No description available.

<p>Crosswind stability of rail vehicles has been a research area for several decades,mainly motivated by vehicle overturning accidents and higher speeds, but in recenttimes also by issues of lower energy consumption and track maintenance costsdemanding lower vehicle weights. During everyday operation, rail vehicles are subjectedto large lateral influences from track irregularities, track curves and crosswind,leading to large suspension deflections and increased crosswind sensitivity.Also unsteady crosswind like gusts calls for attention. Simulations of possible vehicleoverturning are necessary, but need to take large deflections and high shear inthe suspension into account. If delivering reasonable results, simulations representan important tool for overturning prediction of the vehicle.</p><p>In the present work, multibody simulations of a high-speed vehicle at large lateralinfluences from track curves and track irregularities have been carried out, using ahalf-vehicle model in 2D and a model of a whole vehicle in 3D. The vehicle modelsalso include different suspension models. Corresponding field measurements ofthe relative lateral and vertical deflections in the secondary suspension have beenperformed on a fast train and used for validation of the multibody simulations,resulting in good agreement between measurements and simulations.</p><p>The 3D vehicle model was further used to study the vehicle response to unsteadycrosswind during curve negotiation where aerodynamic loads obtained by unsteadyComputational Fluid Dynamics, namely Detached Eddy Simulations, representingthree types of gusts were used. In addition, the method of Quasi Transient GustModelling was evaluated in terms of overturning risk. Strong lateral and roll responsesof the vehicle and influences of the gust duration and the relative differencebetween mean and maximum wind speed were observed. Further, variations of suspensionand mass properties of the vehicle were performed to study the influenceon crosswind sensitivity. The position of the centre of mass of the carbody and thelateral bumpstop clearance showed significant influence on the crosswind stability.</p>

An algorithm for heat transfer prediction of in-service welding operations in a forcedflow of fluid is presented. The algorithm presented is derived from Rosenthal’s 3D heatflow equation and boundary layer approximations. This was possible by the introductionof an apparent thermal conductivity kPL, which is a function of the boundary layer’s heattransfer coefficient f and the base material’s thickness . This implies that a weldcooling time ΔtT1 /T2 in a forced flow of fluid can now be calculated by an ordinaryengineering calculator and thus enabling suitable welding parameters to be determined.The magnitude of kPLf , was established by regression analysis of results from aparametric finite element analysis series of a total number of 112 numerical simulations.Furthermore, the result of the regression analysis was validated and verified by a weldingexperiment series accomplished on an in-house designed and constructed in-servicewelding rig. The principle design of the welding rig as well as its instrumentation, a PCbased Data Acquisition system, is described. In addition, a method to measure the weldmetals cooling time ΔtT1 /T2 by means of thermocouple elements is described. Finally,the algorithm presented in this study proved feasible for industrial in-service weldingoperations of fine-grained Carbon and Carbon–Manganese steels with a maximum Carbon Equivalent (IIW) (CE) of 0.32. / Funktionsstabilitet

Contact is the principal way load is transferred to a body. The study of stresses and deformations arising due to contact interaction of solid bodies is thus of paramount importance in many engineering applications. In this work, problems involving contact interactions are investigated using finite element modeling. In the first part, a new augmented Lagrangian multiplier method is implemented for the finite element solution of contact problems. In this method, a stabilizing term is added to avoid the instability associated with overconstraining the non-penetration condition. Numerical examples are presented to show the influence of stabilization term. Furthermore, dependence of error on different parameters is investigated. In the second part, a disc brake is investigated by modeling the disc in an Eulerian framework which requires significantly lower computational time than the more common Lagrangian framework. Thermal stresses in the brake disc are simulated for a single braking operation as well as for repeated braking. The results predict the presence of residual tensile stresses in the circumferential direction which may cause initiation of radial cracks on the disc surface after a few braking cycles. It is also shown that convex bending of the pad is the major cause of the contact pressure concentration in middle of the pad which results in the appearance of a hot band on the disc surface. A multi-objective optimization study is also performed, where the mass of the back plate, the brake energy and the maximum temperature generated on the disc surface during hard braking are optimized. The results indicate that a brake pad with lowest possible stiffness will result in an optimized solution with regards to all three objectives. Finally, an overview of disc brakes and related phenomena is presented in a literature review. In the third part, a lower limb donned in a prosthetic socket is investigated. The contact problem is solved between the socket and the limb while taking friction into consideration to determine the contact pressure and resultant internal stress-strain in the soft tissues. Internal mechanical conditions and interface stresses for three different socket designs are compared. Skin, fat, fascia, muscles, large blood vessels and bones are represented separately, which is novel in this work.

Den här studien undersöker hur utsläppen av CO2 samt NOx skulle påverkas av att man tog en längre rutt runt ett Natura 2000 område mellan Gotska sandön och Fårö norr om Gotland i Östersjön. Detta för att undvika att köra i ett natura 2000 området och på så sett minska sjöfartens påverkan på djurlivet där. Med hjälp av AIS data har information tagits fram om hur många fartyg som använder rutten genom natura 2000 området. En sammanställning av vilka typer av fartyg samt dess maskineri har också tagits fram med hjälp av detta. Som ligger till grund för uträkningarna för CO2 samt NOx utsläppen. Studien visar på att CO2 utsläppen kan öka med upp till 4,72 ton genom att köra en längre rutt runt området, även NOx utsläppen ökar, med upp till 0,13ton.

<p>Den här rapporten ämnar svara på frågan om och med hur mycket tröskelvärdena av alla inkommande komponenter, tillhörande ett MD-80 Engine change kit, kan höjas med och vilka kostnadsbesparingar en sådan höjning kan medföra. Undersökningen har föranletts av företaget SAS Components vilja att få reda på om en optimering av tröskelvärden kan leda till en minskning av kasserade komponenter hos dem.</p> / <p>This report’s aim is to verify if it is possible, and if so, by how much SAS Component could increase the threshold values of all incoming components belonging to an MD-80 Engine Change Kit. How would this raise in the components threshold lower SAS Component’s expenses?</p>

<p>Sammanfattning</p><p>Dagens stigande bränslepriser gör det alltmer viktigt för tillverkare samt brukare av fordon, att fokusera på detaljer som kan minimera drivmedelåtgången. Scania linjetrafikbussar är utrustade med ett antal olika konfigurationer av kåpor som figurerar på bussarnas tak.</p><p>Projektet har således innefattat att undersöka dessa ur ett aerodynamisk perspektiv i Mälardalens högskolas låghastighetsvindtunnel, förlagt vid Hässlö i Västerås.</p><p>Resultaten som uppnåddes är att motståndskofficienten kan reduceras från CD=0,46 till CD=0,41 genom att omplacera orginalkåporna på andra positioner över taket. CD =0,39 erhålls genom att bruka de aerodynamiskt modifierade kåporna. Det skapar en vinst på 55-60 000 kr för orginalkåporna och motsvarande en vinst på 75-80 000 kr för de modifierade kåporna, räknat under bussens livslängd och en drivmedelkostnad på 8 kr/l. Beräkningarna är snålt tilltagna för att ej ge ett överskattat värde, utan är mer ett resultat i underkant. I bilagorna figurerar även andra värden som ger än mer större vinst i kronor</p><p>Resultat uppnås då man tenderar minimera det återcirkulerande och energialstrande flöde som skapas inledningsvis på bussens tak under dess färd.</p>

<p>This thesis work was executed at Swift Engineering Incorporated located in San Clemente, California during spring in 2009. Placement supervisor from Swift was Mark Page and advisor and examiner from the Division of future products at Mälardalen University, Sweden was Gustaf Enebog.</p><p>The objective with this thesis work was to examine the effects of fitness ratio, lift over drag, lift coefficient at cruise, winglet span, wing sweep angle, wing aspect ratio, wing area and weights with respect to Mach number for a conventional business jet capable of 18 passengers. The cruise speed study range from Mach 0.88 to 0.99.</p><p>The Excel based conceptual design tool Jetsizer 2008c was used to make four models with similar configuration and mission but with different cruise Mach numbers.</p><p>A new Jetsizer module was then created to handle a modification process where the models are optimized for their speed and configuration. The result in this report gives guidelines for the needed values when creating an initial CFD model for this type of airplane.</p>

In this thesis, optimization is used to improve the performance of aircraft. The focus is on operating current generation aircraft more efficiently rather than designing new aircraft. Drag minimization and aircraft trajectory optimization is used to increase efficiency. Optimization methods are implemented and evaluated on different problem formulations. The first part of the thesis presents a drag minimization strategy using multiple control surfaces distributed across the span of an elastic wing. Aeroelasticity is exploited to reduce drag for a wide range of flight conditions. A method to minimize drag during a long distance flight is developed and tested in a wind tunnel environment. The method is based on continuously changing the control surface deflections to obtain a more beneficial load distribution from a drag point of view for the current flight condition. In a second study, the method is extended to include the angle of attack as a variable together with the control surface deflections in the drag minimization algorithm. Extensive wind tunnel testing demonstrates the possibility to reduce drag significantly with the presented method for a wide range of flight conditions. The second topic in the thesis is optimizing the aircraft trajectory. The emissions from the aircraft engine are modeled as smooth functions suitable for optimization using published certification data. These emissions are combined in different environmental indices and used as objective functions in the aircraft trajectory optimization problem. The optimization problem is formulated by discretizing the trajectory in time. The resulting large scale nonlinear optimization problem is solved using a sequential quadratic programming method. The trajectory optimization problem is first studied using a model of the Boeing 737 and the results show that the optimal trajectory depends significantly on the definition of the environmental objective function. A method to treat restricted airspace is also presented and evaluated using a model of the Swedish Air Force trainer SK60. The results show that the method for imposing airspace constraints on the flight path works well, especially when the initial point for the optimization is feasible. / QC 20100720

In vehicles with electric transmission and independent wheel stations, there is apossibility to control propulsion, steering and suspension individually for eachwheel. This makes it possible to improve mobility in terrain as well as performanceand driving safety on road. This contribution concerns how a six wheeledelectric transmission vehicle should be modelled to enable evaluation of thedynamic behaviour both in terrain and on road. This is made by combiningmodelling of vehicle, transmission and tyre/terrain behaviour.A tyre/terrain model is needed to simulate driving on soft ground. Heretyre/terrain models for simulating driving with both rigid and pneumatic wheelson soft ground have been developed. A method to measure terrain parametersand drawbar pull for a six-wheeled vehicle on sand is proposed, tested andevaluated.To simulate a six wheeled vehicle at the handling limit on road, a vehicle modelwith a brush tyre model is used in order to get physically reasonable simulationresults during high combined slip conditions. Different vehicle configurationsare considered, where front wheel steering is combined with eithersecond axle steering, rear wheel steering or individual wheel torque control.By applying different vehicle slip angles and thereby limiting the DOF of thevehicle model, the vehicle configurations are evaluated during different drivingconditions. The results show that by applying individual torque control to thefront wheel steered vehicle, the performance is improved for all evaluated manoeuvres,and the achievable aligning torque during a rear wheel skid increasessignificantly if the vehicle slip angle is larger than the maximum front wheelsteering angle.To conclude, models of a six-wheeled vehicle with electric transmission andtyre models both for soft and rigid ground have been developed. These modelsform a simulation platform, which makes it possible to evaluate controlstrategies for the electric transmission with the purpose to improve mobility interrain as well as performance and driving safety on road. Some examples ofapplications of the models are included, e.g. improving at-the-limit handlingand pivot turning performance. / QC 20101026