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1
Stephens, Arthur William, e 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.
Testo completoAbstract (sommario):
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.
2
Pulugundla, Gautam. "CFD design analysis of ventilated disc brakes". Thesis, Cranfield University, 2008. http://dspace.lib.cranfield.ac.uk/handle/1826/6578.
Testo completoAbstract (sommario):
This thesis reports the numerical investigation of the automotive ventilated disc
brake rotor. Disc brakes operate on the principle of friction by converting kinetic
energy into heat energy. The main objective of a disc brake rotor is to store this
heat energy and dissipate it as soon as possible. This work is carried out in a
area where there is very limited understanding.
Commercial CFD code FLUENT was used for carrying out the simulations with
the rotor rotating in still air. Only one passage and blade were simulated as all
the rotor passages were identical. Uniform temperatures were used on the rotor
to simulate the braking condition.
Sixteen different blade angle sets were simulated and the range of blade angles
having the best aero-thermal performance were identified using mass flow rate,
rate of heat dissipation and temperature uniformity as performance metrics. The
effect of rotational speed and rotor temperature (corresponding to various
braking conditions) on the aero-thermal performance was evaluated. The rotor
speed and temperature were observed to have significant effect on the rotor
performance.
The number of blades in the ventilated disc brake rotor was also varied and was
observed to have an impact on the aero-thermal performance of the disc brake
rotor. Detailed design changes like inlet chamfer, blade leading edge rounding,
and variable thickness blade and passage aspect ratio were incorporated. All
these changes did have an effect on the aero-thermal performance of the disc
brake rotor. The inlet chamfer and the leading edge rounding improved both the
rate of heat transfer and the temperature uniformity. The variable thickness
blade and the lower aspect ratio passage improved the temperature uniformity
of the rotor.
3
Koetniyon, Saiprasit. "Thermal stress analysis of automotive disc brakes". Thesis, University of Leeds, 2000. http://etheses.whiterose.ac.uk/2938/.
Testo completoAbstract (sommario):
A brake disc rotor forms pan of a foundation brake and rotates with the wheel hub assembly. The main function of a foundation brake is to generate a retarding torque by converting mechanical energy to thermal energy by virtue of the frictional work done in relative sliding at the rotor-pad interface. In practice, most brake discs arc made from cast iron and in use arc sometimes subjected to high thermal stresses which can lead to permanent plastic deformation and occasionally rotor cracking. The aim of the present work is to investigate the thermal response of such a cast iron brake disc using the finite element (FE) method. One particular existing brake disc design for a medium passenger car was chosen for the investigation. This is a "back-vented" disc designed to minimise disc coning but the present work also includes an investigation of a conventional "frontvented" disc similar in dimension to the back-vented disc but with different detailed geometry. Experimental work was undertaken to derive the rotor material properties in tension and compression as a function of temperature. This data was used to generate suitable FE material model routines which accurately allow for the different temperature-dependent yield properties of cast iron in tension and compression. The modelling work highlights the role of the rotor geometry in controlling the thermal response of the structure but. more importantly, the necessity for an accurate material model is illustrated, particularly with regard to its ability to predict the accumulation of plastic strain which may lead to rotor cracking. Using the most accurate user developed material subroutine, the thermal response of the back-and front-vented disc designs are compared: the back-vented disc suffers lower thermal distortion but at the expense of higher plastic strain accumulation, particularly near the point of attachment of the vanes.
4
Ahmed, Ibrahim Lotfy Mohamed. "Study of the behaviour of vehicle disc brakes". Thesis, Northumbria University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393861.
Testo completo
5
Dzirasa, Mawuli. "Experimental investigation of dither control for the suppression of automotive brake squeal". Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17604.
Testo completo
6
Leigh, Benjamin David. "Strength degradation of carbon-carbon composites for aircraft brakes". Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285332.
Testo completo
7
Wahlström, Jens. "A study of airborne wear particles from automotive disc brakes". Doctoral thesis, KTH, Maskinelement, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31152.
Testo completoAbstract (sommario):
During braking, both the disc and pads in disc brakes are worn. Since disc brakes are not sealed,some of the wear particles generated can become airborne. Several studies have found anassociation between adverse health effects and the concentration of particles in the atmosphere,so it is of interest to improve our knowledge of the airborne wear particles generated by discbrakes. This thesis deals with experimental and computational methods focusing on airborne wearparticles from disc brakes. The eight appended papers discuss the possibility to both measure andnumerically determine the concentration and size distribution of airborne wear particles thatoriginate from the pad-to-disc contact. The objective is to increase the scientific knowledge ofairborne wear particles generated from disc brakes. Papers A, B and C describe tests of disc brake materials conducted in a modified pin-on-discmachine. The results show that the test set-up can be used to measure and rank disc brakematerials with respect to the concentration of airborne particles generated. Ultrafine (nanosized),fine and coarse airborne wear particles that contain metals such as iron, copper and tin werefound. Papers D and E describe a novel disc brake assembly test stand and tests of disc brake materialsconducted in it. The results show that the test set-up can be used to measure the concentrationand size distribution of airborne wear particles generated from disc brake materials. The resultsalso indicate an ability to rank different pad/disc combinations with respect to the concentrationof airborne wear particles. Furthermore, the results suggest that this test stand can be used tostudy rust layer removal from the disc and that airborne particles are generated even at low brakepressures, such as used to remove dirt from the disc. Paper F compares measurements made in passenger car field tests with measurements made in adisc brake assembly test stand and in a pin-on-disc machine. A promising correlation between thethree different test methods is found. Paper G presents and discusses a simulation methodology that numerically determines theconcentration and size distribution of airborne wear particles generated from the pad-to-disccontact in disc brakes by using general-purpose finite element software. Paper H discusses a cellular automaton model that describes the microscopic contact situationbetween the pad and disc in disc brakes. This model is used to numerically determine the amountof wear that leaves the contact. The results correlate qualitatively with experimental observationsfound in the literature.QC 20110317
8
Steel, William Perry. "Absolute displacement measurement of noisy disc brakes using holographic interferometry". Thesis, University of Huddersfield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418627.
Testo completo
9
Voller, Gordon Paul. "Analysis of heat dissipation from railway and automotive friction brakes". Thesis, Brunel University, 2003. http://bura.brunel.ac.uk/handle/2438/5558.
Testo completoAbstract (sommario):
The thesis presents research into the understanding and improvement of heat dissipation from friction brakes. The investigations involved two brake types, considered to be the most thermally loaded and therefore most challenging; axle mounted high speed railway and commercial vehicle disc brakes. All three modes of heat transfer (conduction, convection and radiation) and airflow characteristics have been analysed experimentally and theoretically in order to increase the understanding of heat dissipation. Despite the very practical aspects of this research, a 'generic heat transfer approach' was applied, enabling wider engineering applications of the results. Experimental analyses conducted on a specially developed Spin Rig allowed measurements of cooling and airflow characteristics for different designs. Methodologies have been developed to determine thermal contact resistance, heat transfer coefficients, emissivity and aerodynamic (pumping) losses. Established values and relationships compared very favourably with theoretical work. Analytical, FE and CFD analyses were employed to further investigate design variations and perform sensitivity studies. Inertia dynamometer route simulations provided disc temperatures for validation of the overall work. Recommendations have been made for optimising heat dissipation, by proposing practically acceptable and economically viable design solutions. A proposed ventilated disc design efficiency ratio allows large, high speed ventilated disc designs, to be efficiently and accurately evaluated and compared, providing a valuable disc design optimisation tool. The determination of the methodologies, parameters and functions defining cooling characteristics, enable heat dissipation to be predicted confidently and accurately for brakes and other engineering assemblies at early design stages.
10
Graf, Aaron John. "Active control of automotive disc bake rotor squeal using dither". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/16933.
Testo completo
11
Rodriguez, Alexander John, e alex73@bigpond net au. "Experimental Analysis of Disc Thickness Variation Development in Motor Vehicle Brakes". RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070209.123739.
Testo completoAbstract (sommario):
Over the past decade vehicle judder caused by Disc Thickness Variation (DTV) has become of major concern to automobile manufacturers worldwide. Judder is usually perceived by the driver as minor to severe vibrations transferred through the chassis during braking [1-9]. In this research, DTV is investigated via the use of a Smart Brake Pad (SBP). The SBP is a tool that will enable engineers to better understand the processes which occur in the harsh and confined environment that exists between the brake pad and disc whilst braking. It is also a tool that will enable engineers to better understand the causes of DTV and stick-slip the initiators of low and high frequency vibration in motor vehicle brakes. Furthermore, the technology can equally be used to solve many other still remaining mysteries in automotive, aerospace, rail or anywhere where two surfaces may come in contact. The SBP consists of sensors embedded into an automotive brake pad enabling it to measure pressure between the brake pad and disc whilst braking. The two sensor technologies investigated were Thick Film (TF) and Fibre Optic (FO) technologies. Each type was tested individually using a Material Testing System (MTS) at room and elevated temperatures. The chosen SBP was then successfully tested in simulated driving conditions. A preliminary mathematical model was developed and tested for the TF sensor and a novel Finite Element Analysis (FEA) model for the FO sensor. A new method called the Total Expected Error (TEE) method was also developed to simplify the sensor specification process to ensure consistent comparisons are made between sensors. Most importantly, our achievement will lead to improved comfort levels for the motorist.
12
Wallis, Lisa M. Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A comparison of bi-directional disc brake rotor passage designs". Awarded by:University of New South Wales. School of Mechanical & Manufacturing Engineering, 2003. http://handle.unsw.edu.au/1959.4/20312.
Testo completoAbstract (sommario):
An important part of automobile safety is the braking system. Disc brakes have been widely used in automobiles for sped retardation for over 30 years. During that time, they have developed from a simple disc to a complex disc with channels, vanes, holes and grooves. The stopping capability of disc brakes is affected by the rate at which heat is dissipated by forced convection and the thermal capacity of the rotor. Catastrophic failure of brake rotors can occur during rapid increases or decreases in rotor temperature where regions of high temperature gradients result in high thermal strains. There is little information in the public domain regarding the relative merits of different disc brake rotor geometries, particularly in terms of airflow patterns, heat transfer rates, and internal thermal gradients. The aim of this research project was to investigate how geometrical variations affect the thermal performance of bi-directional disc brake rotors, particularly for high performance applications. Dynamometer testing showed that respectable increases in braking performance are achievable with relatively simple machining modifications. Tuft and smoke visualization techniques provided a preliminary understanding of the airflow in the passages of three distinct bi-directional rotor designs. Particle Image Velocimetry was used for detailed flow measurements which supported the numerical simulations. Computational Fluid Dynamics was used to predict the airflow and heat transfer associated with eight bi-directional brake rotor designs. The results show that 'pillared' passage designs can achieve higher heat transfer rates than traditional straight radial vane designs and that the heat loss from pillared rotors is generally more uniform than from vaned rotors. Subsequent conjugate heat transfer simulations found that temperature gradients inside pillared rotors are typically lower than inside vaned rotors. Thus failure rates due to excessive thermal strain are expected to be lower for pillared rotors. It was shown that rotor selection based solely on heat transfer rates is inappropriate and different passage designs are suited to different applications. The findings of this research will directly benefit local disc brake manufacturers, who do not have resources to conduct thorough studies comparing the thermal characteristics of different brake rotor designs.
13
Rye, Ryan Patrick. "Investigation of disc brake squeal via sound intensity and laser vibrometry". Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19045.
Testo completo
14
Wahlström, Jens. "Towards a simulation methodology for predictionof airborne wear particles from disc brakes". Licentiate thesis, KTH, Machine Design (Div.), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11044.
Testo completoAbstract (sommario):
During braking, both the rotor and the pads in disc brakes are worn. Since disc brakes are not sealed, some of the wear particles generated can become airborne. Several studies have found an association between adverse health effects and the concentration of particles in the atmosphere, so it is of interest to improve our knowledge of the airborne wear particles generated by disc brakes. However, in field tests it is difficult to distinguish these particles from others in the surrounding environment, so it may be preferable to use laboratory test stands and/or simulation models to study the amount of airborne wear particles generated.
This thesis deals with a simulation methodology for prediction of airborne wear particles from disc brakes and three experimental methods for testing disc brake materials with focus on airborne wear particles. The four appended papers discuss the possibility to both measure and predict the number and size distribution of airborne wear particles that originate from the pad to rotor contact. The objective is to develop a simulation methodology that predicts the number and size distribution of airborne wear particles from disc brakes.
Paper A describes how a modified pin-on-disc machine was used to study airborne wear particles originating from different disc brake materials. The results indicate that the test setup can be used to measure and rank the number concentration and size distribution of the airborne wear particles generated.
Paper B describes a disc brake assembly test stand for measurements of airborne wear particles from disc brakes. The results indicate that the test setup can be used to measure the number concentration and size distribution of airborne wear particles generated from disc brake materials. The results also indicate a promising ability to rank different pad/rotor material combinations with respect to the number concentration of airborne wear particles.
Paper C compares measurements made in passenger car field tests with measurements made in a disc brake assembly test stand and in a pin-on-disc machine. A promising correlation between the three different test methods is found.
Paper D presents a simulation methodology for predicting the number and size distribution of airborne wear particles using finite element analysis (FEA). The simulated number distribution is compared with experimental measurements at component level. The result indicates that the proposed methodology may be used to predict the number concentration and size distribution of airborne particles generated in the pad-to-rotor contact.
15
Bradley, Luke R. "Mechanical testing and modelling of carbon-carbon composites for aircraft disc brakes". Thesis, University of Bath, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426204.
Testo completo
16
Wahlström, Jens. "Towards a simulation methodology for prediction of airborne wear particles from disc brakes /". Stockholm : KTH, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11044.
Testo completo
17
Wahlström, Jens. "Towards a simulation methodology for prediction of airborne wear particles from disc brakes". Licentiate thesis, KTH, Maskinkonstruktion (Avd.), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11044.
Testo completoAbstract (sommario):
During braking, both the rotor and the pads in disc brakes are worn. Since disc brakes are not sealed, some of the wear particles generated can become airborne. Several studies have found an association between adverse health effects and the concentration of particles in the atmosphere, so it is of interest to improve our knowledge of the airborne wear particles generated by disc brakes. However, in field tests it is difficult to distinguish these particles from others in the surrounding environment, so it may be preferable to use laboratory test stands and/or simulation models to study the amount of airborne wear particles generated. This thesis deals with a simulation methodology for prediction of airborne wear particles from disc brakes and three experimental methods for testing disc brake materials with focus on airborne wear particles. The four appended papers discuss the possibility to both measure and predict the number and size distribution of airborne wear particles that originate from the pad to rotor contact. The objective is to develop a simulation methodology that predicts the number and size distribution of airborne wear particles from disc brakes. Paper A describes how a modified pin-on-disc machine was used to study airborne wear particles originating from different disc brake materials. The results indicate that the test setup can be used to measure and rank the number concentration and size distribution of the airborne wear particles generated. Paper B describes a disc brake assembly test stand for measurements of airborne wear particles from disc brakes. The results indicate that the test setup can be used to measure the number concentration and size distribution of airborne wear particles generated from disc brake materials. The results also indicate a promising ability to rank different pad/rotor material combinations with respect to the number concentration of airborne wear particles. Paper C compares measurements made in passenger car field tests with measurements made in a disc brake assembly test stand and in a pin-on-disc machine. A promising correlation between the three different test methods is found. Paper D presents a simulation methodology for predicting the number and size distribution of airborne wear particles using finite element analysis (FEA). The simulated number distribution is compared with experimental measurements at component level. The result indicates that the proposed methodology may be used to predict the number concentration and size distribution of airborne particles generated in the pad-to-rotor contact.
18
Tang, Jinghan. "Finite element modelling of ventilated brake disc hot spotting". Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/13340.
Testo completoAbstract (sommario):
Hot spotting of automotive disc brakes is an undesired thermal localisation phenomenon, which is a challenge for numerical modelling in terms of both accuracy and efficiency especially for complex disc geometry. In this research, the aim was to develop a computationally efficient finite element (FE) approach for 2-piece pin-mounted ventilated disc hot spot prediction with acceptable accuracy enabling parametric studies to contribute to the knowledge of the complex mechanisms. A time reduction strategy for the simulations was established by incorporating an axisymmetric brake pad assumption with material scaling factor and the friction characteristics were defined by a user-subroutine. The computing accuracy and efficiency of this method were then verified by comparing with traditional FE models. 2D in-plane, 2D out-of-plane, and 3D models were performed to investigate the effects of ventilated disc hot spotting, radial hot spot/band migration, and hot spotting of realistic complex disc geometry respectively. Both 2D and 3D results were validated using experimental results based on a laboratory dynamometer and showed good correlation. The results suggested that adequate modelling of friction pair contact pressure distribution and the subsequent non-uniform heat generation is essential for hot spot simulation; speed was identified as the determinant for the number of hot spots, whereas hot spot temperature was determined by energy level. Furthermore, recommendations for vent design, pins, disc run-out, cooling, material selection, wear rate, pad length and loading distribution were given. Finally, hot spotting and hot band migration cause-effect chains were established based on the results and discussion.
19
Loizou, Andreas, Hong Sheng Qi e Andrew J. Day. "A numerical and experimental study on the factors that influence heat partitioning in disc brakes". Scientific Society of Mechanical Engineering (GTE), 2010. http://hdl.handle.net/10454/4413.
Testo completoAbstract (sommario):
yesTo investigate the heat partition on a vehicle disc brake, a small scale test rig with one contact interface was used. This allowed the disc/pad contact temperatures to be measured with fast-response foil thermocouples and a rubbing thermocouple. Based on the experimental conditions a 3D symmetric disc brake FE model has been created. Frictional heat generation was modelled using the ABAQUS finite element analysis software. The interface tribo-layer which affects heat partitioning was modelled using an equivalent thermal conductance value obtained from the authors¿ previous work. A 10 second drag braking was simulated and the history and distribution of temperature, heat flux multiplied by the nodal contact area, heat flux leaving the surface and contact pressure was recorded. Test rig and FE model temperatures were compared to evaluate the two methods. Results show that heat partitioning varies in space and time, and at the same time contact interface temperatures do not match. It is affected by the instantaneous contact pressure distribution, which tends to be higher on the pad leading edge at the inner radius side. They are also affected by the thermal contact resistance at the components contact interface.
IMechE
20
Loizou, Andreas. "Modelling and simulation of themo-mechanical phenomena at the friction interface of a disc brake.An empirically-based finite element model for the fundamental investigation of factors that influence the interface thermal resistance at the friction interface of a high energy sliding pair in a disc brake". Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5489.
Testo completoAbstract (sommario):
The fundamental theories of heat generation and transfer at the friction interface of a
brake assume either matching or not matching surface temperatures by having a
varying or uniform heat partition ratio respectively. In the research presented the
behaviour of heat partition has been investigated in a fundamental study based on
experimental measurements of temperature and the associated modelling and
simulation of heat transfer in a brake friction pair. For a disc brake, an important
parameter that was identified from the literature study is the interface tribo-layer
(ITL), which has been modelled as an equivalent thermal resistance value based on its
thickness and thermal conductivity. The interface real contact area was also an
important parameter in this investigation, and it has been found to affect heat
partitioning by adding its own thermal resistance.
A 2-dimensional (2D) coupled-temperature displacement Finite Element (FE) model is
presented, based on which a novel relationship which characterises the total thermal
resistance (or conductance) at the friction interface has been characterised based on
the ITL thermal properties, the contact area, and the contact pressure at the interface.
Using the model the effect of friction material wear on the total thermal resistance (or
conductance) at the friction interface was predicted and a comparison of the Archard
and Arrhenius wear laws in predicting the wear of a resin bonded composite friction
material operating against a cast iron mating surface is presented.
A 3-dimensional (3D) model is also presented. This model has represented a small
scale disc brake test rig which has been used in parallel with the simulation for
validation in a drag braking scenario. Two simulation conditions with different pad
surface states were investigated, the first having a nominally flat surface, and the
second an adjusted (worn) pad surface based on bedding-in data. The Arrhenius wear
model was applied to significance of including wear on the total thermal resistance at
the friction interface over a short brake application.
A sensitivity analysis on the interface thermal conductance, the location of heat
generation, and the magnitude of contact pressure has identified the importance of
each factor in determining the total thermal resistance (or conductance) at the friction
interface during any friction brake application. It is concluded that the heat
partitioning is insensitive on the location of heat generation, and that the most
sensitive parameter is the contact pressure.Institution of Mechanical Engineers (IMechE)
21
Zagorski, Scott Bradley. "Compatibility of ABS disc/drum brakes on class VIII vehicles with multiple trailers and their effects on jackknife stability". The Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1069788894.
Testo completo
22
Loizou, Andreas. "Modelling and simulation of themo-mechanical phenomena at the friction interface of a disc brake : an empirically-based finite element model for the fundamental investigation of factors that influence the interface thermal resistance at the friction interface of a high energy sliding pair in a disc brake". Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/5489.
Testo completoAbstract (sommario):
The fundamental theories of heat generation and transfer at the friction interface of a brake assume either matching or not matching surface temperatures by having a varying or uniform heat partition ratio respectively. In the research presented the behaviour of heat partition has been investigated in a fundamental study based on experimental measurements of temperature and the associated modelling and simulation of heat transfer in a brake friction pair. For a disc brake, an important parameter that was identified from the literature study is the interface tribo-layer (ITL), which has been modelled as an equivalent thermal resistance value based on its thickness and thermal conductivity. The interface real contact area was also an important parameter in this investigation, and it has been found to affect heat partitioning by adding its own thermal resistance. A 2-dimensional (2D) coupled-temperature displacement Finite Element (FE) model is presented, based on which a novel relationship which characterises the total thermal resistance (or conductance) at the friction interface has been characterised based on the ITL thermal properties, the contact area, and the contact pressure at the interface. Using the model the effect of friction material wear on the total thermal resistance (or conductance) at the friction interface was predicted and a comparison of the Archard and Arrhenius wear laws in predicting the wear of a resin bonded composite friction material operating against a cast iron mating surface is presented. A 3-dimensional (3D) model is also presented. This model has represented a small scale disc brake test rig which has been used in parallel with the simulation for validation in a drag braking scenario. Two simulation conditions with different pad surface states were investigated, the first having a nominally flat surface, and the second an adjusted (worn) pad surface based on bedding-in data. The Arrhenius wear model was applied to significance of including wear on the total thermal resistance at the friction interface over a short brake application. A sensitivity analysis on the interface thermal conductance, the location of heat generation, and the magnitude of contact pressure has identified the importance of each factor in determining the total thermal resistance (or conductance) at the friction interface during any friction brake application. It is concluded that the heat partitioning is insensitive on the location of heat generation, and that the most sensitive parameter is the contact pressure.
23
Clark, Michael A. "Effect of nanoparticles on friction and wear of 2-D and 3-D carbon-carbon composite disc brakes /". Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1095432851&sid=8&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Testo completoAbstract (sommario):
Thesis (M.S.)--Southern Illinois University Carbondale, 2005."Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 84-86). Also available online.
24
Zagorski, Scott Bradley. "Compatibility of ABS disc/drum brakes on class VIII vehicles with multiple trailers and their effects on jackknife stability /". Columbus, Ohio : Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1069788894.
Testo completo
25
Iombriller, Silvia Faria. "Análise térmica e dinâmica do sistema de freio a disco de veículos comerciais pesados". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/18/18135/tde-02022016-114612/.
Testo completoAbstract (sommario):
Este trabalho apresenta um procedimento para a análise dinâmica da frenagem total de emergência de um veículo de dois eixos (4x2), considerando os efeitos do aumento da temperatura no sistema de freios. Um protótipo de ônibus urbano equipado com freios a disco foi utilizado nos ensaios em perímetro urbano e em pista de teste da TRW Automotive em Limeira- SP. O sistema de freios do veículo protótipo foi instrumentado com termopares em diversos de seus componentes, com sensores de velocidade e pressão, percorrendo um perímetro típico urbano com trânsito intenso na cidade de São Paulo. Os pontos críticos de aquecimento foram observados bem como sua tendência de aumento de temperatura no tempo. Paralelamente ao teste em perímetro urbano foi realizado um teste padrão de \"fade\" na pista da TRW Automotive, estendendo o ciclo de frenagens até se observar o aumento e estabilização da temperatura do sistema de freios. Simultaneamente aos testes de pista foi realizado um teste em dinamômetro inercial na Fras-Le, em Caxias do Sul- RS, para se obter a variação do fator de freio com a variação da temperatura do sistema de freios. Parte de um programa computacional em Matlab, que simula computacionalmente o veículo freando, foi desenvolvido, considerando os efeitos da temperatura do sistema de freios, durante frenagens totais de emergência, partindo de diferentes velocidades iniciais de frenagem. O sistema de freios em estudo mostrou-se capaz de simular a frenagem de um veículo em emergência mesmo estando em altas temperaturas, observadas no perímetro urbano.One procedure for vehicle dynamics analysis during total emergency braking in a two axles vehicle (4x2) was showed. For this procedure the effect of increasing temperature in the brake system was considered. A bus (prototype) equipped with disc brake was used in two practical test when the bus go through: a urban rout (São Paulo city) an a TRW\'s test lane (Limeira-SP). Thermocouples were installed in several parts of the brake system as well as velocity and pressure sensors. Acquisitions of date were made during the intensive traffic of São Paulo city. Critical temperature points were observed as well as the raise temperature tendency with the time. Tests in an inertial dynamometer were also performed in Fras-Le company (Caxias do Sul- RS) to get the brake factor variation related to temperature variation of the brake system. Simulation using MatLab program to study the vehicle performance during braking was developed. In this simulation the effect of brake system temperature was considered. Two main conclusions could be obtained: MatLab model is a useful tool to study emergency braking considering the variation of brake system and the brake system studied was able to stop the vehicle in a emergency braking even under high temperature.
26
Alemani, Mattia. "Particle emissions from car brakes : The influence of contact conditions on the pad-to-rotor interface". Doctoral thesis, KTH, Tribologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208701.
Testo completoAbstract (sommario):
Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale. Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissions Paper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified. Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels. Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified. Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities. Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands. Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.På grund av deras negativa hälsoeffekter har partikel emissioner reglerats i över tre årtionden. Bromsslitagepartiklar är den viktigaste icke-avgaskällan, men nuvarande kunskaper är huvudsakligen begränsade till observationsstudier. Avhandlingen syftar till att undersöka förhållandena mellan bromssystemets kontaktförhållanden och de relaterade utsläppen på modellskala. Validera resultaten på komponentnivå och förstå i vilken utsträckning de är betydande i full skala. Papper A undersöker påverkan av nominellt kontakttryck i en modellskala. Resultat visar att högre tryck motsvarar högre utsläpp. Papper B undersöker påverkan av det nominella kontakttrycket, för olika friktionsmaterial, i modellskala. En temperaturtröskel, för en emissionsökning identifieras. Papper C undersöker partikelegenskaper och slitagemekanismer för olika nominella kontakttryck, i en modellskala. Resultat visar ett förbättrat triboskikt vid högre trycknivåer. Papper D undersöker påverkan av bromssystemets förhållanden på utsläpp i en modellskala. Resultat visar att friktionskraften är den viktigaste parametern. En övergångstemperatur oberoende av kontaktförhållandet identifieras. Papper E undersöker likheter som uppträder på komponentskala och modellskala när det gäller emissioner. Resultatet visar en lovande korrelation, och möjligheten att använda en pinne-på-skiva-tribometer för FoU-aktiviteter. Papper F undersöker analogier som förekommer på en komponentskala och en modellskala, vad gäller friktionsprestanda, friktionsyta och kemisk sammansättning. Resultat visar liknande fenomen som förekommer för de två testskalorna. Papper G analyserar verkliga bromssystem arbetsförhållanden i en stadsmiljö som definierar, med hjälp av en tröghetsdyno bänk, de relaterade utsläppen. Resultatet visar utsläppsfaktorer som är förenliga med EURO6 och EURO2-reglerna, i fråga om antal respektive massa.
QC 20170808
REBRAKE Project
27
Dunn, Ashley L. "Jackknife stability of articulated tractor semitrailer vehicles with high-output brakes and jackknife detection on low coefficient surfaces". The Ohio State University, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=osu1061328963.
Testo completo
28
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.
Testo completo
29
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.
Testo completoAbstract (sommario):
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.
30
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.
Testo completoAbstract (sommario):
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.
31
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.
Testo completoAbstract (sommario):
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.
32
Sergent, Nicolas. "Analysis and optimisation of disc brake calipers". Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/10196.
Testo completoAbstract (sommario):
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.
33
Tao, Jiyue, e 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.
Testo completoAbstract (sommario):
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.
34
Bryant, David. "Thermo-elastic deformation of a vented brake disc". Thesis, University of Huddersfield, 2010. http://eprints.hud.ac.uk/id/eprint/9076/.
Testo completoAbstract (sommario):
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.
35
Budinsky, Tomas. "Towards the active suppression of disc brake squeal". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/23007/.
Testo completoAbstract (sommario):
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.
36
Rashid, Asim. "Simulation of Thermal Stresses in a Brake Disc". Licentiate thesis, Linköpings universitet, Mekanik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-94345.
Testo completoAbstract (sommario):
In this thesis thermal stresses in a brake disc during a braking operation are simulated. The simulations are performed by using a sequential approach where the temperature history generated during a frictional heat analysis is used as an input for the stress analysis. The frictional heat analysis is based on the Eulerian method, which requires signicantly lower computational time as compared to the Lagrangian approach. The stress analysis is performed using a temperature dependent material model both with isotropic and kinematic hardening behaviors. The results predict the presence of residual tensile stresses in circumferential direction for both hardening behaviors. These residual stresses may cause initiation of radial cracks on the disc surface after a few braking cycles. For repeated braking an approximately stable stress-strain loop is obtained already after the rst cycle for the linear kinematic hardening model. So, if the fatigue life data for the disc material is known, its fatigue life can be assessed. These results are in agreement with experimental observations available in the literature. The simulation results predict one hot band in the middle of the disc for a pad with no wear history. It is also shown that convex bending of the pad is the major cause of the contact pressure concentration in middle of the pad which results in the appearance of a hot band on the disc surface. The results also show that due to wear of the pad, dierent distributions of temperature on the disc surface are obtained for each new brake cycle and after a few braking cycles, two hot bands appear on the disc surface. This sequential approach has proved tremendously cheap in terms of computational time so it gives the freedom to perform multi-objective optimization studies. Preliminary results of such a study are also presented where the mass of the back plate, the brake energy and the maximum temperature generated on the disc surface during hard braking are optimized. The results indicate that a brake pad with lowest possible stiness will result in an optimized solution with regards to all three objectives. Another interesting result is the trend of decrease in maximum temperature with an increase in back plate thickness. Finally an overview of disc brakes and related phenomena is presented as a literature review.
37
Oues, Adnan Khalil. "PROTECTION OPTIMIZATION OF CARBON-CARBON COMPOSITES AGAINST AIR OXIDATION BY COATING WITH ANTI-OXIDANTS". OpenSIUC, 2017. https://opensiuc.lib.siu.edu/dissertations/1376.
Testo completoAbstract (sommario):
AN ABSTRACT OF THE DISSERTATION OF TITLE: (OPTIMIZATION PROTECTION OF CARBOB-CARBON COMPOSITES DISC-BRAKES MATERIAL BY COATING WITH ANTI-OXIDANTS) Developing glass enhancer mixture solutions (Ki’s), which promote the formation of a stable glass layer, homogenous clear liquid solution, and low viscosity liquid form, are easy to apply, and penetrating. They are compatible with ceramic liquid glass based anti-oxidants for treating surfaces of carbon/carbon composites material, and significantly increase the rate of protection against oxidation. Ki’s’ are comprised of mixing chemical compositions at standard temperature and pressure conditions from group one and two such as Na, K, Ca, Mg, etc. of 5 to 25 wt. %, deionized water from 95 to 75 % by weight, and adding up to 1 % by weight of surfactants such as DF-16, DF-20, and CF-10 with specific proportions, and followed by thorough stirring to produce a homogeneous blend of mixture solution. The glass enhancers, which are aqueous mixture solutions, are applied to the surfaces of carbon/carbon (C/C) composites by dipping, brushing, spraying, or other painting application techniques, followed by annealing, or a heat-treating range of 80 to 110 ℃ for a minimum of 8 hours, and allowing cooling time of the coated C/C composites of a minimum of 12 hours to room temperature. Preferential compatibility of the glass enhancer mixture solutions (Ki's) is with liquid glass former's, anti-oxidants comprised mostly of borate and phosphate glasses. The glass enhancer solution mixtures (Ki’s) are supplemental additions to ceramics’ liquid anti-oxidants coatings used for carbon-carbon composites protection against oxidation, and it will increase the rate of protection against oxidation for low, and moderate temperature’s range from 400 to 900 ℃. The glass enhancer Ki’s mixture solutions should be used with liquid glass former's’ anti-oxidants, such as SiO₂, GeO₂, B₂O₃, and P₂O₅. A series of glass enhancer’s Ki’s, heat treatment cycle (char-cycle) ranged between 700 to 900 ℃, and application methods, were developed and tested experimentally. Two arbitrary isothermal temperatures of 650 ℃, and 871 ℃ were selected for thermal oxidation testing, and a temperature of 650 ℃ was selected, and tested against catalytic thermal oxidation. Additions of glass enhancer Ki’s improved protection of C/C composites disc-brakes against oxidation by double, and triple amount of time in hours versus the use of anti-oxidant coatings alone.
38
Stenberg, Forsberg Niklas, Joakim Tänndal e Joakim Lange. "Wear particle collector concept for a train disc brake". Thesis, KTH, Maskinkonstruktion (Inst.), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-51372.
Testo completoAbstract (sommario):
Vid användandet av en skivbroms på ett tåg frigörs partiklar i friktionskontakten mellan skiva och belägg. Beroende på den aerodynamiska diametern blir partiklar luftburna, och de anses vara farliga för människans andningssystem. Att fånga upp partiklarna och på så vis förbättra luftkvaliteten är därför fördelaktigt.Olika metoder för uppsamling av de luftburna partiklarna utvärderades och den mest lämpliga valdes för vidareutveckling. En konceptuell lösning, för applicering av denna metod på en Reginaboggi, genererades och utformades.Resultatet är en partikelfångare som renar luft med hjälp av filter med tillräcklig uppsamlingseffektivitet. En central uppsamlingsenhet monteras på boggin, och ansluts med rörledningar till insug monterade vid bromsbeläggen. En fläkt genererar ett luftflöde som transporterar partiklarna genom rörsystemet och filtren.In a train disc brake, the frictional contact will generate wear particles in different size ranges. Depending on the aerodynamic diameter some of the particles become airborne; these are considered to be harmful to the human respiratory system. It is therefore beneficial to collect the airborne particles to improve the air quality.Different methods of gathering airborne particles were evaluated and the most suitable was selected. A conceptual solution in how to apply this on a Regina train bogie was then formulated and designed.The result is a particle collector that purifies the air using filters with sufficient efficiency for the application. A central collection unit is fitted on the bogie, connected by tubes to intakes mounted at the brake pads. The system utilizes airflow created by a fan to transport the particles through the tubing and filters.
39
Duranton, Coralie. "Fatigue analysis of two wheel‐ mounted brake disc designs". Thesis, KTH, Spårfordon, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177313.
Testo completoAbstract (sommario):
Due to a need of more compact bogies, the brake discs can be mounted on the railway wheels, bolted through the wheel web. Thus, the wheels are drilled and have multiple areas of contact with the brake discs. To establish maintenance procedures that will be applied to the wheels, SNCF used the feedback from experience (as with the train AGC) which gives perfect performance in terms of safety. However, to optimize the maintenance process, numerical simulations may be preferred since they are less conservative. This report describes the numerical simulations, based on the finite element method, that were conducted to determine if the Régiolis wheel complies with the standard EN 13979-‐1 from a mechanical fatigue point of view. In addition, it provides additional insights regarding the loads and damage suffered by the wheel, which are not taken into account in the standard: the damage induced by disc braking and the fretting that may occur at the contact interfaces. This study has been used as a decision support for the first inspection intervals of the Régiolis wheels.
40
Fieldhouse, John David. "An analysis of disc brake noise using holographic interferometry". Thesis, University of Huddersfield, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358314.
Testo completoAbstract (sommario):
A predominantly experimental approach using the whole body visual technique of holographic interferometry is employed to investigate the mechanisms involved during a noisy brake application. Following the modal analysis of component parts, dynamic trials include the development of the holographic technique, making use of mirrors to permit three orthogonal views of the brake to be recorded simultaneously with smaller inset mirrors allowing for additional areas, such as the ends of the piston pad, to be observed at the same time. These dynamic experiments take the form of changing the operating parameters of the brake through variations in speed, pressure and temperature and through changes in the system geometry by adjustment of pad abutment and pad centre of pressure loading. The tests show that pad abutment plays an important role in the propensity of the system to generate noise and that a relationship between pad abutment, pad material coefficient of friction and interface coefficient of friction between pad-end and calliper-support finger exists which results in an offset in the pad centre of pressure with the spragging angle being satisfied and resulting noise. This is supported by basic theory. Additionally it is shown that the disc/pad interface relationship is complicated and that it is not reasonable to assume mechanical integrity of the pair and as a consequence the use of an "equivalent mass" is not appropriate for high aspect ratio pads. Advancements in the laser triggering process allow for holograms to be taken at specific stages over and along a cycle of excitation by delaying the laser triggering initiation to give variable time delays. The variety of techniques available are used to show that pad excitation plays an important role in the generation of noise and that the piston pad in particular is seen as the initiator leading to system excitation. Mechanical coupling of the component parts is also seen to be fundamental, but not essential, to the generation of noise. The techniques also show that, when complete coupling exists, the disc holds a diametral mode of vibration which travels around the disc at a speed related to the excitation frequency divided by the disc mode order. Results from the application of the techniques also allows component parts to be analysed over a typical cycle of excitation when it is shown that symmetrical components such as the pad are not necessarily excited in a symmetrical manner. Phase relationship between the component parts may also be determined by comparison of related holograms. Holographic interpretations are confirmed and validated by mechanical measurements when it is also demonstrated that noise is often preceded by, or accompanied by, a high frequency excitation which is experienced by the complete brake.
41
Chen, J. P. "Thermo-mechanical behaviour of heavy-duty disc brake systems". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/10701.
Testo completoAbstract (sommario):
In
heavy-duty disc brake systems, braking is a transient, non-linear and
asymmetrical thermo-mechanical process. Surface cracking, rather than wear, is the
major factor limiting the brake disc's life. The disc material (cast-iron), heat transfer
boundary conditions and pad-disc frictional reactions are characteristically non-linear
and
asymmetrical during the friction process. Non-uniform deformation and surface
cracks in brake discs result from the accumulation of excessive residual stress/strain.
During braking processes, many factors affect the distributions of the residual
stress and strain in discs, and hence the propagation of the surface cracks. The disc
material, structure and boundary conditions are three of the crucial aspects. From the
structure, a brake disc could be either solid or ventilated. In practice, solid structures
always have higher anti-cracking performance than the same class of ventilated
designs. However solid discs cost more material and have lower cooling efficiency.
This thesis
presents an improved finite element analysis for heavy-duty disc
brakes and identifies
design improvements. As the friction pads slide against the
disc's surfaces
continuously, the thermal and mechanical loads are functions of time
and
spatial coordinates. A 3-D asymmetrical finite element model was developed to
achieve more accurate simulations of the thermo-mechanical behaviour of brake discs
during braking processes. A non-linear inelastic material model for cast-iron was
employed in the FE model. Permanent plastic stress and strain fields were predicted
and
analysed for multi-stop drag operations. The residual stress/strain fields in the
discs are
investigated to understand the differences between solid and ventilated discs
in terms of the
cracking resistance ability. Several engineering solutions are
recommended for
optimising the performance of the disc brake system. _
The thesis is
organized in five chapters. Chapter One introduces the
background concepts about the commercial disc brake system. In this part, the brake
structure, material and previous researches are reviewed. The goals for this
investigation are also summarised at the end of this chapter. Chapter Two introduces
the
general finite element modelling knowledge, procedures and the modelling
boundary conditions and material models. Chapter Three presents an analysis of the
disc brakes thermo-mechanical behaviour and the
affecting factors. Chapter Four is
focused on the residual stress field
prediction and cracking behaviour analysis. The
project conclusions and further research recommendations are presented in Chapter
Five.
42
Chen, Jing Ping. "Thermo-mechanical behaviour of heavy-duty disc brake systems". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/10701.
Testo completoAbstract (sommario):
In heavy-duty disc brake systems, braking is a transient, non-linear and asymmetrical thermo-mechanical process. Surface cracking, rather than wear, is the major factor limiting the brake disc's life. The disc material (cast-iron), heat transfer boundary conditions and pad-disc frictional reactions are characteristically non-linear and asymmetrical during the friction process. Non-uniform deformation and surface cracks in brake discs result from the accumulation of excessive residual stress/strain. During braking processes, many factors affect the distributions of the residual stress and strain in discs, and hence the propagation of the surface cracks. The disc material, structure and boundary conditions are three of the crucial aspects. From the structure, a brake disc could be either solid or ventilated. In practice, solid structures always have higher anti-cracking performance than the same class of ventilated designs. However solid discs cost more material and have lower cooling efficiency. This thesis presents an improved finite element analysis for heavy-duty disc brakes and identifies design improvements. As the friction pads slide against the disc's surfaces continuously, the thermal and mechanical loads are functions of time and spatial coordinates. A 3-D asymmetrical finite element model was developed to achieve more accurate simulations of the thermo-mechanical behaviour of brake discs during braking processes. A non-linear inelastic material model for cast-iron was employed in the FE model. Permanent plastic stress and strain fields were predicted and analysed for multi-stop drag operations. The residual stress/strain fields in the discs are investigated to understand the differences between solid and ventilated discs in terms of the cracking resistance ability. Several engineering solutions are recommended for optimising the performance of the disc brake system. _ The thesis is organized in five chapters. Chapter One introduces the background concepts about the commercial disc brake system. In this part, the brake structure, material and previous researches are reviewed. The goals for this investigation are also summarised at the end of this chapter. Chapter Two introduces the general finite element modelling knowledge, procedures and the modelling boundary conditions and material models. Chapter Three presents an analysis of the disc brakes thermo-mechanical behaviour and the affecting factors. Chapter Four is focused on the residual stress field prediction and cracking behaviour analysis. The project conclusions and further research recommendations are presented in Chapter Five.
43
Thuppal, Vedanta Srivatsan, e Naga Vamsi Krishna Kora. "HEAT TRANSIENT TRANSFER ANALYSIS OF BRAKE DISC /PAD SYSTEM". Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13461.
Testo completoAbstract (sommario):
Braking is mainly controlled by the engine. Friction between a pair of pads and a rotating disc converts the kinetic energy of the vehicle into heat. High temperatures can be reached in the system which can be detrimental for both, components and passenger safety. Numerical techniques help simulate load cases and compute the temperatures field in brake disc and brake pads. The present work implements a Finite Element (FE) toolbox in Matlab/Simulink able to simulate different braking manoeuvres used for brake dimensioning mainly in the early phase of car development process. The brake pad/disc geometry is considered as an axisymmetric body assuming negligible temperature gradient along the circumference of the disc. Calibration using three control factors namely: heat coefficient during braking , acceleration and emissivity for the implemented thermal model is performed using experimental investigation at Volvo Car Corporation (VCC) for three specific severe load cases. The thermal model is extended to measure brake fluid temperatures to ensure no vaporisation occurs. Simulation results of the brake disc and brake pad show good correlation with the experimental tests. A sensitivity analysis with the control factors showed convective coefficient during acceleration the most sensitive, with temperature change of around 16%.
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Yuen, Dick Kwan Kenneth. "Brake disc life prediction for material evaluation and selection : the application of finite element and fatigue analysis to the prediction of crack initiation in brake discs during operation". Thesis, University of Bradford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363977.
Testo completo
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Feraday, Simon Andrew. "Intelligent approaches to modelling and interpreting disc brake squeal data". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342809.
Testo completo
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Esgandari, Mohammad. "Simulation methods for vehicle disc brake noise, vibration & harshness". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5762/.
Testo completoAbstract (sommario):
After decades of investigating brake noise using advanced tools and methods, brake squeal remains a major problem of the automotive industry. The Finite Element Analysis (FEA) method has long been used as a means of reliable simulation of brake noise, mainly using the Complex Eigenvalue Analysis (CEA) to predict the occurrence of instabilities resulting in brake noise. However it has been shown that CEA often over-predicts instabilities. A major improvement for CEA proposed in this study is tuning the model with an accurate level of damping. Different sources of damping are investigated and the system components are tuned using Rayleigh damping method. Also, an effective representative model for the brake insulator is proposed. The FEA model of the brake system tuned with the damping characteristics highlights the actual unstable frequencies by eliminating the over-predictions. This study also investigates effectiveness of a hybrid Implicit-Explicit FEA method which combines frequency domain and time domain solution schemes. The time/frequency domain co-simulation analysis presents time-domain analysis results more efficiently. Frictional forces are known as a major contributing factor in brake noise generation. A new brake pad design is proposed, addressing the frictional forces at the disc-pad contact interface. This concept is based on the hypothesis that variation of frictional coefficient over the radius of the brake pad is effective in reducing the susceptibility of brake squeal.
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Bakar, Abd Rahim Abu. "Modelling and simulation of disc brake contact analysis and squeal". Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422105.
Testo completoAbstract (sommario):
This thesis proposes a new methodology of predicting squeal using the finite element method in which three validation stages are established. A detailed 3-dimensional finite element model of a real disc brake is not only validated through modal analysis at the components and assembly levels but also through contact analysis where static contact pressure distribution and its contact area match with the experimental results. The main key issue in this research is the refinement of contact interface model of the friction material. Having assumed a smooth and flat surface (or perfect contact interface) in the past, current research considers a real surface topography of which measurementsa re carried out in order to obtain a realistic contact interface model. It is found that with the refined disc brake model, a good correlation is achieved between the predicted results and experimental ones on the contact pressure distribution and contact area at the piston and finger pads. Complex eigenvalue analysis that is available in ABAQUS software package is used as the main tool to predict squeal generation. Prediction of squeal occurrence is limited to a frequency range of I kHz to 8 kHz. Simulations of disc brake squeal are performed at different friction characteristics with the inclusion of friction damping for the perfect contact interface and real contact interface models. It is shown that the real contact interface model predicts squeal occurrences much better than the perfect contact interface model by considering the effect of negative u-v slope and friction damping. Comparison between complex eigenvalue analysis and dynamic transient analysis using a reduced FE model is also made for different contact schemes. It is found that using small sliding with Lagrange multiplier contact scheme predicted results in both analyses in a good agreement. Wear effects on instability of the disc brake assembly are also simulated. The results show that with the inclusion of wear, unstable frequencies are predicted to appear and disappear as wear progresses even though similar boundary conditions and operating conditions are imposed to apparently the same disc brake model. This phenomenon may explain the fugitive nature of squeal behaviour.
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Hussain, Jafar. "Thermal and material characterisation of coated lightweight disc brake rotor". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21609/.
Testo completoAbstract (sommario):
Environmental concerns linked to CO2 emissions have placed the automotive industry under considerable pressure to reduce the carbon footprint of the vehicles that they produce. One way forward involves the use of alternative lightweight materials. The use of aluminium alloy in a brake rotor has the potential to save around 20kg in unsprung mass on a medium sized passenger car. A full scale prototype lightweight coated ventilated aluminium alloy (6082) brake rotor was manufactured to investigate the thermal performance under drag brake test conditions. The brake rotor’s rubbing surface was coated with alumina layer using a plasma electrolytic oxidation (PEO) process. The ventilated brake rotor geometry contributes to the ability of the structure to dissipate heat through the inclusion of an array of appropriately configured vents and so has further bearing on the ability of the rotor to run cool. It is also feasible to explore the impact of vane design on the cooling of the rotor since the vented section of the rotor can be easily reconfigured using the current prototype. Experiments were conducted using a brake dynamometer. Brake rotor rubbing surface temperature, hydraulic pressure, rotational speed and brake torque were monitored during the test. The coefficient of friction was found to be around 0.5. Abaqus software was used to generate a three dimensional finite element model of a section of the coated brake rotor. The simulation results were found to be in good agreement with the experimental results when a heat transfer coefficient of 30 W/m2K was specified on all free surfaces. It was shown that coating thickness has a minimum effect on the substrate temperature. In parallel, a wear analysis has also been carried out using a pin-on-disc experimental setup. The mass of the friction material and the small discs were measured before and after the test. The wear coefficient for both conventional grey cast iron (GCI) and coated aluminium alloy were also measured and compared. It was found that wear rate of the PEO coated disc is about 15 times lower than the GCI. The wear rate of the friction material when run against the PEO coating was about 5 times less than when the same material was run against cast iron, even though the friction coefficient was on average higher (0.6 of 0.5).
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Mohd, Ripin Zaidi Bin. "Analysis of disc brake squeal using the finite element method". Thesis, University of Leeds, 1995. http://etheses.whiterose.ac.uk/4588/.
Testo completoAbstract (sommario):
The problem o f disc brake squeal has been examined by developing a finite element model of the coupled pad-disc system , conducting complex eigenvalue analysis and associating unstable modes with potential squeal problem areas. A key issue in this process is the representation of the contact pressure distribution at the frictional interface between the disc and the pad. Non-linear contact analysis using the finite element model of the pad revealed that contact is only partial at the pad-disc interface and that the contact pressure distribution depends on the friction coefficient, Young’s modulus of the friction material and the way the applied pressure is distributed on the pad backplate. A new method is proposed in which interface contact stiffness is related to brake line pressure using a statistical approach based on the measured surface properties of the interface. Complex eigenvalue analysis of the coupled pad-disc system has shown that unstable modes exist within different ranges of contact stiffness thereby providing an explanation of the effect of varying line pressure on squeal. The two most unstable modes from the analysis show good correlation with experimental squeal results. The coupled model is then used for parametric studies the results of which indicate that high coefficient of friction and uniform contact pressure distribution increase instability whilst a trailing edge biased pressure distribution and a high support stiffness at the pad backplate reduce it. Limiting the disc symmetry by introducing equispaced slots was shown to be effective in reducing instabilities involving diametral modes of the disc with the same order of symmetry only Other modes were stabilised by increasing the rigidity of the pad. The overall results suggest that either the pad or the disc can be mainly responsible for the instability depending on the mode thus unifying the different approaches to disc brake squeal and enabling the most appropriate component to be targeted for squeal abatement purposes.
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Serbino, Edison Marcelo. "Um estudo dos mecanismos de desgaste em disco de freio automotivo ventilado de ferro fundido cinzento perlítico com grafita lamelar". Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-12052005-093850/.
Testo completoAbstract (sommario):
Os principais mecanismos de desgaste, presentes em discos de freio ventilados automotivos, foram determinados utilizando ensaios de bancada em dinamometro inercial. Foram medidas a temperatura, rugosidade, taxa de desgaste, tensões residuais, coeficiente de atrito e desempenho de frenagem. Foi analisado o tribocontato através de técnicas de microscopia eletrônica e ótica.The main mechanims of wear, present in ventilated brake disc had been determined, when submited to the braking test in inertial dynamometric simulator. Were measured wear taxes, temperature, residual stresses, friction coeficient, topographic of relief and analised their tribographics.