Denna kandidatrapport behandlar ett arbete resulterande i en ökning av hållfastheten hos en skidbalk ingående i bandvagnen BvS10. Projektet har utförts på uppdrag av BAE Systems Hägglunds under deras SIRIUS-samarbete med Luleå tekniska universitet. Inom SIRIUS har många utvecklingsprojekt startats, varav ett är E-TED dit det här arbetet hör. Balken har tappat avsevärd hållfasthet då hål utformats i dess yttre sida för att rymma komponenter. Detta har gjorts av anledningar utvecklade inom E-TED. Syftet var därför att utveckla en konceptuell och användbarskidbalk för bandvagnen med målsättningen att erhålla en lika bra eller bättre hållfasthet relativt ursprungsbalken. För att nå målet itererades arbetet mellan finita elementmetoden (FEM) och computer-aided design (CAD) i programmen CATIA V5, ANSA, ABAQUS och META för utveckling av koncept. Itereringen resulterade i två konceptbalkar, varav den sista var fördelaktigast. CATIA brukades för CAD och de resterande programmen brukades respektive som förbehandlare, problemlösare och efterbehandlare för FEM. Av dessa tre utfördes de två första med hjälp av beräkningsavdelningen på BAE Systems Hägglunds och det sista utfördes av författarna. Ursprungs- och konceptbalkarna testades med fem lastfall motsvarande de extremaste förhållanden som uppmätts vid körning av bandvagnen. Förstärkningarna implementerades därefter baserad på teori gällande böj- och vridmotstånd för homogena balkars kvadratiska- och rektangulära tvärsnitt. Spänningsanalys av den slutgiltiga konceptbalken uppvisade effektivspänningar överskridande materialets sträckgräns för tre av lastfallen. För de två mest problematiska av dessa tre fall utformades en analys av kvarvarande plastisk töjning respektive deformation. Detta påvisade att kvarvarande plastisk töjning respektive deformation var i samma storleksordning som vid tidigare undersökningar av idag driftsatta skidbalkar. Alltså drogs slutsatsen att det är möjligt att skapa en SIRIUS-skidbalk med minst lika bra hållfasthet som ursprungsbalken samt att slutgiltiga konceptbalken, ur ett hållfasthetsperspektiv, är redo för användning. / This bachelor report covers a work resulting in an increased strength of a skid girder located on the tracked vehicle BvS10. The project was performed on behalf of BAE Systems Hägglunds under their SIRIUS-collaboration with Luleå University of Technology. Many development projects have been started within SIRIUS, one of these is E-TED where this work belongs. The skid girder has lost considerable strength due to the implementation of holes in its outer side to make room for components. This has been done due to reasons developed within E-TED. The purpose of this project was therefore to develop a conceptual and useable skid girder with the goal to increase the strength to equal or higher levels relative to the original skid girder. To achieve the goal the work iterated between finite element method (FEM) and computer-aided design (CAD) in the software’s CATIA V5, ANSA, ABAQUS and META to develop the concepts. The iteration resulted in two conceptual skid girders of which the last was found more favorable than the other. CATIA was utilized for CAD and the remaining programs were respectively used as pre-processor, solver and post-processor for FEM. The first two of these three were executed with helpfrom the calculations department at BAE Systems Hägglunds and the last one was performed bythe authors. The original and conceptual beams’ were tested with five load cases corresponding to the most extreme conditions measured while driving the tracked vehicle. Reinforcements were thereafter implemented based on theory regarding bending and torsion resistance of homogenous beams’ with squared and rectangular cross-sections. The stress analysis of the final conceptual skid girder demonstrated von Mises stresses exceeding the material’s yield point for three of the load cases. An analysis of remaining plastic strain and deformation were designed for the two most problematic of these three cases. This showed that the remaining plastic strain and deformation were on the same order of magnitude as thoseo btained in previous investigations of operating skid girders today. Thus the conclusion was drawn that it is possible to create a SIRIUS skid girder with equal or better strength than the original skidgirder and that the final conceptual skid girder, from a perspective of strength, is ready foroperation. / SIRIUS

The aerospace sector’s increasing use of composites highlights the need for accuratecharacterization of the material’s properties, particularly regarding failure parameters.This paper goes through the process of physically testing a carbon epoxy composite interms of delamination strength using the ASTM standard in three different mode mixtures.Then, by implementing a Cohesive Zone Modelling approach with a bi-linear tractionseparation law, simulating the coupons in LS-Dyna and performing an iterative correlationprocess to find the material parameters that best replicate the results obtained from the labexperiments.The results showed how the failure load at which the delamination initiates matched theexperimental ones for reasonable values of the material properties, but the displacementat which this load were obtained are noticeably off.In the end, the reason behind this behaviour is discussed and possible solutions forfuture work are presented. / Den ökande användningen av kompositer inom rymdsektorn belyser behovet av noggrannkaraktärisering, särskilt avseende brottparametrar.Denna artikel går igenom processen med fysiskt testning av en kol-epoxi-kompositmed avseende på delamineringssstyrka genom att använda ASTM-standarden i tre olikaförhållanden av felmoder. Sedan, genom att integrera en modellering av kohesiva zonermed en bilinjär drag-separationslag, simuleras kupongerna i LS-Dyna och en iterativkorrelationsprocess utförs för att hitta de materialparametrar som bäst replikerar resultatenfrån labbförsöken.Resultaten visade hur felbelastningen vid vilken delaminering börjar matchade deexperimentella, men förskjutningen vid vilken denna belastning uppnås avviker signifikant.Till sist diskuteras orsaken till detta beteende och möjliga lösningar för framtida arbetepresenteras.

Solar sails are an innovative propulsion mechanism for space exploration, harnessing the momentum of photons from the Sun to propel spacecraft. As material science advances and launch costs continue to fall, opportunities utilising the novel characteristics of solar sails become more and more feasible. Due to the inherit connection between mass and acceleration, it is of great importance to reduce mass to gain acceleration. This thesis investigates the structure of solar sails and provides an analysis of the forces they encounter. The study examines the forces acting on circular solar sails in space, as well as the unique challenges they face on Earth and during the launch phase. The membrane and supporting composite structure is analysed using mathematical models in MATLAB in order to develop and optimize structures for strength and reduced mass. Dimensioning forces were found and a preliminary structure discussed. By understanding these forces, it is possible to optimize the design and deployment of solar sails, paving the way for more efficient space missions. / Solsegel är en innovativ framdrivningsmekanism för rymdforskning som utnyttjar fotoners rörelsemängd från solen fotoner för att driva rymdfarkoster. I takt med att materialvetenskapen utvecklas och uppskjutningskostnader fortsätter att sjunka, blir möjligheterna att anv¨anda solsegels unika egenskaper alltmer genomförbara. På grund av det naturliga sambandet mellan massa och acceleration är det av stor vikt att minska massan för att öka accelerationen. Detta examensarbete undersöker strukturen hos solsegel och ger en analys av de krafter de utsätts för i olika stadier under dess livscykel. Studien granskar de krafter som verkar på seglen i rymden, samt de unika utmaningar de står inför på jorden och under uppskjutningsfasen. Membranet och den stödjande kompositstrukturen analyseras med hjälp av modeller i MATLAB för att utveckla och optimera strukturer med avseende pästyrka och vikt. Genom att förstå dessa krafter är det möjligt att optimera utformningen och utplaceringen av solsegel, vilket banar väg för allt mer effektiva och unika rymduppdrag.

The Hemispherical Resonating Gyroscope (HRG) is an inertial sensor, flagship of Safran’s industry. When exiting the assembly line, it has its own physical flaws. In order to identify and correct them, operators perform several tests on the sensor: this process corresponds to the calibration step of the sensors. The latter is done by a Matlab calibration bench, which allows to calculate compensation polynomial functions, which are then included in the algorithms of the sensor’s implementation card. However, the link between the calculated functions and the sensor’s flaws is not obvious and therefore, it is impossible to check their truthfulness without further verification. In this document, an interfacing method between a calibration bench and a virtual HRG, modeled in Simulink, has been described. After presenting the sensor’s capabilities, several interfacing methods are discussed, before keeping the more dynamical one, based on object oriented programming and the implementation of a time continuity between Simulink data recordings. Such interfacing allows for the simulation of the behavior of a gyroscope during calibration, and the comparison of these results to the ones obtained on real sensors. This comparison highlighted a certain consistency between the results and also several flaws caused by the interfacing. Particularly, the fact that the signal discretization has a significant impact on the errors. Moreover, one can notice that the simulation time is significantly longer than the calibration time and suggests that the interfacing time may require optimization of its efficiency. / HRG är en tröghetssensor som är flaggskeppet inom Safrans industri. När sensorn lämnar monteringslinjen är den inte felfri. För att identifiera och kompensera för dessa fel utför operatörerna flera tester på sensorn, i flera olika kalibreringssteg. De senare görs med hjälp av en Matlab-kalibreringsbänk, som gör det möjligt att beräkna kompensationspolynomfunktioner, som sedan implementeras i algoritmerna på sensorns implementeringskort. Kopplingen mellan de beräknade funktionerna och sensorns fel är dock inte uppenbar och därför är det omöjligt att kontrollera deras noggrannhet utan ytterligare kontroller. I detta dokument beskrivs en gränssnittsmetod mellan en kalibreringsbänk och en virtuell HRG, modellerad i Simulink. Efter att ha presenterat sensorns funktion har flera gränssnittsmetoder studerats, innan man valde den mer dynamiska, baserad på objektorienterad programmering och implementeringen av en tidskontinuitet mellan Simulinkdatainspelningar. Ett sådant gränssnitt gjorde det möjligt att få vissa resultat som simulerar gyroskopets beteende under en kalibrering och att jämföra dessa resultat med dem som erhållits på verkliga sensorer. Jämförelsen visade på en viss överensstämmelse mellan resultaten, men också på flera brister som orsakats av gränssnittet. I synnerhet det faktum att signaldiskretiseringen har en betydande inverkan på felen. Dessutom kan man notera att simuleringstiden är mycket längre än kalibreringstiden och leder till tanken att det finns sätt att förbättra gränssnittet för att göra det mer tidseffektivt.

Forklifts are commonly perceived as simple machines that are not representative of modern technology. However, a deeper analysis uncovers their inherent complexity and sophistication. This project aims to develop a tire model for indoor forklifts with sufficient accuracy that it can replace the need for physical tests and significant calibration, thereby shortening development time and decreasing costs. This report is part of a Master's thesis work on modeling shocks generated when driving over obstacles with a forklift. The project is conducted in collaboration with Linköping University and Toyota Material Handling Manufacturing Sweden. Various methods for modeling tire behavior, along with different contact types, have been explored and tested, primarily focusing on the Fiala tire model. Developing a tire model that accurately captures all aspects of driving over obstacles is a challenging endeavor. Despite several challenges, the findings presented in this report suggest that, with additional time, it is possible to develop a model that effectively simulates shocks across various speeds and obstacle heights.

This study investigates the structural integrity of hydrofoils under three scenarios: regular boating, turning, and collision with an underwater obstacle. To analyse the forces acting on the hydrofoil, calculations were performed and simulations were conducted in SolidWorks using a CAD model of the hydrofoil.The simulations reveal that the weld between the struts and the wing undergoes plastic deformation during both regular boating and turning. This deformation is particularly problematic during turning, as the forces on the weld increase significantly. Under the collision scenario, the bolts at the breakpoint fail before critical damage occurs to the components above.The results highlight the weakness of the weld and the need for a redesign of the hydrofoil to eliminate it. An alternative fastening method, such as bolted joints with watertight sealing, should be considered.

<p>This is a master thesis conducted at KTH Centre for Naval Architecture in collaboration with Wallenius Marine AB.</p><p>Rolling motions is something that is undesired in all kinds of seafaring. In terms of propulsion resistance, comfort and route planning it would be desirable to reduce these motions. This thesis is an investigation on how different roll stabilising systems affect the performance of an 8000 unit PCTC vessel, special emphasis is put on investigating the performance of anti roll tanks. The ship in question has a recorded incidence of parametric rolling and the ability of the tanks to countervail this phenomenon is also investigated.</p><p>The tank and fin stabilising systems are relatively equal when it comes to roll damping performance related to changes in the required forward propulsion power. The tanks however, have a higher potential for improvements, addition of features such as heeling systems and parametric roll prevention systems.</p><p>The tank performance is also independent of the speed of the ship. The tanks are easier to retrofit and do not require the ship to be put in dry dock during installation. The conclusion of this thesis is that a combined anti roll and heeling system should be installed but that a further study has to be made on the performance of active rudder stabilisation.</p><p>It is shown that passive tanks are efficient at preventing parametric rolling in some sea states. A proposal is made for a further study on a control system that could achieve the same performance for all sea states.</p> / <p>HTML clipboard Detta är ett examensarbete utfört på KTH Marina System i samarbete med Wallenius Marine AB.</p><p>Rullningsrörelser är något som är oönskat i all form av sjöfart. Framsteg kan göras i både framdrivningsmotstånd, komfort och ruttplanering om dessa rörelser kunde minskas. Detta examensarbete består av en undersökning hur olika system för rulldämpning påverkar prestandan hos ett 8000 enheters PCTC-fartyg. Speciell vikt har lagts vid att undersöka prestandan hos antirulltankar. Det undersökta fartyget har en dokumenterad incident med parametrisk rullning och tankarnas förmåga att motverka detta fenomen undersöks.</p><p>Tank- och fenstabilisatorer är i princip likvärdiga vad det gäller dämpningsprestanda relaterat till erforderliga ändringar i framdrivningseffekten. Tankarna har dock en större potential för förbättring och tillägg av ytterligare inslag som krängningshämmare och system för motverkan av parametrisk rullning. Tankarnas prestanda är också oberoende av fartygets fart.</p><p>Tankarna är lättare att installera i efterhand och kräver inte att fartyget läggs i torrdocka under installationen. Slutsatsen av detta arbete är att en kombinerad antirull- och krängningshämmande tank bör installeras men att en vidare studie måste göras på prestandan hos aktiva roderstabiliseringssystem.</p><p>Det visas att passiva tankar kan motverka parametrisk rullning i vissa sjötillstånd. Ett förslag om en vidare studie på reglersystem som skulle kunna ge samma prestanda vid alla sjötillstånd ges.</p><p> </p>

<p>Ground vehicles are subjected to crosswind from various origins such as weather, topography of the ambient environment (land, forest, tunnels, high bushes...) or surrounding traffic. The trend of lowering the weight of vehicles imposes a stronger need for understanding the coupling between crosswind stability, the vehicle external shape and the dynamic properties. Means for reducing fuel consumption of ground vehicles can also conflict with the handling and dynamic characteristics of the vehicle. Streamlined design of vehicle shapes to lower the drag can be a good example of this dilemma. If care is not taken, the streamlined shape can lead to an increase in yaw moment under crosswind conditions which results in a poor handling.</p><p>The development of numerical methods provides efficient tools to investigate these complex phenomena that are difficult to reproduce experimentally. Time accurate and scale resolving methods, like Detached-Eddy Simulations (DES), are particularly of interest, since they allow a better description of unsteady flows than standard Reynolds Average Navier-Stokes (RANS) models. Moreover, due to the constant increase in computational resources, this type of simulations complies more and more with industrial interests and design cycles.</p><p>In this thesis, the possibilities offered by DES to simulate unsteady crosswind aerodynamics of simple vehicle models in an industrial framework are explored. A large part of the work is devoted to the grid design, which is especially crucial for truthful results from DES. Additional concerns in simulations of unsteady crosswind aerodynamics are highlighted, especially for the resolution of the wind-gust boundary layer profiles. Finally, the transient behaviour of the aerodynamic loads and the flow structures are analyzed for several types of vehicles. The results simulated with DES are promising and the overall agreement with the experimental data available is good, which illustrates a certain reliability in the simulations. In addition, the simulations show that the force coefficients exhibit highly transient behaviour under gusty conditions.</p> / ECO2 Crosswind Stability and Unsteady Aerodynamics for Ground Vehicles

The topic of this PhD thesis is active suspension in rail vehicles whichis usually realized through sensors, controllers and actuation components.A well established example of an active suspension is the tiltingcontrol system used to tilt the carbody in curves to reduce centrifugalacceleration felt by passengers. Active suspension for rail vehicles is beingstudied since 1970s and in this PhD thesis it has been tried to expandon some aspects of this topic.This study extends the research field by both experimental and theoreticalstudies. In the first phase of the study which led to a licentiatedegree the focus was more on experimental work with active verticalsuspension (AVS). This was implemented by introducing actuators inthe secondary suspension of a Bombardier test train, Regina 250, in thevertical direction. The aim has been to improve vertical ride comfort bycontrolling bounce, pitch and roll motions.In the second phase after the licentiate, the studies have been moretheoretical and can be divided into two parts. The first part of the workhas been more focused on equipping two-axle rail vehicles with differentactive suspension solutions for improving the vehicle performanceregarding comfort and wheel-rail interaction. Three papers are writtenon active suspension for two-axle rail vehicles. Two of the papers discussthe use of H¥ control for wheelset guidance in curves to reducewheel-rail damage. The third paper shows that by use of active verticaland lateral suspension (AVS and ALS) in two-axle rail vehicles goodcomfort can be achieved as well. The paper then studies how the threeactive suspension systems (ALS, AVS, and ASW) interact once implementedtogether on a two-axle rail vehicle.The second part is a study on safety of active suspension systems.The study discusses a possible procedure to ensure that a designed activesuspension for a rail vehicle will be safe in all possible failure situations. / <p>QC 20170602</p>

This Licentiate of Engineering thesis concerns modelling and simulation of hydraulic percussion units. These units are often found in equipment for breaking or drilling in rock and concrete, and are also often driven by oil hydraulics, in which complex fluid-structure couplings are essential for their operation. Current methodologies used today when developing hydraulic percussion units are based on decoupled analyses, which are not correctly capturing the important coupled mechanisms. Hence, an efficient method for coupled simulations is of high importance, since these mechanisms are critical for the function of these units. Therefore, a co-simulation approach between a 1D system simulation model representing the fluid system and a structural 3D FE-model is proposed. This approach is presented in detail, implemented for two well-known simulation tools and evaluated for a simple but relevant model. The Hopsan simulation tool was used for the fluid system and the FE-simulation software LS-DYNA was used for the structural mechanics simulation. The co-simulation interface was implemented using the Functional Mock-up Interface-standard. The approach was further developed to also incorporate multiple components for coupled simulations. This was considered necessary when models for the real application are to be developed. The use of two components for co-simulation was successfully evaluated for two models, one using the simple rigid body representation, and a second where linear elastic representations of the structural material were implemented. An experimental validation of the co-simulation approach applied to an existing hydraulic hammer was performed. Experiments on the hydraulic hammer were performed using an in-house test rig, and responses were registered at four different running conditions. The co-simulation model was developed using the same approach as before. The corresponding running conditions were simulated and the responses were successfully validated against the experiments. A parameter study was also performed involving two design parameters with the objective to evaluate the effects of a parameter change. This thesis consists of two parts, where Part I gives an introduction to the application, the simulation method and the implementation, while Part II consists of three papers from this project.