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1
Conte, Alberto. "Development of brake components: geopolymer based brake pads." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3424930.
Full textAbstract:
The brake disc technology is the most used on commercial vehicle. The main focus of this project was the substitution of the phenolic resin, which is normally used as matrix in brake pads, with inorganic matrix, and in particular with geopolymer.
The inspiration comes from their inorganic structure. Geopolymers have better thermal properties than organic resins, which typically decompose by oxidation starting from 400°C. In fact, during the braking events temperature in the order of 600°C-800°C can be reached.
The research has been financed by ITT Italia s.r.l a world company leader on the production of brake pads. On the base of the guidelines of the company, the goal of the project has been the substitution of the phenolic resin with the geopolymer matrix and without any modification on the production process of brake pads.
Brake pads were produced using a warm press technology in dry conditions. During the pressing step occurs the phenolic resin’s crosslinking which could be completed through a post-curing in oven.
Based on the fact which the geopolymer are synthesized in solution, the first part of the project was focused on the development of geopolymer matrices suitable to be processed in the same conditions used to produce phenolic resin-based brake pads.
Two geopolymer system have been developed:
1. the hydrothermal dry synthesis of hydrosodalite from the reaction of kaolin and sodium hydroxide;
2. the cold sintering of geopolymer powder based on metakaolin and sodium silicate.
The best pressing conditions for the two system were evaluated on the base of their effect on mechanical properties and physical proprieties of geopolymer matrix. To evaluate the feasibility of the production in large scale of the geopolymer based brake pads, for the geopolymer matrices two goals have been followed at the same time:
1. The scale up at an industrial level for the geopolymer matrix production. Tests were carried out before at lab scale and subsequently with industrial technologies.
2. The optimization of the brake formulations has been done in ITT Italia s.r.l. on the base of physical properties and friction characterization of geopolymer based brake pads.La tecnologia di frenata basata sui dischi freno è la più utilizzata sui veicoli commerciali. L'obiettivo principale di questo progetto ha riguardato la sostituzione della resina fenolica, che viene normalmente utilizzata come matrice nelle pastiglie freno, con una matrice inorganica e in particolare con geopolimeri. L'idea deriva dalla loro struttura inorganica. I geopolimeri possiedono infatti proprietà termiche migliori delle resine organiche, le quali si decompongono in genere per ossidazione a partire dai 400 °C. Infatti, in fase di frenata frenata si possono raggiungere temperature dell'ordine di 600 °C - 800 °C. La ricerca è stata finanziata da ITT Italia s.r.l, un'azienda leader mondiale nella produzione di pastiglie freno. Sulla base delle linee guida dell'azienda, l'obiettivo del progetto è stato la sostituzione della resina fenolica con la matrice geopolimerica, e con il vincolo di non introdurre alcuna modifica sul processo di produzione delle pastiglie freno a base di resina fenolica. Le pastiglie freno sono state prodotte utilizzando una tecnologia di pressatura a caldo e a secco. Durante la fase di pressatura, avviene la reticolazione della resina fenolica, che può essere completata successivamente attraverso un post-curing in forno. Sulla base del fatto che il geopolimero è prodotto in soluzione acquosa, la prima parte del progetto, si è concentrata sullo sviluppo di matrici geopolimeriche adatte ad essere lavorate nelle stesse condizioni utilizzate per la produzione di pastiglie freno a base di resine fenoliche. Sono stati sviluppati due sistemi geopolimerici: 1. La sintesi idrotermale a secco di idrosodalite dalla reazione di caolino e idrossido di sodio; 2. La sinterizzazione a freddo della polvere di geopolimero ottenuto dalla reazione tra metacaolino e silicato di sodio. Le migliori condizioni di pressatura per i due sistemi, sono state valutate sulla base del loro effetto sulle proprietà meccaniche e sulle proprietà fisiche della matrice geopolimerica. Per valutare la fattibilità della produzione su larga scala delle pastiglie freno a matrice geopolimerica, per le matrici geopolimeriche sono stati perseguiti due obiettivi allo stesso tempo: 1. L’industrializzazione della produzione delle matrici geopolimeriche. I test sono stati effettuati prima su scala di laboratorio e successivamente con tecnologie industriali. 2. L'ottimizzazione delle formulazioni per pastiglie freno, che è stata effettuata presso il centro ricerche di ITT Italia s.r.l., sulla base delle proprietà fisiche e della caratterizzazione del comportamento ad usura delle pastiglie freno basate sui geopolimeri.
2
Papinniemi, Antti Aerospace Civil & Mechanical Engineering Australian Defence Force Academy UNSW. "Vibro-acoustic studies of brake squeal noise." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Aerospace, Civil and Mechanical Engineering, 2008. http://handle.unsw.edu.au/1959.4/38696.
Full textAbstract:
Squeal noise has been an on-going concern with automotive brake systems since their inception. Even after many decades of research no single theory exists that adequately describes the phenomenon, and no general methods for eliminating squeal noise exist. Broadly speaking, three primary methods of analysis have been applied to understanding and eliminating brake squeal: analytical, experimental and numerical. Analytical models provide some insight into the mechanisms involved when a brake squeals, but have limitations in applicability to specific brake systems. Experimental methods provide the backbone of brake squeal investigations, especially in an industrial environment. However, the core focus of this thesis is to use a large scale finite element analysis (FEA) model to investigate brake squeal. Initially the FEA model was developed and the dynamic characteristics were validated against experimental modal analysis results. A complex eigenvalue analysis was performed to identify potential squeal modes which appear as unstable system vibration modes. Further techniques are described that allow the deeper probing of unstable brake system modes. Feed-in energy, which is the conversion of friction work into vibrational energy during the onset of squeal, is used to determine the relative contribution of each brake pad to the overall system vibration. The distribution of the feed-in energy across the face of a brake pad is also calculated. Component strain energy distributions are determined for a brake system as a guide to identifying which components might best be modified in addressing an unstable system mode. Finally modal participation is assessed by calculating the Modal Assurance Criterion (MAC) between component free modes and the component in the assembly during squeal. This allows participating modes to be visualised and aids in the development of countermeasures. The majority of the work in this thesis was performed using the commercial FEA code MSC.Nastran with user defined friction interfaces. An alternative approach using a contact element formulation available in Abaqus was also implemented and compared to the MSC.Nastran results. This analysis showed that considerable differences were noted in the results even though the overall predicted stability correlated relatively well to observed squeal. Abaqus was also used in a case study into the design of a brake rotor in a noisy brake system. The results of this study provided good correlation to observed squeal and facilitated effective rotor countermeasures to be developed. Some success was achieved in the main aims of predicting brake squeal and developing countermeasures. However, while the tools presented do allow a deeper probing of system behaviour during squeal, their use requires good correlation to observed squeal on brake system to be established. As such, their use as up-front design tools is still limited. This shortcoming stems from the complexity of brake squeal itself and the limitations in modelling the true nature of the non-linearities within a brake system.
3
Day, Andrew J., Hon Ping Ho, Khalid Hussain, and A. Johnstone. "Brake system simulation to predict brake pedal feel in a passenger car." SAE International, 2009. http://hdl.handle.net/10454/3737.
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NoBraking system characteristics, brake system performance and brake system component design parameters that influence brake pedal `feel¿ in a passenger car have been studied using the simulation modelling package AMESim, in particular to model the linear and nonlinear characteristics of internal components. A passenger car hydraulic brake system simulation model incorporating the brake pedal, booster, master cylinder, brake lines and calipers has been developed to predict brake system response to assist in the design of braking systems with the desired brake pedal force / travel characteristic characteristics to create good brake pedal `feel¿. This has highlighted the importance of system components, in particular the master cylinder and caliper seal deformation, and the operating characteristics of the booster in determining the brake pedal force / travel characteristic. The potential contribution of these 3 components to brake pedal `feel¿ improvement has been investigated, and the results of the AMESim model have been verified using experimental measurement data. The model can be used in the future to provide an accurate prediction of brake system response at the design stage thereby saving time and cost.
4
Wiese, Viktor. "Brake noise : A study in multi-tonal brake squeal." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214996.
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Brake squeal is a major problem for the vehicle industry due to recla-mations and quality perception of vehicles, as well as the unpredictability of its occurrence. This report investigates the physical reasons behind a multi-tonal brake squeal generated in a motorcycle disc brake. It also covers why previous remedies to eliminate the noise has had an e↵ect, as well as trying to find a stable cost-e↵ective solution to the problem. The brake components are studied using numerical simulations as well as experimental analysis, the accuracy of which is investigated by analyzing a simple beam and compar-ing the results to analytical calculations. By performing a FEM-simulation of the di↵erent subsystems, the multi-tonal sound was tracked down to the ABS tone wheel, e.a. the sensory ring that is used for wheel speed mea-surements. By simulating the modes with altered tone wheel thickness, the modal pattern remains the same albeit reduced in frequency. A character-istic dimension between the tone wheels mounting points where found, as the frequency where these bending modes between the mounting points oc-curred closely correlated with the frequency content of the measured noise. A thinner tone wheel was then manufactured and field tested, these test results shows a reduction in frequency for the multi-tonal sound, thus the indications from the simulation is confirmed. Furthermore, an investigation in to brake disc properties is carried out in order to explain the reason why discs with altered geometry lacks the squealing problems of the original disc. This is done by a simulation of the sound propagation efficiency of the discs out-of-plane surfaces as well as an experimental study of the insertion loss from the friction surface between the brake disc and the brake pads to the tone wheel. The report ends with suggestions of design changes that can help combat the current issues, as well as problems of the same nature that might arise in future brake designs
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Nilman, Jenny. "Modeling and Simulation of Brake Squeal in Disc Brake Assembly." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-68798.
Full textAbstract:
Brake squeal is an old and well-known problem in the vehicle industry and is a frequent source for customer complain. Although, brake squeal is not usually affecting the performance of the brakes, it is still important to address the problem and to predict the brakes tendency to squeal on an early stage in the design process. Brake squeal is usually defined as a sustained, high-frequency vibration of the brake components, due to the braking action. By using simulation in finite element (FE) method it should be possible to predict at what frequencies the brakes tend to emit sound. The method chosen for the analysis was the complex eigenvalues analysis (CEA) method, since it is a well-known tool to predict unstable modes in FE analysis. The results from the CEA were evaluated against measured data from an earlier study. Even though there are four main mechanism formulated in order to explain the up come of squeal, the main focus in this project was modal coupling, since it is the main mechanism in the CEA. A validation of the key components in model was performed before the analysis, in order to achieve better correlation between the FE model and reality. A parametric study was conducted with the CEA, to investigate how material properties and operating parameters effected the brakes tendency to squeal. The following parameters was included in the analysis; coefficient of friction, brake force, damping, rotational velocity, and Young’s modulus for different components. The result from the CEA did not exactly reproduce the noise frequencies captured in experimental tests. The discrepancy is believed to mainly be due to problems in the calibration process of the components in the model. The result did however show that the most effective way to reduce the brakes tendency for squeal was to lower the coefficient of friction. The effect of varying the Young’s modulus different components showed inconsistent results on the tendency to squeal. By adding damping one of the main disadvantages for the CEA, which the over-prediction of the number of unstable modes, where minimized.
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Ripley, Ian, and ian ripley@qr com au. "An Investigation of Brake Application Delays in Australian Train Brake Systems." Central Queensland University. Engineering, 2005. http://library-resources.cqu.edu.au./thesis/adt-QCQU/public/adt-QCQU20060720.100110.
Full textAbstract:
An investigation of brake application delays in Australian train brake systems
began with a literature review of pneumatic train braking systems. Data located in the
review gave examples of brake application delays of pre 1990 designs from the U.K.,
India and North America. Information on application delays on later Australian designs
was scarce. Reading of literature has shown a difference between the Australian and
North American control valves in the way the propagation of the pressure reduction rate
in the brake pipe is maintained. Control valves of the North American style allow the
brake pipe air to be connected for a short time to a small cavity or quick service volume
of each valve. The quick service volume is then released to atmosphere. The action of
exhausting a small amount of air from the brake pipe helps to ensure a propagation of an
adequate pressure reduction rate as it travels to the next valve. Australian control valves
rely on the ratio of the volume of brake pipe between control valves and the size of the
quick service volume or bulb to ensure the propagation of an adequate pressure
reduction as it travels to the next valve. The air in a bulb of an Australian valve is not
expelled to atmosphere until a brake release is made.
The research explored possible reductions in application delays by utilizing an
experimental pipe test rack that included 4 control valves and 120 meters of brake pipe.
Experiments with different configurations of exhaust orifices or chokes, valves and
branch pipe lengths that supplied the valves gave a record acquired by data acquisition
of the timing of each valve and the local pressure drop from a valve or each valve for
comparison.
Experiments with exhaust chokes that gave a reduction drop rate in the brake pipe
that approached the minimum required to operate a control valve resulted in instability
of the application operation of the control valve. The quick service volume of different
sizes was included in the experiments to give comparisons in the propagation of the
pressure reduction toward the end of a long train. Further increases into the size of the
bulb of a control valve to enhance the propagation features toward the end of a long
train are discussed. The branch pipe with different diameters from 12 mm to 20 mm and
lengths from 160 mm to 800 mm when fitted to an adaptor pipe bracket were
investigated and results show that larger diameters gave larger gulps in the brake pipe.
Other components that were studied included the pipe bracket that is fitted on some
control valves. The pipe bracket and isolation cock was found to add 282 mm of
additional length to the air path and while not changing the operation of the valve, the
results showed a smaller drop in local pressure in the brake pipe to assist the pressure
reduction rate than shown in valves without pipe brackets.
7
Štylárek, Milan. "Konstrukce brzdového systému formule Student." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231480.
Full textAbstract:
Objective of this thesis is design of brake system of new car Formula Student class – Dragon 3. This car was built by students of faculty of mechanical engineering on Brno university of technology. Brake parts selection is described as well as designing hydraulic brake line circuits optimized for stable braking behavior on tracks of Formula Student competitions. One of main parts of this thesis is design of front and rear custom brake discs with related parts. These parts are FEM analyzed. In the end the whole brake system fitted on Dragon 3 car is tested on track and its performance is analyzed too.
8
Lindgren, Arne. "Development of Brake Cooling." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-31225.
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Sports cars need efficient brake cooling as they shall perform well during hard driving conditions, like for example race track driving. Most sports cars use ducts that capture ambient airflow and directs this flow over the brakes to improve the cooling. This project was conducted in cooperation with Koenigsegg Automotive AB and aims to develop more efficient brake cooling ducts for their cars. Computational Fluid Dynamics was used to analyse the convective cooling of the brake disc and the pads. First was the cooling with the previously used ducts analysed in order to establish a reference. Then new concepts were created, analysed and developed in an iterative process. A design is proposed, which have the inlet in the centre of the wheel axle and that directs the air through radial channels to the brake disc. The simulations indicate that the proposed design results in 14% higher heat transfer rate compared to the previously used cooling solution. In addition to the cooling ducts, some passive cooling devices were also simulated. Simulations with these in combination with the proposed design, indicate up to 25% increase in heat transfer rate, but this cannot be fully confirmed due to limitations in the simulation model.Sportbilar behöver effektiv bromskylning eftersom de ska prestera väl under hårda körförhållanden, som till exempel bankörning. De flesta sportbilar använder kanaler som fångar omgivande luftflöde och riktar detta flöde över bromsarna för att förbättra kylningen. Detta projekt genomfördes i samarbete med Koenigsegg Automotive AB och syftar till att utveckla effektivare bromskylkanaler till deras bilar. Computational Fluid Dynamics användes för att analysera den konvektiva kylningen av bromsskivan och bromsbeläggen. Först analyserades kylningen med den tidigare använda bromskylkanalen i syfte att skapa en referens. Sedan skapades nya koncept som analyserades och utvecklades i en iterativ process. En konstruktion föreslås, som har inloppet i centrum av hjulaxeln och som sedan styr luften genom radiella kanaler till bromsskivan. Simuleringarna indikerar att den föreslagna konstruktionen resulterar i 14% högre värmeöverföringshastighet än den tidigare använda bromskylningslösningen. Förutom kylkanalerna har några passiva kylanordningar också simulerats. Simuleringar med dessa i kombination med den föreslagna konstruktionen, indikerar upp till 25% ökning av värmeöverföringshastigheten, men detta kan inte helt bekräftas på grund av begränsningar i den använda simuleringsmodellen.
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Hamnholm, Löfgren Teodor. "Wheel Brake Noise Analysis." Thesis, Linköpings universitet, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138011.
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The scope of this thesis is to investigate methods of recording, processing and analysing sound data from wheel brake testing in dynamometers with focus on detecting and measuring squeal. The desired outcome is a method that Scania can use to record and analyse brake sound. A literature study was made to find relevant methodologies and tools proposed in papers, books and industry standards. These methods were tried and evaluated by recording and analysing real sound data and other signals from one of Scanias dynamometers. The resulting method includes directions on what hardware to use, how to set it up and an algorithm that computes a spectral limit based on normal sound data. This limit is then used as reference when evaluating other recordings. To increase signal to noise ratio, an adaptive filter is proposed to attenuate background noise in the recordings, in particular from the dynamometer and ventilation system. The conclusion is that it is possible to find squeal using spectral limits based on normal data. The performance of the algorithm is a compromise between being very effective but rather complex, or slightly less effective but also less complex. Its performance is also highly dependent on how squeal is defined. A very narrow definition will only find certain types of squeal while a more broad definition will find more squeal, but also potentially mislabel some recordings.
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Ramaratham, Srivatsan. "A mathematical model for air brake systems in the presence of leaks." Texas A&M University, 2008. http://hdl.handle.net/1969.1/86043.
Full textAbstract:
This thesis deals with the development of a mathematical model for an air brake
system in the presence of leaks. Brake systems in trucks are crucial for ensuring
the safety of vehicles and passengers on the roadways. Most trucks in the US are
equipped with S-cam drum brake systems and they are sensitive to maintenance.
Brake defects such as leaks are a major cause of accidents involving trucks. Leaks in
the air brake systems affect braking performance drastically by decreasing the peak
braking pressures attained and also increasing the time required to attain the same,
thereby resulting in longer stopping distances. Hence there is a need for detecting
leaks in an air brake system.
In this thesis, a mathematical model for an air brake system in the presence of
leaks is developed with a view towards developing an automatic leak detection system
in the near future. The model developed here builds on an earlier research at Texas
A&M University in which a "fault free" model of an air brake system is developed,
i.e., a mathematical model of an air brake system that predicts how the pressure in
the brake chamber evolves as a function of the brake pedal input when there are no
leaks in the air brake system.In order to develop a model for an air brake system in
the presence of leaks, one must characterize a "leak". A leak may be characterized by
the location and its size. Since the pipes are short, the location of the leak does not significantly affect the evolution in the brake pressure as much as its size. For this
reason, "effective area" of the leak was chosen as a characteristic of the leak. It was
estimated by fitting an empirical relation for leak with leak flow measurement data.
The supply pressure and effective area of leak comprised the inputs to the model
along with the displacement of the foot pedal (treadle valve plunger). The model was
corroborated with the experimental data collected using the setup at Texas A&M
University.
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Stephens, Arthur William, and arthur stephens esb ie. "Aerodynamic Cooling of Automotive Disc Brakes." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070108.121737.
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Sufficient heat dissipation is crucial to the effective operation of friction based braking systems. Such cooling is generally provided by ensuring a sufficient supply of cooling air to the heated components, hence the aerodynamics in the region of the brake components is extremely important. The objective of the research was to develop an understanding of how aerodynamics could be used to improve the cooling of automotive disc brakes. Two separate sets of wind tunnel experiments were developed. Tests were performed on a vented disc (rotor) to measure the internal flow through the vents on a rotating vented disc under various conditions, including an isolated disc in still air, the disc in still air with the wheel on, the disc in moving air with the wheel on, and an on-road simulation using a ¼ car. On vehicle tests were also performed in a wind tunnel using a purpose built brake test rig. These tests measured the thermal performance of different brake discs under various operating parameters; including constant load braking, and cooling from high temperature under various speeds, wheels and disc types. It was found that airflow through vented rotors was significantly reduced during simulated on-road driving, compared to when measured in isolation, but not particularly affected by the vehicles speed. In the situations tested, vented discs offered a 40+% improvement in cooling over an equivalent sized solid rotors. However the research indicates that the greatest benefit of vented rotors over solid will be in vehicles where air entering the wheel cavity is limited, such as low drag vehicles. It was also found that the most significant improvements in brake thermal performance could be achieved by maximising the airflow into the region of the brake components; including increasing the open area of the wheel, and increasing the vehicle velocity. Other improvements can be achieved by using a wheel material with good conductive capability, and increasing the mass of the disc. Evidence of vortex shedding was also discovered in the airflow at the exit of an internal vented rotor, any reduction in this flow disturbance should lead to increased airflow with associated improvements in thermal performance.
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Kienhöfer, Frank Werner. "Heavy vehicle wheel slip control." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609594.
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MacCrimmon, Donald. "Automotive brake wear debris analysis /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1791982261&sid=5&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Buck, Alexander. "Simulation von Bremsenquietschen (brake squeal) /." Aachen : Shaker, 2008. http://d-nb.info/991204492/04.
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Liermann, Matthias. "Self-energizing electro-hydraulic brake." Aachen Shaker, 2008. http://d-nb.info/990831930/04.
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MacCrimmon, Donald Cody. "Automotive Brake Wear Debris Analysis." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/theses/486.
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Passenger vehicle disk brakes produce large amounts of wear debris that needs to be analyzed to verify its environmental and health impact because its effects are amplified by the massive extent of vehicular transportation around the world. An efficient and thorough method for wear debris analysis should be derived from this research to assist brake manufacturers and researchers in understanding the characteristics of wear particulates being released from current brake materials. In addition, a test method allowing inspection of brake formulations in development phase should be provided and several model "environmentally friendly" brake lining materials should be developed. The most hazardous constituents in a known brake lining formula should be replaced with non-hazardous materials that will obtain performance specifications comparable to the original formula. The brake manufacturing industry and general public should be notified of important findings from this research. Model brake linings fabricated on-site with known constituents were run through an AO4D performance dynamometer test to collect airborne and non-airborne wear debris that is comparable to wear debris produced by an average passenger vehicle. Based on previous experience with analysis of brake linings, this wear debris will be analyzed with scanning electron microscopy equipped with energy dispersive X-ray microanalysis (SEM-EDX), transmission electron microscopy with EDX (TEM-EDX), X-ray diffraction (XRD), polarized light microscopy (PLM), X-ray fluorescence (XRF), and laser scattering particle size distribution analyzer (LSPSDA). Research presented in this report indicates clearly that the previous work published by several groups is lacking sufficient information and the findings should be corrected. For instance the particle size distribution detected by particle size analyzers and impactors (recommended by EPA) is not accurate and TEM as well as SEM studies allowing direct observation of wear particles revealed considerable differences between sizes detected by these analyzers and realistic particle size. EDX in combination with XRF and XRD allows for reliable identification of chemical species and crystalline phases present in wear debris. True airborne wear debris should be sampled from brake exhaust from an appropriate distance. Degummed hemp shows promising results as a copper replacement in low-metallic friction material.
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Kortán, Daniel. "Analýza brzdění vozidla s nestandardním zásahem do brzdové soustavy." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-367510.
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This master’s thesis focused on the issue of the possible conversion of liquid brake systems, in the form of replacement of wheel brakes. The first part focused on the function and description of the construction of different types of brakes. The second part is focused on description the types of brake system testing and the regulations regarding brake systems. The last part focused on the measurement of both vehicles and comparison of the results with the calculations.
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Chen, TzuFu. "Relationship Between Formulation and Noise of Phenolic Resin Matrix Friction Lining Tested in Acoustic Chamber on Automotive Brake Dynamometer." OpenSIUC, 2008. https://opensiuc.lib.siu.edu/theses/482.
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The main objective of this research is to address the relationship between formulation of friction lining materials and their propensity to friction induced noise generation. The basic idea was formulated earlier by Dr. Filip, who showed that the friction layer plays the relevant role when noise is observed during braking. It was shown that when newly formed patches (parts of the friction layer) exhibit a large difference in the coefficient of friction, brake lining is stretched and released repeatedly, which leads to significant vibrations and corresponding noise when coupled with the vibration mode of the system. Farhang ,on the other hand, demonstrated that noise can be related to specific surface roughness parameters and when properties of friction lining and friction layer (such as compressibility, stiffness and modulus of elasticity) fit into certain specific value ranges, noisy behavior occurs. This research will address the braking related to friction induced noise in relation to the properties of the bulk lining material and the character and properties of the friction layer. The friction tests will be performed using the CAFS-developed (Szary and Lee) real time noise measurement system compatible with the major part of SAEJ2521 standard (note that the system does not allow for reliable measurement of frequencies lower than 900 Hz). The mechanical properties of fourteen samples will be investigated. Of the fourteen samples, friction layer of three of the samples will be investigated by several analytical techniques developed by Dr. Filip [1]. They include polarized light microscopy, scanning and transmission electron microscopy equipped with energy dispersive microanalysis, and X-ray diffraction. This research summarizes data from the J2521 dynamometer test of the Dodge Caravan samples exhibiting specific compressibility, porosity and hardness. Also, this research provides the results of friction surface analysis by SEM with energy dispersive microanalysis, light microscopy, surface roughness, and X ray diffraction. Of the fourteen samples, Bendix has the largest occurrence of noisy braking. Based on techniques developed by Dr. Filip, the characteristics of the friction layer strongly influence brake noise propensity. The friction layer characteristics are dependent on brake formulation. As predicted, "noisy stop" and "quiet stop" samples exhibit completely different friction surfaces.
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Drtílek, Juraj. "Experimentální identifikace NVH brzdových soustav." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318537.
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This Diploma Thesis is dedicated to solve the source of noise, observed during braking processes on tested vehicle, called Gouki noise and has been worked out in corporation with Federal Mogul company. The aim of this work to create test methology, which allows to experimentally detect the source of undesirable noise and eventually suggest next steps in its prevention.
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Gay, Sebastien Emmanuel. "Contactless magnetic brake for automotive applications." [College Station, Tex. : Texas A&M University, 2005. http://hdl.handle.net/1969.1/ETD-TAMU-1005.
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Hagerman, Henrik. "Simulation of pneumatics in brake systems." Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39547.
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Pneumatic brake systems use pressurized air to apply the brakes and are used in trucks, amongst other vehicles. Due to the compressibility of the air, there is a time delay from the push-down of the brake pedal to the attainment of the desired brake effect. The time for the pressure in the brake cylinder to reach 75% of its final pressure is subject to legal requirements, and this master thesis studies the possibilities to predict that time by simulation. The program GT-SUITE is chosen for the simulation, since it is shown to be suitable in a survey of potential software and an evaluation. Also, MATLAB is used to simulate an approximate system description. To support the modeling of brake system components, measurements are made on a simple brake rig, gradually extended with common brake components which then can be modeled. Finally, the models are verified with a measurement on a complete brake system. In the simple rigs, the simulations are accurate and able to predict the effect of new components. Verifying the models, though, the simulation is not accurate enough. However, the simulation seems to give conservative results, which means that a truck that in simulation passes the certification is likely to pass it in reality too.
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Vallabh, Priya. "Electrorheological brake for haptic interface systems." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17070.
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Hassan, Muhammad Zahir. "Thermal Deformation Analysis Disc Brake Squeal." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505054.
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Mulchandani, Hiten. "An engine air-brake integration study." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62880.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student submitted PDF version of thesis.
Includes bibliographical references (p. 109-112).
The feasibility of operating an engine air-brake (EAB) integrated with a pylon duct bifurcation in a realistic aircraft engine environment has been analyzed. The EAB uses variable exit guide vanes downstream of a high bypass ratio (BPR) fan rotor to produce drag quietly by swirling flow out of the fan nozzle. The swirling motion yields low pressure in the vortex core from simple radial equilibrium, thereby generating pressure drag. The 4-BB internal plug and 5-BB external plug nozzles of BPR 8 are chosen to provide a realistic environment for model-scale tests at the NASA Aero-Acoustic Propulsion Lab (AAPL). The objectives of this study are to quantify the impact of a pylon on the drag and noise of an EAB, and explore means to mitigate the potential loss of swirling flow and associated drag. Analysis is conducted at approach conditions on the 4-BB nozzle, with fan and core nozzle pressure and temperature ratios obtained from an engine cycle analysis. A pylon is designed to represent engine installations typically encountered in short-range jet aircraft. The pylon is a prismatic NACA 0012 airfoil geometry with swept leading, trailing edges and an extended internal fairing to facilitate compatibility with both nozzles in the AAPL facility. The EAB cases analyzed include three types of pylon/vane configurations: (1) the baseline pylon with un-deflected swirl vanes is used in the calculation of the equivalent drag coefficient (CD); (2) the pylon with the trailing edge (TE) flap deflected full-span by 35 degrees is used to set structural load limits for detailed design of the baseline pylon; and (3) configurations with the pylon TE flap deflected partial-span by 20 degrees and asymmetric swirl vanes are used to generate swirling outflow from the fan nozzle exhaust. The partial-span deflection cases are further categorized by the location of the asymmetric vanes: at the nozzle exhaust (aft) and further upstream. Computational results demonstrate the aft vanes generate CD in the range 0.35-0.61 and the upstream vane cases produce CD between 0.09-0.18. The difference in drag is because the flow avoids the majority of the duct bifurcation in the aft vanes cases to produce stronger swirling outflow. A CD value between 0.7-1.0 is required to achieve a 3-4 degree glidescope change and therefore an overall noise benefit of 2.5 dB for a conventional tube-and-wing aircraft on approach. The aft vane configurations show promise in reaching this target while the upstream vane installation concepts require further investigation.
by Hiten Mulchandani.
S.M.
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Lebeau, Timothy Charles. "Brake drum production by centrifugal casting." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/lebeau.pdf.
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Alnaqi, Abdulwahab Ali. "Characterisation of coated lightweight brake rotors." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7265/.
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Numerical and experimental studies were undertaken using lightweight brake rotors to reduce vehicle weight and thereby improve fuel efficiency and vehicle emissions. Abaqus finite element and Matlab software were used to construct one dimensional (1D), two dimensional (2D) and three dimensional (3D) thermal models to investigate the general thermal performance of disc brakes to develop a valid method of reduced scale testing. Five small scale solid brake rotors were investigated experimentally: grey cast iron, wrought aluminium alloy (6082), the same 6082 alloy with an alumina surface layer applied by plasma electrolytic oxidation (PEO), cast aluminium MMC (AMC640XA) and the same MMC with a PEO alumina surface layer. The disc and pad temperatures, brake pressure, coefficient of friction and brake torque were monitored during the tests for each material. Surface morphology, microstructure and micro hardness of the coatings and substrate were evaluated before and after the tests. Numerical simulations confirmed the equivalence between the full and small scale disc thermal performance using the proposed scaling methodology and also provide a good agreement with the experimental results. The coated 6082 alloy rotor was shown to give good thermal and friction performance up to relatively high rubbing surface temperatures of around 500oC. This rotor failed at a surface temperature of about 550oC due to brittle fracture of the wrought aluminium substrate. The proposed scaling methodology was shown to be a valid method of investigating a rotor design concept in the laboratory at low cost and reduced operating time. The PEO coating on aluminium alloy was denser and more uniform compared to the PEO coating on aluminium MMC. In addition, the PEO coating improved the hardness and thermal resistance of both the aluminium alloy and aluminium MMC. A sensitivity analysis based on the Taguchi approach was carried out on the PEO coated aluminium alloy rotor to investigate the effect of various parameters on thermal performance. Optimisation of the structure was carried out using a genetic algorithm to design coated aluminium alloy discs that are potentially technically viable on small-medium passenger cars.
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Petry, Matthias, Olivier Reinertz, and Hubertus Murrenhoff. "Development of a Simulation Model of a Self-Energizing Hydraulic Brake to Actively Compensate Brake Torque Oscillations." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199896.
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Friction force oscillations caused by changing properties of the contact zone between brake disc and pad are well known from various applications. Resulting effects like brake judder are known phenomena in brake technologies and in the scope of various scientific work. A new measure to potentially reduce brake torque oscillations is the active compensation with the use of the control system of a self-energizing hydraulic brake (SEHB). New in comparison to traditional disc brakes is the fact that the brake torque is measured by the pressure in an additional supporting cylinder. Thus, the brake system is able to work in brake torque control mode. Within this paper a dynamic simulation model of the SEHB is shown and evaluated with measurement data achieved from a full scale test rig for railway applications. Based on the simulation model a pressure control strategy is developed to minimize brake torque oscillations of lower frequencies. The control parameters of the simulation are transferred to the experimental setup. Finally, simulation and experimental results are compared. Future work will deal with the development of control strategies to additionally minimize brake torque oscillations of the higher dynamics.
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Sauer, Heinz. "Burg und Schloss Brake : 1000 Jahre Baugeschichte /." Lemgo : Landesverband Lippe, 2002. http://catalogue.bnf.fr/ark:/12148/cb391278034.
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Henriksson, Tomas. "Driver Assistance Systemswith focus onAutomatic Emergency Brake." Thesis, KTH, Fordonsdynamik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121306.
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This thesis work aims at performing a survey of those technologies generally called DriverAssistance Systems (DAS). This thesis work focuses on gathering information in terms ofaccident statistics, sensors and functions and analyzing this information and shall thruaccessible information match functions with accidents, functions with sensors etc.This analysis, based on accidents in United States and Sweden during the period 1998 – 2002and two truck accident studies, shows that of all accidents with fatalities or sever injuriesinvolving a heavy truck almost half are the result of a frontal impact. About one fourth of theaccidents are caused by side impact, whereas single vehicle and rear impact collisions causesaround 14 % each. Of these, about one fourth is collision with unprotected (motorcycles,mopeds, bicycles, and pedestrians) whereas around 60 % are collision with other vehicles.More than 90 % of all accidents are partly the result of driver error and about 75 % aredirectly the result of driver error. Hence there exist a great opportunity to reduce the numberof accidents by introducing DAS.In this work, an analysis of DAS shows that six of the systems discussed today have thepotential to prevent 40 – 50 % of these accidents, whereas 20 – 40 % are estimated to actuallyhaving the chance to be prevented.One of these DAS, automatic emergency brake (AEB), has been analyzed in more detail.Decision models for an emergency brake capable to mitigate rear-end accidents has beendesigned and evaluated. The results show that this model has high capabilities to mitigatecollisions.
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Hallqvist, Joakim. "Faster Locking Differential Through Active Brake-Control." Thesis, Linköpings universitet, Fordonssystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119423.
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When a vehicle with wheels aligned in pairs turn, the wheel traveling around the outside of the curve has to roll farther than the wheel on the inside. This means that some sort of device must must be used to allow the drive wheels to rotate at different speeds to prevent wear on the tires. This is usually a mechanical device where the input rotation controls the sum of the two output rotations, this is known as a differential. This solution however has some shortcomings, the biggest one is that the total amount of force that can be transferred between the tires and the road surface is limited by the tire with the least traction. In slippery conditions this can be a big problem since it only takes one wheel to lose traction in order to prevent the vehicle from accelerating. In this thesis a locking differential is used to overcome this shortcoming, this gives the driver the option to lock the shafts of the driving wheels together. This is done by pushing two cogwheels, one attached to each shaft, together. The aim of this thesis is to shorten the lock- and unlock-time of the locking differential by aligning the cogwheels using the service brakes and available sensors. The results were evaluated by implementing the software in a truck and doing test runs on Scanias test track. These tests showed that the system greatly improved both lock- and unlock-times but at cost of lower driver comfort. With additional work with some fine tuning of the system, the overall performance could probably be increased even more.
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James, Simon. "An experimental study of disc brake squeal." Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399154.
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Disc brake vibrations are a cause of concern for automobile users and manufacturers. The user can find the noise of brake squeal annoying and sometimes worrying. The manufacturer suffers the immediate costs involved in vehicle warranty claims and may lose sales if a particular vehicle model develops a reputation for noise problems. The measurement of disc brake squeal and its relationship to audible and structureborne vibration measurement is difficult to determine without influencing the vibration by the measurement technique. Ideally, measurements would be taken under 'real' conditions. The complexity and cost of 'in-car' testing was prohibitive. Instead, the approach taken was to use a real car brake system, but mounted in such a way that the support structure carrying the knuckle was as rigid as practically possible. This allowed an array of non-contact displacement transducers to measure the vibration at the disc surface. This experimental approach was used to investigate how the displacement signals produced by a squealing disc could be processed to determine the mode shapes of the disc and the behaviour of the waves that generate the audible squeal noise. The two methods used in the analysis of the squeal data were the fast Fourier transform of each data channel and the least-squares analysis of the time domain data. The least-squares approach was the more difficult to achieve, but successfully produced detailed analysis of the behaviour of the wave motion in the disc from the available data.A finite element analysis of the brake structure compared favourably with the frequencies and mode shapes obtained by both modal hammer tests and squeal tests. The use of this type of dynamometer, measurement system and analysis method has proved successful in providing a deeper understanding of the mechanisms involved in disc brake squeal.
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Buck, Alexander [Verfasser]. "Simulation von Bremsenquietschen (Brake Squeal) / Alexander Buck." Aachen : Shaker, 2008. http://d-nb.info/1161305882/34.
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Sergent, Nicolas. "Analysis and optimisation of disc brake calipers." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/10196.
Full textAbstract:
Disc brake calipers are subjected to complex mechanical loading and interaction of
individual components in a typical brake assembly makes design improvement very
challenging.
To analyse caliper behaviour, complex Finite Element models were created and
successfully validated using a variety of experimental techniques, including
exceptionally suitable Digital Image Correlation. A novel methodology to optimise
caliper design was developed, using non-linear contact Finite Element Analysis and
topology optimisation, to generate lightweight, high performance brake calipers. The
method was used on a Formula 1 brake assembly and significant improvement in
structural design was achieved, with the new caliper being lighter and stiffer than the
original. The same approach was used on more conventional 4 pistons calipers using
various boundary conditions with particular focus on mass reduction and considerably
lighter designs were achieved. The influence of specific features of the optimised
calipers on the structural performance was also successfully investigated.
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Massi, Francesco. "Dynamic and tribological analysis of brake squeal." Lyon, INSA, 2006. http://theses.insa-lyon.fr/publication/2006ISAL0101/these.pdf.
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This thesis is addressed to understand the physics of the instability that is at the origin of squeal noise. Due to the interdisciplinary nature of this issue, involving especially dynamic and tribological aspects, the work is organized into four main branches, developed parallely. I) A linear finite element model is developed to predict the squeal frequencies by a parametrical analysis (complex eigenvalue analysis). Ii) The unstable values of the system parameters are introduced into a nonlinear finite element model to study the system vibrations and the behaviour of the contact stresses with and without squeal. Iii) A dynamic experimental analysis is performed to understand the macroscopic behaviour of the system and to link the squeal instability with the system dynamics. The design of a simplified brake set-up, characterized by a dynamics that can be simply monitored and modified, allows to highlight the modal coupling (lock-in) phenomenon. Iv) A tribological experimental analysis is developed to understand the role of the components of the tribological triplet (mechanism, first bodies, third body). The topography of the contact surfaces allows to validate the numerical results and to evidence fatigue phenomena. The results obtained from the four branches of the research converge together, characterizing the squeal as a dynamic instability of the brake system due to unstable couplings between two modes of the brake components. The coupling occurs at the contact where the oscillations of the local contact stresses and the friction coefficient couple the normal and tangential vibrations of the brake components, causing auto-excited vibrations of the systemLe but de cette thèse est l’étude des phénomènes d’instabilités à l’origine des bruits de crissement lors du freinage. L’interdisciplinarité du sujet qui traite majoritairement des aspects tribologiques et dynamiques, est prise en compte. Le rapport est structuré en quatre parties principales, menées en parallèle. I) Un modèle numérique linéaire basé sur la méthode des éléments finis est développé pour prédire les fréquences de crissement avec une analyse paramétrique. Ii) Les valeurs instables des paramètres sont alors introduites dans un modèle numérique non linéaire développé pour les problèmes de contact. Les nonlinéarités du contact sont donc prises en compte et la simulation numérique dans le domaine temporel permet d’analyser les vibrations du système et le comportement local des contraintes de contact. Iii) Une analyse dynamique expérimentale est effectuée pour comprendre le comportement macroscopique du système et lier l’instabilité de crissement à la dynamique du système. V) Une analyse tribologique expérimentale est conduite pour comprendre les rôles des éléments du triplet tribologique (mécanisme, premier corps et troisième corps). Les résultats obtenus dans chacun des quatre parties de ce travail convergent et permettent l’interprétation de la physique du phénomène du crissement : l’instabilité est due au couplage entre deux vecteurs propres du système. Le couplage s’initie dans la surface du contact où l’oscillation local des contraintes de contact et le coefficient de frottement assurent le couplage entre les vibrations tangentielles et normales des composants du système de freinage, et causent ainsi les vibrations auto-excitées du système
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McKavanagh, David Sean. "ON SCALING OF BRAKE TEST SAE J2522." OpenSIUC, 2020. https://opensiuc.lib.siu.edu/theses/2710.
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Friction brakes represent the most important safety feature literally in all vehicles and their rigorous “friction testing” is usually performed on several platforms/scales and completed with field tests. Since friction and wear are system properties, it is not trivial to design “small scale” tests and to correlate data generated at different levels of testing complexity. Nevertheless, the economy of the brake materials development process could be improved, when interpretation of friction and wear test data is based on a deeper/proper understanding of physics and chemistry of ongoing friction phenomena. This contribution follows the two series previously presented at SAE Brake Colloquia and compares the data generated in the full-scale brake dynamometer SAE J 2522 performance test (Link Engineering 2800M dynamometer) with data generated in bench-top (small scale) friction tester (Bruker UMT) equipped with environmental chamber controlling temperature. Scaling laws of physics were adopted for design of the small-scale testing procedure, however, a different scaling philosophy as well as different friction materials were used when compared to the previously reported findings. Identical commercial OEM brake pad samples containing biodegradable environmentally friendly fibers and commercial OEM cast iron rotors were used in both dynamometer and scaled-down bench-top friction tests. Friction and wear surfaces/mechanisms were studied by using scanning electron microscopy (Quanta FEG 450 by FEI) equipped with the energy dispersive X-ray microanalysis (Inca System), and 3D optical microscope (NPFLEX by Bruker). Major conclusions proposed for this study can be summarized as follows: 1) Proper scaling by using physics principles allows for reasonable correlation of dynamometer and bench-top test data, although the results differentiate, particularly during fade and high temperature tests. These findings further support the previously published data and indicate that differences in scaling philosophy neither the types of tested materials have considerable impact on the generated data. 2) It is very important to properly select representative pad samples, as their size is considerably smaller compared to full pads. When the identical rotor materials are used, the repeatability of data is excellent and the sensitivity to typical differences of the bulk microstructure of cast iron is minimal. 3) When the testing results generated on dynamometer and bench tester matched well. the friction surfaces of full pads tested in dynamometer and the friction surfaces of small pad samples exhibited identical topography and chemistry.
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Thiyagarajan, Kamesh. "Conceptual development of brake friction estimation strategies." Thesis, KTH, Fordonsdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285677.
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The thesis work investigates brake friction estimation strategies. The friction between the brake disc and brake pads is not constant during the braking application and contributes to the amount of brake torque achieved at the wheels. In this study, it is considered that any change in the brake torque between the requested and achieved values is only due to the varying brake friction coefficient. The work gives three different approaches to estimate the brake friction coefficient using two prominent state estimation strategies, Unscented Kalman Filter and Moving Horizon Estimation. The inputs to the estimators are obtained from a Vehicle model, which is built using the wheel balance equations. The estimators have been tuned to minimize the estimation error in nominal conditions and tested for their robustness through a wide analysis, where the sensitivity of the strategies is checked against a spectra of potential system parameters and boundary conditions. Throughout all the analysis, the developed models estimate the brake friction coefficient within an acceptable error range. This work opens up opportunities for further studies that can be performed using the built estimator models.Detta examensarbete studerar strategier för skattning av bromsfriktion. Friktionen mellan bromsskivan och bromsbeläggen är inte konstant under bromsförloppet och det är denna som genererar bromsmomentet för varje hjul. I detta arbete så antas att förändringen i bromsmoment mellan begärd och uppnått endast är på grund av varierande bromsfriktion mellan bromsbelägg och bromsskiva. Arbetet presenterar tre olika sätt att skatta bromsfriktionen genom användning av två kända skattningsmetoder, Uncented Kalman Filter och Moving Horizon Estimation. Ingående värden till skattningsmetoderna fås från en fordonsmodell som är byggd med hjälp av hjulbalansekvationer. Skattningsmetoderna har justerats så att de minimerar skattningsfelet i nominella fall och de är testade för robusthet genom en bred analys där känsligheten hos metoderna testas genom en flora av potentiella systemparametrar och gränsvärden. Genom hela analysen så uppnår de utvecklade skattningsmetoderna bromsfriktionsvärden med acceptabla felnivåer. Detta arbete öppnar upp för möjligheter för vidare analyser där de utvecklade metoderna kan användas.
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Hagler, Lisle Bruce. "Friction induced vibration in disk brake systems /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/7119.
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McKinlay, Andrew James. "The phenomenon of vehicle park brake rollaway." Thesis, University of Leeds, 2007. http://etheses.whiterose.ac.uk/4412/.
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When a vehicle is parked on a slope with hot brakes, what appears to be a sufficient parking brake action can sometimes become insufficient. When the brakes cool down, the braking force reduces due to relaxation of the entire parking brake system, and the vehicle may start to move, leading to obvious catastrophic consequences. This phenomenon is known as vehicle rollaway. This thesis describes the problem in detail and postulates a mechanism that accounts for the occurrence of the rollaway event on vehicles using integrated rear callipers. Different testing methods are presented that are used to investigate the propensity of a vehicle's parking brake system to rollaway. These include on-vehicle evaluations and laboratory based measurements. A description is given of a novel dynamometer facility that was developed for this research that is capable of testing vehicle parking brake systems for rollaway. Two mathematical modelling techniques are presented that demonstrate how the parking brake system parameters influence the likelihood of rollaway occurring. A finite element model was used to simulate the change in contact pressure at the frictional interface during a rollaway event. A numerical model was also used to predict the change in torque developed by a parking brake system cooling from an initial elevated temperature. The change in clamp load at the frictional interface was modelled using an essentially I-D quasi-static system that showed how the stiffness and the thermal properties of the system qualitatively affect the phenomenon. The research found that rollaway does not always start with a uniform motion, but with a stick/slip motion. The likelihood of rollaway occurring was found to be directly linked to the temperature of the brake when the vehicle is parked. Rollaway can be reduced by lowering the initial temperature of the brake prior to parking. Rollaway can also be reduced by increasing the input load to the system when applying the parking brake. The research identifies the key design parameters of the brake system components whose values require close control within the real system if rollaway is to be avoided.
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Mahmoud, Khaled Rabie Megahed. "Theoretical and experimental investigations on a new adaptive duo servo drum brake with high and constant brake shoe factor /." Paderborn : HNI, 2005. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=014814060&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Motl, Jakub. "Vliv okamžité hmotnosti vozidel na jejich brzdnou dráhu." Master's thesis, Vysoké učení technické v Brně. Ústav soudního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-232480.
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This diploma thesis is engaged in analysis of braking process of vehicles, especially heavy utility vehicles, with regard to their instantaneous weight. This thesis features survey and division of braking systems and function of brakes including schemes and descriptions. Also there is introduce of some systems improving vehicle properties. Furthermore this work puts mind to possibilities of examination of brakes, measurement of braking distance and braking retardation namely in brake test rooms or by outdoor driving tests including descriptions of particular methods and equipment. There is also mention about legislative requirements for braking distance and braking retardation. The conclusion of this thesis compares numerically predicted braking distance and real braking distance measured for factual vehicle during outdoor driving test
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Daei, Amir Reza. "IMPACT OF SOLID LUBRICANTS ON FRICTION PERFORMANCE OF ADVANCED AUTOMOTIVE BRAKE MATERIALS." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/1900.
Full textAbstract:
Automotive brake lining materials are complex composites consisting of numerous ingredients allowing for their optimal performance. Different types of carbons have been used in all types of brake pad formulations for more than century. The role of carbon, however, does not seem to be completely understood, since carbon materials possess a wide variety of characteristics and properties and they interact with other ingredients present in the friction process. Carbons/graphites are commonly considered to be solid lubricants but this role is only available at relatively low temperatures and at a sufficient humidity. Since regulations are increasingly limiting Cu content in brake pads and Cu exhibits extremely high thermal conductivity, graphites, being excellent heat conducting materials themselves, are often considered for use when potential Cu replacement options in the low-metallic, non-asbestos organic, hybrid, and ceramic pads are explored. This paper surveys the role of two types of graphites with high thermal conductivity but different mechanical properties and morphology: the so-called i) purified flake graphite (PFG) and the ii) resilient graphitic carbon (RGC). A successful “high-end” commercial low-metallic brake pad was re-formulated (SIU Carbondale) by removing of over 20 wt. % of Cu and replacing it with a cocktail of ingredients including 15 wt. % of these two graphite types. OEM Crown Victoria 1999 mold was used to prepare the pads and they were subjected to the SAE J2430 test and BEEP evaluation using the full-scale automotive brake dynamometer (Link Engineering) and original hardware (rotor and caliper). After friction tests, the surfaces of pads were explored using scanning electron microscopy equipped with the energy dispersive X-ray microanalysis (FEG450 and Inca System) and X-ray diffraction (Rigaku Max-Flash-B). Although the brake pad formulations were otherwise identical and were prepared at the same conditions, the performance of two different low-metallic pads was different. The effectiveness of PFG sample reached value 0.5 and wear of pad was 5.3 g, while the effectiveness was 0.4 and wear detected was 5.9 g in the case of RGC containing sample. Both formulations exhibited extremely good stability of friction during fade section and only low sensitivity to speed variations between 50 and 160 km/h. Surfaces of both pads were covered by a discontinuous (patchy) friction layer which was formed as a consequence of a gentle abrasive mechanisms involved. The different friction levels and different wear of samples were related to the specific character/differences in detected different friction layers. Importantly, the capacity of the PFG to reduce surface oxides is considerably higher when compared to the RGC. It was concluded that the proper understanding of role of individual graphitic forms in particular formulations can be very beneficial when optimizing the performance of brake pads.
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Ren, Haichuan [Verfasser]. "Investigations on Wear of Brake Pads / Haichuan Ren." Aachen : Shaker, 2016. http://d-nb.info/1084536676/34.
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Tao, Jiyue, and Asnaf Aziz. "Simulation of thermal stresses in a disc brake." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH. Forskningsmiljö Produktutveckling - Simulering och optimering, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-19163.
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The heat flux produced from the friction between a disc and pad system leads to a high temperature which causes thermal stresses in the disc and after a number of repeated braking cycles, cracks might be initiated. The finite element analysis (FEA) is performed to determine the temperatures profile in the disc and to analyze the stresses for the repeated braking, which could be used to calculate the fatigue life of a disc.Sequentially coupled approach is used for thermo-mechanical problem and the problem is divided into two parts, heat analysis and thermal stress analysis. The heat analysis is obtained by including frictional heat and adopting an Eulerian approach. The heat analysis is conducted by using Abaqus and the toolbox developed by Niclas Strömberg. The thermal stress analysis, which is the main focus of this thesis, is followed using Abaqus. The plasticity theory as background for stress analysis is discussed in detail. The rate independent elasto-plastic plasticity is used in the stress analysis. Temperature independent material properties are considered throughout the thesis work.Isotropic, kinematic and combined hardening models are analyzed for simple 2D academic models for different types of cyclic loads. A benchmark disc and pad model, which is less complicated than the real disc-pad model, is also studied. The linear kinematic hardening model with rate independent elastic-plastic plasticity is used for benchmark and real disc-pad model. The results of the benchmark model and the real model are observed to be similar in terms of plasticity theory.
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Bryant, David. "Thermo-elastic deformation of a vented brake disc." Thesis, University of Huddersfield, 2010. http://eprints.hud.ac.uk/id/eprint/9076/.
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The subject of retarding a moving vehicle or object in a controlled manner has been investigated over hundreds of years with many different solutions being developed over the years. As time has progressed a common overall design has almost uniformly been agreed upon for vehicle use; a brake disc and caliper or brake drum arrangement. As vehicle refinement has improved there has been increasing focus on the refinement of such designs with regards to their noise, vibration and harshness (NVH)characteristics. Whilst brake noise has had significant research analysing its cause, effect and solutions, brake judder has had less research focussed upon it. The principal reason for past research priorities and the recent interest in judder is because of the increased demands being placed on brakes – higher power absorption with lighter structures. The subject of this thesis was to address the least known phenomena of brake judder, that of the thermo-elastic deformation of vented brake discs. The research utilised experimental, analytical and empirical methods to give a broader understanding of the transient deformation process, both thermo-plastic and thermo-elastic, of a high performance vehicle disc brake. Initial characterisation of thermal judder was carried out on-vehicle where it was identified that brake pressure could be used as a reliable indicator to show the developing nature of this phenomenon. The brake pressure pulsation was shown to change from low order (first or second order) to high order (up to eighth order) over the duration of a high speed vehicle brake test which involved up to thirty braking events. The pressure pulsation indicated a link to brake disc deformation with the magnitude and order of brake pressure variation increasing with increasing disc temperature. The highly dynamic, transient, nature of brake disc distortion was also investigated on a bespoke quarter car suspension brake dynamometer. Thermoelastic wave-like deformation was shown to occur during the process of a single braking event with the order of deformation corresponding to the brake pressure variation. The order of this wave-like deformation was shown to be linked to the amount of energy transferred into the braking system with higher energy braking events resulting in higher order deformation. Thermal images of the brake disc have shown an equispaced formation of hot-spots on the inboard and outboard friction ring surfaces which was linked to the disc waveform. The wave-like deformation was attributed to circumferential buckling of the brake disc as suggested by Lang [1]. This resulted from rapid thermal expansion of the friction rings due to the sudden - 4 - influx of heat during braking. Thermal gradients between the hot and cold regions of the brake disc constrained the radial thermal expansion of the friction ring and caused compressive stresses to build up. When the tangential load causing the stress was in excess of the critical buckling load, buckling of the brake disc occurred with the mode order of the buckled disc related to the temperature of the friction ring. Stress relieving of the brake disc was shown to occur during brake testing on the brake dynamometer causing a thermo-plastic effect. This “in service” stress relieving effect removed the retained stresses resulting from the casting and machining processes and allowed the disc to adopt a second order mode of deformation. Data from the on-vehicle and dynamometer testing was used to generate and validate finite element analysis simulations which were used to investigate thermal inputs and heat dissipation from the brake disc. These findings were then combined with that of an associated aerodynamic study [2] to generate a modified brake disc vent profile which reduced the surface temperature variation, thermal gradients and maximum disc temperature. On-vehicle testing of the prototype design showed an average 14% reduction in maximum disc temperature and it was proposed that this would reduce the propensity for the disc to generate judder by reducing the thermal deformation of the brake disc.
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Tuchinda, Anantawit. "Development of validated models for brake squeal predictions." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405834.
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Lang, Allan M. "An investigation into heavy vehicle drum brake squeal." Thesis, Loughborough University, 1994. https://dspace.lboro.ac.uk/2134/7447.
Full textAbstract:
Many mechanisms have been suggested for brake squeal over many years. In order to identify the most appropriate of these mechanisms, an experimental investigation has been carried out to define in detail the vibration characteristics of a squealing heavy vehicle air operated drum brake on both a vehicle and a laboratory brake test rig. This required the development of a novel 'scanning' technique for the modal analysis of the rotating drum, which showed the presence of well-defined complex wavelike modes. From these results, the dynamic behaviour of the drum, in particular, is found to be in good qualitative agreement with the predictions of a simple 'binary flutter' mechanism of squeal. Based on the role of rotor symmetry in this mechanism, a means of decoupling, flutter modes is developed involving a reduction in the rotational symmetry of the drum by means of attaching masses in a defined pattern at its periphery. It is shown theoretically that such decoupling would be expected to increase the dynamic stability of the brake, and experimental application of the technique confirms its effectiveness in reducing or eliminating squeal. Practical design aspects of reducing the rotational symmetry of the drum are considered, using finite element modelling, and it is also shown that the technique can be effective in other types of vehicle brake, such as disc brakes and hydraulic drum brakes. The simple lumped parameter models used in the above work are inadequate as brake design tools, however, and so a novel application of finite element modelling is used to extend the principle of the binary flutter mechanism to a more detailed model of a complete brake. This is shown to be capable of predicting known features of squeal and may be used as a brake design tool for both the brake structure and the friction material.
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Budinsky, Tomas. "Towards the active suppression of disc brake squeal." Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/23007/.
Full textAbstract:
This work is concerned with disc brake squeal that is widely accepted as a friction-induced self-excited vibration of the brake assembly. The present thesis aims to investigate the possibility of active disc brake squeal suppression using a method of varying the leading and trailing piston pressures in a multi-piston opposed brake caliper. This thesis describes the development of a new prototype four-piston brake caliper, a two-channel brake actuation system and an advanced control system, which is capable of varying the leading/trailing pressure ratio (LTPR) when squeal is detected. This causes the centre of pressure (CoP) position at the pad/disc interface to move, which leads to new dynamic parameters of the brake system and thereby to different squeal propensity. The control system maintains the overall brake torque to a constant value, so the variation of the LTPR on the brake performance is minimised. Other novel approaches described in the thesis include a new three-dimensional analytical model of the brake pad, which was used to predict the CoP position in both circumferential and radial directions for a given LTPR. A reduced finite-element model of the current brake setup was also developed to predict positions of the CoP and unstable modes of vibration for varying LTPR. Using low-cost piezoresistive force sensors, a new embedded brake pad sensor was designed that can determine the current position of the CoP during a braking event. The new brake pad sensor along with the new 3D analytical model served as indicators of the current CoP position during brake tests. Experiments using the current disc brake setup showed that by varying the LTPR, thereby changing the CoP position, the squeal occurrence can be controlled. It was shown that the new squeal control system operating in an automatic mode reduced the squeal occurrence significantly for a given duty cycle.
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Wilson, Andrew Kirk 1977. "Design of an automated on-car brake lathe." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8550.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (p. 91-92).
An on-car brake lathe resurfaces disk-brake rotors by rotating them "in place" and making a light cut along the surface of the disk. The primary goal of this thesis is to develop an automated cutting head for an on-car brake lathe. The new cutting head must produce a surface finish that matches or exceeds that of the current (manual) cutting head. Pro-Cut International, a leading manufacturer of on-car brake lathes, developed functional requirements and cost constraints for the automated cutting head. Technical challenges include design and fabrication of low-cost precision linear bearings and actuators with dynamic stiffness sufficient to suppress chatter. During this thesis, two prototype cutting heads were designed, manufactured, and tested. The first prototype employed modular linear bearings, and produced unacceptable surface finish due to chatter. Cutting-tip vibration measurements combined with modal testing showed that chatter was caused by low structural stiffness of the modular bearing rails. A second prototype employing a unitary ground bearing system produced an acceptable surface finish of 70 [mu] -inch at 0.015" depth of cut per side. The key components of this design can be extruded and sliced to form the assembly, thereby meeting cost constraints.
by Andrew Kirk Wilson.
S.M.
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Goldfarb, Michael 1966. "A control-brake orthosis for FES-aided gait." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12035.
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Hsueh, Jen-Chun, and 薛任鈞. "Brake Judder Analysis of Vehicle Disc Brakes." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/07323911705811800014.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
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This study analyzes causes of the brake judder, the forced vibration of the fore brake system and the front chassis system to the vibratory response of the brake judder and the effect of design parameters on the brake judder. Elastic contact equations are derived by using the two-dimensional contact surface between the brake pad and the brake disc. An elastic contact model is built, and the surface pressure distribution, the surface deformation, the deformational friction and the brake torque are obtained when the sliding contact occurs between the brake pad and the brake disc. The effects of the brake disc surface wave amplitude and design parameters of the fore brake system on the brake torque variation are analyzed. The brake torque variation increases when the brake disc surface wave amplitude or the disc thickness variation increases. The brake torque variation is quite sensitive to design parameters of the brake system. If the modulus of elasticity of the brake disc increases 10 percent, the brake torque variation decreases about 10 percent. Dynamic machnical software ADAMS is used to build a dynamic model of the front chassis system including brakes.The frequency response of the vehicle caused by the brake torque variation is analyzed. The results show that the front chassis system has significant frequency response when it is subjected to forced vibration with frequencies of 22.6 Hz and 38.2 Hz. The effects of the bushing stiffness, the damping coefficients and mass of the component in the front chassis system on the frequency response are analyzed. It shows that the bushing stiffness and the damping coefficient of components in the front chassis system has significant effect on the vibratory response, especially the stiffness and damping coefficient in the x direction of the aft bushing connected by the lower control arm and the vehicle body. If the stiffness of the bushing in x direction becomes twice of the original value, the frequency response of the vehicle body and the steering wheel shifts from 22.6 Hz to 29 Hz. The correspond vehicle speed increase from 21.8m/s (78.4 km/hr) to 28 m/s (100.6 km/hr), that is higher than the common vehicle driving speed. If the damping coefficient of the bushing in x direction becomes twice of the original value the vibratory acceleration amplitude decreases from 2.4 mm/s2 to 1.6 mm/s2. Hence, the brake judder can be improved by varing bushing parameters.