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.

<p>By today’s date there are a lot of companies that are in great need of restructuring their paperwork in a more organized way. This can be excellent arranged with the help of properly constructed computer software. The aviation industry is no exception, but actually a good example of this. Täby Air Maintenance (TAM) is a company which is situated in Örebro. Their main business is aircraft maintenance on a variety of aircraft models. TAM has so far handled their work by hand or with the help of a majority of small computer programmes. The information has now become too abundant and the different kinds of software being used are no longer a working tool for the company. There is therefore a demand for an exhaustive programme which has the capacity to take care of all parts in logistics and production. The purpose is to examine and evaluate three different makes of software and form a recommendation to TAM of which one suits their needs the best. The software was Airsoft, MX System and System Airline Management (SAM). The evaluation has been performed with the help of demo versions of the programmes, manuals and support from contacts at the different manufacturers. The programmes were initially dealt with one at a time and then compared towards each other and towards the demands from TAM. The software which in the end was recommended was SAM, and the decision was based on a number of reasons. The main reason was the user friendliness of the software - the fact that its logical structure makes it easy for its user to swiftly understand the concept and thus learn how to use it quickly. This results in profits, both in time and money.</p> / <p>Idag är många företag i trängande behov av att strukturera upp sitt pappersarbete på ett mer ordnat sätt. Detta kan ske på ett effektivt sätt med ett anpassat och ändamålsenligt strukturerat datorprogram. Flygbranschen är inget undantag, snarare ett bra exempel på detta. Täby Air Maintenance (TAM) är ett företag som är beläget i Örebro och utför underhåll på flygplan i varierande storlek. TAM har hittills skött arbetet för hand och med hjälp av ett flertal mindre datorprogram. Informationen har dock blivit alldeles för omfångsrik och de olika programmen är inte längre ett fungerande instrument för verksamheten. Det krävs därför ett heltäckande program som har kapaciteten att ta hand om alla delar, såväl logistik som produktion. Syftet är att undersöka tre olika program och ge en rekommendation på det som passar företaget bäst. Programmen är Airsoft, MX System och System Airline Management (SAM). Undersökningen har utförts med hjälp av demoversioner, manualer och stöd från kontaktpersoner hos tillverkarna. Programmen undersöktes först var för sig och därefter jämfördes de mot varandra och mot TAMs krav. Det program som rekommenderades var SAM. Detta beror på en mängd orsaker, där den främsta orsaken var programmets användarvänlighet - det faktum att dess logiska uppbyggnad gör det lätt för användaren att snabbt kunna sätta sig in i strukturen och därmed lättare kunna lära sig att använda det. Detta i sin tur ger vinster i både tid och pengar.</p>

<p>An engineering firm which handles and constructs drawings needs well defined routines and structures which should be homogeneous through all the different departments. A common drawing system results in better quality and cooperation between the departments.</p><p>SAS Technical Services (STS) did not have a common drawing system which had led to development of different routines in the different regions and departments. Requested was development of new routines regarding engineering drawings, such as drawing numbering structure, revision and subscription routines, which standards to adhere to, custom made drawing templates and management of the drawings with belonging documents.</p><p>Each requested task was broken into minor tasks and analyzed. Solutions by different leading engineering companies were used for comparison and ideas.</p><p>All the tasks were collected and organized in one single document which is the result of the thesis; a drawing instruction.</p><p>The drawing instruction will after a learning phase ease the work for the STS engineers as all necessary information can be found in one single place. Also, work with contractors will be time-saving as the instruction can be handed out for guidance.</p> / <p>En ingenjörsfirma som hanterar och skapar mängder med ritningar behöver väldefinierade rutiner och strukturer som är homogena genom hela bolaget. Ett gemensamt ritningssystem resulterar i bättre kvalitet och bättre samarbete mellan de olika avdelningarna.</p><p>SAS Technical Services (STS) hade inte ett gemensamt ritningssystem vilket har lett till att de olika avdelningarna har utvecklat olika rutiner rörande ritningar. Önskemålet var utvecklande av nya rutiner rörande ingenjörsritningar såsom ritningsnumreringsstruktur, revisions- och prenumerationsrutiner, vilka standarder som skall följas, egna ritningsmallar och skötsel av ritningar med tillhörande dokument.</p><p>Varje önskad uppgift blev uppdelad i mindre uppgifter och analyserad. Lösningar från olika ledande ingenjörsbolag användes för jämförelse och idéer.</p><p>Alla uppgifterna samlades och organiserades i ett och samma dokument som är resultatet av detta arbete; en ritningsinstruktion.</p><p>Ritningsinstruktionen kommer efter en inlärningsfas underlätta arbetet för ingenjörerna på STS eftersom all nödvändig information nu finns på ett och samma ställe. Arbeten med entreprenörer vill också bli underlättande eftersom instruktionen kan delas ut för vägledning.</p>

<p>For every operating condition of an internal combustion engine there exists an optimal spark timing, called maximum brake torque (MBT), which maximises the output torque and the efficiency of the engine. Traditionally MBT timing is implemented as an open-loop control where the ignition timing is found by using a combination of static lookup tables and sensor information. With a direct closed-loop control from the combustion process the performance of internal combustion engines could be improved. The thesis investigates if it is possible to estimate the MBT timing from the ionization current for every operating condition of a spark ignited engine where the operating conditions are defined by the engine parameters lambda, internal exhaust gas recirculation, engine load, engine speed and spark advance.</p><p>First an investigation of how much loss of torque an error from the MBT position corresponds to is made. Then the influence of the engine parameters on the shape of the ionization current was studied. Last different peak pressure position (PPP) estimating algorithms are presented and a new technique is developed where an engine operating point dependant part of the ionization current is used depending on the current operating condition of the engine. Two of the presented PPP estimating algorithms are then complemented with this technique and the results look promising.</p>

Composite structures can lower the weight of an airliner significantly. Due to the higher process complexity and the high material cost, however, the low weight often comes with a significant increase in production cost. The application of cost-effective design strategies is one mean to meet this challenge. In this thesis, a simplified form of direct operating cost is suggested as a comparative value that in combination with multidisciplinary optimization enables the evaluation of a design solution in terms of cost and weight. The proposed cost optimization framework takes into account the manufacturing cost, the non-destructive testing cost and the lifetime fuel consumption based on the weight of the aircraft, thus using a simplified version of the direct operating cost as the objective function. The manufacturing cost can be estimated by means of different techniques. For the proposed optimization framework, feature-based parametric cost models prove to be most suitable. Paper A contains a parametric study in which a skin/stringer panel is optimized for a series of cost/weight ratios (weight penalties) and material configurations. The weight penalty (defined as the specific lifetime fuel burn) is dependent on the fuel consumption of the aircraft, the fuel price and the viewpoint of the optimizer. It is concluded that the ideal choice of the design solution is neither low-cost nor low-weight but rather a combination thereof. Paper B proposes the inclusion of non-destructive testing cost in the design process of composite components, and the adjustment of the design strength of each laminate according to inspection parameters. Hence, the scan pitch of the ultrasonic testing is regarded as a variable, representing an index for the guaranteed material quality. It is shown that the cost for non-destructive testing can be lowered if the quality level of the laminate is assigned and adjusted in an early design stage. In Paper C and Paper D the parameters of the manufacturing processes are upgraded during the cost optimization of the component. In Paper C, the framework is extended by the cost-efficient adaptation of parameters in order to reflect the situation when machining an aluminum component. For different weight penalties, the spar thickness and stringer geometry of the provided case study vary. In addition, another cutter is chosen with regard to the modified shape of the stringer. In Paper D, the methodology is extended to the draping of composite fabrics, thus optimizing not only the stacking layup, but also the draping strategy itself. As in the previous cases, the design alters for different settings of the weight penalty. In particular, one can see a distinct change in fiber layup between the minimum weight and the minimum cost solution. Paper E summarizes the work proposed in Papers A-D and provides a case study on a C-spar component. Five material systems are used for this case study and compared in terms of cost and weight. The case study shows the impact of the weight penalty, the material cost and the labor rate on the choice of the material system. For low weight penalties, for example, the aluminum spar is the most cost-effective solution. For high weight penalties, the RTM system is favorable. The paper also discusses shortcomings with the presented methodology and thereby opens up for future method developments. / QC 20100723 / European Framework Program 6, project ALCAS, AIP4-CT-2003-516092 / Nationella flygtekniska forskningsprogrammet (NFFP) 4, project kostnadseffektiv kompositstruktur (KEKS)