microscopicamente. Foram produzidos corpos de prova com adi??o de res?duo nas propor??es de 5%, 10%, 15% e 20% em massa, para determina??o de propriedades t?rmicas: condutividade, capacidade calor?fica e difusividade t?rmica, do ?ndice de absor??o sonora e densidade aparente. Os resultados foram comparados aos isolantes t?rmicos e absorventes sonoros comerciais. De acordo com a an?lise dos resultados, concluiu-se que o comp?sito desenvolvido possui caracter?sticas que o qualificam como um isolante t?rmico com desempenho superior aos isolantes comerciais e com capacidade de absor??o sonora maior que o poliuretano de mamona sem a adi??o do res?duo

Questões ligadas ao desempenho térmico e acústico de edificações têm sido cada vez mais abordadas, num cenário em que ganham importância a economia de energia e o controle do ruído. O advento dos materiais compósitos propiciou o emprego de resíduos de processos que, aliados a materiais de origem renovável, contribuem para a obtenção de produtos de reduzido impacto ambiental. Neste contexto, o presente trabalho teve como objetivo a produção e caracterização de painéis de partículas e espuma poliuretana à base de óleo de mamona, para destinação em composições termoacústicas. Os painéis de partículas foram produzidos utilizando-se resíduos de madeira de Pinus sp., tratado com CCB (preservante de cromo, cobre e boro - base óxido), borracha de pneus inservíveis e adesivo poliuretano à base de óleo de mamona. Foram adotadas variações na produção dos painéis, quanto aos fatores: proporção e configuração da borracha, espessura e pressão de prensagem; verificando sua influência no desempenho dos painéis. As propriedades físicas e mecânicas dos painéis foram determinadas conforme a ABNT NBR 14810-3 (2006) e avaliadas segundo os principais requisitos de normas neste âmbito. Análises estatísticas (ANOVA) foram realizadas para verificação da influência dos fatores de produção, e de suas interações, nas propriedades físicas e mecânicas dos painéis. Também foram avaliadas a morfologia e estabilidade térmica dos painéis e espumas. O isolamento térmico foi avaliado pela determinação experimental da condutividade térmica. A absorção sonora dos painéis e espumas, em diferentes montagens, foi determinada por medições em câmara reverberante, conforme ISO 354 (1985). Os resultados das propriedades físicas e mecânicas dos painéis estiveram em grande parte condizentes com os documentos normativos. O teor de borracha e a sua interação com os demais fatores apresentaram influência estatística nas propriedades físicas e mecânicas dos painéis. A morfologia dos painéis e espumas permitiu visualizar sua adequação aos produtos propostos, por meio da porosidade. Em relação ao isolamento térmico e absorção sonora, os painéis e espumas, bem como as composições formadas, apresentaram desempenho coerente com produtos e normas utilizados como referência. Sendo assim, verificou-se a viabilidade de produção e aplicação dos painéis e espuma poliuretana à base de mamona em composições destinadas ao conforto termoacústico. / Issues relating to thermal and acoustic performance of buildings have been increasingly addressed in a scenario where energy savings and noise control are essential. Advent of composite materials enabled the use of residues from production processes that, coupled with renewable source materials, contribute to obtain products with low environmental impact. So, this study aimed to the production and characterization of particleboards and castor-oil-based polyurethane foam, for thermo-acoustic compositions. Panels were produced with residues of Pinus sp., treated with CCB (chromium, copper and boron basic oxide preservative), tire rubber wastes and castor-oil-based polyurethane adhesive. Variations in the production parameters were adopted: proportion and configuration of tire rubber; panels thickness; and pressing pressure, to determine their influence on panel performance. Physical and mechanical properties of particleboards were determined based on ABNT NBR 14810-3 (2006) and evaluated according to the main requirements of standards in this area. Statistical analysis (ANOVA) was performed to check the influence of production factors, and their interactions, in those properties. Morphology and thermal stability of foams and panels were also evaluated. Thermal insulation was evaluated by experimental values of thermal conductivity. Sound absorption of the panels and foams, in different assemblies, was determined by measurement in a reverberation room, according to ISO 354 (1985). Results of evaluated panel properties were consistent with the normative requirements. The tire rubber content and its interaction with other factors influenced in almost all physical and mechanical properties of the particleboards. Morphology of the foams and panels permitted confirming their suitability to the proposed product by the porosity. With respect to thermal insulation and sound absorption, panels and foams as well as the correspondent compositions showed performance consistent to the references. Therefore, it was demonstrated the production feasibility and applying of studied compositions intended for the thermo-acoustic comfort.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / In urban areas, where noise is significant, the facades and roofs must submit a performance capable of ensuring insulation required for the acoustic comfort of the users. The roof, although important elements of the envelope of buildings, has been little studied in Acoustics. The validity of ISO 15575 Residential Buildings - Performance impacted mainly the construction industry suppliers, who needed to characterize their products and systems. Also in 2015 came the NBR 16373 - tiles and thermoacoustic panels - Performance requirements. This Thesis aimed to establish a methodology to analyse the acoustic performance for sandwich tiles considering regulatory standards and experimental trials. It started from the requirements of ISO 16373 for performing absorption tests and sound transmission loss of sandwich type of shingle tiles + EPS. The experimental procedure used to determine the sound absorption coefficient (α) was the method of the reverberation chamber in a diffuse field standardized by ASTM C423. The results showed behaviour with greater absorption (0.29) in a narrow band around 250 Hz and stabilized above 1600 Hz, with values similar to 0.06. These factors mean rank 1 according to the NBR 16373, in other words, the worst performance scale. Regarding the sound insulation test, performed according to ISO 10140 in reverberation room, it was quantified the Weighted Sound Reduction Index, Rw = 20 dB, above the expected performance because resulted close to the performance of other more valued tile commercially. The information given on NBR 16373: 2015 for the experimental analysis of sandwich tile are very incomplete, so difficult the tests. To facilitate implementation, minimizing errors due to erroneous interpretations of the techniques involved standards, we established a specific analysis methodology for trials in shingles or tiles. Therefore, it is proposed that the adequacy of samples of the tests, the individual analysis of each material that compose the shingle and evaluation of the two faces of the composite tiles, in order that they may have different types of finish (liner, liner-film, perforated panel, among others) and therefore the analysis of the lower tile becomes effective in assisting in the determination of the acoustic conditioning of the interior environments. Another suggestion is the evaluation of the rain impact noise on tiles. Finally, we reiterate the importance of the technical product information are clear and complete, allowing consumers to obtain adequate acoustic performance in their buildings. / Em áreas urbanas, onde o ruído é significativo, as fachadas e coberturas devem apresentar um desempenho capaz de garantir a isolação necessária para o conforto acústico dos usuários. As coberturas, embora sejam elementos importantes da envoltória das edificações, tem sido pouco estudadas na área de Acústica. A vigência da NBR 15575 Edificações habitacionais Desempenho impactou, principalmente, o setor de fornecedores da construção civil, que necessitaram caracterizar seus produtos e sistemas. Além disso, em 2015, surgiu a NBR 16373 Telhas e painéis termoacústico Requisitos de desempenho. A presente Dissertação teve como objetivo principal estabelecer uma metodologia de análise da performance acústica para telhas sanduíche, considerando padrões normativos e ensaios experimentais. Partiu-se das exigências da NBR 16373 para a execução dos ensaios de absorção e perda de transmissão sonora das telhas sanduíche do tipo telha + EPS. O procedimento experimental utilizado para a determinação do Coeficiente de Absorção Sonora (α) foi o método da câmara reverberante em campo difuso, normatizado pela ASTM C423. Os resultados mostraram um comportamento com maior absorção (0,29) numa faixa estreita em torno de 250 Hz e uma estabilização acima de 1600 Hz, com valores similares a 0,06. Tais coeficientes significam classificação 1, de acordo com a NBR 16373, ou seja, o pior desempenho da escala. No que tange ao ensaio de isolamento sonoro, executado de acordo com a ISO 10140, em câmara reverberante, foi quantificado o Índice de Redução Sonora Ponderado, Rw= 20 dB, desempenho acima do esperado, pois resultou próximo ao desempenho de outra telha mais valorizada comercialmente. As informações constantes na NBR 16373:2015 para a análise experimental da telha sanduíche são muito incompletas, por isso dificultam a realização dos ensaios. Para facilitar a execução, minimizando os erros decorrentes de interpretações equivocadas das normas técnicas envolvidas, estabeleceu-se uma metodologia de análise específica para ensaios realizados em telhas ou coberturas. Assim, propõe-se a adequação das amostras dos ensaios, a análise individual de cada material que compõe a telha e a avaliação das duas faces das telhas compostas, tendo em vista que elas podem possuir diferentes tipos de acabamento (forro, forro-filme, painel perfurado, entre outros) e, por isso, a análise da parte inferior da telha torna-se eficaz no auxílio da determinação do condicionamento acústico no interior de ambientes. Outra sugestão é a avaliação do ruído de impacto da chuva em telhas. Por fim, reitera-se a importância de que as informações técnicas sobre os produtos sejam claras e completas, permitindo que os consumidores finais possam obter um adequado desempenho acústico em suas edificações.

The following project has been carried out in collaboration with Abstracta AB (AAB), a company based in Lammhult with specialization in sound landscapes for indoor environments. The company manufactures different types of products with sound-absorbing properties where sustainability and design are in great focus. A new product idea of the company is based on developing an A-classified discreetly designed wall absorber that is considered more as a "wall" than a "wall with mounted absorbent on". The purpose of the project was to develop the following product on a conceptual level. A main research question with two underlying issues was developed that served as a support during the project. Question 1: How can an A-rated discreetly designed sound wall absorber be developed? 1.a: How can an A-rated sound wall absorber be developed? 1.b: How can a sound wall absorber achieve a discreetness in its design? The project followed a product development process where the mainly focus was on concept development and concept testing. The concept was developed based on data collected from a literature study and with the use of a sound absorption calculator. A sound absorption test and an examination form regarding the discrete modeling and design of the absorbent were performed for the final concept that the project resulted in. The project showed that an A-rated discreetly designed sound wall absorber can be developed through a process where design-critical specifications that affect the absorber's discrete design control how the object can be modeled. Via a sound absorption calculator, concepts can be designed that theoretically indicate an A-rate while the design-critical specifications are not exceeded. Based on the concept, a prototype is manufactured that can undergo a sound absorption test to determine the absorbent's actual sound absorption capacity. Finally, an examination is made to analyze whether the absorbent is considered a discrete alternative or not. Based on the project's results, the work process proved to be advantageous as the concept indicated a sound absorption capacity that exceeded the requirements of the A-rating and at the same time obtained a discreet design and modeling. This was achieved in connection with the manufacturing materials achieving their technical specifications and a square meter cost lower than expected. Based on the project's results, the work process proved to be advantageous as the concept indicated a sound absorption capacity that exceeded the requirements of the A-rating and at the same time obtained a discreet design and modeling. This was achieved in connection with the manufacturing materials achieving their technical specifications and a square meter cost lower than expected. In the further development of the final concept, a solution for how the absorbent is to be mounted on the wall must be developed as this was not focused on in the project based on its boundaries. To achieve a valid A-rate, an additional sound absorption test must also be performed where a larger object area of 10–12 m2 is tested. In future work, the concept's discrete modeling and design should also be examined based on physical treatment to review how the examination form's response results relate to this. / Följande projekt utförs i samarbete med Abstracta AB (AAB), ett företag som är stationerat i Lammhult och är specialiserade inom ljudlandskap för inomhusmiljöer. Företaget framställer olika typer av produkter med ljudabsorberande egenskaper där hållbarhet och design även är i stort fokus. En ny produktidé av företaget grundar sig i att utveckla en A-klassificerad diskret utformad väggabsorbent som betraktas mer som en ”vägg” än en ”vägg med uppmonterad absorbent på”. Syftet med projektet var att framta följande produkt på en konceptuell nivå. En huvudsaklig forskningsfråga med två underliggande frågeställningar togs fram som fungerade som ett stöd under projektets gång. Fråga 1: Hur kan en A-klassificerad diskret utformad ljudväggabsorbent utvecklas? 1.a: Hur kan en A-klassificerad ljudväggabsorbent utvecklas? 1.b: Hur kan en ljudväggabsorbent uppnå en diskrethet i sin design? Projektet följde en produktutvecklingsprocess där det största fokuset låg på konceptutvecklingen och koncepttestningen. Koncepten utvecklades utifrån insamlade data från en litteraturstudie och med användning av en ljudabsorptionskalkylator. Ett ljudabsorptionstest och ett undersökningsformulär gällande absorbentens diskreta utformning och design utfördes för det slutgiltiga konceptet som projektet resulterade i. Projektet visade att en A-klassificerad diskret utformad ljudväggabsorbent kan utvecklas genom en process där designkritiska specifikationer som berör absorbentens diskreta utformning styr hur objektet kan formges. Via en ljudabsorptionskalkylator kan koncept designas som teoretiskt indikerar en A-klassning samtidigt som de designkritiska specifikationerna ej överskrids. Utifrån konceptet tillverkas en prototyp som kan genomgå ett ljudabsorptionstest för att fastställa absorbentens verkliga ljudupptagningsförmåga. En undersökning görs slutligen för att analysera huruvida absorbenten betraktas som ett diskret alternativ eller ej. Utifrån projektets resultat visade sig arbetsprocessen vara fördelaktig då konceptet påvisade en ljudabsorptionsförmåga som överträffade A-klassningens krav och samtidigt erhöll en diskret utformning och design. Detta åstadkom i samband med att tillverkningsmaterialen uppnådde sina tekniska specifikationer och en kvadratmeterkostnad lägre än väntat. I fortsatt utveckling av det slutgiltiga konceptet måste en lösning till hur absorbenten ska monteras på väggen tas fram eftersom detta inte fokuserades på i projektet utifrån dess avgränsningar. För att en giltig A-klassificering ska nås måste även ytterligare ett ljudabsorptionstest utföras där en större objektarea på 10–12 m2 testas. I framtida arbete bör även konceptets diskreta utformning och design undersökas utifrån fysiska bemötanden för att granska hur undersökningsformulärets svarsresultat förhåller sig till detta.

<p dir="ltr">In the field of noise control engineering, the development of effective low-frequency sound absorption treatments has long been a challenge, since conventional solutions tend to require impractically thick layers of traditional porous materials, such as fibrous materials and foams. In contrast, high surface area particles, such as granular activated carbon (GAC) particles, milled aerogels, and zeolites, have inner-particle pores at micro and nano scales, which improve the low-frequency absorption by slowing the local sound speed. As a result, a 30 mm thick GAC stack can achieve an absorption coefficient of 0.3 at 100 Hz. Hence, these materials have already been used in various low-frequency applications in place of fibrous or foam layers: e.g., MEMS speaker back cavities, Helmholtz resonator liners, micro-perforated panel absorbers, and membrane absorbers. One major practical goal of this research was to determine how best to model and optimize novel treatments consisting in whole or in part of high surface area granular materials. </p><p dir="ltr">The detailed work presented in this thesis starts with a review of acoustical models of various material types, followed by two approaches to modeling and coupling different types of layers in a general and stable manner. In particular, in the second approach, a large, complicated system is divided into a series of small systems, hence avoiding the direct inverse solution of large systems. As a result, the second approach is more efficient and enables computationally intensive tasks such as multi-layer material characterization and sound package optimization. In addition to the modeling techniques, different types of granular stacks’ acoustical behavior were also experimentally investigated and summarized: i.e., 1. the edge-constraint effect resulting from the friction at the wall of the impedance tube; 2. level-dependent behavior; 3. time-dependent behavior; and 4. other non-linear behavior. To capture the observed acoustical physics of GAC stacks, a triple-porosity poro-elastic model with a depth-dependent modulus was described, followed by characterization frameworks to model the stacks subject to the edge-constraint effect as well as varying excitation levels. These frameworks were validated by comparing the absorption spectra predicted by using the inferred material properties with impedance tube measurements of GAC stacks with varying depths, diameters, and exposure levels. In the end, a novel sound absorption treatment was presented (a GAC stack supported by a soft, porous layer), which was subsequently optimized to develop broadband absorbers.</p>

[ES] Los niveles de presión acústica experimentados por las naves espaciales y las lanzaderas durante las fases iniciales del lanzamiento (ignición de motores y despegue) pueden ser muy significativos para estructuras ligeras y cargas externas y apéndices, como paneles solares y antenas. En este contexto, el fondo del canal de evacuación de gases actúa como un espejo desde el punto de vista acústico, y devuelve la energía liberada directamente al cohete y a las estructuras que transporta. Esta gran cantidad de energía puede poner en riesgo algunas misiones de lanzamiento, con las consecuencias económicas y de seguridad que ello conlleva. A pesar de esto, existe todavía poco conocimiento sobre las características de las fuentes y el comportamiento de las instalaciones de suelo en referencia a la dispersión, difusión y absorción del sonido. En este contexto se desarrollará el objetivo principal de esta Tesis, cuyo propósito es el diseño y optimización de un prototipo de sistema basado en un array de resonadores de Helmholtz para maximizar la absorción y dispersión del sonido y, por tanto, mitigar los niveles de presión sonora generados en estos eventos en el contexto aeroespacial. Los trabajos de esta Tesis se llevan a cabo en el marco del contrato Networking/Partnership Initiative de la Agencia Espacial Europea. / [CA] Els nivells de pressió acústica experimentats pels vehicles espacials durant les fases inicials del llançament (ignició de motors i enlairament) són extremadament elevats i poden afectar significativament a estructures lleugeres transportades, com panells solars i antenes. L'intens soroll generat per les fonts primàries, el motor i el raig, es veu reforçat per la reflexió en el fons del canal d'evacuació de gasos, que actua com un mirall des del punt de vista acústic, i retorna l'energia alliberada directament al coet i a les estructures que transporta. Aquesta gran quantitat d'energia pot posar en risc algunes missions de llançament, amb les conseqüències econòmiques i de seguretat que això comporta. Tot i la rellevància d'aquest problema, el coneixement sobre les característiques de les fonts, el comportament de les instal·lacions de sòl en referència a la dispersió, difusió i absorció del so, i les possibles mesures per mitigar l'impacte és encara escàs. En aquest context es desenvoluparà l'objectiu principal d'aquesta Tesi, el propòsit de la qual és el disseny i optimització d'un prototip de sistema basat en una matriu de ressonadors de Helmholtz per maximitzar l'absorció i dispersió del so a nivell de terra i, d'aquesta manera, mitigar els nivells de pressió sonora generats en aquests esdeveniments en el context aeroespacial. Els treballs d'aquesta Tesi s'han dut a terme en el marc del contracte Networking/Partnership Initiative 441-2015 de l'Agència Espacial Europea. / [EN] The sound pressure levels experienced by space vehicles during the initial stages of launch (engine ignition and lift-off) are extremely high and can significantly affect light transported structures, such as solar panels and antennas. The intense sound generated by the primary sources, the engine and the jet, is reinforced by the reflection at the bottom of the gas evacuation channel, which acts as a mirror from the acoustic point of view, and returns the energy released directly to the rocket and the structures it carries. This large amount of energy can put some launch missions at risk, with the economic and security consequences that this entails. Despite the relevance of this problem, knowledge about the characteristics of the sources, the behavior of ground facilities in reference to the dispersion, diffusion and absorption of sound, and the possible measures to mitigate the impact is still scarce. In this context, the main objective of this thesis will be developed. The purpose of this work is the design and optimization of a prototype system based on an array of Helmholtz resonators to maximize the absorption and dispersion of sound at ground level and, in this way, mitigate the sound pressure levels generated in these events in the aerospace context. The work of this thesis has been carried out within the framework of the Networking/Partnership Initiative contract 441-2015 of the European Space Agency. / None of the work presented here could have been possible without the funding provided by the European Space Agency. In this institution, I want to specially thank Julián Santiago (who sadly passed away in December 2018) and Ivan Ngan, both from the Structures, Mechanisms and Materials Division, for their help to make this project possible. / Herrero Durá, I. (2020). Acoustic noise reduction methods for the launch pad [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/146650

La zona en estudio, ubicada entre los kilómetros 31 y 35 de la carretera Panamericana Norte, posee un nivel de presión sonora promedio de 76.48dB y 74.76dB en el horario diurno y nocturno respectivamente, y tomando como base Los Estándares de Calidad de Ruido Ambiental (ECA) se puede determinar que la zona en estudio se produce contaminación acústica. Por ello, las personas que frecuentan y/o circulan por esta zona se encuentran propensas a contraer distintas enfermedades y molestias producto de la contaminación sonora, entre ellas: Estrés, pérdida de audición con el paso del tiempo, problemas cardiológicos, entre otros. Ante lo mencionado, la presente tesis busca controlar el ruido generado por el parque automotor mediante la instalación de Barreras Acústicas en la sección vial de la Panamericana Norte, utilizando como materiales principales dos tipos de concreto, el concreto convencional y el concreto con agregados ligeros de aserrín y viruta. Para ello, el concreto con agregados ligeros de aserrín y viruta, material absorbente del sistema de Barrera Acústica, se lleva al laboratorio acústico para ensayar mediante el método del Tubo de impedancia, para obtener el coeficiente de nivel de presión sonora. Siendo este valor promedio de absorción sonora máxima de las muestras (α) 0.23. En conclusión, el sistema de barrera acústica diseñado alcanza a absorber hasta 23% del nivel de presión sonora percibido, y con ello la zona en estudio se encuentra dentro de los Estándares de Calidad de Ruido Ambiental. / The area under study, located between kilometer 31 and kilometer 35 of the Northern Pan-American Highway, has an average sound pressure of 76.48dB during daytime and 74.76dB during nighttime. Taking the Environmental Noise Quality Standards (ECA, in Spanish) into consideration, it can be determined that the noise pollution occurs in the area under study. Therefore, the people who frequent or pass by this area are prone to contract various diseases or malaise as a result, such as stress, gradual hearing loss, heart issues, among others. Given the situation, this thesis aims at controlling the noise produced by motorized vehicles by installing sound barriers on said road section of the Northern Pan-American Highway, using two types of concrete as main materials: conventional concrete and concrete with light sawdust and woodchip aggregates. The concrete with light sawdust and swarf aggregates, absorbent material of the sound barrier system, is taken to the sound laboratory to perform tests through the impedance tube method to obtain the sound pressure level. This is the average value of the maximum absorption level of the samples (α) 0.23. In conclusion, the designed sound barrier system manages to absorb up to 23% of the perceived sound pressure level. With that, the area under study falls within the Environmental Noise Quality Standards. / Tesis