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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Energiabsorberande material : en studie av 3D-väv, non woven och D3O för förebyggande av höftfrakturer hos äldre vid fallolyckor

Saleem, Hayvee, Wictorson, Johanna January 2018 (has links)
Höftfrakturer är ett stort problem för äldre i dagens samhälle och för samhället i stort. Många drabbas vilket leder till stort lidande och för samhället höga kostnader. Detta har Professor Peter Apell vid Chalmers University of Technology uppmärksammat. Han har startat upp flera projekt inom området Innovative textiles in healthcare för att hitta nya och bättre lösningar på problem relaterade till vård och hälsa. Det här projektet är ett av de projekt som uppkommit genom hans engagemang. Projektets fokus har varit att undersöka dämpning och spridning av kraft samt energiupptagningsförmåga hos tredimensionell väv i kombination med non woven. Samma typ av undersökning har utförts på ett polymert material kallat D3O. D3O används i nuläget i viss typ av skyddsutrustning men inte inom området höftskydd för äldre. De olika materialens egenskaper har därefter jämförts. Intresset för att undersöka 3D-textil i sammanhanget skyddsmaterial är grundat i att det kan ha flera fördelar i förhållande till de material som används i befintliga skydd idag. Många höftskydd på marknaden har skumgummi som skyddsmaterial. En fördel med textila skydd är möjligheten att producera skydd och hållare för skyddet i ett och samma material vilket förenklar framtida återvinning. Med textila skyddspaneler finns även möjligheten att framställa lätta och flexibla skydd för ökad komfort. Projektets största begränsning har varit testutrustning och testmetoder, en begränsning för hela industrin inom utveckling av höftskydd. Den testutrustning som använts i projektet har varit en fallrigg med tillhörande fallkropp i form av en kula, hos företaget Industritextil Job i Kinna, samt två olika dragprovare med speciellt framtagna hållare och klämmor vid Textilhögskolan i Borås. De textila konstruktionerna som undersökts under projektet har framställts av författarna med hjälp av maskiner och textila material som varit tillgängliga på Textilhögskolan. Flera bindningar togs fram, dessa vävdes och studerades. Två varianter av distansvävar med stående distanser ansågs ha potential tillsammans med två olika konstruktioner av non woven. D3O-materialet köptes in i form av färdiga höftskydd. Projektet har resulterat i att de konstruktioner som tagits fram i väv och non woven har potential men i nuläget troligtvis inte tar upp tillräckligt mycket av kraften för att undvika en frakturskada. Undersökningen har dock visat att det finns mycket att utveckla och forska vidare på inom området 3D-textil. Det polymera skyddet D3O visade goda resultat teoretiskt och praktiskt i den utsträckning det kunde undersökas med tillgänglig testutrustning. Mer arbete med utformning av materialet rekommenderas för att ta fram ett skydd som är bra ur både komfort- och funktionssynpunkt. Det krävs ytterligare tester med bättre anpassad testutrustning innan skyddseffekten kan bekräftas vara tillräcklig. / Hip fractures are a big problem for the elderly in today's society and a problem for our society as a whole. A lot of people get affected by it and it leads to suffering and a large cost for society. This is something Professor Peter Apell at Chalmers University of Technology has noticed. He has started several projects within the field of Innovative textiles in healthcare to find new and improved solutions to issues related to health and welfare. This project is one of the projects started because of his commitment to the cause. The focus of the project has been to explore the attenuation of force, dispersion of force and energy absorption of distance weaves in combination with non woven materials. The same type of exploration has been applied to a polymer material called D3O. D3O is already being used in some types of protective gear but not within the area of hip protection for the elderly. The different materials characteristics have thereafter been compared. The base of the interest in exploring 3D textile protection is that it could provide certain advantages which some of the hip protection products of today lacks. Many of the products today use foam rubber as the base of protection. An advantage with protective panels made by textiles is the possibility that the whole of the protective product can be made in one and the same material throughout which will simplify future recycling. Another advantage with textile protective panels is the possibility of light and flexible constructions for increased comfort. The most influential restriction to the project has been equipment for performing tests on the materials, which is a big restriction in the whole business of developing hip protection. The testing equipment used in this project has been a setup for performing drop testing with a cylindrical impact body, at the company Industritextil Job in Kinna, and two different tensile machines with specially made clamps at the University of Borås. The textile constructions examined during the project has been manufactured with the use of machines and materials available at the Swedish School of Textiles at the University of Borås. Different weaves were constructed, produced and studied. Two of the three dimensional weaves were regarded as having potential if combined with two different non woven structures. The D3O material was bought, readymade, in the form of hip protection panels. The project has shown that the contextures produced have potential but as of now probably is not enough to protect the hip from fracturing. They did show that there is a lot to explore further within the area of 3D-textiles. D3O, showed good results theoretically and practically to the extent possible to test with the available equipment. More work is advised concerning the shape of the protection panel to make it comfortable and effective in its protection. Further testing with other more adapted testing equipment is required before it can be said with certainty that the protective panel reduces applied forces enough for it to avoid a fractured hip.
32

Influência do fator de cobertura nas propriedades de permeabilidade de tecidos planos / Influence of the coverage factor on the permeability properties of flat fabrics

Eduardo Antônio Crepaldi 06 November 2017 (has links)
Este projeto, \"Influência do fator de cobertura nas propriedades de permeabilidade de tecidos planos\", descreve um breve histórico sobre a Tecelagem e seu crescimento na indústria Têxtil mundial, sendo muito importante o seu desenvolvimento para a indústria. Será apresentado também o conceito sobre Fator de cobertura de tecidos planos. Com o objetivo de avaliar a correlação entre o fator de cobertura e a permeabilidade dos tecidos planos, foram desenvolvidas 18 amostras de tecido com fio 60/2 Ne 100% agodão no urdume e na trama, em ligamento tela, sarja e cetim com densidades de trama 16tramas/cm, 24tramas/cm e 32tramas/cm, e com densidade de urdume 16fios/cm e 32fios/cm . Foi calculado o fator de cobertura para todas as amostras e foram realisados ensaios de gramatura, permeabilidade ao ar, permeabilidade ao vapor de água e permeabilidade a água, com a observação do indice OMMC (Capacidade de gestão global de umidade) do aparelho MMT (Moisture Management Tester). Este estudo se mostra como um caminho na Utilização do fator de cobertura, como item a ser considerado no desenvolvimento de novos artigos. Os resultados mostram para cada ligamento e fator de cobertura o comportamento com relação à permeabilidade dos Tecidos / This project, \"Influence of the coverage factor on the properties of permeability of woven\", describes a brief history on Weaving and its growth in the world textile industry, being very important its development for the industry. The concept of woven coverage factor, will also be presented. In order to evaluate the co-relation between the coverage factor and the permeability of woven, 18 wovens samples were developed with 60/2 Ne 100% cotton thread in the warp and the weft, inwoven twill and satin weave with warp weights 16 yarn/cm, 24 yarn/cm and 32 yarn/cm and with warp density 16 yarn/cm and 32yarn/cm. The coverage factor was calculated for all samples and weight, air permeability, water vapor permeability and water permeability tests were performed with the observation of the OMMC (Global Moisture ManagementCapacity) index of the MMT (Moisture Management Tester).This study shows as a path in the use of the coverage factor, as an item to be considered in the development of new articles. The results show for each ligament and cover factor the behavior regarding the permeability of the wovens
33

Mechanical characterisation and numerical modelling of 3D woven composites

Dai, Shuo January 2014 (has links)
Three-dimensional woven composites were developed to improve the through-thickness properties which conventional two-dimensional laminate composites currently lack. However, these textile composites generally show lower in-plane mechanical properties due to fibre crimping, and also encounter modelling difficulties due to the complex geometries. In this thesis, the static and fatigue mechanical behaviour of several types of 3D woven composites were experimentally characterised, the influence of the weave architecture on the mechanical performance was revealed, and meso/macro scale numerical models with improved failure criteria were developed to simulate the tensile behaviour of the 3D woven composites. The mechanical characterisation was conducted on six woven structures under tension, compression, and flexural loading, and were also carried out on two weaves under open-hole quasi-static tensile and fatigue loading. Digital image correlation and thermoelastic stress analysis were used to characterise the strain and damage development during static and fatigue loading. The testing results showed that the angle-interlock weave W-3 had higher in-plane quasi-static properties, lower notch sensitivity, higher fatigue damage resistance, but lower delamination resistance. The meso-scale model was developed on the unit cell of the woven structure and the macro-scale model (mosaic model) was created on the testing samples. Both un-notched and notched tensile behaviour were modelled for the angle-interlock weave W-3 and a one-by-one orthogonal weave W-1, and the difference between the predicted and experimental results was within 16% for the unit cell models and within 21% for the mosaic models. A modified failure criterion was developed to better simulate the damage behaviour of the notched macro-scale model and improved the predicted notched strength by 10-20%. Whilst further experimental investigation and improvement in the modelling techniques are still required, the data presented in this thesis provided an essential update for the current 3D woven composites research, and the presented models offered the potential to predict the damage behaviour of large 3D woven structures.
34

Tekstas, įprasmintas audimu / The Meaning of the Woven Text

Škulienė, Jelena 03 July 2014 (has links)
Šiuolaikiniame pasaulyje bei mene akcentuojamas kokybiškas rezultatas, gaunamas per trumpą laiko tarpą. Audimas rankomis (pvz., rankinėmis staklėmis, ant vertikalaus rėmo) – imlus laikui procesas, vis labiau tolstantis nuo kasdienės šiuolaikinių tekstilės menininkų praktikos. Nors tekstas yra populiari meno forma, austą tekstą galima sutikti retai. Šis meninis tyrimas analizuoja audimo ir teksto sinkretiškumą. Bandoma atsakyti į klausimus: kokias reikšmes šioje sąjungoje galima įžvelgti, kokia prasmė jai gali būti suteikiama. Austas tekstas, kaip tyrimo objektas, virto pagalba kalbėti apie tekstilės menininko tapatybę šiuolaikiniame mene. Tekstilės autorius, pasirenkantis kurti darbą audimo pagalba, atsiduria tradicijos ir šiuolaikines aplinkos sankirtoje. Tyrimo šaltiniais tapo interviu su austo teksto kūrėjais Lietuvoje, o taip pat literatūra, meno publicistika, straipsniai periodiniuose leidiniuose, kiti duomenys, leidžiantys įžvelgti naujų austo teksto reikšmių. Tyrimo tikslas buvo atskleisti bei surinkti galimas reikšmes, žyminčias ryšį tarp audimo ir teksto. Visos tyrimo metu surinktos reikšmės: priešprieša; laikas, laikinumas, ilgaamžiškumas; pabėgimas, atsiribojimas, išsigelbėjimas, sustojimas; meditacija, įsijautimas; istorija, tradicija; lyta; patvarumas, tvirtumas, tikrumas; komunikacija, intymumas, priminimas; sakralumas, religija; politika, ekonomika; kančia, sunkumas, sudėtingumas, sunkus darbas, meistrystė; tapatybė; prabanga. Visas šias reikšmes galima taikyti... [toliau žr. visą tekstą] / Contemporary world and art emphasise a high-quality result produced within a short period of time. Manual weaving (e.g. by handloom machine or on a vertical loom) is a time-consuming process which is broadly becoming an obsolete practice amongst contemporary textile artists. Although text is a popular form of art, woven text is very rare. This study intends to analyse the syncretic association between weaving and text. The following questions are raised: what are the meanings of this association and what purpose can be derived from it. Woven text, as the study object, has become an assisting instrument in the discussion of a textile artist in contemporary art. A textile artist, who decides to create art by means of weaving, finds himself standing at the crossroads of tradition and contemporary environment. The following study sources were used: interviews with Lithuanian woven text creators, as well as literature, art journalism, articles in periodic publications, and other data which allow finding new meanings of woven text. The objective of the study is to assemble the possible meanings which define the relationship between weaving and text. Meanings found in the study were the following: opposition; time, transience, longevity; escape, isolation, salvation, halt; meditation, empathy; history, tradition; tactility/touch; durability, strength, genuineness; communication, intimacy, reminiscence; sacredness, religion; politics, economics; suffering, complexity, hard work... [to full text]
35

Essais virtuels et modèle statistique de multifissuration transverse des fils dans les composites tissés à matrice céramique / Virtual testing and statistical model of transverse multiple cracking of tows in ceramic matrix composites

Pineau, Pierre 15 December 2010 (has links)
Ce travail concerne l’étude et la modélisation du phénomène de multifissuration transversedes fils dans les CMC tissés. Sa connaissance est fondamentale pour déterminer soneffet sur les champs de contraintes, la progression des endommagements et la durée de viedu matériau.À partir d’observations sur des coupes de CMC, des matériaux virtuels sont développéset des essais virtuels réalisés. Différentes séquences de fissuration transverse sont simuléessur diverses microstructures de CMC. Ces simulations se substituent à des observations expérimentalesimpossibles à réaliser.Un modèle statistique de multifissuration est développé sur la base du principe dumaillon faible appliqué à une distribution ponctuelle de Poisson. Les singularités micostructurellessont représentées par des défauts dans un milieu homogène équivalent (MHE).Les modifications des fonctions de distribution au cours de la multifissuration sont modélisées.Le modèle statistique permet de réaliser un changement d’échelle à la suite duquel lamultifissuration transverse est simulée dans le MHE avec une réduction des temps de calculde l’ordre de 90%. / This work deals with the study and modeling of multiple crakcing of tows in wovenCMCs. Its understanding is fundamental to determine the effect on stress fields, the evolutionof damage and the lifetime of material.From observations on real CMC pieces, virtual materials are developed and multiplecracking virtual testing is achieved. Different scenarii are simulated on various CMC microstructures.These simulations are a substitute for impossible experimental observations.A statistical model for multiple cracking based on the weakest link principle applied to adistribution of Poisson is developed. Micostructural singularities are represented by defectsin a homogeneous medium equivalent (EHM). Modifications of distribution functions duringthe multicracking are modeled.The statistical model realizes a scale changing : transverse multicracking is simulated inthe EHM with a reduction of almost 90% for computational time.
36

Elektriskt ledande filter : funktionoch prestanda

PETTERSSON, EMILIE, LIEU, NI GIAN January 2013 (has links)
Denna rapport ger en bild över luftfilteroch dess funktioner. Syftet med arbetet var att undersöka hur elektriskt ledande luftfilter tillsammans med en joniseringsenhet fungerar samt hur de står sig i förhållande till de mekaniska.Det låg även i syftet att titta på hur andra parametrar påverkar filtrering såsom tjocklek och innehåll av olika andel konduktivt material. Bakgrunden till arbetet var att VokesAir AB hade testat att tillverka elektriskt ledande filter med jonisering i filtret vilket hade fungerat i lite skala men inte i större. Det gjorde att man i detta arbete ville titta på om det kunde fungera om man satte joniseringen utanför filtret istället. Nio stycken luftfilter tillverkades i ennon-woven konstruktion med olika andel konduktivt material och i olika tjocklekar. Utförandetav testerna gjordes i entestriggliknande den i EN779:2012dock med vissa modifieringar. En av dem varatt ett joniseringsrörsomvar fäst före filtretsom tillverkar joner som i sin tur kan fastna på partiklar vilket ger partiklar en laddning. När partiklar tillsammans med joner sedan kommernära luftfiltret innehållande konduktivt material kan de fastnai filtret.Resultatet visade att deelektriska ledande filtrena hade en högre effektivitet när det gällde filtrering av partiklar än de mekaniska. Dock visade inte resultaten någon tydlig skillnad vad det gäller effektiviteten. När det gäller hur tjockleken och andelen konduktivt material påverkade filtreringsförmågan var det svårt att utläsa några tydliga trender. Andelen konduktivt material hade en viss riktning åt att mera andel konduktivt / Program: Textilingenjörsutbildningen
37

Mr Chester Jester / Mr Chester Jester

Ågren, Johanna January 2012 (has links)
Jag har i mitt projekt jobbat med mönsterformgivning och produktion av vävda möbeltyger, digitaltryckta tapeter- och textilier för en fiktiv hemmiljö. Mina designbeslut grundar sig på en fiktiv karaktär, Mr Chester Jester, hans estetiska preferenser och behov i samrådan med mina egna. Arbetets resultat är en gestaltning av världen han lever i, komprimerad till ett hemma hos reportage på gränsen mellan verklighet och illusion. Jag har jobbat med dubbelhet och speglingar - av mönster, av rummet, av tekniker och mig själv. Jag har undersökt illusionens verklighet och verklighetens illusion.My bachelor project is a work of pattern design and production of woven upholstery fabrics, digital prints on textile materials and wallpaper, made for a fictional home environment. The desicions for the designs are based on a fictional character, named Mr Chester Jester. His preferences and needs combined with my omn are the result of this project. The outcome of the work is a formation of his world, made into a study of his home on the edge of reality and illusions. It is a work of duplicities -of pattern, room, technique and of an alternate side of myself.I have investigated the illusion of reality, and the reality of illusions. / Program: Textildesignutbildningen
38

Skogens Eko / Eco of the Forest

Mattsson, Anna January 2013 (has links)
Naturen inspirerar mig, i detta projekt jobbar jag med strukturen hos trädstammar och bark, och översätter det jag ser till vävda textiler. När jag befinner mig i naturen känner jag mig ofta lugn och kan koppla bort allt annat i min omgivning. Det lugnet vill jag återskapa och föra in i en rumslighet. I barkens olika strukturer såg jag intressanta varierande ytor som jag ville jobba med i textil. I mitt examensarbete har jag designat textilier med uppmätt akustiska egenskaper för offentlig miljö. Genom att testa materialen på SP Sveriges Tekniska Forskningsinstitut, har jag undersökt hur akustiskt dämpande de är. Resultatet har blivit en kollektion med tre vävda textilier med olika utseende och ljudpåverkande funktioner.Nature inspires me, in this project I am working with the structure of tree trunks and bark, and the translation of things I see into woven fabrics. When I am in the nature I often feel calm and relaxed. I can ignore everything else in my environment. I would like to re-create this calm feeling and bring it into a room. In the different bark structures can I see an interesting variety in the shapes witch I would like to work with in textile. In my bachelor degree work I have designed textiles with measured acoustical effects for public spaces. By making samples and test them at SP Technical Research Institute of Sweden, I have examined the acoustic damping of the materials. The result is a collection of three woven fabrics with different appearances and sound affecting functions. / Program: Textildesignutbildningen
39

Study on the ballistic performance of quasi-isotropic (QI) panels made from woven and unidirectional (UD) structures

Yuan, Zishun January 2018 (has links)
Quasi-isotropic (QI) structure for multi-layer fabric panel is believed to be a promising construction to manufacture soft body armour with higher efficiency of ballistic protection based on two hypotheses. The first one is that QI structure panel could involve more secondary yarns in transverse deformation, and the second one is that the more involvement of the secondary yarns could result in the corresponding increase of the energy absorption. However, recent study found that the advantage of QI panel made from Dyneema® woven fabrics was very limited over the aligned panel and potential reasons have not been identified for the lack of systematic studies. Accordingly, this research aims to provide explicit guidance on how to improve the QI structure panels for ballistic protection by studying the mechanisms of aligned and QI panels of multi-layer Dyneema® woven fabrics. The two hypotheses were tested to identify the mechanisms. The ballistic performance of the aligned and QI panels of 2-layer, 3-layer and 4-layer Dyneema® woven fabrics were experimentally investigated using a ballistic test apparatus and a panel clamping system to evaluate the energy absorption of specimens. In order to further study the response of the ballistic panel, a yarn-level Dyneema® woven fabric model was developed. The shear moduli of the yarn (G13 and G23) was found to be the most important elastic constants in simulating ballistic fabrics using orthogonal experiments in this study, and were identified to 0.27GPa and 0.80GPa. The model was agreeably validated by comparing the FE modelling results of multi-layer panels under ballistic impact with the experimental counterparts. Based on this validated model, the areas, shapes of the transverse deformation bases were specifically evaluated. The first hypothesis was verified that the areas of the deformation bases of the back layer fabrics in QI panels of 2-layer, 3-layer, and 4-layer fabric models were more than 10% larger than the areas of the corresponding parts in aligned panel models, especially at medium and late stages. Moreover, the increases of the areas were attributed to the more involvements of the secondary yarns in the deformation, and more circular shapes of the deformation bases of the fabrics in QI panels were identified by using a mathematic measurement method created in this study. The kinetic energy (KE) and total strain energy (IE) evolution of primary yarns and secondary yarns in two panels were further specified. It was found that altering the aligned panel to QI panel not only changed the energy absorption of secondary yarns, also significantly changed that of primary yarns. This indicated that the second hypothesis was not suitable for the cases of panels of the Dyneema® woven fabrics for the influence of the primary yarns after the panel structure changed were neglected. The reason of the alterations of the primary yarns was that the slip-off time or failure time of most primary yarns was changed. The morphology evolution of primary yarns in 2-layer aligned and QI panels were investigated and the results showed that the space between adjacent warp or weft primary yarns and the interactions between some primary yarns and the adjacent primary yarns in another layer significantly affected the slip-off time and failure time of most primary yarns. The influence of these two factors derived from the feature of woven fabrics, which was the crimp. In order to verify the new understanding of the QI ballistic panels from the numerical analysis, a non-crimp fabric, namely Dyneema® SB51, was used to investigate the ballistic performance of the aligned and QI panels. It was found that the energy taken by QI panels was approximately 25% higher than the energy taken by the corresponding aligned panels. This result verifies the analysis conclusion and paves the solid way for further investigation of QI structure panels made up of biaxial fabrics.
40

Etude du comportement mécanique des matériaux composites à matrice céramique de faible épaisseur / Mechanical behaviour of thin ceramic matrix composites

Dupin, Christophe 26 November 2013 (has links)
La prochaine génération de moteur d'avion civil, LEAP, développé par Snecma (groupe Safran) et General Electric, intègrera de nombreuses innovations matériaux qui contribueront à la réduction de la consommation de carburant, d'émission de polluants et du bruit. Parmi ces innovations, l'utilisation d'aubes de turbine en CMC (Composites à Matrice Céramique) permettra une réduction significative de la masse du moteur. Les travaux présentés concernent à la fois la caractérisation du comportement mécanique de composites tissés 3D-SiC/Si-B-C et le développement d'une approche multi-échelle du comportement élastique adaptée aux structures CMC complexes. Un premier modèle à l'échelle du fil a été développé en prenant en compte la variabilité du matériau (porosité, architecture, usinage, etc...). Le modèle HPZ (Homogénéisation Par Zone) reposant sur la discrétisation du domaine d'homogénéisation permet de faire le lien entre l'échelle mésoscopique et l'échelle de la structure. / Due to their high thermo-mechanical properties and low densities, ceramic matrix composites (CMC) are candidate materials for hot parts in gas-turbine engines. Various applications have been identified for several types of CMC including C/SiC (nozzles), SiC/SiC (compressor blade) and all oxide composites (combustors). This work presented relates to both the characterization of the mechanical behaviour of woven composites 3D-SiC/Si-BC and the development of a multi-scale elastic behaviour suitable for complex CMC structures approach. A first model at the mesoscale has been developed taking into account the variability of the material (porosity, architecture, manufacturing, etc ...). The HPZ model ("Homogenisation par Zone" in French) based on the discretization of the homogenization field allows to link the mesoscopic scale and the scale of the structure.

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