This thesis presents a multiscale investigation and characterization of additive manufactured Polyamide material using fused deposition modelling technique. Manufacturing was performed using Markforgeds – Mark one 3D printer.  A multiscale investigation dedicated to minimizing the effect of shape distortion during 3D printing are presented, focusing on both molecular alignment in microstructure and implementing internal structures in mesostructure. Characterization on samples investigating microstructure was performed with coefficient of linear thermal expansion measurement and 3-point bending experiment. Different samples with varying infill patterns are tested and results indicates an isotropic behaviour through the manufactured samples and implies no molecular alignment due to printing pattern. In meso-structure, an implemented internal pattern is investigated. All samples are measured with 3D scanning equipment to localize and measure the magnitude of shape distortion. Attempts to find relationships in shape distortion and porosity between the samples resulted in no observed trends. Compressive experiments where performed on samples in axial- and transverse directions resulting in anisotropic behaviour. The largest compressive stiffness is recorded in axial direction reaching 0,33 GPa. The study is done in collaboration with Swerea SICOMP and Luleå University of Technology.

Polyethylene is a widely-used material in package industries. The fracture behavior of this material has not been studied in the plastic region in many years. In this thesis work, the J-Integral which is one material property used to represent the plastic material strength is calculated through the numerical analysis. To build a correct numerical model, the material behavior is summarized from previous uniaxial tensile test. The result from the fracture experiment for variable initial crack length is used to validate the reliability of the numerical model. The numerical analysis is done by the software ABAQUS which has the function to get the value of J-Integral directly. The final result contains the comparison between experiments and numerical analysis and the value of J-Integral at the crack initiation.

The present study was conducted in Umfakarin natural forest reserve, South Kordofan, Sudan. The main objective was to investigate the possibility of managing Acacia seyal Del. variety seyal for the production of gum talha. Three stand densities (strata), namely dense, medium, and slight, were distinguished based on the number of trees per hectare. During the sampling phase, the study adopted the method of identifying the competitors (neighboring trees) from the subject one (trees selected for gum production experiments). From the three stand densities, a total of 482 subject trees, covering variable diameter ranges (d= 9-11.5, 13.5-16, 18-20.5 and above 21 cm) were selected, based on the diameter at 0.25 m height (d0.25). In each stratum, competitor trees were identified within a radius equal to the height of subject tree multiplied by a factor (1.25). The diameter at breast height, height to crown base, height, crown radii, and tree coordinates were measured for each of the subject trees and its competitors. Subject trees were exposed to tapping on first of October, the fifteenth of October, and the first of November, using local tools (Sonki and Makmak). Additionally, untapped trees were used as controlling-variables. The initial gum collection was completed fifteen days after the tapping, while the subsequent (7-9 pickings) were done at an interval of fifteen days. Six stand height functions were tested and the results illustrated that the Michailow stand height function was suitable for predicting the height of Acacia seyal in Umfakarin natural forest. The predictive ability of this height function ranged from 19.3% to 24%. The volume function used in this study was able to predict the volume of standing trees with more than 92 percent accuracy. Competition among trees of Acacia seyal was assessed in terms of competition indices. Eight competition indices were quantified using the CroCom program. The relationship between these indices and tree dimensions (diameter at breast height, height and crown diameter) was tested using logarithmic models. Among these indices, the Hegyi_2 index is considered a suitable index to be applied for estimating the degree of competition in natural stands of A. seyal of dense stratum when using diameter at breast height as a predictor. About 70% of the total variability is explained by this logarithmic model. Gum yielded by each subject tree per season was obtained by summing up the gum samples collected from all pickings. Gum production per unit area was also determined. Regression tree, general linear model (GLM) and logistic regression techniques were used for analyzing the obtained data. The results of the study indicated that the gum yield is independent of stand density. Tapping has influence on gum yield. Trees tapped by sonki on the first of October at medium stand density have the highest gum with an average value of about 56 g/tree/season. Significant difference (p = 0.021) was detected between two groups of dates; the first of October and first of November in medium stand density. The results also revealed that the most important variable influencing gum production was found to be diameter at breast height with 23.95 cm threshold. Between 41-53 percent of subject trees produce gum less than 50 g/season. The results indicated that A. seyal species produces a very low quantity of gum talha (3.6-4.8 kg/ha) and for economic reasons, its tapping is not recommended. The findings of the regression analysis revealed to a model which could be used to estimate the yield of gum talha from A. seyal natural stands in the Umfakarin forest, South Kordofan, Sudan. Conducting experiments on the production of gum talha in permanent plot trials in different climatic regions of the Sudan is highly recommended.

This master thesis studies the recycling prospects of textiles. The textile industry contributes negatively to the global environmentthrough the release of greenhouse gases and consumption of resources. In order to achieve a circular textile industry, textiles must be recyclable by both chemical and mechanical means. Here, the focus is on mechanical extraction of staple fibres, particularly cotton, for reentry into yarn production. Experiments show that used, but undamaged, cotton sateen and cotton twill responds differently to abrasion with stochastic surfaces. Previous studies on the conventional shredding processes have shown positive impact from lubricants on extracted fibre lengths, by reducing inter-fibre friction. In the present study on abrasion, variables such as alignment of the weave pattern, lubrication and load are shown to have little to no impact on extracted fibre length, but notable effects on overall fibre quality. These analyses are supported by manual length assessment, electron micrographs and tensile tests using load cells. Furthermore, simple tests and observations on structured diamond surfaces constructed through chemical vapor deposition are promising for mechanical fibre release directly from a woven fabric. Suggestions are made on continued research in this field.

Detta är en undersökning av textila material för utomhusmiljöer med särskilt fokus på båtars dynor. Målet har varit en kartläggning av olika tänkbara material för utsatta miljöer och utprovning av bästa sömnadsätt. Genom omvärldsanalys av tillgängliga material och inventering av nutida tapetserares kunskaper, kompletterade med en historisk research och mina egna tester kommer jag fram till följande. En historisk tillbakablick visade att så länge fritidsbåtar var åtkomliga för enbart överklassen handlade det om att ha det finaste materialet och bästa hantverket för att visa upp sin rikedom inför vänner och bekanta. När fritidsbåten sedan gjorde entré i de svenska folkhemmen så blev det delvis mer hemmafixande och enkla lösningar. Varpå ”lyxfritidsbåtar” alltid behållit en hög standard på dynklädseln. Som en röd tråd genom alla tider har det praktiska och lättskötta varit viktigt. Vid en närmare undersökning av nutida lämpliga textilfibrer så är helsyntetiska konstfiber att föredra gentemot regenatfibrer. Men det är inte endast råmaterialet som styr kvaliteten hos slutprodukten. Textiliers egenskaper beror till mycket stor grad även på den färdiga textiliens egenskaper som den fått under tillverkningsprocessen. Det handlar bland annat om dess sammansättning, tekniker av tvinning och väv samt impregnering. På marknaden finns en uppsjö av textilier men endast ett fåtal som profilerat sig mot marknaden för utomhusmiljöer klarar förhållandena mycket bra. Det är därför viktigt som kund att införskaffa en högkvalitativ textil för lång livslängd. De vanligaste typerna av marin textil till båtar är vinyl, akryl eller polyestertyg. Det finns inte ett tyg som stålsätter sig mot alla tänkbara utmaningar men finns det flertalet textilier som är sammansatta på ett sätt så att de klarar förutsättningarna tillräckligt bra under en längre tidsperiod. Hur lång tidsperiod är svårt att säga då det helt och håller beror på hur dynan är tillverkad (dvs sömnadsteknik, stoppning mm). Även miljön har en stor inverkan på livslängden. Rengöring av dynorna förlänger livslängden. Finns det möjlighet att ta in dynorna eller täcka dem med tex ett kapell så att de är skyddade från så mycket påverkan som möjligt så är det att föredra. Förutom själva textilen till dynklädseln har även tapetserarens kunskap och yrkesskicklighet en mycket stor bidragande del till om slutprodukten lever upp till förväntan eller ej. Sömnadstekniken, val av tråd, dragkedja, kardborrband, knappar, stoppning och så vidare spelar en mycket stor roll. Placeringen av eventuella skarvar och sömmar har också väldigt stor betydelse. Vanliga problem med dynor som används i sittbrunnar är att vatten kan tränga in i sömmarna och därmed vattenfylls skumplasten. Detta kan förhindras genom att försegla sömmen genom att applicera ett vattenavstötande medel på sömmen. Enkelfällsöm eller keder med långa stygn visade sig vara lämpligaste sömnadsteknikerna för att minska vattengenomträning. Dragkedja av plast som inte ärjar är att föredra liksom grov tråd med kärna av polyester och ytterhölje av bomull, denna tråd kombinerar polyesterns styrka och bomullens tätande egenskap. Kallskum rekommenderas som stoppningsmaterial. För utsatta miljöer där vattengenomträning riskeras rekommenderas material som ej suger fukt så som polyeterfilter. / This is an investigation of textile materials for outdoor environments with a particular focus on boat cushions. The ambition has been a survey of various conceivable materials for exposed environments and test of best sewing methods. Through analysis of available materials and knowledge of upholsterer inventory, supplemented by a historical research and my own tests, I found out following. A historical research showed that as long as recreational boats were accessible to the upper class only, it was about having the finest material and the best craftsmanship to show their wealth to friends and acquaintances. When the recreational boats entered many of the Swedish ordinary homes, it became partly more home-fixing and simple solutions. Whereupon "luxury leisure boats" have always maintained a high standard of fabric. An important red thread of all time has been the practicality and easy cleaning. After a closer research of contemporary adequate textile fibers, is synthetic fibers to preferable instead of regenerate fibers. But it is not only the textile fiber that controls the quality of the finished product. The quality of the fabric depends on the quality of the finished textiles, which it obtains during the manufacturing process. It includes for instance the fabrics composition, twisting and weaving techniques and impregnation. The market has a big variation of textiles, but only a few who are profiled against the market for outdoor environments are able to handle the outdoor conditions well. It is therefore important as a customer to purchase a high-quality textile for a long lifetime. The most common types of marine textile for boats are vinyl, acrylic or polyester fabric. There is not a fabric that stands up to all possible challenges, but there are several fabrics that are composed in such way that they can handle the conditions well for a long period of time. The lifetime limit is difficult to say, it depends completely on how the cushion is made (for example sewing technique and padding.) The environment has also an impact on the lifetime limit. Cleaning the cushions extends the lifetime limit. If it is possible it ́s preferable to bring the cushions inside or cover them with for example a chapel for protection from as much impact as possible. Aside from the fabric of the cushions, the upholsterer's knowledge and professional skills have a big impact and large contributing part of how ever the final product lives up to the expectations or not. The sewing technique, thread choice, zipper, velcro, buttons, padding is very important. Placement of seams is also very important. Common problems with cushions on boats is that water can get through the seams and water fill the padding. This can be prevented by sealing the seam by applying a water repellent to the seam. Single-stitch or keder with long stitching proved to be the most suitable sewing technique to reduce water leak. Non-iron plastic zipper is preferred and thread with polyester core and cotton outer layer as this thread combines the strength of the polyester and the sealing quality of the cotton. High density foam is recommended as padding material. For exposed environments where risk of water leaks exists are other materials more suitable, such as polyetherfilter that don’t absorb moisture.

Global warming sets a high demand to reduce the CO2 emissions of vehicles. In the European Union heavy-duty road transports account for 6 % of the total greenhouse gases and one of the main factors affecting these emissions is related to the rolling resistance of tyres. The optimal usage of tyres is an important part of solving these challenges, thereby it is important to understand the parameters affecting rolling resistance and the different compromises coupled to them. These compromises could be analysed using computational and experimental methods. To set out the groundwork necessary to minimise the energy consumption of trucks and assess the different parameters affecting tyre behaviour, the following studies have been conducted during this thesis. A framework to model and parametrise truck tyre rubber has been developed for finite element simulations. The presented parallel rheological material model utilises Mooney-Rivlin hyperelasticity, Prony series viscoelasticity, and perfectly plastic networks. A method to reduce tuneable parameters of the model, which significantly simplifies possible parameter studies, is presented. The model has been parametrised using test data from dynamic mechanical analysis of samples from a long haulage heavy truck tyre, and shows a good agreement with the test data. To test the suitability of the modelling technique for tyre simulations, the constitutive model is used in various tyre simulations using the arbitrary Lagrangian-Eulerian method. The material modelling technique is shown to work for static force-deflection as well as dynamic simulations estimating longitudinal force build-up with varying slip levels. Additionally, the modelling technique captures the uneven contact pressure in steady-state rolling, which indicates that the model could also be used in rolling resistance simulations. To study the change of ambient temperature on rolling resistance using experimental methods, a climate wind tunnel is used where the rolling resistance is quantified using a measurement drum. Tests were conducted between -30 °C and +25 °C, and a considerable ambient temperature dependency on rolling resistance was found. Moreover, temperature measurement inside a tyre shoulder is a good indicator for rolling resistance in a broad range of ambient temperatures. Finally, battery-electric long haulage truck driving range calculations are also conducted with varying rolling resistance and air density at different temperatures, showing a significant decrease of driving range with decreasing ambient temperature. / Den globala uppvärmningen ställer höga krav på att minska tunga fordons CO2-utsläpp. Tunga transporter står för 6 % av de totala växthusgaserna i Europeiska unionen och att fokusera på optimal användning av däck är en viktig del för att minska förorenande växthusgaser. Därför är det viktigt att förstå parametrar som påverkar rullmotståndet och olika kompromisser kopplade till dem. Dessa kompromisser skulle kunna analyseras med hjälp av beräkningsmetoder och experimentella metoder. För att lägga grunden för att minimera energiförbrukningen för lastbilar och bedöma olika parametrar som påverkar däckens beteende, har följande studier genomförts i denna avhandling. Ett ramverk för att modellera och parametrisera lastbilsdäcksgummi utvecklades för finita elementmetod-simuleringar. Den presenterade parallella reologiska materialmodellen använder Mooney-Rivlin hyperelasticitet, Prony-series viskoelasticitet och perfekt plastiska nätverk. En metod har utvecklats för att reducera antalet justerbara materialparametrar i modellen, vilket avsevärt förenklar möjliga parameterstudier. Modellen har parametriserats med hjälp av testdata från dynamisk mekanisk analys och visar en god överensstämmelse mellan testdata och simuleringar. Provstavarna skars ut från ett lastbilsdäck för tunga fordon. För att testa modelleringsteknikens lämplighet användes den konstitutiva modellen i olika däcksimuleringar. Materialmodelleringstekniken har visat sig fungera för statisk vertikalstyvhet såväl som dynamiska simuleringar som uppskattar longitudinell kraftgenerering med varierande slipnivåer och olika friktionskoefficienter. Modelleringstekniken fångar ojämnt kontakttryck vid stationär rullning, vilket indikerar att modellen även kan användas i simuleringar av rullmotstånd. För att studera omgivningstemperaturens inverkan på rullmotståndet med experimentella metoder användes en klimatvindtunnel. Tester utfördes mellan -30 °C och +25 °C och rullmotståndet bestämdes med en mättrumma. Ett avsevärt beroende av omgivningstemperaturen på rullmotståndet påvisades. Dessutom indikerade provningen att temperaturmätning inuti däckskuldran är en bra indikator för rullmotstånd i ett brett område av omgivningstemperaturer. Räckviddsberäkningar för en elektrisk fjärrtransportlastbil utfördes med varierande rullmotstånd och luftdensitet vid olika temperaturer, vilket visade en signifikant minskning av körräckvidden med sjunkande omgivningstemperatur. / <p>QC 220525</p>

Mechanical parameter characterization of very thin polymer films using digital im- age correlation is performed in this work. At present days DIC is widely used in the construction, food industries, and aviation. Despite advantages when compared to other conventional methods, but users still face difficulties with the analysis of thin polymers like low-density polyethylene (LDPE) and polyethylene terephthalate (PET) thin polymer films. For the application of sprays to obtain the best pattern quality as well as the potential of thin-film material properties tempering from the stochastic pattern paint. This research work will investigate the effect of several spray paints on the material response of thin polymer film. It also shows how to achieve good surface traction, time effect, and the type of spray to be used for DIC analysis. Finally, this research also studies how the width of the specimen affects the wrinkling effect, which is a common phenomenon while testing the thin polymer films and exhibits the appropriate width for reducing wrinkles on thin polymer films.

Role of silane-treated stöber silica as reinforcing filler for nitrile rubber (NBR) has been studied. Stöber silica is synthesized by sol–gel method, and the surface of silica is modified with the treatment of silane-coupling agent viz. γ-mercaptopropyltrimethoxysilane (γ-MPS) in varying proportions. Average particle size of stöber silica of spherical shape in the range of 200 to 400 nm is evident from scanning electron microscopy (SEM). Surface modification of silica particle with silane-coupling agents decreases surface energy and reduces agglomeration of silica particles in rubber matrix. Stress–strain study and dynamic mechanical analysis of silica-filled composites are compared with the unfilled ones. Analysis of cross-linking density, mechanical properties, and storage moduli indicates a strong rubber–filler interaction in the silane-treated, silica-filled NBR composites. Silane treatment is found to be effective in uniform dispersion of silica in rubber matrix and in improving the mechanical properties of rubber composite. Different functionalities of organosilane at its both end improve the compatibility of silica with rubber matrix and offer better rubber–filler interaction.

A novel constitutive characterization method for uncured rubber behaviour has been developed in this article. A systematic measuring procedure was designed to fully investigate the uncured rubber complex stress–strain behaviour under different deformation patterns, which integrated three kinds of tests – the uniaxial tensile, the compression test and the shear test. It can be found from the observed behaviour that the uncured rubber has similar but much pronounced non-elastic stress–strain relationship, which is highly non-linear and highly rate dependent. A generalized Maxwell model with modified Yeoh model is developed to constitutively describe the observed phenomena in which parameters are identified by an evolution optimization scheme. Good agreement can be found between the model and the test data. Another finding is that, similar to vulcanized rubber, multi-test data are needed to obtain compatible constitutive models. The test results, findings and the developed model help rubber engineers deeply understand the uncured rubber’s mechanical behaviour and provide a base for rubber manufacturing simulation.

The report describes a project aimed at finding a way to warm a seat. Etac, one of the leading manufacturers and developers of disability aids has received feedback from customers that the shower seats they produce are cold when the user has just sat down. This seemed to the user that showering is associated with inconvenience. To answer the purpose, 3 questions were formulated. To get more understanding of the task, a feasibility study was carried out and various methods were used during the development process. A market survey has been carried out, various solution proposals have been developed and then a test survey was carried out on the concepts that have been developed. As a result of the project, 3 concept proposals have been produced. / Rapporten beskriver ett projekt som syftar till att hitta ett sätt att värma en sits. Etacsom är ett av ledande tillverkare och utvecklare av funktionshindrade hjälpmedel har fått feedback av kunder att duschstolarna de tillverkar är kalla när brukaren precis har satt sig ner. Detta tycktes brukaren att duschandet förknippas med besvär.För att kunna besvara syftet så utformades 3 frågeställningar. För att få mer förståelse på uppgiften så gjordes en förstudie, olika metoder har använts under utvecklingsprocessen. Det har gjorts en marknadsundersökning, olika lösningförslag har tagits fram därefter gjordes en testundersöknings på de koncept som har tagits fram. Som resultat på projektet har 3 konceptförslag framställts.