High-speed planing craft is designed to overcome conventional hull’s speed barrier associated with wave making resistance and high frictional forces. Despite being able to reach high speeds, some planing hull forms will develop large volumes of spray attached to the hull surface, which can account for a large proportion of the total resistance. In this study, an experimental evaluation of the novel spray deflector technology proposed by Petestep AB is carried out in model scale at the Davidson Laboratory towing tank. The spray deflectors are compared against a time-proven spray rails technology and bare hull configuration. A modular hull design was developed that allows for rapid conversion between the three hull configurations and for future modifications to the design. The calm water resistance tests have shown up to 9% resistance reduction for spray rails and up to 25.75% reduction for spray deflectors as compared to the bare hull configuration. The running position of the spray deflector configuration was affected by the selected deflector design and differed from the spray rail and bare hull configuration, making the direct comparison of the technologies inapplicable. The Irregular waves tests have shown that for the current deflector design, the significant accelerations are approximately the same for the spray rail and spray deflector configurations. Both the technologies have led to increased accelerations at the center of gravity as compared to the bare hull. The spray deflector configuration, however, experienced lower accelerations in the bow area. A number of improvements to the current model design were proposed for the next series of experiments.

The sales of all-terrain vehicles (ATVs) are increasing year by year, especially in countries like Sweden, Australia and New Zealand. With the increase in sales, a proportional rise in number of accidents involving all-terrain vehicles is also evident. Of these accidents the major cause was identified as rollover occurrence. While there are some protection devices, the lack of rollover prevention devices available is glaring. In addition to that, ATVs do not have many control units or electronic systems compared to modern-day cars. This makes it difficult to implement complicated computer technology to improve vehicle stability or act as a prevention system. In this thesis, a couple of active safety systems to prevent rollover have been proposed. Lateral Load Transfer Ratio (LLTR) is used as the primary parameter to analyse and signify rollover. First, an alarm has been proposed based on LLTR and roll angle. Two different types of alarms have been analysed, one based on real-time values and the other on predicted values. The prediction-based alarm shows better performance over the other alarm by giving the driver more time to take action. Second, to remove the flaws of the alarms and take away control from the driver, in case of impending rollover, an active braking system has been proposed. Multiple braking strategies have been simulated. The strategy where the brakes are applied on the outer wheels was found to be most effective. / Försäljningen av terrängfordon (ATV:s) ökar år för år, särskilt i länder som Sverige, Australien och Nya Zeeland. Som effekt av den ökande försäljningen kan man observera en proportionell ökning av antalet olyckor med terrängfordon. Bland dessa har huvudorsaken identifierats till vältningsolyckor. Även om det i dagsläget finns anordningar som skyddar förare av ATV:s vid tippning så råder det en tydlig brist på utrustning som förebygger själva vältningen. Dessutom har ATV:s inte många reglerenheter eller elektroniska system jämfört med moderna bilar. Detta gör det svårt att implementera komplicerad elektronisk teknologi för att förbättra stabilitet och förebygga uppkomsten av vältning. I denna avhandling har flera aktiva säkerhetssystem som förebygger vältning föreslagits. Lateral Load Transfer Ratio (LLTR) används som den primära parametern för att analysera och visa på risken av vältning. Först har ett varningssystem föreslagits i form av ett larm baserat på LLTR och krängningsvinkel. Två olika typer larm har analyserats, ett baserat på realtidsvärdena av dessa parametrar och det andra på deras predikterade värden. Larmet baserat på prediktering har visat bättre resultat gentemot realtidsalarmet genom att förse föraren med mer tid för att utföra en stabiliserande manöver. För att förbättra effektiviteten av säkerhetssystemet och befria föraren från att behöva vidta åtgärder har även ett aktivt bromssystem föreslagits där olika bromsstrategier simulerats. Av dessa vältningsförebyggande bromsstrategier har det som bromsar de yttre hjulen visat bäst resultat.

This thesis report presents a comprehensive study on the design and development of an Additively manufactured Unit cell for car door panels, aiming to enhance impact resistance and reduce noise transmission to the vehicle cabin. In order to accomplish these goals, the study focuses on combining two novel techniques namely quasi-zero stiffness (QZS) structures and phononic crystals (both scattering and locally resonating type).The research begins by looking into similar research work, choosing appropriate unit cell topologies, and characterizing the materials suitable for AM. The performance of the unit cell design is then assessed using FEA simulations. To improve noise absorption and impact resistance, optimization techniques can be used.The experimental results demonstrate that the combination of QZS structures effectively enhances the unit cell’s ability to withstand impacts by redistributing and dissipating energy. Additionally, phononic crystal integration that employs both scattering and locally resonating mechanisms proves successful in attenuating noise transmission across a wide frequency range.The projected performance advantages of the 3D printed unit cell prototypes are confirmed by experimental testing. Measurements of noise absorption, impact resistance and mechanical testing confirm the viability of the suggested design.The findings of this research contribute to the advancement of additive manufacturing techniques in the automotive industry. The proposed unit cell design for 3D printing exhibits potential for enhancing occupant safety and acoustic comfort in automotive door panels. The proposed technologies have the potential to be further optimized and integrated to produce enhanced automotive door panels with higher impact resistance and noise reduction capabilities

As axle loads and speeds constantly increase in rail transport, new track systems are being developed. One such development is the ballastless track system. Today there are several types and variations of slab tracks, but how do they differ, and which one is the best? This thesis aims to answer these questions for given scenarios as each system has its unique set of strengths and therefore performs differently compared to the other systems for different projects. In this thesis, several existing ballastless track solutions have been studied. This was done viaballastless system manufacturer websites, brochures, other notable literature as well as multiple meetings with each of the system manufacturers. As a result, a descriptive list of nine different systems has been developed as well as a more detailed comparison in the shape of a table. To find out which one should be used and when, a model was developed for comparison of them. This model is based on a Multiple-criteria decision analysis (MCDA). This is a tool that can be used to compare different alternatives, based on several, often conflicting criteria. In the end, the VIKOR method was chosen. The choice was based on VIKOR’s user-friendliness, as well as implementation of auxiliary features, such as regret-value and compromise solutions. The MCDA based model was built in Excel and MATLAB and is expandable to the needs of the user. To test the model and whether it contains any bias, a sensitivity study was carried out. Ten hypothetical scenarios were set up and corresponding importance weights were assigned accordingly. The results were mixed and sparse for the different hypothetical scenarios and showed that no, or little, inherent biases were present in the model. Thus, the model proved to be successful in the end, and can therefore be a good addition to the selection process of a ballastless system alongside other studies, such as Life-cycle cost analysis (LCCA). There is however still some more development that could be done to improve the model. Finally, to demonstrate how the model is implemented for a rail project, a case study was carried out. The case study was conducted for a single hypothetical tunnel close to a city, assumed to be in Sweden. The background conditions were described, and the weighting process was illustrated and inserted to the model. For this particular case the ÖBB-Porr system from the Porr group proved to be the most suitable choice. / Över tid har spårfordon blivit tyngre och snabbare. Samtidigt har nya spårsystem utvecklats. En sådan utveckling är ballastfria spårsystem. Idag finns det ett brett utbud av sådana system, men hur skiljer de sig åt och vilket är bäst? I detta examensarbete söks svar på de frågorna förgivna scenarier. Detta görs eftersom de olika systemen har olika styrkor och därför lämpar sig bäst för olika projekt, jämfört med övriga system. I detta examensarbete har ett flertal ballastfria spårsystem studerats. Detta har gjorts genomtillverkares hemsidor, broschyrer, annan relevant litteratur så väl som genom möten med representanter från olika tillverkare. Som ett resultat av detta har systembeskrivningar av nio olika system och en mer detaljerad jämförelsetabell utförts. För att ta reda på vilket spårsystem som lämpar sig bäst i en given situation har en matematisk modell utvecklats med målet att jämföra olika system. Modellen är baserat på en Multiplecriteria decision analysis (MCDA). Detta verktyg kan, baserat på kriterier, jämföra och rankasystemen. I detta examensarbete valdes VIKOR-metoden (en av flera MCDA:s) baserat på dess relativt enkla struktur, valfria användandet av regret-value och lösningskompromisser. Excel och MATLAB användes för att bygga modellen som även är anpassad för framtida expansion. För att kontrollera om modellen är opartisk utfördes en känslighetsanalys. Tio olika scenarier skapades och vikter baserat på scenariernas krav på kriterier sattes. Resultaten var blandade vilket tyder på att modellen är opartisk eller nära opartisk. Modellen kan därmed anses vara ett bra supplement till andra beslutsmetoder, såsom Life-cycle cost analysis (LCCA). Det finns dock fortfarande möjliga förbättringar för framtida studier att ta itu med. I slutändan visas det på hur modellen kan användas på ett spårprojekt i form av en fallstudie. Studien gjordes på en hypotetisk tunnel som mynnar ut i en stad, vars antagna land är Sverige. En bakgrund beskrevs och vikter togs fram därefter och användes i modellen. För detta hypotetiska projekt visade sig systemet ÖBB-Porr från Porr group vara bäst lämpat.

The automotive industry stands in front of a great challenge, to decrease its impact on the environment. One important part in succeeding with this is to decrease the structural weight of the body structure and by that the fuel consumption or the required battery power. Carbon fibre composites are by many seen as the only real option when traditional engineering materials are running out of potential for further weight reduction. However, the automotive industry lacks experience working with structural composites and the methods for high volume composite manufacturing are immature. The development of a composite automotive body structure, therefore, needs methods to support and guide the conceptual work to improve the financial and technical results. In this thesis a framework is presented which will provide guidelines for the conceptual phase of the development of an automotive body structure. The framework follows two main paths, one to strive for the ideal material diversity, which also defines an initial partition of the body structure based on the process and material selection. Secondly, a further analysis of the structures are made to evaluate if a more cost and weight efficient solution can be found by a more differential design and by that define the ideal part size. In the case and parameter studies performed, different carbon fibre composite material systems and processes are compared and evaluated. The results show that high performance material system with continuous fibres becomes both more cost and performance effective compared to industrialised discontinuous fibre composites. But also that cycle times, sometimes, are less important than a competitive feedstock cost for a manufacturing process. When further analysing the manufacturing design of the structures it is seen that further partition(s) can become cost effective if the size and complexity is large enough. / <p>QC 20140527</p>

To reduce development cost and to avoid late design fixes in aircraft design, methods that are fast and economic in estimating the aerodynamic characteristics of complex flight vehicles at the preliminary design stage are desired. This work and thesis focus on the adaptive-fidelity CFD approach, with emphasis on the high end of the CFD tools available today. The core idea of the method is to use computationally cheap modeling in the part of the flight envelope where it is applicable. When the complexity in the flow field increases more details and realism is included in the mathematical model, at a computationally higher cost. A typical case where this would be required could be at the border of the flight envelope, where flow phenomena such as shocks, flow separation, and interacting vortex systems could occur. Since the number of cases needed to resolve the flight envelope could be in the order of ten thousands automation is required. The bottlenecks are the discretization of the fluid volume and evaluation of raw CFD data and post processing of the data. These issues are also discussed in this work. The method has been tested on two real flying aircraft, the X-31 delta-winged aircraft with vector thrust, and the Ranger 2000 Jet trainer, as well as on the SACCON preliminary wing-body UCAV design. The results provide improved understanding of the usefulness of this method as an analysis tool during the preliminary design phase all the way into the flight test diagnostic phase of a new aircraft. / QC 20110314

In aircraft design, methods for rapid aerodata assessment and data screening at early stages are instrumentalin reducing development cost and first-time-right processes. New efficient tools for the analysis can easethe transition as the traditional and rigidly structured sequential design process gives way to a concurrentmulti-disciplinary process with the compressed time-span required in the competition for market shares. The CEASIOM-SUMO-EDGE software suite provides a way from initial sizing to stability and control design andassessment, including effects of aero-elasticity. CEASIOM ongoing and further development is driven by user needs, and the thesis reports on fourdifferent design and analysis cases which required enhancement of CEASIOM in several respects. The validation study on the B-747 with its multitude of control surfaces required generalizationof control surface definition and modeling. The clean-sheet design of the TransCruiser Mach 0.97passenger transport required compilation, fusion, and screening of aerodynamics data from many sourcesand in different formats. The DanBus and the asymmetrical twin-prop pusher-puller configuration required translationof geometry representation and development of simple propeller models in the automatic meshgeneration and CFD analysis. The way forward is provided by adoption of common data formats and geometry (and structural, etc.)modeling conventions. To this end the current proprietary XML format should be replaced by a more generalXML system such as CPACS under development at DLR which will be made public in the near future. / QC 20110629 / SimSAC, 6th EU Framework Programme

Vehicles with different capabilities for automated driving will gradually be deployed in road transportation systems over the coming decades. Mixed traffic conditions may change the characteristics of the traffic flow dynamics.  Microscopic traffic simulation is used for studying traffic flow dynamics in transportation systems. By simulating the interactions between individual vehicles, effects caused by changes in the road infrastructure, by road closures, or by the number and the types of vehicles can be investigated. Impacts on traffic performance can be analyzed in terms of travel times, travel time delays, queue formations, or vehicle throughput. To evaluate the impact of automated driving on traffic performance using microscopic traffic simulation, existing microscopic driving models need to be further developed to describe automated driving.  The aim of this thesis is to investigate how to further develop microscopic traffic simulation models for automated driving. In this investigation, the aspects to consider in simulation experiments including automated driving are identified. These aspects are the vehicle system, the role of authorities, the role of the users, of the infrastructure, of connectivity features, and of the sensor-based perception of the vehicles. A microscopic traffic simulation experiment showing the possible effects on a motorway in terms of vehicle throughput and travel delays is presented.  A conceptual model that describes how driving automation systems deal with the perception tasks is proposed. Future research directions will focus on implementing this model for perception in traffic simulation platforms and on the modeling of lateral tactical maneuvers. iii

Delsbo Electric är en årlig tävling mellan olika lag från diverse universitet och högskolor. Tävlingen går ut på att tillverka ett rälsfordon som kan köra på en 3,36 km lång bana med så låg energiförbrukning som möjligt. Rälsfordonet måste ha plats för en till sex passagerare och måste vara batteridrivet. Inför tävlingen 2022 bestämde sig en grupp med KTH-studenter för att delta. Denna rapport beskriver processen från konceptdesignen till tillverkningen av bottenplattan för rälsfordonet tänkt att delta i tävlingen. Målet med bottenplattan var att göra tillverkningsprocessen så enkel, billig och miljövänlig som möjligt. Det fanns även en önskan om att göra hela designen modulär så att man enkelt skulle kunna återanvända önskvärda delar och/eller enkelt byta ut delar för framtida tävlingar. En koldioxidanalys gjordes för råvarorna och tillverkningen av bottenplattan samt för axeln och axelkåpan. Externa och interna belastningar beräknades och olika utföranden och material testades. Resultatet blev en bottenplatta av plywood med fyra L-profiler och två U-profiler av aluminium. Plattans totala längd blev 3,5 m och 0,6 m bred. Den totala kostnaden uppskattades till 1470 kr. Totala ekvivalenta koldioxidutsläppet beräknades till mellan 64,23 – 134 kg CO2e, beroende på återvunnen av plywooden och aluminiumet.

This thesis research the system safety aspects of a Steer-by-Wire system by studying how a driver handles faults in the system. To start with, identification of risks in the SbW system was performed, followed by identification of potential faults with the help of a HAZOP study. Furthermore, an assessment of risk severity and controllability was performed by the use of the ISO26262 standard and its ASIL classification scheme, as well as the safety analysis FMEA. A steering feel model, with the possibility to simulate the faults from the risk assessment research, were implemented in Simulink and CarMaker. A vehicle model as well as a test scenario were built for both country road driving and highway driving. An experimental study was done using a Logitech G29 steering wheel where six test subjects were involved. To analyse the experiment results and evaluate the severity of the system faults, both subjective evaluation criteria and objective evaluation criteria were introduced in this study. A trend of severity was seen in the majority of the evaluation criteria, showing the signal delay and reduction in steering gear ratio as the two most severe faults. Finally, some examples of mitigation strategies, such as the use of redundancy, was discussed. / Denna avhandling studerar systemsäkerhetsapsekterna av ett Steer-by-Wire system genom att undersöka hur en förare hanterar situaitonen när systemet fallerar. Först startades en process av identifiering av risker, som följdes av en process av identifiering av potentiella fel med hjälp av en HAZOP studie. Därefter var en utvärdering av risk gjord i enlighet med ISO26262 standarden och dess ASIL klassificeringsplan, samt en säkerhetsanalys enligt FMEA. En modell av styrningen med möjligheten att simulera fel skapades i Simulink och implementerades i CarMaker, där ett antal fel injicerades i enlighet med tidigare riskundersökning. En fordonsmodell samt testscenario skapades för både landsvägskörning samt motorvägskörning. En experimentell studie med en Logitech G29 ratt gjordes med sex deltagare. För att analysera de experimentella resultaten och utvärdera allvarlighetsgraden för de studerade systemfelen introducerades både subjektiva kriterier och objektiva kriterier. En trend för allvarlighetsgraden urskiljades i majoriteten av kriterierna, där signalfördröjning samt reduktion av styrningens utväxling uppfattades som de allvarligaste felen. Till sist, undersöktes exempel på mildrande strategier, som t.ex. användandet av redundans.