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By applying the finite element approach to the design and analysis of the impact diffusion helmet, many helmet configurations were able to be analyzed. Initially it was important to determine what design variables had an influence on the impact reducing abilities of the helmet design. The helmet was run through a series of Abaqus simulations that determined that a design with two oval shaped channels running along the length of the helmet was best. Next, these options were optimized to generate the helmet that produced the greatest impact reduction. The optimization simulations determined that a helmet that pushed the channels as far from the impact zone as possible reported the lowest acceleration. This indicated that removing the channels from play was most advantageous from an impact reduction perspective. Finally, a 3-D printed experimental helmet was impact tested and compared to a 3-D printed control helmet. The experimental helmet brought the channels back into the impact zone in order to judge if they had a physical effect on the acceleration. Both the simulations and the subsequent physical testing indicated that the Impact Diffusion Helmet design has a negative influence on the concussion reducing properties of a football helmet.

Volvo Construction Equipment (VCE) has invested in an advanced lasermachine that can cut sheet metal parts with angled edges. As a result, thedevice provides expanded possibilities in the design and production of sheetmetal products.The material cost component is significant in the production of sheet metalproducts. This cost can be reduced by reducing the plate's thickness andchanging its dimensions.This study examines the effects of a thinner plate thickness combined withchanged height and width dimensions and a more robust weld joint inmanufacturing a so-called A stay, a part of the articulated hauler from VCE.The study was conducted with the Design for Six Sigma (DFSS) process,product research, development, and R&D methodology, which falls under theoverall scientific, technical research methodology "Systems Engineering."The study's conclusion shows that material saving with a thinner sheet is at theexpense of reduced quality and product cycle life. In addition,recommendations for in-depth analyses have also been proposed in the study'sdiscussion section.

Nowadays, the forestry industry still uses heavy machinery damaging both the forest and the soil. The start-up AirForestry is currently developing a sustainable way to thin and harvest trees. With their 6.2m wide electric drone carrying a harvesting tool, they can reach, thin, cut and carry trees without the need for access roads. Naturally, the drone needs to be as lightweight as possible to increase its endurance and operation range. Therefore, the first version of the drone was manufactured before the thesis with a carbon fibre laminate.  The purpose of this thesis is to study and optimize the composite structure of the drone. The first step is to characterize the existing design through experiments and simulations using the software ANSYS. Static bending loads, free vibrations, and forced vibrations are investigated against a set of predefined design requirements. This study shows that the contact surfaces between each arm and with the motor holders have high-stress concentrations compared to the rest of the arm. This means that most of the arm can be made thinner to lessen the weight with some extra reinforcement on those problematic areas.  The second step is to optimize the laminate to decrease the weight of the structure. A preliminary optimization was made and manufactured at the beginning of the thesis with strict limitations on the choice of the lamina or available thicknesses. Similar bending and vibration experiments and simulations are conducted on the new design to compare it with the older model. While the mass was expected to decrease by about 30 $\%$, the final measured weight of the arms indicates a drop of only 15 $\%$ of the mass. The model is then optimized further with more freedom in the design variables. Several variables are successively optimized: the material choice for the laminae, the thickness then of the laminae, and the angles of the plies. The mass of the structure with the final laminate has an expected decrease in mass of 45$\%$, saving more than 12kg in total / I dag använder skogsindustrin fortfarande tunga maskiner som skadar både skogen och marken. Det nystartade företaget AirForestry utvecklar för närvarande ett hållbart system för att gallra och skörda träd: en 6,2 meter breda elektriska drönare som bär ett avverkningsverktyg. Med den kan de nå, gallra, avverka och bära träd utan att behöva använda tillfartsvägar. Naturligtvis måste drönaren vara så lätt som möjligt för att öka dess uthållighet och räckvidd. Därför tillverkades den första versionen av drönaren före examensarbetet med ett kolfiberlaminat.  Syftet med detta arbete är att studera och optimera drönarens kompositstruktur. Det första steget är att karakterisera den befintliga konstruktionen genom experiment och simuleringar med hjälp av programvaran ANSYS. Statiska böjningsbelastningar, fria vibrationer och påtvingade vibrationer undersöks med avseende på en uppsättning fördefinierade konstruktionskrav. Det andra steget är att optimera laminatet för att minska strukturens vikt. En preliminär optimering gjordes och tillverkades i början av arbetet med strikta begränsningar för valet av lamina eller tillgängliga tjocklekar. Liknande böjnings- och vibrationsexperiment och simuleringar utförs på den nya konstruktionen för att jämföra den med den äldre modellen. Även om massan förväntades minska med cirka 30 $\%$, visar den slutliga uppmätta vikten på armarna att den endast minskat med 15 $\%$. Modellen optimeras sedan ytterligare med större frihet i konstruktionsvariablerna. Flera variabler optimeras successivt: materialvalet för lamellerna, lamellernas tjocklek och vinklarna på skikten. Strukturen med det slutliga laminatet får då en förväntad minskning av massan med 45 $\%$, vilket innebär en total besparing på mer än 12 kg.

Space equipment is often subjected to mechanical shocks. Some devices like electronics are sensitive to shocks, and they can easily be damaged. To protect these devices, it is important to study shock penetrations in space structures. The Finite Element Method is an effective tool to simulate response to transient excitations. Unlike Statistical Energy Analysis (SEA) which can ensure sufficient accuracy in high frequency range, Finite Element Analysis (FEA) is limited to low frequency range, but has no spatial restrictions. In this thesis, Tuma’s digital filter method and Irvine’s recursive digital method were combined to calculate the Shock Response Spectrum (SRS). FEA models based on a given experimental system, i.e., shock table were used to predict the structural response to Haversine shaped forces. The modal transient structural analysis in ANSYS Workbench was used as the solver. Transient analysis based on modal results neglects material and structural non-linearities, so it uses less memory and computation time. FEA and the Bernoulli beam equation were employed to simulate the shock response of cantilever beams and fixed-pinned beams to validate the FEA models. SRS calculated from FEA results were compared with those from the beam equation results. Almost no difference between Bernoulli beam equation results and FEA results for thin beams reveals that the FEA models were validated. The SRS of two beam models calculated from FEA using solid elements were compared with those using beam elements. The results from two different element types are almost consistent with each other. Response at different positions on the shock table were measured to predict the shock attenuation. The attenuation was described in the way of remaining percentage from shock source, and the curve from FEA simulation roughly agreed with the attenuation rule from the ESTEC database. / Rymdutrustning utsätts ofta för mekaniska stötar, s.k. mekanisk chock. Vissa enheter, som elektronik, är känsliga för stötar och de kan lätt skadas. För att skydda dessa enheter är det viktigt att studera chockdämpningen i rymdstrukturer. Finita elementmetoden är ett effektivt verktyg för att simulera responsen vid transienta excitationer. Till skillnad från statistisk energianalys (SEA) som kan säkerställa tillräcklig noggrannhet i högfrekvensintervall, är finit elementanalys (FEA) begränsad till lågt frekvensområde, men har inga rumsliga begränsningar. I detta examensarbete kombinerades Tumas digitala filtermetod och Irvines rekursiva digitala metod för att beräkna Chockresponsspektrum (SRS). FEA-modeller baserade på ett givet experimentellt system, d.v.s. chockbord, användes för att förutsäga den strukturella responsen på Haversine-formade krafter. Den modala transienta strukturanalysen genomfördes med ANSYS Workbench. Den transienta analysen baserad på modala resultat försummar icke-linjäriteter i material och struktur för att använda mindre minne och förkorta beräkningstiden. FEA och Bernoulli-balkekvationen användes för att simulera chockresponsen av konsolbalkar och balkar med fast inspänning i ena änden och fri uppläggning i den andra änden, för att validera FEA-modellerna. SRS beräknat från FEA-resultaten jämfördes med resultat från balkekvationen. Ingen avgörande skillnad noteras mellan Bernoullis balkekvationsresultat och FEA-resultat för tunna balkar, vilket validerar FEA-modellerna. SRS för två balkmodeller beräknade från FEA med solida element jämfördes med de som använde balkelement. Resultaten från de två olika elementtyperna överensstämmer mycket bra. Responsen vid olika positioner på chockbordet mättes för att förutsäga chockdämpningen. Chockdämpningen beskrivs som kvarvarande procent av responsen vid chockkällan och kurvan från FEA-simulering överensstämde ganska bra med tumregeln för chockdämpning från ESTEC-databasen.

This thesis has taken place at ABB High Voltage Cables in Karlskrona and focuses on their reinforcement process (AR50) which reinforces the cable by application of reinforcement wires. The research is strictly limited to only the short period during the application of the wire on the cable and investigates stress differences in one reinforcing wire depending on cable - and wire dimensions as well as brake forces used in the production. The study follows a model - and theory development research process combined with a testing process to obtain the results. The study aims is to increase and expand ABB's knowledge about the reinforcing process that is used to strengthen and protect ABB’s all different high voltage cables together with a computational calculation model. The model is developed in the FEA (Finite Element Analysis) program ABAQUS through a dynamic explicit model. An explanation of how the calculation model has been built and the parameters used are described in this report. These parts then contribute to the outcome of the study which provides a sense that the brake force used in AR50’s reinforcement process does not need to be controlled with a high precision so long as it is large enough to hold the reinforcement wire stretched upon the application. The study also shows that different cable - and wire dimensions does not affect the stress levels somewhat significantly by reinforcing the process and that the nipple used in reinforcement process to press down the reinforcing wire on the cable is the main source that determines how the stress distribution looks like on the reinforcement wire. / Detta examensarbete har tagit plats på ABB High Voltage Cables i Karlskrona och fokuserar på deras armeringsprocess (AR50) som förstärker kabeln genom påläggning av armeringstrådar. Arbetet är starkt begränsat till enbart den korta perioden för själva påläggningen av tråden och undersöker spänningsskillnader i en armeringstråd beroende på olika kabel – och tråddimensioner samt bromskrafter som används i produktionen. Studien följer en modell – och teoriutvecklande forskningsprocess kombinerat med ett utprövande resultatbildande. Studiens syfte är att tillsammans med en beräkningsmodell öka och fördjupa ABBs kunskaper kring armeringstråden som idag används för att stärka och skydda ABBs alla olika högspänningskablar. Beräkningsmodellen tas fram i FEA (Finita Element Analys) prorammet ABAQUS genom en dynamisk explicit modell. En förklaring till hur beräkningsmodellen har byggts upp och vilka parametrar som används beskrivs i rapporten. Dessa delar bidrar sedan till resultatet i studien som ger en bild av att bromskraften som används i AR50s armeringsprocessen inte behöver kontrolleras med en hög precision så länge den är tillräckligt stor för att hålla armeringstråden sträckt vid påläggningen. Studien visar också att olika kabel – och tråddimensioner inte påverkar spänningsnivåerna något markant vid armeringsprocessen och att nippeln som används i armeringsprocesen för att trycka ner armeringstråden mot kabeln bestämmer hur spänningsbilden ser ut. / <p>This thesis is kept confidential</p>

Photovoltaic vehicles are designed to harness solar energy and use it for self-propulsion. In order to collect sufficient energy to propel a passenger, a relatively large photovoltaic array is required. Controlling the loads imparted by the array and the body that supports it, while protecting the passenger and minimizing vehicle weight, presents a unique set of design challenges. Weight considerations and geometric constraints often lead system designers toward unconventional structural solutions. This report details analytical and experimental processes aimed at proving the concept of integrating aluminum space-frame elements with composite panels. Finite element analysis is used to simulate load conditions, and results are compared with empirical test data. / text

Many metals used in modern engineering exhibit anisotropy. A common assumption when modelling anisotropic metals is that the level of anisotropy is fixed throughout the calculation. As it is well understood that processes such as cold rolling, forging or shock loading change the level of anisotropy, it is clear that this assumption is not accurate when dealing with large deformations. The aim of this project was to develop a tool capable to predict large deformations of a single crystal or crystalline aggregate of a metal of interest and able to trace an evolution of anisotropy within the material. The outcome of this project is a verified computational tool capable of predicting large deformations in metals. This computational tool is built on the Crystal Plasticity Finite Element Method (CPFEM). The CPFEM in this project is an implementation of an existing constitutive model, based on the crystal plasticity theory (the single crystal strength model), into the framework of the FEA software DYNA3D® . Accuracy of the new tool was validated for a large deformation of a single crystal of an annealed OFHC copper at room temperature. The implementation was also tested for a large deformation of a polycrystalline aggregate comprised of 512 crystals of an annealed anisotropic OFHC copper in a uniaxial compression and tension test. Here sufficient agreement with the experimental data was not achieved and further investigation was proposed in order to find out the cause of the discrepancy. Moreover, the behaviour of anisotropic metals during a large deformation was modelled and it was demonstrated that this tool is able to trace the evolution of anisotropy. The main benefit of having this computational tool lies in virtual material testing. This testing has the advantage over experiments in time and cost expenses. This tool and its future improvements, which were proposed, will allow studying evolution of anisotropy in FCC and BCC materials during dynamic finite deformations, which can lead to current material models improvement.

This thesis focuses on permanent magnet "direct drive" electrical generators for wind turbines with large power output. A variety of such generator topologies is reviewed, tested and optimised in an attempt to increase their potential as commercial concepts for the wind industry. Direct drive electrical generators offer a reliable alternative to gearbox drivetrains. This novel technology reduces energy loses thus allowing more energy to be yield from the wind and decreases the maintenance cost at the same time. A fundamental issue for these generators is their large size which makes them difficult to manufacture, transport and assembly. A number of structural designs have been suggested in the literature in an attempt to minimise this attribute. A set of design tools are set out in an attempt to investigate the structural stiffness of the different permanent magnet direct drive generator topologies against a number of structural stresses that apply to such wind turbine energy converters. Optimisation techniques, both analytical and structural, are also developed for minimising the total mass of a variety of "directly driven" machines with power output of 5MW or greater. Conventional and promising generator designs are modelled and optimised with the use of these optimisation techniques. The topologies under examination are then compared in terms of structural mass, stiffness and cost. As the number of wind turbine manufactures who adopt the direct drive concept increases, it is important to outline the unique characteristics of the different topologies and increase their manufacturing potential. Discussions and conclusions will provide an indication of the design solutions that could help decrease the mass and cost of such machines.

Metallic additives, also known as anticorrosive pigments, can provide sacrificial cathodic protection and complement the barrier protection afforded by heterogeneous organic coatings to metallic substrates. The unique systematic study of the corrosion resistance of an epoxy coating reinforced with different sizes (80nm, 500nm, 10um) and continuous multiple pigment volume concentration (0, 2%, 10%, 20%, 45%) below global critical pigment volume concentration of zinc particles were studied. The thesis is developing the fundamental understanding to optimize corrosion protection and predicting the protection with time. The properties of these cathodic coatings were investigated by a single-frequency electrochemical impedance spectroscopy (EIS) and open circuit potential (OCP) measurements that can be used as to understand cathodic protective state. Finite Element Analysis (FEA) has been applied here for modeling and simulating part of actual experiments. This thesis will help understanding the sensitivity and efficiency to various size and loading of metallic additives for corrosion protection.