| 1. |
- Alemani, Mattia, et al.
(författare)
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Scaling effects of measuring disc brake airborne particulate matter emissions – A comparison of a pin-on-disc tribometer and an inertia dynamometer bench under dragging conditions
- 2018
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : Sage Publications. - 1350-6501 .- 2041-305X. ; 232:12, s. 1538-1547
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Tidskriftsartikel (refereegranskat)abstract
- An important contributor to non-exhaust emissions in urban areas is airborne particulate matter originating from brake systems. A well-established way to test such systems in industry is to use inertia dynamometer benches; although they are quite expensive to run. Pin-on-disc tribometers, on the other hand, are relatively cheap to run, but simplify the real system. The literature indicates promising correlations between these two test stands with regard to measured airborne number distribution. Recent studies also show a strong dependency between the airborne number concentration and the disc temperature. However, a direct comparison that also takes into account temperature effects is missing. The aim of this paper is, therefore, to investigate how the transition temperature is affected by the different test scales, under dragging conditions, and the effects on total concentration and size distribution. New and used low-steel pins/pads were tested against cast iron discs/rotors on both the aforementioned test stands, appositely designed for particulate emission studies. A constant normal load and constant rotational velocity were imposed in both test stands. Results show that a transition temperature can always be identified. However, it is influenced by the test scale and the frictional pair status. Nevertheless, emissions are assessed similarly when an equivalent frictional pair status is analysed (e.g. run-in). Further investigations for fully run-in samples on the pin-on-disc should be performed in order to finally assess the possibility of using the tribometers for the initial assessment of different friction materials.
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| 2. |
- Bergseth, Ellen, 1979-, et al.
(författare)
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Study of surface roughness and surface orientation on friction in rolling/sliding contacts: barrel-on-disc versus twin-disc
- 2017
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Konferensbidrag (refereegranskat)abstract
- Gears are one of the most important means of mechanical power transmission. Even though the efficiency is high for a gear pair today, further decrease in friction can contribute to lower the fuel consumption. A barrel-on-disc machine (same setup as ball-on-disc) to simulate a rolling/sliding gear contact was used to study the impact of manufacturing method, grinding and superfinishing, on friction. To evaluate the extent to which friction and wear can be diminished by reducing surface roughness and changing surface orientation. Measurement results showed that the change of lubricant had an impact on friction in the mixed to boundary lubrication regimes similar to that of the change of main surface orientation. The results were compared with those from a parallel study involving a twin-disc machine, also used to simulate rolling/sliding contacts (see Figure). Measurements and simulations showed that the barrel-on-disc and twin-disc setups reflected the same friction trends. However, the friction coefficient using the barrel-on-disc setup was almost twice as large as that found using the twin-disc machine. The wear mechanisms also differed: micropits occurred on discs used in the twin-disc set-up whereas normal or no wear was found on the barrel-on-disc specimens. The difference in contact geometry is believed to be the main reason for the higher friction level in the barrel-on-disc machine. A computer contact analysis was used to clarify the differences using perfectly smooth and computer-generated textured surfaces.
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| 3. |
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| 4. |
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| 5. |
- Lindén, Julia
(författare)
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Supporting complete vehicle reliability forecasts
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reliability is one of the properties that customers of heavy trucks value highest.Dependent on all parts and functions of the vehicle, reliability is a complexproperty, which can normally be measured only towards the end of a developmentproject. At earlier development stages, forecasts can give valuable decision supportfor project planning.The main function of a heavy truck is to transport goods, but the truck also hasinteractive functions as the working environment of the driver. Interactivefunctions are functions experienced by the driver. They are subjective, in the senseof being person dependent, so that a system can be experienced as inadequate byone user but satisfactory by another. Examples of interactive functions of heavytrucks are climate comfort and ergonomics, which are experienced differently bydifferent drivers. Failures of these functions lead to costs and limited availabilityfor the customer. Therefore it is important to include them in reliability forecasts.The work described in this thesis concerns some elements of the system reliabilityforecast. Two studies are presented, one proposing a qualitative systemarchitecture model and the other reviewing and testing methods for evaluating theimpact of varying operating conditions. Two case studies of a truck cab in a systemreliability test were made. The first case study shows that the system architecturemodel supports reliability forecasts by including interactive functions as well asexternal factors, human and environmental, which affect function performance.The second case study shows that modelling uncertainty is crucial for interactivefunctions and recommends a method to forecast function performance while takingvarying operating conditions into account.
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| 6. |
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| 7. |
- Wahlström, Jens, et al.
(författare)
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Contact pressure and sliding velocity maps of the friction, wear and emission from a low-metallic/cast-iron disc brake contact pair
- 2017
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Ingår i: Tribology in Industry. - : Faculty of Engineering, University of Kragujevac. - 0354-8996 .- 2217-7965. ; 39:4, s. 460-470
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Tidskriftsartikel (refereegranskat)abstract
- Particulate matter with an aerodynamic diameter less than 10 µm (PM10) from car disc brakes contribute up to 50% of the total non-exhaust emissions from road transport in the EU. These emissions come from the wear of the pad and rotor contact surfaces. Yet few studies have reported contact pressures and offered sliding speed maps of the friction, wear, and particle emission performance of disc brake materials at a material level. Such maps are crucial to understanding material behaviour at different loads and can be used as input data to numerical simulations. A low-metallic pad and grey cast-iron rotor contact pair commonly used today in passenger car disc brakes was studied using a pin-on-disc tribometer at twelve contact pressure and sliding speed combinations. Maps of the coefficient of friction, specific wear rate, particle number, and mass rate are presented and discussed.
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| 8. |
- Williamsson, David, et al.
(författare)
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A Hunt For the Hidden Reasons Behind a Product Architecture
- 2018
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Ingår i: DS 96: The 20th International DSM Conference. - : The Design Society. ; , s. 93-103
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Konferensbidrag (refereegranskat)abstract
- A modular product architecture is a strategic means to deliver external variety and internal commonality. In this paper, a heavy duty modular gearbox architecture is represented and analyzed. In focus is re-engineering of hidden technical complexity and business strategy concerns behind an existing product architecture. The architecture of the investigated gearbox is represented and analyzed with a Product Architecture DSM and the Integrated Modularization Method (IMM). Furthermore, a Cluster Match Matrix (CMM) is proposed as a means to compare multiple clustering results. The case study indicates that the IMM methodology and CMM can be used for analyzing and finding the explicit and/or implicit reason for a targeted existing product architecture.
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| 9. |
- Williamsson, D., et al.
(författare)
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Product architecture transition in a modular cyber-physical truck
- 2019
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Ingår i: Journal of Computing and Information Science in Engineering. - : American Society of Mechanical Engineers (ASME). - 1530-9827 .- 1944-7078. ; 19:3
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Tidskriftsartikel (refereegranskat)abstract
- A modular product architecture is a strategic means to deliver external variety and internal commonality. In this paper, we propose a new clustering-based method for product modularization that integrates product complexity and company business strategies. The proposed method is logically verified by a studied industrial case, where the architecture of a heavy truck driveline is analyzed in terms of how it has evolved over a couple of decades, due to changed business strategies and the evolution of new technology. The presented case indicates that the new methodology is capable of identifying and proposing reasonable module candidates that address product complexity as well as company-specific strategies. Furthermore, the case study clearly shows that the business strategic reasons for a specific architecture can be found by analyzing how sensitive the clusters are to changes in the module drivers (MD).
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| 10. |
- Williamsson, David, et al.
(författare)
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Product Architecture Transition in a Modular Cyber-Physical Truck
- 2018
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Ingår i: ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. - : ASME Press. - 9780791851722
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Konferensbidrag (refereegranskat)abstract
- A modular product architecture is a strategic means to deliver external variety and internal commonality. In this paper, we propose a new clustering based method for product modularization that integrates product complexity and company business strategies. The proposed method is logically verified by a studied industrial case, where the architecture of a heavy truck driveline is analyzed in terms of how it has evolved over a couple of decades, due to changed business strategies and the evolution of new technology. The presented case indicates that the new methodology is capable of identifying and proposing reasonable module candidates that address product complexity as well as company-specific strategies. Furthermore, the case study clearly shows that the business strategic reasons for a specific architecture can be found by analyzing how sensitive the clusters are to changes in the module drivers.
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| 11. |
- Williamsson, David, et al.
(författare)
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Product architecture transition in an evolving multi-brand organisation
- 2018
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Ingår i: Proceedings of International Design Conference, DESIGN. - Glasgow : Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia; The Design Society, Glasgow, UK. - 9789537738594 ; , s. 929-940
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Konferensbidrag (refereegranskat)abstract
- A modular architecture is a strategic means to deliver external variety and internal commonality. A methodology for product modularization that integrates complexity and strategies is proposed and logically verified with an industrial case from the heavy truck business area. The case study indicates that the new methodology is capable of identifying and proposing reasonable module candidates that address product complexity as well as company specific strategies.
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| 12. |
- Williamsson, David, et al.
(författare)
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The hunt for proper relation weights in product architecture clustering
- 2018
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Ingår i: Proceedings of NordDesign 2018, Linköping, Sweden, 14th - 17th August 2018. - : The Design Society. - 9789176851852
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Konferensbidrag (refereegranskat)abstract
- A common view is that a module should be a functional building block, with well-defined and standardized interfaces between the modules, and that it should be chosen for company specific reasons. A modular product architecture is a strategic means to deliver external variety and internal commonality. Today, multiple modularisation methodologies exist to support the highly complex task to identify module candidates in the product architecting phase. One methodology is Modular Function Deployment with the Modular Indication Matrix (MIM) representation of company-specific module drivers. Other methodologies, such as Design Structure Matrix (DSM) clustering, may be used to identify modules from a technical complexity point of view. In this paper, the performance of the newly proposed Integrated Modularization Methodology (IMM), which is based on clustering of a strategically adapted DSM, is conceptually verified. The core of the IMM is to transfer company specific module drivers from the MIM into the component-DSM, before clustering this hybrid representation. A re-architecting industrial case, where a truck manufacturer with a unique business strategy had to redesign parts of its modular gearbox architecture to also become a First-Tier OEM-supplier to another large truck manufacturer, is used as test bench. Reverse engineering of the investigated gearbox architecture indicates that the current modules are most likely not only based on technical complexity concerns. They are rather derived from different types of business strategic aspects, e.g. outsourcing. The study also indicates that the IMM is capable of identifying clusters without strategic conflicts, and with the most similar result to the analysed architecture, which is assumed to be based on expert judgements.
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