One of the common failure modes in rolling contacts, such as in gears and rolling element bearings, is micropitting which has become a big issue. It is considered as a fatigue indicator and can lead to premature gear and bearing failure. This development work requires availability of a versatile test rig which reproduces the pitting or micropitting phenomenon under controlled conditions in the laboratory. The thesis has been carried out in the Department of Machine Design at KTH Royal Institute of Technology. It is a continuation of the project in the Advanced Machine Design course or Maskinkonstruktion högre kurs HK (in Swedish) as part of the Machine Design master programme at KTH. After specifying the scope and analyzing the challenges, this work deals with design modifications and further development of the previous test rig. All the problems addressed at the beginning have been solved. At the end, the newly assembled test rig indicates a stable, quieter and well performed working status as intended. The thesis work turns out a cost-effective way of developing micro-pitting test rig. Apart from physical deliverables; feasible solutions, recommendations and relevant documents such as specifications, program codes are provided in this paper. Some experience and thoughts during the project are also discussed in detail. Based on these, the mentioned future work can be performed and promoted to an advanced level. / En av de vanligaste typ av fel i rullande kontaktmekanik, såsom i kugghjul och kullager, är mikropitting. Fenomenet har nämligen blivit ett stort problem och betraktas som en tidig indikator för utmattning samt kan leda till tidiga utmattningsbrott i kugghjul och kullager. Detta utvecklingsarbete krävs en mångsidig testrigg som kan återskapa gropfrätning och mikropitting under kontrollerade förhållande I laboratorium. Denna examensarbete har genomförts inom Avdelningen för Maskinteknik vid Kungliga Tekniska Högskola (KTH). Arbetet utgör en vidareutveckling påett projekt för kursen ”Maskinkonstruktion högre kurs” inom maskindesignprogrammet. Utöver en analys av utmanningarna, det nuvarande arbetet presenterar designförändringar och vidareutveckling från det tidigare testriggen. Alla problem som påträffades har kunnat lösas. Till slut uppvisar den nymonterade testriggen alla förväntade egenskaper, nämligen stabilitet, förbättrad tysthet samt god performans. Den föreslagna metoden utgör därmed ett kostnadseffektivt sätt att utveckla testrigg för mikropitting. Arbetet består, utöver det fysiska produkten, av lösningar, rekommendationer och relevanta dokument såsom monteringsschema och programkod. En utförlig diskussion av tankar och erfarenheter från projektet presenteras. Baserat på dessa kan det nämnda arbetet genomföras och höjas till en advancerad nivå.

This study aimed to facilitate evaluation of alternative refrigerants for the air conditioner market. In order to achieve this target, two objectives were set. The first being the identification of alternative refrigerant with regard to regulations and trends. The second being enabling of thermodynamic evaluation of refrigerants for single components in air conditioners via design and installation of a test rig. A literature review was conducted to investigate the regulations, standards and trends for nine regions with high market shares. Furthermore, refrigerant substitutes for R410A and R22 where identified. The literature showed strong indications that a global HFC phase down is on the horizon, but that the approach and urge for such a phase down varies between regions where three main priorities could be seen; efficiency, GWP values and safety. Comparing these priorities with simulated refrigerant characteristics such as Carnot efficiency, GWP values, volumetric capacity and the liquid density using RefProp, identified alternatives. Further the literature showed that the lower flammability limit (LFL) and the amount of charge allowed were limiting factors for flammable refrigerant. There are many new refrigerants that could have less charge for the same capacity the LFL however restricts the refrigerants like R290, R441A and R443A only to be used in small systems. A test rig was designed and constructed in order to enable testing of single components in air conditioners. To verify the test rig, tests conducted with an evaporator using two refrigerants: R410A and R32. The reliability and validity of the tests was studied by comparing the results from the air side and refrigerant side, via uncertainty calculations using the GUM method and by a thermodynamic evaluation. The results of the repetition tests showed an expanded uncertainty, with a confidence interval of 95%, of 26 W for a cooling capacity of 2190W for R410A (Q̇evap,R410A=2190±26W). For R32 the expanded uncertainty was 27W for a cooling capacity of 2795W (Q̇evap,R32=2795±27W). Also the test rig was verified to be used for analyzing detailed evaluation of evaporators such as looking at heat transfer and the differential pressure drop. Further the study presented six conclusions: When evaluating refrigerants regional priorities between efficiency, safety and GWP values, refrigerant characteristics and type of unit need to be considered. Safety standards need to be more acceptable towards flammable refrigerants in order to meet low GWP targets. The change in market trends leads to new roles for the refrigerant and compressor suppliers and put higher demand on air conditioner manufacturers to consider refrigerant characteristics in product development. The importance of experimental thermodynamic evaluation on refrigerants effect on single components is increasing. Performance of different refrigerant for single components can be evaluated for optimizing cycle performance. Leapfrogging in the developing world can lead to a faster introduction of low GWP refrigerants.

This thesis work is dedicated towards finding a feasible test rig design, which can expose small components, produced by SAAB, to a variety of accelerations under different conditions. A literature study is conducted with the objective of gathering information regarding high acceleration testing, where relevant components, designs and calculation methods are presented. A series of concepts are presented and evaluated against a requirement specification, the first concept iteration concerns the method of acceleration whereas the second and the third concept iterations concerns the design of the test rig on different levels of detail. The third concept evaluation is strengthened by several calculations, which indicates the feasibility of the concept in some manner. One concept achieved the highest score in the third concept evaluation and as such is presented as the best suited concept for further development. / Denna avhandling är dedikerad till framtagningen av en möjlig design för en provningsrigg, som kan utsätta små komponenter, som produceras av SAAB, för flera olika accelerationer under olika förhållanden. En litteraturstudie genomförs med syftet att samla information om provning under höga accelerationer, där relevanta komponenter, designer och beräkningsmetoder presenteras. En serie koncept presenteras och utvärderas med hjälp av en kravspecifikation. Den första konceptiterationen berör metoden för acceleration, medan den andra och den tredje konceptiterationen berör designen av provningsriggen. Den tredje koncept utvärderingen stärks av flera beräkningar, som indikerar konceptets lämplighet ur något perspektiv. Ett koncept uppnådde högst poäng i den tredje koncept utvärderingen och presenteras därav som det bäst lämpade konceptet för vidare utveckling.

Bicycles are becoming always more popular as a cheap and healthy tool for urban travels. The concerns für crowded public transport means are changing the habits after the pandemic situation caused by Covid-19, encomaging people towards the use of bicycle. As stated in literature, tyres play a large role in the handling ofbicycles . This is why it is necessary to characterize tyres so as to derive useful parameters for modeling. To this purpose, proper experimental methods have been implemented for bicycle tyres. A deepen knowledge of the phenomena occurring at tyre/road contact patch is indeed fundamental to ensure proper adherence and safety conditions, especiatly for vehicles as bicycles or motorcycles working with high camber angles. This paper aims at enabling the future development of bicycle tyres, in order to improve the safety and the performances. Specifically, the focus is devoted to understand how the road temperature can impact on tyre performances, and therefore on bicycle handling. After a brief section describing the methods and instruments used für this research activity, the results of an experimental campaign carried out on road racing tyre are presented and discussed. The remarkable variation of temperature oftyre rolling surface can have multiple impacts on the performances. lt can affect the noise emissions as weil as rolling resistance, as noted in, where higher temperature was co.rrelated to lower rolling resistance coefficient. In the temperatu.re influence on car tyre lateral characteristics is investigated on a drum testrig. A They found a decrease in cornering stiffness as temperature increases, while no particular variations on relaxation length were observed. Despite the known influence of the temperature on tyre properties, there is a lack of studies regarding bicycle tyres. In a test on testrig of wintertype tyre revealed remarkable differences with respect to the mechanical characteristics of other tyres tested at room temperature. This may suggest the important role played by temperature on bicycle tyres characteristics, thus affecting the tyre/road interaction.

As the demands for precision in nutrunners increases, the testing equipment at manufacturers of these tools also need to get better. At Atlas Copco in Tierp there are a number of test rigs that compare the torque that the nutrunners indicate, with the torque that a sensor records. In these AR-rigs a bolted joint is tightened with a nutrunner by the help of a solution containing a sensor, a telescoping component and sockets or adaptors to compensate for different torques. This is done as a finishing check for every nutrunner. In the current design of the rig, there are some known errors and trade-offs in the 20 year old base design. One of the known problems is the alignment between the nutrunner and the bolted joint. To further investigate this, and to lessen possible measuring errors due to misalignment of components, this master thesis was carried out at Rejlers AB. To start with, a number of requirements were done and five design concepts were generated that would fulfil the requirement specification. These concepts were then compared to each other in a Pugh’s evaluation matrix and after discussion with Atlas Copco, one of the concepts were further developed. This concept comprised a locking of the sensor’s rotation and an assembly of the sensor and telescoping component placed together. A detailed 3D CAD-model was done on the new design and solid mechanics calculations were performed on the bottom plate for the sensor. Also Eigen frequencies and theoretical alignment possibilities were calculated. Furthermore an experiment was carried out, were the impact from several components were investigated. This experiment was also used to compare the current design with the new concept. The solid mechanics calculations showed that the largest deformation, 0.0062 mm, had minimum impact on the alignment. Also the maximum stress of 1.53 MPa was of insignificant size, far from the yield strength of aluminium. The calculated Eigen frequencies of the concept exceeded the rotational speed of the nutrunner’s output shafts. An alignment method was proposed using a multi-dot laser, to achieve a maximum displacement of only 0.55 mm for the centerlines of the remaining subsystems. The experiment was used as a base for calculations comparing the new concept and the current design. In the end, future work, such as the building of a prototype and testing, was proposed. / I samband med att kraven på precision hos mutterdragare ökar, måste testutrustningen hos tillverkare av dessa också bli bättre. På Atlas Copco i Tierp finns ett flertal testriggar som jämför momentet som mutterdragarna indikerar, mot det som en givare registrerar. I dessa AR-riggar dras ett testförband åt med mutterdragaren via en konstruktion innehållandes givare, teleskop och hylsor eller adaptrar för att kompensera för olika moment. Detta görs som ett slutligt prov för varje mutterdragare. I den nuvarande konstruktionen finns ett antal kända problem och kompromisser i riggens grundkonstruktion som är 20 år gammal. Ett av dessa problem är linjeringen mellan mutterdragare och testförband. För att utreda det närmare och minska möjliga mätfel på grund av olinjerade komponenter utfördes detta examensarbete på Rejlers AB. Till en början ställdes ett antal krav upp och fem konstruktionskoncept genererades som skulle uppfylla kravspecifikationen. Dessa koncept jämfördes mot varandra i en Pughs matris och efter diskussion tillsammans med Atlas Copco togs ett av koncepten vidare för fortsatt utveckling. Detta koncept innehöll en låsning av givarens rotation och ett paket där givare och teleskopet sattes samman. På konceptet gjordes en detaljerad 3D CAD-modell och beräkningar på hållfasthet på bottenplattan som givarpaketet placeras på. Utöver det beräknades egenfrekvenser samt teoretiska linjeringsmöjligheter. Dessutom utfördes ett experiment där påverkan av flera komponenter i konstruktionen undersöktes. Detta experiment användes också för att jämföra konceptet med den nuvarande lösningen. Hållfasthetsberäkningarna visade att den största nedböjningen på 0,0062 mm av konstruktionen hade minimal påverkan på linjeringen. Dessutom var den maximala spänningen på 1,53 MPa som uppstod av givarpaketets vikt av obetydande storlek, långt under sträckgränsen för bottenplattans aluminium. De beräknade egenfrekvenserna för konceptet överskred rotationshastigheten för mutterdragarnas utgående axlar. En linjeringsmetod föreslogs med en flerpunktslaser, för att kunna uppnå en teoretisk förskjutning på centrumlinjer av delsystemen i konceptet på maximalt 0,55 mm. Experimentet och beräkningar låg till grund för en jämförelse mellan det nya konceptet mot den nuvarande konstruktionen och kravspecifikationen. I slutändan föreslogs framtida arbeten, såsom bygge av prototyp och testning.

Virtual reality (VR) head-mounted displays provide a high definition, immersive experi-ence to the viewer. However, most existing technologies have flaws like bulky design and vergence-accommodation conflict that may cause stress in the neck muscles, posture issues, nausea, motion sickness and dizziness. Similarly, augmented reality (AR) displays, which use transparent light modulators, exist, but they possess low field of view and a limited number of discrete depth planes when wide field of view and continuous depth would be ideal. The ultimate goal of my research is use leaky mode waveguide devices to create wide-view angle, transparent near eye holographic displays for AR with strong continuous depth accommo-dation and no vergence-accommodation conflict. The leaky mode platform has the advantages of low fabrication complexity and monolithic design. Unfortunately, bottom-exit leaky mode devices to date have had produced relatively small view angles. The specific objective of this thesis is to explore the use of static structures in leaky mode waveguide devices to increase field of view. In this work I will show that it is theoretically possible to achieve increased field of view with increased resolution and no overlap among view zones. My specific contributions to this research include: i) modeling of integrated Lithium Nio-bate device and testrig that contains quartz substrates on MATLAB, ii) construction of a simulator of the integrated device which involved fabrication of a prototype test rig for intermediate laser induced structures, iii) fabrication of intermediate diffractive structures by photolithography and by femto-second laser ablation which involved - 100 sample test, dose test and creation of sample femtograting on Lithium Niobate substrate. Results which are obtained from the modelling of inte-grated device and the prototype simulator are analysed. This analysis is provided in my manuscript to show how precise is the prototype simulator when compared with integrated device. The ob-tained result of the integrated device is 52.4541° where as it is 69.113° for prototype simulator. This effort was reported in a publication and presentation at Brigham Young University, Provo, Utah.

Due to the environmental problems associated with fossil fuels and a big need from the market, the majority of the automotive industry is going towards fully electric vehicles (EVs). To further reduce the environmental footprint there is ongoing research on the use of fossil-free lubricants, if they could be used to lubricate the drive train which could further reduce the use of fossil oil in the automotive industry. These lubricants have also been shown to have lower friction and could thus increase the efficiency of the transmission and therefore the driving range. To ensure the performance and reliability of these new lubricants they need to be evaluated and tested in monitored environments. This master thesis is about designing a gear test rig to test and evaluate the efficiency, reliability and wear rate of new types of fossil-free lubricants such as water-based lubricants (WBL) for use in electric vehicle gear transmissions. By first doing an external analysis of current solutions for gear test rigs, and having discussions with researchers at the university and competent people in the industry, product requirements were set. Then by following Ulrich, Eppinger & Yang's product development process concepts could be found and evaluated until a final concept was further developed. After dimensioning and specifications of the sub-systems, a detail-designed test rig and proposal on solutions could be delivered with a list of components and suppliers.

Vibrations is a phenomenon that can cause problems to systems if not dealt with. In heavy duty trucks, vibrations are mainly caused by uneven roads and from the combustion engine. Vibrations can damage components, reduce their service life and cause discomfort for the driver. To manage the problem, vibration isolators can be used to absorb energy and thus reduce the vibrations. Rubber is a commonly used material for vibration isolators thanks to its viscoelastic properties. However, due to the characteristics of rubber, there are difficulties to make accurate simulation models of components such as vibration isolators. To improve the accuracy in simulations, physical testing can be performed to measure the material properties and characteristics such as hysteresis to get a better understanding of how the material and the component will behave. The purpose of the master thesis was to generate and develop concepts of a test rig for a specific vibration isolator from Scania where the force as a function of displacement in the component’s Z-direction should be measured as well as the force in the component’s Y-direction. Further, the component should be compressed in a vertical linear motion. Based on the background information, the following research questions were stated: - How can a hysteresis curve based on frequency input be found by performing physical testing? - How can a test rig be designed to test and measure the material properties of a rubber component in order to parametrize the material? The vibration isolator was investigated and analyzed. From the analysis, seven concepts were generated and were evaluated with a Pugh matrix. From the evaluation, two concepts were chosen to be further developed before a final evaluation using a desirability chart was made. The master thesis resulted in two concepts that were developed named Hinged beam and Guiding plates. Guiding plates was the concept that scored the best in the final evaluation, but the concepts had different strength and weaknesses. Both concepts fulfilled the requirement of compressing the vibration isolator in a vertical linear motion but the measurement of the force in the component’s Y-direction needs to be further investigated. / Vibrationer är ett fenomen som kan orsaka problem för olika typer av system om det inte hanteras. I lastbilar är vibrationer huvudsakligen orsakade av ojämnt underlag samt av förbränningsmotorn. Vibrationerna kan orsaka skada på komponenter, reducera deras livslängd och även orsaka obehag för föraren. Det här problemet kan hanteras genom användning av vibrationsisolatorer som minskar effekten fr.n vibrationerna genom att absorbera dess energi. Gummi är ett material som ofta används för att isolera vibrationer tack vare dess viskoelastiska egenskaper. Egenskaperna gör det dock svårt att skapa noggranna simuleringsmodeller av komponenter så som vibrationsisolatorer. För att öka noggrannheten i simuleringarna kan fysisk testning genomföras och materialegenskaper så som hysteres kan mätas för att få en bättre förståelse för hur både material och komponent beter sig med olika laster. Syftet med det här masterexamensarbetet var att generera och utveckla koncept för testriggar för en specifik vibrationsisolator tillhandahållen av Scania. Kraft som funktion av förskjutning i komponentens Z-riktning samt kraft i dess Y-riktning skulle vara möjligt att mätas. Utöver det var ett krav att komponenten endast ska komprimeras i en vertikal linjär rörelse. Baserat på bakgrundinformationen kunde följande forskningsfrågor formuleras: - Hur kan en frekvensbaserad hystereskurva tas fram genom fysisk testning? - Hur kan en testrigg designas för att kunna testa och mäta materialegenskaper hos en gummikomponent för att kunna parametrisera materialet? Vibrationsisolatorn undersöktes och analyserades. Efter analysen genererades sju koncept som utvärderades med en Pugh matris. Utvärderingen resulterade i att de två bäst presterande koncepten valdes för vidareutveckling innan en sista utvärdering genomfördes med hjälp av ett så kallat desirability chart. Masterexamensarbetet resulterade i två koncept som vidareutvecklades, ett som kallas Hinged beam och ett vid namn Guiding plates. Guiding plates var det konceptet som presterade bäst i den slutgiltiga utvärderingen, men de olika koncepten har dock olika styrkor och svagheter. Båda koncepten uppnådde kraven gällande att kompression av vibrationsisolatorn endast ska ske i en vertikal rätlinjig rörelse men hur krafterna i komponentens Y-riktning ska mätas behöver vidare undersökning.

Studded tires are widely used in Nordic areas like Sweden for its good road-gripping performance on icy roads. However, the pavement wear and aerosol caused by studded tires become big concerns considering the usage of studded tires. Studies are carried to quantify the wear and aerosol generated during the process. Among the existing test rigs, most of them which includes a full wheel as specimen have relatively large size. This thesis aims on designing a full wheel testrig with small scale which can fit in a common lab room and be easy to operate. / Dubbdäck används i stor utsträckning i nordiska områden som Sverige för sin goda väggreppande prestanda på isiga vägar. Trottoarslitage och aerosol som orsakas av dubbdäck blir dock stora bekymmer med tanke på användning av dubbdäck. Studier genomförs för att kvantifiera slitage och aerosol som genereras under processen. Bland de befintliga testriggarna har de flesta, som innehåller ett helhjul som prov, en relativt stor storlek. Denna avhandling syftar till att designa en fullhjulstestrigg med liten skala som kan passa i ett gemensamt labbrum och vara lätt att använda.

Yes / An experimental study of wheel movement arising from compliance in the front suspension and steering system of a passenger car during braking is presented. Using a Kinematic and Compliance (K&C) test rig, movement of the front wheels and the suspension sub-frame, together with corresponding changes in suspension / steering geometry under simulated braking conditions, were measured and compared with dynamic measurements of the centre points of the front wheels. The resulting knowledge of front wheel deflections has enabled the causes and effects of steering drift during braking to be better understood in the design of front suspension systems for vehicle stability.