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| 2. |
- Andersson, Sören, et al.
(författare)
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A random wear model for the interaction between a rough and a smooth surface
- 2008
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 264:9-10, s. 763-769
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Tidskriftsartikel (refereegranskat)abstract
- Contact surfaces in many applications change form due to plastic and elastic deformation and to wear. This study focused on the plastic deformation and wear of the asperities on a rough surface rubbing against an opposite smooth, hard and wear-resistant surface. A stochastic model for the prediction of plastic deformations and wear of a rough surface is proposed. The surface roughness and the interaction between the surfaces are also represented by stochastic models. A single asperity is studied as it comes into contact and interacts with the opposite surface. Since the wear process is simulated as an initial-value problem, the proposed general wear model is formulated as a first order differential equation system representing events during the rubbing process at all of the asperities considered on a surface.
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| 3. |
- Andersson, Sören, et al.
(författare)
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Frictions models for sliding dry, boundary and mixed lubricated contacts
- 2007
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 40, s. 580-587
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Tidskriftsartikel (refereegranskat)abstract
- Friction, lubrication, and wear have a strong influence on the performance and behavior of mechanical systems. This paper deals with different friction models for sliding contacts running under different conditions. The models presented are suited to different situations, depending on the type of contact, running conditions, and the behavior of interest. The models will be discussed from simulation and tribological points of view. The different types of friction models considered are:center dot friction models for transient sliding under dry, boundary and mixed lubrication conditions,center dot friction models for micro-displacements of engineering surfaces subjected to transient sliding,center dot friction models often used in the simulation and control of technical systems,center dot combined friction models that represent physical behaviors fairly well but are also suitable for use in simulating systems,center dot friction models that take into account the stochastic nature of interacting surface asperities
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| 4. |
- Söderberg, Anders, 1977-
(författare)
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Interface modeling - friction and wear
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general trend toward increased use of computer models and simulations during product development calls for accurate and reliable product models. The function of many products relies on contact interfaces between interacting components. Simulating the behavior of such products requires accurate models of both components and interfaces. Depending on the purpose of the simulation, interface models of different degrees of detail are needed. In simulating very large systems with many interfaces, it might be computationally expensive to integrate detailed models of each individual interface. Condensed models, or abstractions, that describe the interface properties with the fewest degrees of freedom are therefore required. This thesis deals with the modeling and simulation of mechanical interfaces in a systems context. The five appended papers discuss the issue from both the simulation and tribological points of view. The aim is to study how friction and wear can be modeled in the behavioral simulation of technical systems and to discuss the convenience and applicability of using different types of models as building blocks of a system model in simulations. Paper A reviews existing friction models of sliding contacts under different running conditions. Paper B uses a simplified contact model, the elastic foundation model, to model friction in a boundary-lubricated rolling and sliding contact. The model is integrated into a dynamic rigid body model of a mechanical system, and the system behavior is simulated. Paper C discusses the application of the elastic foundation model to rough surface contact problems and investigates how the error in its results depends on surface roughness. Papers D and E address how the wear of the contact surfaces at the pad-to-rotor interface in a passenger car disc brake can be simulated using finite element analysis (FEA).
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| 5. |
- Söderberg, Anders, 1977-, et al.
(författare)
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Modeling transient behavior of a mechanical system including a rolling and sliding contact
- 2005
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Ingår i: Proceedings of IMECE 1005, 2005 ASME Interantional Mechanical Engineering Congress and Exposition. ; , s. 229-238
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Konferensbidrag (refereegranskat)abstract
- Thefriction and wear of rolling and sliding contacts are criticalfactors for the operation of machine elements such as bearings,gears, and cam mechanisms. In precision machines, for example, themain concern is to compensate for frictional losses, so asto improve control accuracy. In other applications it is oftendesirable to minimize friction losses to improve efficiency, though sometimeshigh friction is desired to prevent sliding and wear. Theaim of this study is to simulate the behavior ofa test equipment and show that simulations can be usedto study and optimize mechanical systems that include rolling andsliding contact. Simulations can be used to study the systemas a whole, as well as the contact conditions. Thetest equipment and the measurement procedure used are described. Inthe simulations, a contact model designed to handle transient contactconditions is integrated into a system model. The results showthat the contact strongly influences the system. The simulations showthat the use of a contact model allows the simulationof systems that contain contacts with different amounts of slip,and that such simulations can be used to study thecontact as well as the system. Surface roughness influences thecontact stiffness and is included in the simulations.
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| 6. |
- Söderberg, Anders, 1977-, et al.
(författare)
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Simulation of wear and contact pressure distribution at the pad-to-rotor interface in a disc brake using general purpose finite element analysis software
- 2009
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 267:12, s. 2243-2251
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Tidskriftsartikel (refereegranskat)abstract
- Passenger car disc brakes are safety-critical components whose performance depends strongly on contact conditions at the pad-to-rotor interface. The interface can be classified as a conformal dry sliding contact. During braking both brake pad and rotor surfaces are worn, affecting the useful life of the brake as well as its behavior. This paper discusses how wear of the pad-to-rotor interface can be predicted using general purpose finite element analysis software. A three-dimensional finite element model of the brake pad and the rotor is developed to calculate the pressure distribution in the pad-to-rotor contact. A wear simulation procedure based on a generalized form of Archard's wear law and explicit Euler integration is used to simulate the wear of the brake pad under steady-state drag conditions.
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| 7. |
- Söderberg, Anders, 1977-, et al.
(författare)
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Using finite element analysis to predict the brake pressure needed for effective rotor cleaning in disc brakes
- 2008
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Ingår i: SAE Technical Paper 2008-01-2565. - USA : SAE. ; , s. 1-10
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Konferensbidrag (refereegranskat)abstract
- This paper presents an approach to simulating wear on both contact surfaces at the pad-to-rotor interface in discbrakes using general purpose finite element software. Itrepresents a first step toward a method of simulating the brake pressure needed to effectively clean the rotor ofunwanted oxide layers. Two simulation cases are presented. The first addresses running-in wear underconstant load and corresponds to repeated brakeapplications at the same constant brake load. Thesecond studies what will happen if a lower load is applied after the contact surfaces have been run-in at ahigher load level. This lower load is applied to wear off an oxide layer after a sequence of repeated stop braking at higher load levels.
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| 8. |
- Wahlström, Jens, et al.
(författare)
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A disc brake test stand for measurement of airborne wear particles
- 2009
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Ingår i: Lubrication Science. - England : John Wiley & Sons, Inc.. - 0954-0075. ; 21:6, s. 241-252
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Tidskriftsartikel (refereegranskat)abstract
- During braking, there is wear on both the rotor and the pads. This process generates particles that may becomeairborne. In field tests, it is difficult to distinguish these particles from others in the surrounding environment.Therefore, a laboratory test stand has been designed which allows control of the cleanliness of the surroundingair. The test stand consists of a front right brake assembly mounted in a sealed chamber. A braking load is appliedby a pneumatic system and the rotor, which has been pre-conditioned with a rust layer to simulate a car standingparked overnight in a wet environment, is driven by an electric motor. The number and size of airborne wearparticles are then measured. This experimental set-up has been verified by an initial test series performed at lowbraking loads. The results suggest that this test stand can be used to study rust layer removal from the rotor.
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| 9. |
- Wahlström, Jens, et al.
(författare)
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Simulation of airborne wear particles from disc brakes
- 2009
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Ingår i: SAE Technical Paper 2009-01-3040. - USA : SAE.
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Konferensbidrag (refereegranskat)abstract
- During braking, both the rotor and the pads are worn in disc brakes. This wear process generates particles which may become airborne. In passenger car field tests it is difficult to distinguish these particles from others in the surrounding environment. It may therefore be preferable to use laboratory test stands and/or simulation models to study the amount of airborne wear particles generated. This paper discusses the possibility of predicting the number distribution of airborne wear particles generated from the pad to rotor contact in disc brakes by using general purpose finite element software. A simulation methodology is proposed where the particle coefficient is established by testing at material level. This coefficient is then used in numerical wear simulation at component level. The simulated number distribution is compared to experimental measurements at component level. The result indicates that the proposed methodology may be used to predict the number and distribution of airborne particles generated from the pad to rotor contact.
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