This master’s thesis is concerned of ride comfort. It uses MBS simulation software MSC Adams, especially its Car module. It contains simulations of ride over the road with obstacles that represent the everyday conditions in real traffic. The main area of focus is to find acceleration data that are present on the driver’s seat and co-driver’s seat in relation on specific suspension settings which affect the ride comfort.

M.Tech. (Chemical Engineering) / Solid waste management is a growing environmental concern in developing countries such as South Africa. Waste tyres fall under the general solid waste category give rise to land filling, health and environmental challenges. As a result, majority of these waste tyres accumulate in large quantities at landfill sites or end up being illegally disposed in open fields. Thus, sustainable remedial technologies such as pyrolysis which are environmentally friendly must be developed. Pyrolysis offers a number of attractive advantages as a treatment option such as the production of primary and secondary economic valuable products, namely pyrolysis gas, oil, char and steel wires. The objective of this work was the development of a business model which includes costing, procurement, installation, commissioning and operating a batch pyrolysis plant in Gauteng, South Africa. In addition this work assesses the environmental, socio-economic aspects for waste tyre derived products. The study objectives were achieved through literature research, site visits, telephonic and personal interviews as well as questionnaires. An order of magnitude costing method was used for the construction of the pyrolysis business model. The model showed that it is possible to operate and sustain a batch pyrolysis plant with a constant supply of waste tyres in the Gauteng region. This research has also shown that a batch plant with a 12 year life span and a projected payback period of approximately 5 years can be operated. However, an initial capital incentive of R 10 173 075.00 is required which includes the cost of all major equipment, plant assessment costs, building and structure, engineering and construction and other costs such as contingency fees and office utilities. Four major income streams are expected to be core revenues for the business; the waste tyre gate fee, tyre derived pyrolysis oil, carbon black and steel wire. Project evaluation methods such as the Return on Investment (ROI), Return of Assets (ROA) and the Rate of Return (ROR) were in strong agreement with those obtained from literature. In addition, the positive net present value shows that the project is viable. However, a stable and well regulated market should exist for the pyrolysis products.

Boliden Mineral AB är ett metallföretag som producerar metaller för det moderna samhället. Företaget har två dagbrottsgruvor belägna i Aitik strax utanför Gällivare i norra Sverige, varav en är landets största dagbrott. Stora gruvtruckar av två olika modeller transporterar malm från gruvan till anrikningsverket där koppar och andra metaller utvinns. Truckarna utgör en viktig del av logistiken som influerar den totala produktiviteten i verksamheten. Skadade truckdäck har visat sig vara en av de största orsakerna till tillgänglighetsförluster för truckarna. Studiens syfte var att skapa en nulägesbeskrivning gällande underhållskedjan av skadade truckdäck i företaget samt ge förslag på förändringar av däckunderhållet för att förbättra tillgängligheten på truckarna genom att minska nedtiden för däckskador. Intervjuer med inblandade personalgrupper i underhållskedjan samt analyser av underhållsdata ligger till grund för resultatet i studien. En RAMS-analys utfördes för att finna felorsaker i underhållskedjan som bidrar till lägre driftsäkerhet av gruvtruckarna med avseende på däckskador. RAMS-analysen påvisade att de flesta flaskhalsarna i underhållskedjan finns inom området underhållssäkerhet, vilket innebär att underhållsorganisationen reagerar för långsamt för att underhållet ska kunna bedrivas optimalt. Däckunderhållet tar generellt för lång tid i förhållande till de ideala feltider som vore möjliga att uppnå för båda truckmodellerna. Tillräcklig utbildning för att bedömma skadade truckdäck saknas stora delar av dygnet, resursbrist kan förekomma i truckverkstaden samt otydliga direktiv råder mellan arbetsgrupper hur kommunikationen skall förmedlas vilket förlänger nedtiderna. I syfte att optimera underhållssäkerheten bör tydliga rutiner mellan arbetsgrupperna skapas, vidare bör utbildningen utökas till berörda arbetsgrupper vilket innebär att bedömning av däckskador kan ske oavsett tid på dygnet. Arbetsfördelningen för de inblandade arbetsgrupperna bör omfördelas för att skapa en mer effektiv underhållskedja. Utifrån funktionssäkerheten visade studien att den nyare truckmodellen har större problem med däckskador än den äldre truckmodellen. Av de truckdäck där drifttiden analyserats visade sig ett av däckmärkena ha för korta drifttider jämfört med Bolidens internt uppsatta gränsvärden. Underhållsmässigheten visade att den nyare truckmodellen är svårare att underhålla eftersom komponenterna är större samt att utrustning saknas för att utföra fler än ett däckbyte samtidigt. I övrigt har Boliden två olika avtal gällande däck och studien presenterar förändringar i dessa som möjliggör att företaget ska kunna höja tillgängligheten. För att kunna göra bättre kartläggningar och analyser om underhållskedjan utifrån underhållsdata kring däckskador på truckarna bör företaget skapa bättre rutiner för inrapportering och dokumentation. / Boliden Mineral AB is a mining company producing metals for the modern society. The company have two open-pit mines in Aitik, situated in Gällivare in the northern part of Sweden. One of these open-pit mines is the largest in the country. Two models of large mining trucks transports ore from the mine to the concentrator where copper and other metals are recovered. The trucks play a key role in the logistics of ore, therefore their availability affect the total production capabilities of the mine. Damaged truck tires is one of the main reasons of downtime of the trucks. The aim of this study was to present a status report of the maintenance chain regarding damaged truck tires in the company and give suggestions about changes in tire maintenance to obtain better availability for the trucks regarding damaged truck tires. The study is based on interviews with workers from different working places who are involved in the maintenance chain as well as studies of maintenance data regarding truck tires. A RAMS (Reliability, Availability, Maintainability and Supportability) analysis was performed in order to discover causes of breakdown and bottlenecks in supportability, maintainability and reliability in the maintenance chain, all of which affect the availability of the plant. Findings in the RAMS analysis demonstrated that most bottlenecks were found in the supportability of the maintenance organization underlining unsatisfactory reaction times during tire breakdowns. The study further exposed the fact that downtime on behalf of damaged truck tires is too long in comparison to the ideal times achievable for the organization. Main causes to this problem is the fact that educated personnel with sufficient knowledge to inspect tire damage is missing most of the day, occasional resource shortages in the truck workshop as well as uncertainty in the communication between different working places which increases the downtime. To optimize the supportability of the maintenance chain the company have to introduce clear routines between the different departments and make sure that necessary education is provided to all sectors so that inspections are possible at any time. The study shows that the reliability for the newer truckmodel have greater problems with damaged truck tires compared to the older model. The lifespan for one of the analyzed truck tires in the study was shorter than the limit put up by the company. The analysis regarding the maintainability displayed the fact that maintenance is more difficult to perform because of larger components. The workshop have merely one device to perform multiple tire changes at the same time which also increases the downtime. This study underlines the fact that changes in the two existing agreements for truck tires may increase availability of the trucks for the company.

This thesis presents a comparison of different methods for measuring road surface skid resistance and an assessment of whether there is a functional dependency in between measurement results of these methods. It consists of a description of the physical quantities, which are measured by these methods and equipment used for these measurements. The work includes the measurement and comparison of measurement outputs with each other. Among the measurement methods there can be seen similar development of their values, with two exceptions there is similar difference between the results of the measurement methods. When comparing the results XL Meter instrument seemed more accurate than the RaceLogic due to its higher frequency of data recording. By using numerical method of comparison between XL Meter device and multipurpose device TRT there was a constant by which the results differed from each instrument, with value of 0,35, using the method of interspacing the resulting differences of values by a line, the resulting constant by which the results differed between the devices had the value of 0,33.

When designing roads it’s important to know what loads will be driven on it. The axles on heavy vehicles can either have super single tires or dual tires which, according to studies, damage the roads differently. The Swedish Transport Administration is developing an understanding for the character of these different kinds of axle and tire types on the loads induced on Swedish roads. In this thesis a field study was conducted to determine the distribution between axles with super single tires and axles with dual tires on heavy vehicles. A highway, a country road and a national road were investigated during the study. The result showed that the number of trucks with single tire axles, i.e. those with super single tires, varies between 39 and 48 percent on the different types of road. That the truck has a single tire axle means that the truck has at least one axle with single tires in addition to the steering axle. A small study was conducted to determine the width of tires on heavy vehicles. A comparison of trucks with single- and dual tire axles was carried out in terms of degradation of the roads. Permanent deformation of unbound layers and fatigue cracking were investigated since these degradation mechanisms are currently used as design parameters in the design of roads. Load values from Bridge Weight In Motion (BWIM) data were used in the calculations and vehicle type 113, 123 and 12211 were investigated. Permanent deformation and fatigue cracking were calculated according to the criteria given in ATB VÄG 2005. Dissipated Creep Strain Energy (DCSE) has been calculated for the selected truck types. The study showed that trucks with axles with single tires accelerate the degradation of the roads. The permanent deformation was almost the same for the two different kinds of axle types.

With advancements in technology, electric vehicles are dominating the world making Internal Combustion engines less relevant, and hence vehicles are becoming quieter than ever before. But noise levels remain a significant concern for both passengers and automotive manufacturers. The vehicle's interior noise can affect the overall driving experience and even the safety of the driver and the passengers. The two main sources of vehicle interior noise are attributed to air-borne noises and structure-borne noises. A modern automobile is a complicated vibration system with several excitation sources like the engine, transmission system, tire/road interface excitation, and wind noise. With electric vehicles on the rise, the engine and transmission noise is practically eliminated, and effective preventive measures and control systems are already in place to reduce the aerodynamic-based noise, vibrations, and harshness (NVH) in modern automobiles making the structure-borne noise the most crucial of the noise sources. Tire/road interaction noise being the most dominant among the structure-borne noise is the main concern of the vehicle interior noise. The two main sources of vehicle interior noise induced by the tire pavement interaction noise are structure-borne noise induced by the low-frequency excitation and air-borne noises produced by the mid and high-frequency excitation. The present study tested an all-season tire over varying operational conditions such as different speeds, normal loads, and inflation pressures on an asphalt surface. Two tri-axial accelerometers attached 1800 apart from each other on the inner liner of the tire of a Volkswagen Jetta were used to measure the circumferential, lateral, and radial acceleration data. An Inertial Measurement Unit (IMU) and velocity box (VBOX) were instrumented in the vehicle to measure the acceleration at the center of gravity (COG) position of the vehicle and the longitudinal velocity of the vehicle respectively. The vehicle was also equipped with a modified hybrid of Close Proximity Testing (CPX) and On-Board Sound Intensity (OBSI) sound measurement systems which were designed and manufactured in-house to measure the tire/road interaction noise at the leading and trailing edges of the tire/road contact patch. Another microphone was instrumented inside the passenger compartment of the vehicle at the passenger's seat right ear position over the tire mounted with the sound measurement system to measure the vehicle interior noise as interpreted by the passengers in the vehicle. Two data acquisition systems coupled with a real-time Simulink model were used to collect all the measured data, one for the noise signals and the other for velocity and acceleration signals. The focus of the current study is to review different generation and amplification mechanisms of the structure-induced tire/road interaction noise and find the relevant dominant frequency ranges of the vehicle interior noise induced by the structure-borne noises using already established physics-based models and correlation techniques. It also aims to find correlations between tire acceleration, vehicle interior noise, and tire pavement interaction noise and their effect on different operational conditions like load, inflation pressure, and velocity. All the signals are studied in the time, frequency, and spectral domain and insights have been drawn on different tire/road noise generation and amplification mechanisms. / Master of Science / Structure-induced vehicle interior noise is one of the main concerns surrounding the automotive NVH industry and tire/road interaction noise being the most dominant source among the structure-borne noises affecting the vehicle interior noise is a major problem to the tire and automotive manufacturers nowadays. It leads to discomfort for the driver and the passengers in the vehicle and can cause fatigue, which in turn can directly affect the vehicle's safety. Several attempts have been made to reduce vehicle interior noise using statistical, physics-based, and hybrid models, but the research is still nowhere near completion. The current study aims to identify the frequency ranges affecting the structure-borne noise-induced vehicle interior noise and uses data-driven approaches in estimating the vehicle interior noise using only the acceleration of the tire. A test setup was designed and developed in-house where a tri-axial accelerometer embedded inside the inner liner of the tire measures the X, Y, and Z acceleration signals. Several microphones are instrumented at the tire/road contact surface and inside the passenger cabin to measure the tire/road interaction noise and the vehicle interior noise. The longitudinal velocity of the vehicle and the accelerations at the center of gravity of the vehicle have also been measured. Multiple data-driven models have been developed to directly predict the vehicle interior noise and tire/road interaction noise using the accelerometer data. This research is directly helpful for the automotive and tire industries by giving them insights on designing and developing quieter tires by using data-driven approaches and further using these with active control systems can mask the vehicle interior noise to acceptable levels in real-time.

När en lastbil färdas på väg utsätts den för ett antal krafter. Däckens rullmotstånd utgör ungefär 36 till 60 % av färdmotståndet. Att kunna validera rullmotståndet vid egen testning är värdefullt för en fordonstillverkare som Scania. Däcktillverkare tillhandahåller en konstant rullmotståndskoefficient men det är oklart om den går att använda i beräkningar för Scanias testsetup.Provningen går ut på att undersöka om testuppställningen möjliggör uppmätning av däckens rullmotstånd på chassidynamometer med momentnav. För den experimentella delen av examensarbetet har en kvantitativ datainsamlingsmetod använts för vidare maskinell analys och manuellt utföra statistisk undersökning. Testdriven utveckling (TDD) har tillämpats för att utifrån testresultaten kunna arbeta iterativt.Vid testningen går rullmotståndskoefficienten upp, ner eller ligger stabilt. Detta beror på att Kistler (Kistler momentnav består av två fälgar som innehåller universalsensorer för att kunna mäta vridmoment) har elektrisk drift som korrelerar till spridning av uppmätt rullmotståndskoefficient. Kistler momentnav är inte repeterbart på grund av drift. Det är möjligt att kompensera för den elektriska driften i Kistler momentnav och beräkna rullmotståndskoefficienten baserat på sista analyspunkten från körningarna.Mätvärden från Kistler momentnav har spridning. Genom att beräkna medelvärde för rullmotståndskoefficienten fås bättre noggrannhet. Medelvärde indikerar att rullmotståndskoefficienten har inget eller litet hastighetsberoende.Det går att använda Kistler momentnav och chassidynamometer 2 som testuppställning för att mäta upp av däckens rullmotståndkoefficient. Det är möjligt för Scania att fortsätta använda denna testuppställning för att bland annat undersöka fler däck. / When a long haul truck travels on a road it’s subjected to a number of forces. The tires rolling resistance is approximately 36 to 60% off the total travel resistance. Being able validate the rolling resistance during own testing is valuable to vehicle manufacturers like Scania. The tire manufacturers provide a constant rolling resistance coefficient but it’s unclear if it can be used in calculations for Scanias test setup.The purpose of the testing is to investigate if the test setup enables measuring the tires rolling resistance on a chassis dynamometer with torque wheels. For the experimental part of the degree project, a quantitative data collection methodology has been used for further machine analyzation and manually performing statistical analysis. Test driven development (TDD) has been applied to work iterative based on the test results.During testing the value of the rolling resistance coefficient went up, down or was stable. This is dependent on the electrical drift Kistler have (Kistler torque wheel consists of two rims that contain universal sensors to measure torque), that correlated with the distribution of the measured rolling resistance coefficient. It’s possible to compensate for the electrical drift in Kistler torque wheel and calculate the rolling resistance coefficient based on the last analyzation point from the tests.The measurements from Kistler torque wheel are distributed. By calculating the average of the rolling resistance coefficients a higher degree of accuracy is obtained. The average indicates that the rolling resistance coefficient have no or a small speed dependency.It’s possible to use Kistler torque wheel and chassis dynamometer 2 as a test setup to measure the rolling resistance of the tires. It’s possible for Scania to continue using this test setup to investigate more tires.

Doctor of Philosophy / The control systems installed in modern vehicles lack crucial information regarding the interaction between the tires and the road surface. This knowledge gap significantly impacts the safety and control of the vehicle. Thus, to address this issue, this research introduces a novel fusion approach to estimate friction at the tire-road contact interface. This hybrid fusion friction estimation algorithm employs techniques like signal processing and machine learning, backed up by information from various vehicle and tire dynamics models, to develop algorithms that estimate the level of friction between the tire and the road. This fusion approach enables more precise estimations of the friction coefficient in both normal driving situations and scenarios involving sudden changes in speed or road conditions. Therefore, this research aids in enhancing vehicle safety and control by providing improved information about such tire-road interactions.

Tires, being the only component of the vehicle in contact with the road surface, are responsible for generating the forces for maintaining the vehicle pose, orientation and stability of the vehicle. Additionally, the on-board advanced chassis control systems require estimation of these tire-road interaction properties for their operation. Extraction of these properties becomes extremely important in handling limit maneuvers such as Double Lane Change (DLC) and cornering wherein the lateral force transfer is dependent upon these computations. This research focuses on the development of a high-fidelity vehicle-tire model and control algorithm framework for vehicle trajectory tracking for vehicles operating in this limit handling regime. This combined vehicle-tire model places an emphasis on the lateral dynamics of the vehicle by integrating the effects of relaxation length on the contact patch force generation. The vertical dynamics of the vehicle have also been analyzed, and a novel double damper has been mathematically modeled and experimentally validated. Different control algorithms, both classical and machine learning-based, have been developed for optimizing this vertical dynamics model. Experimental data has been collected by instrumenting a vehicle with in-tire accelerometers, IMU, GPS, and encoders for slalom and lane change maneuvers. Different state estimation techniques have been developed to predict the vehicle side slip angle, tire slip angle, and normal load to further assist the developed vehicle-tire model. To make the entire framework more robust, Machine Learning algorithms have been developed to classify between different levels of tire wear. The effect of tire tread wear on the pneumatic trail of the tire has been further evaluated, which affects the aligning moment and lateral force generation. Finally, a Model Predictive Control (MPC) framework has been developed to compare the performance between the conventional vehicle models and the developed vehicle models in tracking a reference trajectory. / Doctor of Philosophy / In our rapidly advancing world, self-driving or autonomous vehicles are no longer a vision of the future but a reality of today. As we grow more reliant on these vehicles, ensuring their safety and reliability becomes increasingly critical. Unlike traditional vehicles, self-driving cars operate without human intervention. Consequently, the onus of passenger and pedestrian safety falls squarely on the vehicle's control systems. The efficiency and effectiveness of these control systems are pivotal in preventing accidents and ensuring a smooth ride. One vital aspect of these control systems lies in understanding the tires' behavior, the only parts of the vehicle that are in contact with the road surface. A tire's interaction with the road surface significantly impacts the vehicle's handling and stability. Information such as how much of the tire is in contact with the road, the forces and moments generated at this contact point, becomes valuable for optimizing the vehicle's performance. This is particularly crucial when a vehicle is turning or cornering, where the forces developed between the tires and the road are key to maintaining control and stability. In this research, a framework has been designed to improve the vehicle performance, primarily by improving the modeling of tire lag dynamics. This refers to the delay or 'lag' between a change in tire conditions (such as pressure, wear, and temperature) and the corresponding change in tire behavior. In addition, in this research a vertical dynamics model of the vehicle has also been developed incorporated with a novel double damper suspension system. To complete the entire framework, the effect of tire wear over time and how this affects its performance and safety characteristics has also been examined. By estimating and understanding this wear, we can predict how it will affect the dynamic properties of the tire, thus improving the reliability and efficiency of our autonomous vehicles. The last piece of this framework comprises the development of an MPC controller to track a reference trajectory and evaluate the performance of the developed model.

[pt] O volume de pneus inservíveis continua aumentando a cada ano, se tornando um tema de grande preocupação para a sociedade. Motivados por esta problemática ambiental, o presente estudo experimental propõe utilizar a borracha de pneu triturada como reforço de solos, em duas diferentes granulometrias (chips e fibras), como material alternativo para o reforço de dois tipos de solos (areia e solo argiloso). Com este fim realizaram-se ensaios mecânicos, tais como ensaios de compactação proctor standard, ensaios triaxiais do tipo consolidado e isotropicamente drenado e ensaios de adensamento unidimensional, para avaliar os efeitos da granulometria da borracha de pneu, triturada em chips e fibras (com os tamanhos médios de 4,6 mm e 2 mm, respectivamente) e do teor de borracha de pneu (5, 10 por cento e 15 por cento em relação à massa de solo seco), no comportamento mecânico de misturas de areia-borracha e de misturas solo argiloso-borracha. Os resultados mostraram que tanto os chips como as fibras de pneu de borracha contribuem no aumento dos parâmetros de resistência ao cisalhamento de ambos os solos e aumentam a energia de deformação absorvida durante o cisalhamento. Ao analisar a resposta obtida em ambos os solos, se evidencia que, tanto para a argila quanto para a areia, foi mais efetivo o reforço com 10 por cento de fibras de borracha de pneu. Todos os compósitos estudados possuem características de resistência que poderiam cumprir as exigências de determinadas obras geotécnicas (aterros sobre solos moles, reforço de taludes, solo de base de fundações superficiais), portanto o uso da borracha de pneu como reforço de solos contribuiria com o menor consumo de material natural e redução dos custos de transporte e volume de material mobilizado. / [en] The volume of discarded tires continues to increase each year, becoming a major topic of concern for society. Motivated by this environmental issue, this experimental study proposes using tire chips and tire buffings as an alternative material to improve the shear strength of two types of soil (sand and clayey soil). Because of this, standard Proctor compaction tests, consolidated-drained triaxial tests and compressibility tests were performed to assess the influence of tire rubber particle size, (with average sizes of 4.6 mm and 2 mm, respectively) and tire rubber content (5, 10 percent and 15 percent by dry weight of soil) into the mechanical behavior of sand and clayey soil. The tests results showed that both, chips and buffings contribute increasing the shear strength parameters of both the soil and increase the strain energy absorbed during the shear phase. By analyzing, the mechanical response both for clayey soil and for sand was found that the best shear strength improvement was obtained at 10 percent of tire buffings. All the composites showed resistance characteristics that would ensure the requirements for many geotechnical applications (embankments over soft soils, slope reinforcement and surface foundations), so the use of waste tires as a reinforcement material would help solve problems associated with natural resources and reducing transportation costs and earthmoving.