The diploma thesis, which belongs to the area of vehicle dynamics, deals with the issue of suspension of trucks cabins. In particular, it focuses on the suspension of a race truck cab such as the Rally Dakar. Includes an overview of truck suspension (especially cabs), driving comfort assessment methods and the impact of vibration on human. To verify the suitability of using different cab suspension concepts, a multibody model was built in program MSC ADAMS. Suitable primary suspension has been found appropriate for this model. Cab suspension was tested for driving safety, but first for driving comfort.

This thesis deals with an axle design for an autonomous minibus. The theoretical part is about axles then the next one goes over the given parameters. Following with a selection of suitable parts for use and designs of parts for production. This chapter is also about geometry and driving characteristics analyzation. The next chapters are devoted to the calculations of the loads on the lower arm, its design and static analysis. The last chapter combines all the parts together into a conceptual design.

The first part of the master's thesis deals with basic types and functions of dampers, together with a search of commonly used methods of damper force measurements. Consequently, a design of an on-road damper force measuring assembly is made and positioned onto a 3D model of a vehicle's damper. In the final part of the thesis there is made an evaluation of conditions of use of the measuring assembly together with its versatility.

A promising energy harvesting technique involves the use of thermal nanofluids, capable of collecting solar UV/visible radiation and storing it as latent heat in phase change materials (PCM), i.e. molten salts. Carbon-based materials are very interesting candidates for UV/visible light absorption and heat transfer in the nanofluid. The crucial point of the development is the stabilisation of dispersed carbon in a suspension. This works is an investigation on the preparation of stabilized suspensions of carbon black, mesophase carbon beads or exfoliated graphite, in aqueous solutions. To achieve this goal, chemical modifications of the surface functional groups of the carbon grains have been attempted. Carbon has many allotropes in which it can exist such as diamond, graphite and amorphous carbon. None of these forms a stable suspension in water without a proper surface treatment. The first priority of this study was to identify possible surface treatments that would modify the surface complex on the carbon materials. Once the treatments had been identified, the focus of the study moved to selecting the most effective treatment based on its dispersion properties. The temperature ranges under which the carbon material remained in a suspension were measured. Finally, the effect of the surface area of the treated carbon material on the stability of the carbon material suspension was investigated. The characterisation techniques that contributed to achieving these objectives were observations with the naked eye, mass spectrometer measurements, thermogravimetric analysis, BET and scanning electron microscope images. The mass spectrometer and scanning electron microscope provided information on the modification of the surface complexes to gain an understanding of the effect of the treatment on the surface of carbon materials. The stability of the carbon and water suspension was measured by using the mass spectrometer and doing a thermogravimetric analysis. The BET results indicated the size of the specific surface area. The size of the surface area could assist in understanding of the stability of the carbon and water suspension. Following an analysis of the results, the researcher reached the following conclusions: First, acid treatments with a concentration of 1 molar for the duration of a minimum of 4 days modify the surface complexes of the carbon black. Second, the treatment with the most stable dispersion properties is the potassium permanganate and nitric acid treatment, which is the only treatment that formed a stable suspension. Carbon materials with a smaller surface area than the treated carbon black does not form a stable suspension, even though they have similar surface complexes. The stable dispersion remains stable only up to 250 ºC. Higher temperatures cause the carbon material to start decomposing, when the carbon surface complexes are broken and released. / Dissertation (MEng)--University of Pretoria, 2018. / Chemical Engineering / MEng / Unrestricted

A well-known challenge in vehicle dynamics is to design a vehicle that will not only keep the occupants comfortable, but will also ensure safe and stable operation during various manoeuvres over multiple driving surfaces. A soft and compliant suspension is generally required for good ride comfort, while a stiff suspension with a low centre of mass is required for improved handling. These contradicting factors in the design process is commonly referred to as the ride comfort versus handling compromise. A newly developed semi-active hydropneumatic suspension system is proposed to reduce or negate this compromise by being able to change its characteristics according to the dynamic state of the vehicle. The unit is equipped with two proportional solenoid valves that can provide continuously variable damping. In addition, the valves are able to completely close off flow to compressible gas volumes to provide four discrete stiffness characteristics. This suspension system is based on a previously developed suspension that had only two state (open or closed) valves, which provided discrete damping characteristics. A thorough investigation of the older system proved that the system was capable of addressing the ride comfort versus handling compromise. The purpose of this study was to investigate whether the updated design could deliver improved performance and to recommend focus areas for future research initiatives. The suspension system’s characteristics were determined experimentally by actuating the unit on a test bench. Results indicated that the unit produced the desired stiffness, low damping and response time characteristics. A mathematical model of the suspension unit was developed and validated against experimental data. The model was used in single degree of freedom simulations to investigate both passive and semi-active controlled performance. Results indicated that the suspension could be semi-actively controlled for improve ride comfort. However, the magnitude of improvements with semi-active control, which includes a suitable response time, proved to be rather insignificant compared to the optimum passive suspension. / Dissertation (MEng)--University of Pretora, 2019. / Mechanical and Aeronautical Engineering / MEng (Mechanical) / Unrestricted

We find a set of conditions on a roof function to ensure topological mixing for suspension flows over a topological mixing base. In the measure theoretic case, such conditions have already been established for certain flows. Specifically, certain suspensions are topologically mixing if and only if the roof function is not cohomologous to a constant. We show that an analogous statement holds to establish topological mixing with the presence of dense periodic points. Much of the work required is to find properties specific to the equivalence class of functions cohomologous to a constant. In addition to these conditions, we show that the set of roof functions that induce a topologically mixing suspension is open and dense in the space of continuous roof functions.

I takt med att allt fler städer i Europa och i världen förbjuder biltrafik i centrum finns en efterfrågan på att ersätta fordonen med avgasfria fordon. En skåp-eller lastbil transporterar inte många gånger mer ombord än vad som får plats på en fraktcykel som är ett bättre alternativ av flera anledningar. Arbetet har utförts på Starke Cycles som är ett tillverkningsföretag där de utvecklar fraktcyklar med arbetslivserfarenhet från cykelåkeriet MOVEBYBiKE. Med åren har de stött på problem med åkkomforten och att bakaxeln gått av på de fraktcyklar som används idag på grund av att fraktcykeln saknar en hjulupphängning.Under 2017 har en första prototyp utvecklats men den är för bred för att kunna få ett typgodkännande beviljat. Syftet med arbetet är att lösa problemet med bakaxelns livslängd och åkkomforten hos de fraktcyklarna som används idag, samt att lösa problemet med den första prototypens bredd.I arbetet har framtagandet av ett hjulupphängningssystem fokuserat på att leverera ett kostnadseffektivt hjulupphängningssystem till Starke Cycles som kan tillverka det och tillämpa på den andra prototypen som är under utveckling. Det har möjliggjorts genom att studera och undersöka nuvarande fraktcykelnskonstruktionför att få en uppfattning om vilka hjulupphängningssystem som är möjliga att tillämpa. Därefter har de tänkbara systemen analyserats och det bäst lämpade systemet valdes med en systematisk och objektiv metod, genom konceptutvärdering. Med hjälp av mekanikberäkningar har ett hjulupphängningssystem med dubbla länkarmar tagits fram och hållfastheten i utvalda komponenter i konstruktionen har analyserats med FEM-simulering i Creo Parametric efter att materialvalet gjorts. I arbetet har inte konstruktionens livslängd mot materialutmattning analyserats. Resultatet presenteras som en 3D-modell och hjulupphängningen når målen som var satta i arbetet. Detaljritningarna på hjulupphängningssystemet har skickats iväg till en mekanisk verkstad för tillverkning. Materialvalet föll på enaluminiumlegering och FEM-analysen visar att spänningarna i de analyserade komponenterna klarar av kraven på hållfastheten. / As the number of cities in Europe and the world increasingly prohibit car traffic in the center, there is a demand to replace the vehicles with exhaust-free vehicles. Many times, a van or a truck does not carry more than what you can carry in a heavy cargo bike though it is a better option for several reasons. The work has been done at Starke Cycles, a manufacturing company where they develop heavy cargo bikes based on their work experience from MOVEBYBiKE, which is a freight company. Over the years, they have encountered problems with the ride comfort and that the rear axle has broken off the heavy cargo bikes used today. These problems have occurreddue to that the heavy cargo bikeslack of suspension. During2017, a first prototype has been developed but it is too wide to be approved by the Swedish Transport Agency which is required for a newly manufactured vehicle. The purpose of the work is to solve the problem of the rear axles sustainability and the ride comfort of the heavy cargo bikes that is used today, as well as solving the problem of the first prototypeswidth.The work of developing a suspension has focused on delivering a cost-effective suspension to Starke Cycles to produce and apply on the second prototype that they are developing. The work started with studying and examining the current heavy cargo bikes construction to get an idea of which type of suspensionsare possible to apply to the second prototype. Therefor has the possible suspensions been analyzed and the best suited system chosen with a systematic and objective method, concept evaluation. With the results from the mechanical calculations a double wishbone suspension was developed. The mechanics of materials has been analyzed on chosen components of the suspension in a FEM-simulation in Creo Parametric after a case study in materials selections had been made. The work has not analyzed the constructionslife expectancy against material fatigue.The result is presented as a 3D-model where the goals of the work have been met and drawings on the suspension have been sent to a mechanical workshop for manufacturing. The material selection fell on an aluminumalloy and the FEM-analysis shows that the stress in the analyzed components meet the strength requirements.

The problem studied in this dissertation involved the disciplinary practices of school administrators and how the practices influenced the trend of suspensions based on socioeconomic status. The dissertation involved an exploration of the disciplinary practices of administrators, more specifically suspensions, within 19 middle schools in the northwest region of the United States. The purpose of the study was to provide insight regarding how leadership and disciplinary procedures affected the educational process. The purposefully selected sample involved 19 middle school principals and vice-principals, as well as students at the middle schools who had suspensions. Quantitative data were collected for three research questions. These data were collected with a modified version of the Schools and Staffing Survey, and suspension data came from the district’s computer database. The research design was an ex post facto design. The Statistical Package for the Social Sciences was used to compute descriptive statistics that included frequencies, percentages, means, standard deviations, effect sizes, and point-biserial correlations, as well as statistics from the t test for independent samples. Findings for Research Question 1 showed that administrators reported the principal was responsible for making the decision to suspend a student; teachers and principals impacted a student’s ability to display positive behaviors. Point-biserial correlation findings for Research Question 2 showed there was a large inverse relationship of -.532 between poverty and middle school suspensions. Results for Research Question 3 suggested that 13 of 19 (68.42%) of the schools had a greater number of students on free and reduced lunch suspended than students who did not receive free and reduced lunch. The mean difference between suspension scores for students on free and reduced lunch and students not on free and reduced lunch was 43.11, suggesting statistical significance, p = .001, with a large Cohen’s d effect-size indicator of 1.22. A primary implication was that future policy on research-based disciplinary polices to improve administrators’ attitudes and competence toward executing discipline policies should be implemented in all middle schools.

In this dissertation, a freight train suspension system is presented for all possible types of motion. The suspension system experiences impacts and friction between wedges and bolster. The impacts cause the chatter motions between wedges and bolster, and the friction will cause the stick and non-stick motions between wedges and bolster. Due to the wedge effect, the suspension system may become stuck and not move, which cause the suspension lose functions. To discuss such phenomena in the freight train suspension systems, the theory of discontinuous dynamical systems is used, and the motion mechanism of impacting chatter with stick and stuck is discussed. The analytical conditions for the onset and vanishing of stick motions between the wedges and bolster are presented, and the condition for maintaining stick motion was achieved as well. The analytical conditions for stuck motion are developed to determine the onset and vanishing conditions for stuck motion. Analytical prediction of periodic motions relative to impacting chatter with stick and stuck motions in train suspension is performed through the mapping dynamics. The corresponding analyses of local stability and bifurcation are carried out, and the grazing and stick conditions are used to determine periodic motions. Numerical simulations are to illustrate periodic motions of stick and stuck motions. Finally, from field testing data, the effects of wedge angle on the motions of the suspension is presented to find a more desirable suspension response for design.

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