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En textilprodukts produktionsprocess beräknas stå för 80% av dess totala klimatutsläpp. Produktionen förorenar både vatten och land. Ännu är inte återvinning svaret på den negativa klimat- och miljöpåverkan som den textila värdekedjan medför. All textilproduktion och återvinning kräver resurser i form av vatten, kemikalier och energi. Enligt studier konsumerar den genomsnittliga svensken 14 kg textilier varje år men den tid som textilierna används blir kortare och kortare på grund av bristfällig kvalitet. Inom cirkulär textil är en viktig del återanvändning, för att det skall kunna ske i högre utsträckning är det av vikt att de textilier som produceras är av god kvalitet. Idag kvalitetstestas nyproducerade, oanvända och konditionerade plagg direkt efter produktion enligt gällande standarder genom mekaniska påfrestningar, ofta testas slitaget tills det inte längre kan anses vara acceptabelt ur ett kundperspektiv. Dessa tester mäter dock inte den verkliga användningen. Vilket innebär att det inte finns något verkligt underlag för att avgöra om det material som använts har en tillräckligt god kvalitet för att hålla för verklig användning och slitage i ett längre perspektiv eller bara uppfyller kravspecifikationen som upprättats. Arbetet i denna rapport har haft som syfte att identifiera vilka kvalitetsbrister som uppstår vid användning av plagg och genom simulerad användning med hjälp av standardiserade testmetoder försökt utvärdera plaggens fysiska livslängd. För att om möjligt kunna användas av företag i samma syfte. Som fallstudie har ett företag studerats och sex olika byxor har testats. Kvalitativa och kvantitativa studier resulterade i ett antal tester till att simulera användning för att försöka utvärdera plaggens fysiska livslängd. De valda testerna för att simulera slitage var upprepad tvätt, nötningshärdighet och rivstyrka, färgförändring, och dimensionsstabilitet vilka har representerat de visuella kvalitetsbrister som kan uppstå. Resultaten från testerna visar att de vanligaste kvalitetsbrister som konsumenter upplever är att det uppstår hål i materialet, att plagget tappar form och att det sker färgförändringar. En av sex byxor uppfyllde kraven i de tester som utförs för validering av testutrustningen. Efter att samtliga byxor testats enligt de utvalda metoderna var det ingen byxa som uppfyllde alla de ställda kraven. Slutsatsen av arbetet är att simulerad användning inte är omöjligt som metod men det går inte fullt ut att återskapa det mekaniska dagliga slitage som ett plagg genomgår hos konsumenten. För att bli en fullgod metod behöver ett mer omfattande arbete göras. Det går inte att med de resultat som återfinns i arbetet att ge konkreta förslag på förbättringar för en ökad livslängd. Det krävs utförliga kravspecifikationer för plaggen som gäller för en hel livslängd. Vilka inte är generella utan uppförda för de olika produktkategorierna i större detalj för att ha kontroll över hela produktionskedjan. / The production process for textiles is estimated to be responsible for 80 % of the total climate emissions made by the industry. The production pollutes both water and land. Recycling, though on the rise, does not offer the necessary solution at the time to deal with the negative climate- and environmental impact of the textile industry. All textile production including recycling requires resources in the form of water, chemicals and energy. The average Swede consumes 14 kg of textiles annually, but the user time is decreasing because of defective quality according to studies. In circular textiles the term re-use is of importance, and to possibly implement it to a greater extent it is of importance that the textiles produced are of good quality making it more probable that the end use will be prolonged. Today, a garment is tested unused and conditioned directly after production, according to standardized test methods through the means of mechanical wear, which is measured to the point where the wear is considered nonacceptable from a consumer perspective. However, these tests do not measure the real wear and tear. Meaning there is no proper basis to decide whether the material used, reaches the level of quality needed for real use in a larger perspective or if it just fulfills the set requirements. The purpose of this project has been to identify what quality deficiencies consumers experience during the use-phase of garments. Through simulated use according to standardized test methods, evaluate the physical lifespan of the garments. With the prospect that fast-fashion companies can implement it to ensure the quality of their materials. As a case study, a company has been studied and six different trousers have been tested. Qualitative and quantitative studies resulted in several tests to simulate use to try to evaluate the physical life of the garments. The tests chosen to simulate wear were repeated washing, abrasion resistance, tear strength, color change, and dimensional stability which represented the visual quality defects that may occur. The test results showed that the most common quality deficiencies that consumers experience are breakage in the material, shape and color changes. One out of six trousers met the requirements of the tests performed for the validation of the test equipment. After all trousers were tested according to the selected methods, no trousers met the set requirements. In conclusion simulated use is not undoable as a method but it cannot fully recreate the mechanical daily wear and tear that a garment undergoes during the user-phase. For it to become an effective method, more extensive work needs to be carried out. It is not possible with the results drawn from this study to give concrete suggestions for improvements for increased longevity. Detailed garment, yarn and requirements specifications are essential. They need to be in greater detail for the various product categories and not be general for all.

Technological developments in digital Jacquard weaving, as well as material research, have a strong influence on today‘s possibilities of textile production. These advancements enable to shift the perspective of textile as a flat surface to textile as a three-dimensional form and push two-dimensional weaving into the third dimension. Utilizing recent technologies in the form of applying multi-layering weaving techniques and embedding heat-reactive shrinking material, the research of Woven Forms aims to explore the forming method of construction through weaving to create abstract forms transformed from flat and to investigate its textile-form properties of shape, texture, color, and scale. The developed method of Embedded Form Weaving is set within experimental design research and structures a systematical approach to generate three-dimensional forms activated from flat surfaces. The outcome in form of abstract, self-supporting textile-forms showcases the multitude of form expressions and variety of formal variables within two construction-form-thinking families. This research contributes to the field of 3D weaving, demonstrates the potential for further research and application possibilities in other disciplines and fields, and evaluates the potential of seeing the weaving loom as a forming tool. While the fundamental base is the interlacement of warp and weft, technology, material science, and textile engineering shift the perception of woven textiles: from a rectangular piece of cloth to the opportunity to construct textile-forms.

High voltage bushings are the most critical components of power transformers. A common material used in bushings is resin impregnated paper (RIP). Hitachi Energy is investigating whether this can be replaced with a new material, resin impregnated non-woven (RIN). One of the main reasons is that non-woven is less prone to absorb moisture compared to paper. Thus, for design purposes the mechanical, thermal and absorption properties of RIN have been studied and compared to RIP. The mechanical properties were tested by tensile and bending tests at room temperature and 80 ℃, showing that RIN has a lower elastic modulus and tensile strength than RIP at both temperatures. However, it was demonstrated that RIN does not retain its elongation at break and elasticity properties at elevated temperatures. The bending test showed no significant differences in flexural properties for RIN between room and high temperature. The thermal properties were studied with the transient plane source method (TPS) showing that both RIN and RIP had a higher specific heat capacity than pure epoxy. The thermal conductivity of the materials will be measured and included later. Lastly, the water absorption test was performed in order to provide information about the suitability of the materials used in bushings. For this different methods were used; water immersion andwater vapor testing. The immersion test showed that non-woven is more water resistant than paper and that the composites only absorb a small amount of water. No useful information was achieved from the water vapor test due to limited testing time. The results demonstrate the promising potential of RIN in bushings.

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Les travaux de cette thèse se sont intéressés à l’obtention du comportement d’un composite sergé 2x2 verre/PA66 via un outil numérique basé sur une double homogénéisation : la première concerne les torons et la seconde le volume élémentaire représentatif du composite. A partir d’une campagne de caractérisation expérimentale sur le PA66, nous avons dans un premier temps identifié l’influence à la fois de l’hygrométrie et de la température sur le comportement de la matrice en quasi-statique. Ensuite, nous avons élaboré, implémenté et validé une loi de comportement isotrope élasto-plastique endommageable. Cette loi a servi à identifier par homogénéisation le comportement des torons en supposant un collage parfait des fibres et de la matrice ainsi qu’une homogénéité de l’eau dans le toron. Grâce à ces comportements identifiés et à l’élaboration d’une loi de comportement anisotrope élasto-plastique endommageable, nous avons pu déterminer les caractéristiques élastiques dans un premier temps et les comportements longitudinaux et en cisaillement dans un second temps. Les comparaisons aux résultats expérimentaux menés sur le composite offrent des résultats satisfaisants et permettent de penser que l’outil numérique développé, permettrait, à termes, d’aider à une conception rapide incluant ce genre de matériau en diminuant le nombre d’essais expérimentaux à faire. Des perspectives enfin sont proposées notamment pour l’extension aux comportements en dynamique (crash). / The objective of this PhD thesis is to create a methodology to simulate the behavior of a 2x2 glass/PA66 twill composite using homogenization. To achieve this goal, we use two steps: first one is dedicated to represent the yarn behavior and the second one to represent the behavior of the composite RVE. An experimental characterization campaign about the PA66 has been done in order to quantify the influence of both hygrometry and temperature on the behavior of the matrix in quasi-static. Then, we formulated, implemented and validated an isotropic elasto-plastic damageable constitutive law. It was used to identify by homogenization the behavior of the yarns by assuming a perfect bonding of the fibers and the matrix as well as a water homogeneity inside the yarn. Thanks to the identified behavior of the yarns and by formulating a compatible constitutive law (anisotropic elasto-plastic damageable), we have determined for the woven composite on one hand the elastic properties and in the other hand the longitudinal/transversal and shear nonlinear behaviors. The comparisons of the numerical and experimental results offer satisfactory results. It provides good outlook in short-term in regard of structures design which include this type of woven composite materials. The main advantage of the methodology is to decrease the number of required experimental tests. Some outlook dedicated to crash studies are finally suggested.

Les composites tissés 3D, à l'aide de leurs grandes libertés de conception, peuvent fournir des propriétés mécaniques adaptées aux besoins spécifiques d'une structure. La complexité architecturale de ces matériaux induit néanmoins des propriétés, des comportements ainsi que des endommagements très difficiles à prédire. Les travaux présentés dans ce manuscrit s'inscrivent directement dans cette problématique et cherchent à développer des outils permettant, par simulation numérique, de prévoir les caractéristiques mécaniques de ce type de matériaux. Afin de répondre à cet objectif, une approche multiéchelle, alliant essais expérimentaux et simulations numériques, a été adoptée. Cette démarche permet, en appliquant des sollicitations réelles, de considérer la géométrie des renforts et les hétérogénéités du matériau, observables à l'échelle mésoscopique, qui sont responsables du comportement macroscopique du composite tissé. Le travail d'investigation expérimentale s'est attaché à caractériser le comportement d'un composite interlock 2,5D et des ses constituants ainsi que les mécanismes et cinétiques de rupture, pour des sollicitations de traction/flexion, grâce à des observations tomographiques aux rayons X et au concept d'interzone. En ce qui concerne la modélisation numérique, un critère de rupture permettant de simuler la dégradation ultime du composite, en coupant les fils de renforts, a été présenté et testé sur une cellule représentative du composite expérimentale. Les résultats en termes de localisations, d'orientations et de cinétiques de l'endommagement sont en accord avec les observations expérimentales. Ensuite, après avoir estimé l'influence des différents paramètres architecturaux sur le critère de rupture avec une campagne de calcul éléments finis, des architectures optimisées, pour les sollicitations considérées, ont pu être proposées et comparées à l'interlock 2,5D. Toujours dans l'optique d'une meilleure prédiction du comportement des composites tissés, les travaux se sont également intéressés à une modélisation plus fine des mécanismes d'endommagement. Une approche fiabiliste a donc été introduite sur le critère de rupture à l'aide d'une distribution statistique de Weibull. De plus, un autre mécanisme d'endommagement a aussi pu être pris en compte dans la modélisation en simulant, avec le modèle GTN (Gurson-Tvergaard-Needleman), la cavitation de la matrice. Enfin, des techniques de réduction de modèle ont été employées pour diminuer le coût calcul de la modélisation multiéchelle afin d'identifier, par exemple, des propriétés matériaux par méthode inverse ou de simuler des essais de fatigue. / With their large flexibility of design , 3D woven composites can provide mechanical properties tailored specificially to structural needs. However, the architectural complexity of woven reinforcements presents serious challenges when predicting properties, behaviours and damage processes. The present work deals with these challenges and seeks to develop numerical tools which are able to foresee the mechanical characteristics of this kind of materials. For this purpose, a multiscale approach, which combines experimental tests and numerical simulations, has been adopted. This approach allows, simultaneously, to take into account the loads and composite behavior, at the macroscopic scale, also the reinforcement geometry and the material heterogeneities which are only visible at the mesoscopic scale. The experimental investigation has been carried out to characterize the behaviour of an 2.5D interlock composite and its constituents. Examinations of the damage mechanisms have also been performed, using tomography and the interzone concept, for this woven composite under loadings in tension and combined tension and bending. With regards to the numerical modeling part, the ultimate degradation of the composite was simulated by cutting the reinforcement yarns with a failure criterion, previously reported, on a 3D representative cell of the experimental composite. For the two kinds of macroscopic loadings, the locations, orientations and kinetics of the damage were found to be fully in agreement with the experimental results. The influence of the architectural parameters on the failure criterion was then evaluated by finite element calculation. Consequently, it has been possible to proposed optimized architectures and make a camparison, for the two macroscopic loadings, with the 2.5D interlock woven composite. Still motivated to improve the prediction of the behaviour of woven composites, this work has also been on developing a finer modeling approach to the understanding of damage mechanisms. A stochastic approach was therefore introduced to the failure criterion using a Weibull statistical distribution. In addition, matrix cavitation has also been taken into account in the modelling. This damage mechanism was simulated using the GTN (Gurson-Tvergaard-Needleman) model. Finally, model reduction techniques have been applied to lower the cost of computing multiscale modeling in order to identify, for example, material properties by an inverse method or to simulate fatigue tests.

The future of the aerospace industry in large part relies on two factors: (i) development of advanced damage tolerant materials and (ii) development of advanced smart sensors with the ability to detect and evaluate defects at very early stages of component service life. Laminated composite materials, such as carbon fibre reinforced plastics (CFRP), have emerged as the materials of choice for increasing the performance and reducing the cost and weight of aircrafts, which leads to less fuel consumption and therefore lower CO2 emissions. However, it is well known that these materials exhibit fragile behaviour, poor resistance to impact damage caused by foreign objects and require a relatively slow and labour intensive manufacturing process. These factors prevent the rapid expansion of composite materials in several industrial sectors at the current time. Inspired by the use of rope throughout history and driven by the necessity of creating a lean manufacturing process for composites and enhancing their impact properties, the first part of this work has shown that enhanced damage tolerance and pseudo-ductile behaviour can be achieved with standard CFRP by creatively arranging the fibres into a 3D twisted helical configuration. Through an extensive experimental campaign a new method to arrange fibre reinforcement was presented and its effect investigated. The second part of this PhD work focused on developing a new smart sensor. A spiral passive electromagnetic sensor (SPES) for damage detection on CFRP and glass fibre reinforced plastics (GFRP) is presented in this work. A range of defect types in glass and carbon composite has been considered, such as delamination, perforated holes and cracks. Furthermore, throughout this work, the SPES has been exploited as a multi-sensing device allowing the ability to detect temperature and humidity variation, presence of ice and act as an anti/de-icing device.