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Bruken av hydrofoiler i kiteboarding har de siste ˚arene blitt stadig mer populært og vil for første gang bli inkludert i de olympiske leker i 2024. Siden oppstarten har den primære utviklingsinnsatsen vært˚a optimalisere ytelsen og˚a implementere avanserte materialer, som pre-preg karbonfiber. Dette har ført til at hydrofoiler er dyre. Denne oppgaven tar sikte p˚a ˚a undersøke designprinsippene til hydrofoiler og ˚a utforske et unikt og rimelig designkonsept med tilstrekkelig ytelse sammenlignet med mer tradisjonelle design. Betydningen av hydrodynamiske designparametere ble analysert ved bruk av Xflr5-simuleringer. Resultatene ble oppsummert i en tabell som kan konsulteres for designutvikling. Ved ˚a bruke tabellen ble det hydrodynamiske designet tilpasset kravene til nybegynnere. Et strukturelt designkonsept ble foresl˚att gjennom en sammenligning av forskjellige materialer og produksjonsmetoder. Konseptet inneholder et kompresjonsstøpt karbon-epoksy material kjent som smidd karbonfiber. P˚a grunn av mangel p˚a informasjon om smidd karbonfiber, ble 4-punkts bøyestesting utført for ˚a bestemme mekaniske egenskaper. Den elastiske modulusen ble bestemt til ˚a være 25670 MPa, og den karakteristiske styrken ble bestemt til ˚a være 191 MPa. En endelig elementanalyse ble utført i Abaqus for˚a undersøke det foresl˚atte strukturelle konseptet. Potensialet til smidd CFRP som et strukturelt materiale ble sammenlignet med mer tradisjonelle materialer. Det ble funnet at styrken til smidd CFRP ikke var tilstrekkelig for dette designet. En designiterasjon til ble utviklet, og dette designet lyktes med en sikkerhetsfaktor p˚a 1,33. Basert p˚a det vellykkede designet ble prototypedeler i 60%-skala laget av en smidd karbonfiber for mounting plate og fuselage. Delene ble kompresjonsstøpt i 3D-printede PLA-støpeverktøy. Støpeprosessen var vellykket, men delene kunne ikke anses som egnet for kommersiell bruk. Det ble konkludert med at designkonseptet og produksjonsprosessen har potensial for˚a lage rimelige, lette deler. Bedre produksjonsutstyr er imidlertid nødvendig for˚a oppn˚a en kommersiell standard. Det ble ogs˚a antatt at bedre mekaniske egenskaper kunne oppn˚as med solide, permanente former. Imidlertid ble produksjonsprosessen brukt i denne oppgaven ansett som en effektiv m˚ate ˚a lage prototyper p˚a. Ytterligere forskning bør ta sikte p˚a˚a utnytte industrielt produksjonsutstyr for˚a utforske det fulle potensialet til kompresjonssmiing og de tilhørende mekaniske egenskapene. The use of hydrofoils in kiteboarding has gained traction in recent years and will be featured for the first time in the 2024 Olympic Games. Since its inception, the primary development effort has been on optimizing performance and implementing advanced materials, such as pre-preg carbon fiber. This has led to hydrofoils being expensive. This thesis aims to investigate the design principles of hydrofoils and to explore a unique and affordable design concept with adequate performance compared to more traditional designs. The significance of hydrodynamic design parameters was analyzed through the use of Xflr5 simulations. The results were summarized in a table that can be consulted for design development. By using the table, the hydrodynamic design was tuned for the requirements of novice riders. A structural design concept was proposed through a comparison of different materials and manufacturing methods. The concept incorporates a compression molded carbon-epoxy material known as forged carbon fiber. Due to the lack of information about forged carbon fiber, 4-point flexural testing was conducted to determine mechanical properties. The elastic modulus was determined to be 25670MPa, and the characteristic strength was determined to be 191MPa. A finite element analysis was conducted in Abaqus to investigate the proposed structural concept. The viability of forged CFRP as a structural material was compared with more traditional materials. It was found that the strength of forged CFRP was not adequate for this first design. A second design iteration was developed, and forged CFRP this design succeeded with a safety factor of 1.33. Based on the successful design, 60%-scale prototype parts were made of a forged carbon fibre mounting plate and fuselage. The parts were compression molded in 3D printed PLA molding tools. The molding process was successful, but the parts could not be considered fit for commercial applications. It was concluded that the design concept and manufacturing process has the potential for creating inexpensive, lightweight parts. However, better manufacturing equipment is needed to achieve a commercial standard. It was also hypothesized that better mechanical properties could be achieved with solid, permanent molds. However, the manufacturing process used in this thesis was deemed an efficient way of prototyping parts. Further research should aim at using industrystandard manufacturing equipment to explore the full potential of compression forging and the related mechanical properties.

Å gi en plate nye egenskaper kun ved å kutte et mønster inn i den kan ha mange bruksområder som kan oppdages av kreative sinn, både hos fagfolk og lekmenn. Til dette formålet må bøyningsmønstre gjøres mer tilgjengelige. Denne oppgaven bidrar til dette ved å utføre eksperimenter på mønstrede plater, måle deformasjon under forskjellige lasttilfeller, og sammenligne eksperimentelle resultater med simulerte resultater. Visualiseringen av disse resultatene bidrar til bedre forståelse av teorien bak bøyningsmønstre. I tillegg er det laget en webapplikasjon for å forenkle generering av bøyningsmønstre med brukerdefinerte parametere. Giving a plate new properties simply by cutting a pattern into it can have many uses which can be discovered by creative minds, professionals and laymen alike. To this end, flexure patterns must be made more accessible. This work contributes to this by performing experiments on patterned plates, recording deformation under different load cases, and comparing experimental results with simulated results. The visualization of these results contributes to better understanding of the theory behind flexure patterns. In addition, a web application is created to facilitate the creation of flexure patterns with user-defined parameters.

Fiber-reinforced polymer (FRP) composites have seen a rapid rise in use in the past 50 years due to their high strength, stiffness, relatively light weight and relatively high corrosion resistance, especially when compared with more traditional structural materials such as steel and aluminum. Composite materials are widely used in structural applications in marine, offshore and oil & gas industries. A typical design lifetime of offshore FRP structures is 25 or more years in direct contact with water leading to some deterioration of the material properties. Knowing and forecasting the extent of the material property deterioration in water is of great interest for designers and users of the offshore FRP structures. The environmental durability becomes a limiting factor in the use of composites for structural applications, since the superior material properties are compromised by the uncertainty of the material interaction with the environment. Each of the composite constituents (matrix, fibers and sizing-rich interphase) is affected differently by interaction with water molecules. It is therefore of high importance to understand the degradation severity and mechanisms of each of the constituent material due to aging in water. The materials studied are amine-cured epoxy matrix, R-glass fibers and the epoxysilane-based sizing-rich composite interphase, which, combined, constitute the fiber-reinforced composite laminate. Degradation mechanisms for each constituent material were identified, and novel tools, i.e. models and methods, were developed for prediction of long-term properties of composite materials and its constituents. These practical tools are to be of assistance in partially substituting the rigorous physical testing procedures in the state-of-the-art situation. Prediction of long-term properties of composites should significantly reduce costs associated with extensive testing and should already allow a partial transition towards the multiscale modeling approach. Brief description of the results A spectroscopic method for true water content determination and monitoring in polymers and composites was developed. Aging mechanisms and changes in the chemical structure of the amine-based epoxy were investigated. No chain scission (hydrolysis or oxidation-induced) was present, whilst thermo-oxidation and leaching occurred. Four unique reactive sites responsible for thermo-oxidation were found. The only mechanism that was important for the strength reduction of the studied polymer was swelling. Mechanical properties of the epoxy could be regained upon redrying the material to the initial water content. An analytical method for predicting anisotropic swelling in composites from the swelling of the epoxy was developed and explained. Aging of glass fibers occurred in two distinct phases: a short-term non-steady-state (Phase I) and long-term steady-state (Phase II). Phase I was very complex and involved many competing processes in parallel, such as ion exchange, gel formation and dissolution. Phase II was dissolution-dominated. A chemical kinetic model termed the Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was developed for predicting mass loss and a decreasing radius of glass fibers at various environmental conditions. The sizing-rich composite interphase was degrading due to hydrolysis, resulting in the formation of the interphase flaws. These flaws could further develop into fiber/matrix debondings, matrix cracks and splitting along the fibers. The internal volume created by the flaws and cracks could then be filled with water leading to the observed mass increase of a typical composite. All known environmental aging mechanisms of the studied composite constituents were systematized and a phenomenologically complete mass balance was presented. Using the mass balance, it was possible to deduce the dissolution kinetics of the sizing rich-composite interphase.

Denne studien var utført i samarbeid med Kongsberg Ferrotech, som utvikler en autonom robot som skal utføre komposittreparasjoner på offshore stigerør. Ved å utvikle en slik effektiv reparasjonsprosess har komposittreparasjoner potensialet til å bli mer konvensjonelt. Målet med prosjektet var å finne en effektiv metode å overvåke kvaliteten og integriteten til komposittreparasjoner. Fra forstudien [1] var det tydelig at et optical backscatter reflectometer (OBR) var den mest lovende overvåkningsteknikken, og er en overvåkningsteknikk som gir målinger med høy oppløsning over et stort måleområde ved å bruke optiske fibre. Egenskapene til OBRen ble undersøkt i termisk sykling tester i vann. En rørseksjon, innstøpte optiske fibre, en glassfiberreparasjon med innstøpte feil utgjorde testprøven, og ble utsatt for temperaturendringer over en viss tid. De eksperimentelle funnene ga en tydelig indikasjon på debonding hvor de innstøpte feilene var, og elementanalyse (FEA) var utført for å støtte funnene. Resultatene bekreftet at OBR overvåkning er egnet for denne applikasjonen, og viste tegn på skade på et tidlig stadium. Ingen vekst av detekterte feil ble registrert, noe som indikerer at reparasjonen hadde akseptable egenskaper. Både forhåndsdefinerte feil og andre mulige feil ble funnet, men variasjoner i tøyningsrespons kan være forårsaket av faktorer som ikke er forbundet med feil i glassfiberkompositten eller substratet. The presented study is completed in cooperation with Kongsberg Ferrotech, whom is developing an autonomous robot to perform composite repair on offshore risers. By developing such an effective repair process, composite repairs have the potential of becoming more conventional. The aim of this project was to find an effective method to monitor the quality and integrity of composite repairs. It was clear from the preliminary study [1] that the optical backscatter reflectometer (OBR) was the most promising monitoring technique to utilize in strain monitoring of composite repairs on risers, which gives high resolution measurements and large measurement range using optical fibers. The OBR’s capabilities were investigated through thermal cycling tests in water. Moreover, a test sample consisting of a pipe section, embedded optical fibers, a glass fiber composite repair including predefined failures were subjected to temperature variations over a certain period of time. Finite element analysis (FEA) was performed to support the findings of the experiments. The results confirmed that OBR monitoring is suitable for the given application, and successfully showed signs of damage at an early stage. No growth of detected failures was recorded, which indicates that the repair possessed satisfactory qualities. Both predefined failures and other possible failures were found, however variations in strain response may be caused by factors not associated with failures in the glass fiber composite or the substrate.

I denne oppgaven studerer vi statorer til elektriske motorer laget med en ny produksjonsteknologi og disses oppførsel under termisk ekspansjon og herdekrymp. Statoren, som er den stasjonære delen i en elektrisk motor, genererer et roterende magnetisk felt som påfører den roterende delen, rotoren, et dreiemoment og får den til å rotere. Statorer produsert med denne produksjonsmetoden er essensielt fiberkopositter hvor fiberretningen varierer kontinuerlig. Avstanden mellom rotor og stator bør minimeres for maksimal effektivitet, og grunnet dette ønsker vi å kunne forstå og redusere den termiske ekspansjonen i statoren. Termisk ekspansjon og herdekrymp for en kommersielt tilgjengelig epoxy blir funnet eksperimentelt. Ved hjelp av skriptet FE-analyse undersøker vi effekten av alle geometriske parametere på termisk ekspansjon. Herdekrymp er modellert som en modifisert termisk ekspansjonsmekanisme. Vi konkluderer med at ved å endre geometriske variabler, kan statorens termiske ekspansjonskoeffisient nær halveres sammenlignet med koeffisienten til hovedmaterialet. Spesielt er det variablene som bestemmer de ytre dimensjonene til statoren: diameter, aksiallengde og tykkelse, som har størst effekt. Vi konkluderer også med at ved bruk av nåværende produksjonsprosess, vil herdekrymp trolig ikke føre til deformasjoner av betydning eller oppsprekking. In this thesis, we study the behavior of stators for electric motors made with a novel production technique under thermal expansion and cure shrinkage. A stator, being the stationary part of an electric motor, produces a rotating magnetic field which imposes a torque on the rotating part, the rotor, and causes it to turn. Stators produced using this novel technique are essentially fiber composites in which the fibers are electrical wires and the fiber orientation is continuously varying. The gap between rotor and stator should be minimized for maximal efficiency, and for this reason we seek to understand and reduce thermal expansion of the stator. Thermal expansion and cure shrinkage for a commercially available epoxy are found experimentally and used for finite element modelling. Using a script that enables a large number of finite element analyses to be done on different geometries, the effect of all geometric parameters on thermal expansion are investigated. We conclude that by manipulating geometric variables, the thermal expansion coefficient of the structure can be lowered to close to half that of its main constituent material. The geometric variables that influence the thermal expansion the most are the diameter-to-axial length ratio and the total thickness of the stator. An upper bound for cure shrinkage is found using the same finite element model with customized material properties. Experimental data suggests that cure shrinkage is unlikely to cause significant deformations or cracking of the structure.

By cutting specific patterns in thin sheets of material it is possible to acquire a high degree of compliance in and out of the plane. These structures, called flexure patterns, are often applied in situations causing large deformations and contact. This is known from theory to introduce a non-linear behavior, in which the load and deformation no longer has a linear relation. This thesis sets out to analyze these sources of non-linearity, and find their significance in design applications. This is done by performing a parametric study of the base repeating unit of two known patterns: the LET/Slits pattern and the YdX. The goal is to contribute to the knowledge and understanding of the mechanical behaviour of flexure patterns. Non-linear simulations with the FE-software ABAQUS have been used in combination with python to make the analyses as automatic as possible. The results show that for some load cases there are small deviation between the linear and the non-linear simulation. The deformation mechanisms of important structural members are assumed to play significant roles as sources of geometric non-linearities. In addition, the results indicate that an automatic analysis of contact non-linearities would require further work and is a complete study by its own.

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The objectives of this thesis have been to develop a script for a multiscale method based on first order homogenisation, to investigate estimation of properties and behaviour of unidirectional (UD) fiber composites. To model composites on the microscale, an algorithm that generates periodic representative volume elements (RVE) geometries from controllable parameters and a pseudo random factor was developed. The output of this algorithm (fiber populations) was used to create heuristic RVE models in the Finite Element Analysis (FEA) software, Abaqus 6.14-4. These heuristic RVE models consist of fibers, matrix and an interface. The fibers in the models were assigned linear elastic material properties and the matrix and interface were assigned elastic, plastic and damage material properties. To simulate deformations and loads, macro strains were imposed on the heuristic RVE models through constraint equations. As the properties of the RVE varied with the distribution of the fiber populations, the creation of RVE models was automated to perform multiple iterations to calculate estimations of the average properties and the statistical dispersion of these. The effect of design parameters on stiffness estimations was investigated. To get insight into the local stress field in the RVE models, the maximum principal stress and maximum shear stresses were found for normalized linear elastic load cases. The strength of the RVEs was predicted by simulating nonlinear behaviour with different assigned material models. Consistent macrostrains for the non-linear analyses were maintained by an iterative backward force balancing procedure. The results showed that the stiffness estimations generally follow micromechanical approximations based on the rule of mixture. For the strength estimations, the produced results correlate with comparable methods and results found in the literature. This suggests that the method is feasible for microscale modelling of an RVE of UD fiber composites. Further development into material models, damage models and confirmation and calibration of results with empirical data should be investigated before using such a tool for design estimates.

A flexure pattern increases the ability of a plate to undergo large elastic deformations. It is characterized as a 2D mechanical metamaterial that consist of flexures configured in a pattern that increase the compliance compared to the bulk material of which it has been made. This work contributes to the basic understanding of flexure patterns by describing the geometry, symmetries, principle deformation mechanisms and anisotropic elastic properties, using of the computational homogenization technique. The criteria for diagonal, orthogonal, tetragonal and isogonal elasticity is categorized though the minimal symmetries found in the pattern. Various examples of auxetic (materials with negative Poisson's ratio), orthogonal and isogonal patterns are explored and the relations between geometrical parameters and elastic properties are found. A set of design principles and methods are compiled to a framework that enables creation of new patterns from a set of desired behaviors.

Kitemill is developing a new concept to harness wind energy. Their concept is shaped like a glider, and takes advantage of the high wind speeds at high altitudes. Operations in such environments require strong and lightweight materials. This thesis will focus on the production method, material type and lay-up for a structural composite beam inside the horizontal stabilizer. Kitemill currently use wet lay-up bladder moulding technique to make the part. In this process where an inflatable bicycle tube is used to generate pressure on the composite in a closed mould. The maximum load of the piece they made by this process was set as the benchmark loading. The material used in this production method is a combination between Textreme (76 gsm) and Renlam M1 Epoxy. This material combination was tested according to the ASTM standard of composite testing, with some simplifications. The laminate constants were calculated from these results. These constants were used to create an Abaqus model which simulated the bladder moulded beam in a three-point bending test. A second production technique was created. The aim was to build a sample that could take the benchmark loading, but weighing less. This was done by creating a parametric optimization of lay-up for composites with the software program Isight. This lay-up was used together with a compression moulding technique where a core-material is squeezed into the mould. Pre-Preg composite material was used for this concept. The results indicated that the focus should be changes from the maximum load to production quality . The compression moulding production technique seems to be a better alternative than the bladder moulding technique due to air bubbles in the laminate. However, this is a more expensive production technique. The structure of the optimization program is good, but it needs some adjustments before it can be useful for real design applications. The program was computational heavy because the program had too many variables. There was also a problem with the way the simulation was set up. The result av this was that Abaqus ignored the difference between a continuous ply and a non-continuous ply. The conclusion is that the bladder molding technique can be used for the prototype glider, but the material should be changed to Pre-preg to minimize production flaws.

This master s thesis should focus on measuring the buckling suffered by tubes from external pressure. The technique to be studied, is Rayleigh optical backscatter reflectometry (OBR), which through swept wavelength interferometry, measures backscatter as a function of length with high resolution optical fibers. It offers continuous monitoring of strain and temperature along these fibers. Used in Structural Health Monitoring (SHM) as a regular early measurement analysis for possible accidents and dangerous states, this technique have been improved for the last 30 years, getting the same accuracy as current devices working in the same field. The main structure of the thesis will be divided into three blocks, with different objectives. The first one, analytical and numerical study, explains through simulations in Abaqus CAE Software, the behavior of different tubes exposed to external pressure, giving non-critical values and other information that is quite important for future studies. FEA analysis is the main focus of this part. Therefore, non-critical values are quite high, allowing us to test different situations without not much restrictive limitations. The second one, experimental study, is responsible of obtaining signals, strain profiles and values regarding deformation due to pressure applied on experimental tubes in the laboratory of the department in which the thesis is being developed. In order to do that, information obtained in previous block will be helpful, and Luna OBR Software is the program which will give us every needed data for a conclusion. Trial and error is the best method used in this part because of the several amount of ideas and possibilities that appear at doing these experiments. Lots of problems and factors that quite significant have been found and should be studied in future developments. The last one should be an analysis of the results obtained in both last parts, the methods used to get those results, and an analysis of sensibility. Thoughts and statement here will be the basis of the conclusions that must have this thesis about the Rayleigh OBR technique regarding case results, methods and future studies recommendations. Therefore, by this simple study, it can be said that this technique has so much potential not only for SHM, but for other areas too, being a really good focus for future studies.

In this report, the mechanical behavior of the semi-crystalline thermoplastic, polyamide 11, has been investigated. The material is commonly used in flexible pipes to ensure safe transportation of oil and gas offshore. The high temperature and chemical agents in the pipe results in changes in the mechanical properties. This has been explored for a virgin- and degraded material by conducting mechanical tests. Further, a numerical model has been developed and validated on a sample with a crack. The laboratory work includes tension and compression experiments at room temperature. In addition, the samples have been subject to two different rates and tested for anisotropy. The effect of stress triaxiality was examined by carrying out a tension test on a specimen with a circular notch. Parameters related to elasticity and plasticity have been identified analytically by utilizing optical measurements of the tension- and compression tests. The damage model was developed through parametric studies in Abaqus of the notch tension experiment. The fracture test was designed to simulate a loading scenario in a flexible pipe, by applying tension on a compact specimen with a sharp crack. The two materials tested, show different mechanical responses. The degraded material is stiffer, display a higher yield stress and more propensity to soften after necking. In addition, the degraded material shows more increase in volume and a lower failure load in all experiments. The fracture test reveals that the degraded material has a lower capacity to withstand further development of initial cracks. The failure is attributed to formation and growth of cavities since the surface gets a white appearance. This was less pronounced for the virgin material. The simulations have been carried out in Abaqus, employing the calibrated material model. Simulations of the tension test show that the material model is able to capture the main characteristics of the material. However, the volume increase is not well predicted. The damage model relies on these predictions and the error is therefore also seen in the simulations of the notch tension test. Further, the ability to carry load is overestimated in the validation of the fracture test. This results in a late damage and reluctant evolution in comparison to the experiment.

Masteroppgaven tar for seg utviklingen av batterikassen til Revolve NTNUs firehjulsdrevne helelektriske racerbil. Oppgaven inneholder en lett gjennomgang av det mekaniske designet av batteripakken, med blant annet plasseringen av de elektriske komponentene i batteripakken, batteripakkens plassering i bilen og dens innfestning til monocoquen. Videre følger en grundig gjennomgang av materialtestene av karbonfiberkomposittpanelene som er utført i forbindelse med prosjektet, samt analyse av disse og å vise ekvivalens opp mot regelverket Revolve NTNU følger. Dette er hovedtyngden av oppgaven.

This study has introduced a novel non-annealed stainless steel fiber with 8 $\mu m$ diameter to make a steel fiber reinforced polymer composite pipe. The primary objective was to make the pipes by the filament winding method. The aim was to report on the mechanical properties, and failure modes of these stainless steel fiber reinforced polymer composite pipes with a ductile epoxy resin system and to evaluate their performance for potential applications in the offshore industry. The mechanical behavior under quasi-static compression was evaluated experimentally in both axial and radially to the hoop directions, along with the in-plane shear properties. The in-plane mechanical properties were determined by use of resistance strain gauge measurements bonded to the axial and hoop directions of the test samples. Also, their buckling behavior under external pressure was evaluated experimentally to understand their buckling behavior. Microscopy, burn-off test, and thickness measurements were performed on the produced test samples to determine the volume fraction of fiber, void content, and thickness. Stainless steel fiber reinforced polymer composite cylindrical pipes with $\pm 55\degree$ layup, and different thickness (three and six layers) were successfully made by the filament winding method. Test results indicate that the steel fiber reinforced polymer composites exhibit a much higher strain-to-failure than a typical UD carbon fiber composite (almost three times) combined with a high stiffness (about 80 $GPa$). Also, the SFRP composites exhibit similar ductile deformation behavior to that of the dry UD continuous steel fiber, i.e., an initial elastic response, a definite yield point and consecutive plastic and strain hardening behavior.

New methods to produce environmentally-friendly energy, is a growing technology area. By using wind at high altitudes, Kitemill wants to be a part of this revolution. Operations in the air requires high quality and security of components. Furthermore, rough conditions make demands on excellent material properties. For this purpose carbon fiber composite is suited for use. This is one of the areas of expertise at Kongsberg Defence Systems (KDS), and it is in their interest to develop new utilization for the technology. Kitemill's concept is based on a plane consisting of a wing, divided into two separate parts. To connect the two halves, a joiner is needed. During this master work design, manufacturing process and production of an optimized joiner, together with a finite element analysis (FEA), has been the main focus. Two different designs for the joiner have been evaluated, a rectangular box profile and an I-beam with foam core. A manufacturing process for the two profiles were developed, using Kitemill's existing mold tool as base. During the layup of the two joiners, differences and experiences were detected to discuss further improvement of the manufacturing process. A four point bending test were performed to test the two manufactured joiners. The results from the bending test were verified through a FEA analysis, and the results corresponded well. Furthermore, a buckling analysis were performed, and confirmed that failure due to buckling will not be crucial for the applied loads. Finally, all results and processes were compared, to obtain the most suited design and manufacturing process for the joiner. The results from experimental work and FEA analysis concluded with the I-beam as the best design for the joiner. Furthermore, some recommendations was given to improve the manufacturing process.

A concept for a lightweight Remotely Operated Vehicle (ROV) named the Manta was designed for inspection of the net cages and collection of dead fish at aquaculture facilities. The current thesis presents the initial development and engineering design of the product, including requirements and need findings, material selection, technical solutions and design verification by the finite element method. The Manta has a streamlined body with an internal cavity. Three vertical thrusters are mounted into thin wings on the exterior of the hull, and two horizontal thrusters are located inside the hull cavity. The ROV will use the suction through the hull created by the main thrusters to collect the dead fish into a rear-mounted net. Harsh environment and rough handling will require a robust design- and material selection. The hull of the Manta has been designed and engineered based on the currently chosen components, which may be changed in the future. Based on the combination of easy manufacturing, good impact properties, low density and low cost, ABS plastic was selected as material for the hull. The hull design is based on 4 mm thick ABS plastic sheets manufactured by vacuum forming, with a total component weight equal to 6,6kg. The sections are joined together by adhesives and bolts. The estimated manufacturing cost of the hull is approximately 2000 NOK per unit including tool cost for 100 units. The vertical thrusters, which are located in the wings, must have a low profile. A mechanical design of a so-called rim-driven thruster (RDT) has been developed and the current design has a predicted weight of 1,7kg. This is a design where the propeller is fitted permanent magnets on an outer ring instead of being powered by a centre axle. The resulting geometry has a significantly lower profile than conventional ROV thrusters, and a higher torque per length ratio. A thruster prototype and a special designed test rig for the prototype has been developed and manufactured at the IPM workshop. This test rig has been submitted to Argus for completion of their electromagnetic design. Commercially available thrusters will be used for horizontal propulsion. These thrusters have to be streamlined since they are oriented parallel to the main direction of travel, as opposed to the vertical thrusters. The RMI 1000 thruster from RoboMarine Indonesia is the most relevant candidate, with a weight of 2kg and a 200N nominal thrust force. The ROV now has an estimated total weight of 29kg, which is within the limits set by the requirements. The final weight may, however, differ slightly due to the uncertainties of the thrusters mass.

I arbeidet med denne avhandlingen har det blitt utført et omfattende arbeid på ulike aspekter ved utviklingen av et monocoque chassis designet for å konkurrere i Formula Student. Analyse, dimensjonering og produksjon er hovedtema i denne oppgaven. Fokuset har ligget i å beskrive den tilnærmingen som brukes i designfasen, analyse og testing av lokaliserte laster på sandwichpaneler, samt utvikle en produksjonsprosess for chassiset. Alt av dimensjonering, analyse og testing er utført på sandwich paneler representativt for et monocoque chassis. Hovedfokuset har vært et racerbilchassis for Revolve NTNU, med tilhørende laster. Monocoque-chassiset er en selvbærende konstruksjon hvor hjuloppheng, girkasse, veltebøyler og andre innfestninger går direkte i chassiset som tar opp alle kreftene. Mye av arbeidet har blitt gjort i analyse og eksperimentell testing av lokaliserte laster på sandwich paneler med såkalte inserts , da dette er den mest brukte metoden for å overføre laster inn på et skjærsvakt sandwichpanel. Eksperimeter og testing har vært en stor del av denne avhandlingen. Den meste av teorien som er beskrevet og brukt i denne oppgaven er også basert på empiriske resultater. Mye av arbeidet har bestått av den faktiske produksjon av strukturen, og tilhørende måling og verifisering av strukturen.

Reduction targets for greenhouse gas emissions and the need of national energy security has led to a push in R&D of renewable energy sources such as tidal power the recent years. SmartMotor AS has engineered a tidal energy generator prototype, which is cur-rently being deployed in the sea. The magnetic core in the generator s rotor must be rela-tively thick to avoid losses caused by induced eddy currents in the underlying steel carry-ing structure. A non-magnetic carrying structure can potentially reduce the thickness of this member, resulting in lower overall mass and inertia. The purpose of this study was to enable this reduction through a redesign of the rotor structure utilizing non-magnetic composite materials. A non-magnetic composite rotor structure, which seems possible to manufacture, have been proposed and analysed implementing design philosophy from the DNV-OS-C501 Composite Components standard. The standard was not followed in detail, but the re-sults can be used to indicate the feasibility of the proposed composite structure. A bolted composite joint between the shaft and the rotor structure was designed and ana-lysed in detail utilizing FEA including a contact analysis. Local stresses caused by the generator torque load were found acceptable, and alternative joints were discussed. Solu-tions for improving the stiffness of the structure were evaluated. FEA indicated that the stiffness of the proposed structure is sufficient to avoid resonance from relevant excita-tion sources, and to keep global displacements from static load cases within specifica-tions. The local stress response of the structure to a set of static load cases was shown to be within material strength limits. Linear elastic buckling eigenvalue analyses indicated low risk of local and global buckling. The proposed composite structure gives a reduction in weight (28%) and inertia (34%) compared to the original rotor with a steel structure. The use of a composite structure seems therefore possible, but testing and analyses with more realistic load cases following the standard are required for verification. Before deciding to go further with a composite structure, a cost comparison of the existing- the new- and alternative non-magnetic struc-tures should be performed.

Carbon fiber reinforced polymers is an advanced material with unique material properties that is being used more and more in the subsea and petroleum industry. Well intervention is one of many well suited applications for hollow carbon fiber reinforced tubes. Due to the material?s properties, the composite material is well suited for many applications when dealing with conditions similar to the environment inside an oil well. It has a much higher stiffness to weight ratio than most materials, great thermal resistance and it is less subjected to fatigue. The material is non-corroding and may be designed for chemical resistance which is a huge benefit in the harsh conditions found for example subsea or in a well. The dominating load in an oil well environment is the extreme pressure. Carbon fiber reinforced polymers is a very strong material, and by customizing its laminate layup, its full strength can be utilized for any loadcase it may be subjected to.The main focus of this task was to study the behavior of relevant thick-walled fiber composite tubes subjected to external pressure employing both numerical and experimental methods. Three principal composite layups were analyzed, both numerically and experimentally by high pressure testing and axial compression tests. Test samples were produced and evaluated for these tasks, and compared with results from representative finite element models.Test samples with [±80°], [±45°] and [±80°,±9°] layups were analyzed. The experimental work for the [±80°] samples was done in a previous work, and only the results were presented in this thesis. The samples for the high pressure testing were 150mm long, and the outer and inner diameters were 15mm and 12mm, respectively. The same diameters were used for the axial compression samples, but the length was reduced to 20mm. The dimensions were determined by conventional design criteria for well intervention. The samples were produced by using the filament winding machine at NTNU, and an epoxy bath was used for impregnation.Puck?s failure criterion was implemented in the numerical calculations for material failure prediction. An eigenvalue buckling analysis procedure was conducted for buckling failure prediction. All samples for both test methods failed very close to the predicted failure loads with relatively low percentage difference. The differences were found to be between -11.1% and 12.7%, and a discussion was conducted on possible sources of deviation.Due to the low deviation between predicted and factual failure loads, it could be concluded that the assumed strength and elasticity parameters of the material was reasonable and that the experimental testing procedures was well fitted for the study of the behavior of composites subjected to compression.Based on these results, a discussion of an optimized structure was conducted. The geometry analyzed in this thesis had much higher buoyancy than desired for the application. It could thus be concluded that the material has a great potential for the use in oil-well environment.

Filament winding is a fabrication method for composite material structures, in which fibres are wound around a rotating mandrel. It is a versatile and dexterous process especially well-suited for creating and optimizing parts with a linear rotational axis. Products like pressure tanks, golf clubs or violin bows are commonly created using this technique. The winding itself is done through software solutions that generate a CNC program for the part in question. There are several such software solutions commercially available, all with different modes of operation and functionalities. However, they are also proprietary and offer little to no access into their inner logic. To optimise a part before production Finite Element Analysis software is often used. The part in question is modelled; material, forces and constraints are applied; and an analysis is run. Currently (June 2012), there are few options available for analysing filament wound products. Modelling a part with accurate filament winding layup generally has to be done manually, in a very time-consuming process. In this thesis, the author has performed a pilot study into the development of filament winding software. Software has been developed, capable of integrating both with a filament winding machine and with Finite Element Analysis software, and operating as a link between the two. The software has functionalities to extract geometrical variables from an Abaqus mandrel model; to write G codes and create a CNC program file; simulate a filament winding process in the Abaqus viewport; and, using a CNC program file, add accurate and corresponding layup to an Abaqus part. The main goal of this thesis, however, has been to create something that will serve as a basis from which others can continue development. The intention being that the software will be open source, so that anyone and everyone using it may change, improve and add on to it.

Carbon composite materials and structures have low weight, high stiffness, high strength and chemical resistance. Throughout this master thesis a feasibility study to utilize carbon composites in tubes, designed to withstand high pressures, is undertaken both analytically and experimentally. The tube is meant to be used for well intervention, replacing the current solid carbon rod. In such operations is low weight, in addition to above mentioned properties, a critical factor for long reach. To extend the reach of the equipment the submerged weight of such a tube must be as low as possible.To enable a tube to withstand the high pressures, which can reach more than 1000bar, a thick walled tube is the only alternative to decrease the submerged weight compared to a solid rod. Work and literature on thick walled composite tubes with inner diameter to thickness ratios as low as 2 is minimal, if not absent.A two layered laminate structure was chosen for the tube. The inner layer existing of hoop winded fibers and the outer layer of longitudinal UD fibers. Such a layup will give both high radial strength and axial stiffness.Throughout the analysis it was found that the cause of failure would be instability. This conclusion was drawn as instability would occur before any of the chosen failure criterions were fulfilled. This implies that the strength of the material is utilized maximally.The experimental results had good coherency with the analytical results. Results from physical tests had a large scatter, but this was predicted as a result of a manual production process leading to uneven distribution of fibers and medium to large voids.Several parameters, both regarding load cases and necessary material properties, for the given requirements of the tube have not been assessed. However, results from conducted analytical and experimental work shows that thick walled composite tubes are able to withstand the given loading conditions, together with keeping the submerged weight sufficiently low.Future work based on the results in this thesis should include test results with statistical significance, analyses on the more complex load cases, optimal laminate design and identifying a suitable matrix material which can withstand the necessary temperature requirement.