QC 20120131 / MOJO

Composite layups have been continuously used over many years in various applications. It is necessary to optimize its composition by studying various parameters influencing the mechanical properties and studying the failure behavior. In this master thesis, the objective was to test five different plies manufactured using thick and thin plies and various combinations of thick and thin laminates called hybrid laminates. Bearing tests are performed for five layups with each layer has its thickness varying from 40μm to 130μm, and a combination called hybrid laminate, and the results from the tests are investigated. The resulting system has a good performance with onset damage above 700 MPa and an ultimate failure above 1130 MPa, using fibers' full potential. Also, the different failure modes like fiber kinking, matrix crack, delamination, and their effect on the layup's strength are investigated using fractography. This paper also investigates the influences of the thickness of the laminate on the strength of hybrid composites jointed using different mechanisms, and its failure modes are checked. Results from this experiment are used to validate in the form of FEM model, which is a part of an internal project at RISE SICOMP AB. This thesis is suitable for an engineering student in mechanical engineering, material science interested in composite materials and fractography.

Carbon fibre reinforced polymer (CFRP) composite materials exhibit high specificstrength and stiffness therefore they can be a lightweight alternative to metalliccomponents for the front section of an aero-engine. Despite the benefit of CFRP composite materials for aero-engine applications, there arealso new challenges due to their inherent properties compared to conventionalaerospace metallic structures, such as a lower erosion resistance, poor thermalresistance, and poor electrical conductivity. In aero-engines, some components can be subjected to harsh erosive environmentsduring operation, therefore the erosion resistance of CFRP composite materials need tobe investigated. CFRP composites are not able to withstand as high temperatures astraditional metallic components and their ability to resist fire events need to beenhanced. On the other side, the poor electrical conductivity of CFRP composites canalso be critical when the aircraft is struck by lightning. Therefore, improving theconductivity of CFRP composite is of large interest. This thesis work is focusing on investigating innovative coating solutions to overcomethese three independent challenges in order to enhance CFRP composite applicationsinto the front section of an aero-engine. Coating systems for lightning strike protection have been investigated and developed.A fire protection has been identified and tested; the tests showed promising results forfire application. Furthermore, investigations on erosion resistant coatings indicated thepossible improvement of replacing the currently used erosion resistant coating by othercoatings presented in this thesis work.

Sporopollenin is considered a resistant material and might be applicable in flame retardant material. The use of renewable material in fields mainly dominated by toxic materials, such as bromides in flame retardant materials, could greatly improve the sustainability in those fields. A renewable porous film could be of interest in applications were cellophane is used today. The aim of this report is to investigate some basic properties of films made from nanofibrillated cellulose (NFC) and Lycopodium spores with a specific focus on flame retardant and mechanical properties. These properties were investigated using machines such as SEM, a universal electromechanical tester, TGA and vertical flame testing. During the production of the films an ultra turrax, rotavapor and rapid köthen was used. The films containing spores did not improved properties such as flame retardancy and mechanical properties when compared to the original NFC film. Density was lowered by almost half in some cases compared to the original NFC-film. Mechanical properties of the alkali-treated spores showed a significant increase compared to the untreated spores. An increased spore-ratio shows a decreased Young’s modulus. Further research on flame retardancy could be done using xyloglucan or another more flame retardant organic compound as a matrix. A foaming agent inside the sporopollenin could also contribute to flame retardancy. The mechanical properties could be compared to cellophane in order to see any future possibility of application. If possible pure sporopollenin should be used instead of whole spores. / Degree Project in Polymeric Materials, First Cycle

Indoor photovoltaics is an emerging technology that could power the Internet of Things (IoT)devices with low energy requirements. The conventional silicon-based photovoltaics is notsuitable for indoor lighting conditions, opening the door for organic photovoltaics (OPV).When fabricating OPV devices, a transparent and conductive electrode is needed. Indium tinoxide is a common transparent for research, but it is expensive and difficult to use in roll-toroll (R2R) production. PEDOT:PSS is a cheap conductive polymer compatible with R2Rprocessing, but its relatively low conductivity limits cell size and geometric fill factor. Addingsilver nanowires to the PEDOT:PSS solution could improve conductivity but raises the risk ofshort-circuiting the devices. In this thesis, organic photovoltaic devices have been fabricatedusing electrodes based on a commercially available solution of PEDOT:PSS dispersed withsilver nanowires to test its viability. Devices utilizing the novel electrode demonstrated aforward current density of 2,905 mA/cm2, dark current density of -1,25E-05 mA/cm2, shortcircuit current density of 0,037 mA/cm2, open-circuit voltage of 0,630 V, and fill factor of76,6%. Performance for devices with the a reference electrode of pure PEDOT:PSS was aforward current density of 0,94 mA/cm2, dark current density of -2,35E-05 mA/cm2, shortcircuit current density of 0,0341 mA/cm2, open-circuit voltage of 0,630 V, and fill factor of76%. However, the resistance in the novel electrode appears to degrade faster than in thereference electrode, even in an inert atmosphere, which motivates further studies ondegradation mode and methods to prevent it.

The report contains an account of a development project done during 10 weeks of the spring semester at Luleå University of Technology 2021. The project is done as a final thesis for the program Bachelor of Science with a focus in industrial design. The development project resulted in a prototype lamp. The functioning prototype is an embodied union of the perspectives environment and living environment. Through smart lighting of the home, the living environment, a room can become more flexible and adaptable. It is easier to install new lighting than it is to move a wall. The lamp is created to improve lighting and spaciousness. A light source's use of contrasts and illumination in all directions can make a room feel more comfortable to be in and larger than it is. The environmental perspective is based on materials science. When designing new products, a factor that controls the product's climate footprint and environmental impact is the choice of material. Greater and greater value is placed in the environmental impact of products and consumers have actively begun to influence their buying behaviors based on striving for a better relationship with the environment, this work has taken advantage of. A biocomposite has therefore been created consisting of a matrix material of potato plastic combined with fiber reinforcement made from dried fruit residues from juice production. Especially potatoes and carrots. This gives a result of a 100% bio-based material. The work has followed an iterative process and used creative methods to stimulate innovation and solutions. A great focus has been placed on the prototype's material and the production of samples of biocomposites. Which has given rise to a lamp whose aesthetics are governed by the material. The lamp has a function of giving off two completely different looks when it is on and off. In an off position, the hardness of the material is emphasized, and when it is lit, it comes to life. Like a sun hanging from the ceiling, the lamp extends the days into the night. / Rapporten innehåller en redogörelse av ett utvecklingsprojekt gjort under 10 veckor av vårterminen på Luleå Tekniska Universitet 2021. Projektet är gjort som ett avslutande examensarbete för programmet Teknologiekandidat med inriktning Teknisk design. Utvecklingsprojektet resulterade i en prototyp-lampa. Den fungerande protypen är en förkroppsligad förening av perspektiven miljö och livsmiljö. Genom smart ljussättning av hemmet, livsmiljön kan ett rum bli mer flexibelt och anpassningsbart. Det är lättar att installera ny belysning än vad det är att flytta en vägg. Lampan är skapt för att förbättra ljussättning och rumslighet. En ljuskällas användning av kontraster och upplysning åt alla håll kan få ett rum att upplevas bekvämare att vara i och större än det är. Miljöperspektivet grundat sig i materiallära. Vid utformning av nya produkter är en faktor som styr produktens klimatavtryck och miljöpåverkan valet av materialet. Ett större och större värde läggs i produkters miljöpåverkan och konsumenter har aktivt börjat påverka sina köpbeteenden utifrån att sträva efter ett bättre förhållande med miljön detta har arbetet tagit vara på. En biokomposit har därför skapats bestående av ett matrismaterial av potatisplast kombinerat med fiberarmering gjort av torkade fruktrester från juiceproduktion. Framförallt potatis och morot. Detta ger ett resultat av ett 100 % biobaserat material. Arbetet har följt en iterativ process och använt kreativa metoder för att stimulera innovation och lösningar. Ett stort fokus har lagts på protypens material och framtagning av prover på biokompositer. Vilket har get ett resultat av en lampa vars estetik styrs av materialet. Lampan har en funktion av att ge ifrån sig två helt skilda utseenden när den är tänd och släckt. I ett släckt läge framhävs materialets hårdhet med när det sedan tänds kommer den till liv. Likt en sol hängande från taket förlänger lampan dagarna in i natten.

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The research field of composite materials is particularly fascinating due to the design freedom they offer and the infinite number of constituent combinations, including those that are already explored, and many more that are yet to be tried. One composite material that holds great potential contains carbon in its fiber shape. Carbon fibers possess unique properties that excel in mechanical aspects, as well as interesting electrical and thermal properties that are yet to be fully explored. These fibers are readily available on the market and can be introduced as reinforcement in various lengths and orientations, yielding diverse results depending on the intended effect. Although carbon fiber reinforced polymer composites (CFRP) are present on the market for quite some time, specifically in high-performance applications, they are predominantly used when their performance outweighs their cost. Meanwhile, carbon fiber composite waste is starting to cumulate in noticeable amounts. This waste originates from both, production scrap and end-of-life scenarios, as components introduced in service life in the past 30 years are being decommissioned and discarded. Unfortunately, the prevalent solution for handling this waste is landfilling, due to its ease, affordability, and accessibility. Consequently, substantial amounts of composite waste are accumulating worldwide. Furthermore, it has finally come to our attention that our planet's resources are finite. Our exploitation of these resources has been largely devoid of consideration for the needs of future generations. As a result, recently, sustainability has emerged as a key enabler for a circular economy, driven by increasing environmental concerns and demands from customers and users for market transformation. The implementation of sustainable practices is now underway, albeit at a gradual pace.   In summary, we find ourselves facing a trifold predicament: a splendid material being underutilized due to production costs, the cumulative generation of CFRP waste resulting from a lack of foresight and suitable alternatives, and the urgent need to transition towards a circular economy due to resource depletion. This research work aims to address all three challenges by developing an integrated solution.   The current work demonstrates that it is possible to recycle carbon fiber model composites through a two-step pyrolysis treatment, a fully mature recycling technology. The study has been done in two stages which are presented in two journal papers included in the thesis. The primary objective of the first paper is to identify and optimize process parameters that maximize the retention of mechanical properties in the recovered fibers. The overall results achieved show good retention value; with over 90% retention on stiffness and 90% on strength. Encouraging results from initial experimental work, have spurred the research focus towards further investigation. Thus, the second paper reports on repetitive manufacturing and recycling cycles of two sets of identical model composites by using the two most effective recycling treatments identified through the parameter optimization. The mechanical performance and structural changes of the recycled fibers are characterized and analyzed. Although further analysis is required, current mechanical behavior shows recovered fibers suitable for secondary applications after two recycling cycles, with an abrupt decay in fiber properties after the third cycle.   With the waste challenge under control, through successful recycling of composite waste, it is time to find concrete applications for this research. Having recycled carbon fibers (rCF) with comparable performance to virgin carbon fibers (vCF) opens up opportunities for rCF mats and other intermediate products to compete in previously inaccessible markets.

Microvascular composites are materials with an inner hollow network which allows thecirculation of fluids. This functionalizes the composite materials, giving them furtherapplications such as self-healing or active cooling. Some of the already existingmicrovascular composites are made with fiber reinforced epoxy resin with cavitiescreated by removal of a sacrificial low temperature resistant polymer insert. Currentresearch is focused on the obtention of microvascular composites that can withstandhigher service temperatures than epoxy, using polyimide as the high-temperature resinmatrix. The aim of this project is to find a suitable sacrificial material that will withstandthe higher curing temperatures of the polyimide while allowing its easy removal fromthe matrix. Three different candidate sacrificial materials were studied for this purpose:PEEK, PPS, and PC. Preliminary DSC test showed that the melting temperature of the PEEK was close to therange of the chosen resin. PPS melting temperature and PC glass transition temperaturewere below this range of curing temperatures. TGA test revealed that the degradationsuffered by the different materials at the curing temperature of the polyimide wasconsiderably low. A small-scale test mimicking the actual microvascular compositemanufacturing conditions was designed to study the actual behavior of the differentmaterials when heated. It was seen that both the PEEK and the PPS could not flowwithout applying extra pressure for the desired range of temperatures. Furthermore, ascaled model test revealed that there was no visible interaction between the differentmaterials tested and the polyimide resin. The initial study showed that PEEK and PPS arenot readily viable to use due to the apparent difficulties to remove them from thecomposite by just applying heat. PC was also considered not viable for this applicationsince it softened too much a too low temperature.

This report presents the first steps of development aiming towards making, the open-source aeroelastic code, GEBTAero flight dynamics capable. The implementation was done partly in the Fortran code and part in the GEBTAero Python API with the objective of reusing as much of the existing code as possible with as little substantial architecture modification. The added capacities include the widening of the purview of the software to take into account beam assembly arranged in a plane-like structure, a trim function for the steady level flight was also implemented and the twelve degree of freedom flight mechanics system of equations was introduced in the algorithm. In this short time, unfortunately, few tests were performed fully but important foundation work giving preliminary results was carried out. This includes the verification of the structural modes simulation as well as several bug and inacuracy fixes. / Den här rapporten presenterar de första utvecklingsstegen som syftar till att göra, öppen käll aeroelastisk koden, GEBTAero flygdynamik kapabel. Implementeringen gjordes dels i Fortran-koden och dels i GEBTAero Python API med målet att återanvända så mycket av den befintliga koden som möjligt med så lite väsentlig arkitekturändring. De tillagda kapaciteterna inkluderar utvidgningen av programvaransräckvidd för att ta hänsyn till strålmontering anordnad i en flygplansliknande struktur, en “trim” funktion för jämn nivåflygning implementerades också och de tolv frihetsgraderna flygmekanik system av ekvationer introducerades i algoritmen. Under denna korta tid utfördes tyvärr få tester helt men viktigt grundarbete med preliminära resultat utfördes. Detta inkluderar verifiering av strukturlägen simulering samt flera korrigeringar av fel och felaktigheter.