scholarly journals Maximum temperature of the disc during repeated braking applications

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983782 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Element Model ◽  
Maximum Temperature ◽  
Bulk Temperature ◽  
Brake Disc ◽  
Subsequent Stage ◽  
System Of Equations ◽  
Brake Pads ◽  
Brake Application ◽  
The Mean

A computational finite element model of a brake disc for determining transient axisymmetric (two-dimensional) temperature field during repeated brake application has been proposed. The presented research is a subsequent stage of a previous study on the coupling of velocity and maximum temperature for a single braking in accordance with the system of equations of heat dynamics of friction and wear. In the analysed case, changes in the mean, flash, maximum and bulk temperature of the disc were determined and discussed. The calculations were carried out at the temperature-dependent coefficient of friction, the thermophysical properties of cast-iron disc combined with cermet brake pads and the time-varying contact pressure. The obtained results were compared with the reference values from the braking simulation at constant operating parameters and independent of temperature properties of materials. It was shown that the maximum values of the mean temperature for both cases differed slightly during the entire process. The flash temperature determined from the heat dynamics of friction and wear system of equations was the highest at the beginning and gradually decreased with the number of brake applications.

scholarly journals Finite element solution of the three-dimensional system of equations of heat dynamics of friction and wear during single braking

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880864 ◽  
Author(s):  
Piotr Grzes
Keyword(s):  
Friction And Wear ◽  
Mutual Influence ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Dimensional System ◽  
System Of Equations ◽  
Sliding Velocity ◽  
Flash Temperature ◽  
Disk Brake ◽  
Discrete Contact

A three-dimensional numerical model of a disk brake to study temperature on a discrete contact of rough surfaces has been developed. It includes the system of equations formulated based on thermotribological postulates of heat dynamics of friction and wear with mutual influence of contact pressure, velocity, properties of materials, and temperature. Two approaches of calculation of the flash temperature and its influence on the maximum temperature during a single braking application were studied. Changes in the contact temperature, sliding velocity, and the thermomechanical wear during braking were shown and discussed. It was found that two of the examined variants of calculation of the flash temperature agree well for the three considered materials of the brake pads combined with the cast iron disk, at each initial sliding velocity in the range from 5 to 20 m s−1.

THE NEW INERTIA DYNAMOMETER FOR FRICTION AND WEAR TESTING OF BRAKE PADS AND BRAKE DISCS

Tribologia ◽  
2019 ◽  
Vol 286 (4) ◽  
pp. 113-119
Author(s):  
Waldemar TUSZYŃSKI ◽  
Michał GIBAŁA ◽  
Andrzej GOSPODARCZYK ◽  
Stanisław KOZIOŁ ◽  
Krzysztof MATECKI ◽  
...  
Keyword(s):  
Tribological Properties ◽  
Friction And Wear ◽  
Wear Testing ◽  
Driving Safety ◽  
Brake Disc ◽  
Brake Pad ◽  
Vehicle Class ◽  
Brake Pads ◽  
Test Methodology ◽  
Brake Discs

For the sake of driving safety, the right choice of the brake pad friction material and its manufacturing processes to obtain the appropriate tribological properties is a matter of priority for brake pad manufacturers. Determination of the tribological properties is best done in component tests, i.e. in the setup: brake pads – brake disc. At the request of one of the domestic brake pad manufacturers, as part of the POIR project, an inertia dynamometer for testing friction and wear of brake pads and brake discs was developed and manufactured, which was given the symbol T-33. A test methodology was developed based on the “Cold application section” procedure described in SAE J2522:2003. The T-33 inertia dynamometer is designed for testing brake pads and brake discs intended for five vehicles representing the passenger vehicle class and vans. The paper presents the new test stand, test methodology, and results of verification tests of the T-33 dynamometer (interlaboratory comparison tests) performed on the Cinquecento vehicle brake setup.

scholarly journals Simulation Study on Friction and Wear Law of Brake Pad in High-Power Disc Brake

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
S. Zhang ◽  
Q. Hao ◽  
Y. Liu ◽  
L. Jin ◽  
F. Ma ◽  
...  
Keyword(s):  
High Power ◽  
Friction And Wear ◽  
Element Model ◽  
Calculation Model ◽  
Brake Disc ◽  
Disc Brake ◽  
Wear Depth ◽  
Brake Pad ◽  
Wear Calculation ◽  
Wear Law

For the serious and uneven wear of the brake pad in the high-power disc brake during braking, the dynamic variation of the brake disc and the brake pad interface variable is considered, the wear calculation model is established based on the friction and wear mechanism, and the wear depth and volume of the brake pad can be calculated by equations. A finite element model of the brake disc and the brake pad is established by DEFORM software which can analyze wear of the brake pad directly. The variation trend of wear during braking is studied, and influences of braking load and initial braking speed on the wear are analyzed. The results show that the amount of the wear increases rapidly in the early wear stage of braking, and it becomes slow in the later stage; the wear of the brake pad is serious at the friction inlet and outlet, and the middle area of the brake pad is lightly worn; heavy braking load and high initial braking speed can exacerbate the wear of the brake pad.

Stability Improvement of Brake Disc to Mode Coupling at High Frequency Squeal

2020 ◽  
Author(s):  
Anutcharee Khuntiptong ◽  
Chak Chantalakhana
Keyword(s):  
Field Test ◽  
High Frequency ◽  
Element Model ◽  
Modal Testing ◽  
Brake Disc ◽  
Complex Eigenvalue ◽  
Brake Pads ◽  
Locking Mechanism ◽  
Out Of Plane ◽  
Complex Eigenvalue Analysis

In this research study, the high-frequency squeal noise of a brake disc was found to occurred at a frequency of about 15 kHz. The potential root cause has been studied where mode frequency coupling and shape locking mechanism of brake disc and brake pads components are the main investigated topic. From the vehicle field test and the Dynamometer test, the braking condition, friction coefficient and braking pressure, have been confirmed to be used in numerical experiments. The updated finite element model (FEM) with the modal testing data of the existing brake components are formulated for the Complex Eigenvalue Analysis (CEA). In this study, the modification is based on in-board and out-board cheek thickness of the brake disc. Two of nine modifications of the brake disc cheek thickness are proposed with the method of separation the brake disc out-of-plane and in-plane modes and the method of avoiding shape locking between the brake disc and the brake pads modes. The constructed prototypes are verified with the vehicle field test and well agreed with the CEA.

Effects of Ni-Coated Graphite Flake on Braking Behavior of Cu-Based Brake Pads Applied in High-Speed Railway Trains

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Peng Zhang ◽  
Lin Zhang ◽  
Kangxi Fu ◽  
Peifang Wu ◽  
Jingwu Cao ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
High Speed ◽  
Maximum Temperature ◽  
Graphite Flake ◽  
Wear Loss ◽  
Linear Wear ◽  
High Speed Railway ◽  
Brake Pads ◽  
The Mean ◽  
Braking Process

Cu-based brake pads applied in high-speed railway trains containing Ni-coated graphite flake and uncoated graphite flake were fabricated by powder metallurgy. The braking properties of the brake pads were investigated by a scaled down testing apparatus with the pad-on-disk configuration under various braking speeds and braking pressures. Compared with the brake pads containing uncoated graphite flake (designated GF), the brake pads containing Ni-coated graphite flake (designated NGF) exhibits a similar braking performance at lower braking speed and pressure. However, NGF shows more stable friction coefficient, lower linear wear loss, and lower maximum temperature during the braking process at worse braking conditions, e.g., 350 km/h, 1.5 MPa. The Ni-coating on the surface of Ni-coated graphite can transfer the mechanical bonding between copper and graphite to diffusion bonding so that there is a stronger interface bonding between copper and Ni-coated graphite. Further, the multiple linear regression analyses reveal that the mean friction coefficient of NGF is more sensitive to braking pressure than braking speed because of the better thermal resistance of NGF, while the mean friction coefficient of GF and the linear wear loss are mainly affected by braking speed.

Theoretical analysis of a rolling-sliding elastohydrodynamic lubrication line contact with a subsurface inclusion

2019 ◽  
Vol 233 (8) ◽  
pp. 1197-1207
Author(s):  
Armando Félix Quiñonez ◽  
Guillermo E Morales Espejel
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Element Model ◽  
Von Mises Stress ◽  
Transient Effects ◽  
Mean Velocity ◽  
The Matrix ◽  
Soft Inclusion ◽  
The Mean ◽  
Von Mises ◽  
Fully Coupled

This work investigates the transient effects of a single subsurface inclusion over the pressure, film thickness, and von Mises stress in a line elastohydrodynamic lubrication contact. Results are obtained with a fully-coupled finite element model for either a stiff or a soft inclusion moving at the speed of the surface. Two cases analyzed consider the inclusion moving either at the same speed as the mean velocity of the lubricant or moving slower. Two additional cases investigate reducing either the size of the inclusion or its stiffness differential with respect to the matrix. It is shown that the well-known two-wave elastohydrodynamic lubrication mechanism induced by surface features is also applicable to the inclusions. Also, that the effects of the inclusion become weaker both when its size is reduced and when its stiffness approaches that of the matrix. A direct comparison with predictions by the semi-analytical model of Morales-Espejel et al. ( Proc IMechE, Part J: J Engineering Tribology 2017; 231) shows reasonable qualitative agreement. Quantitatively some differences are observed which, after accounting for the semi-analytical model's simplicity, physical agreement, and computational efficiency, may then be considered as reasonable for engineering applications.

Friction and Wear Properties of Magnetron Sputtered DLC/SiC Films on Magnesium Alloy

2009 ◽  
Vol 610-613 ◽  
pp. 853-858 ◽  
Author(s):  
Xiao Jing Xu ◽  
Deng Fu Xia
Keyword(s):  
Friction And Wear ◽  
High Hardness ◽  
High Wear Resistance ◽  
Modulus Ratio ◽  
Wear Properties ◽  
Silicon Carbon ◽  
Alloy Az91d ◽  
The Mean ◽  
Friction And Wear Properties ◽  
Sic Films

The nano-indentation response and the friction/wear properties of DLC/SiC (diamond-like carbon/silicon carbon) double layer thin films deposited on Mg alloy (AZ91D) substrate using magnetron sputtering technique at room temperature were investigated. The results show that the DLC films displayed low nano-hardness (3.05 GPa), low Young's modulus (24.67 GPa) but high hardness-to-modulus ratio (0.124). The films-substrate system exhibited a good friction and wear properties with the mean friction coefficient of about 0.175, the special wear rate in the magnitude order of 10−6 mm3 m−1 N−1 together with little film-cracking and interface-delaminating, when sliding against Si3N4 (silicon nitride) ball using ball-on-disc wear tester under dry frictional condition. The high wear-resistance is in accordance with high ductility of the films, good modulus match in the films-substrate system, and high hardness-to-modulus ratio of the films. The underlying factors are discussed and are believed to be due to the substrate is Mg, a metal with high activity.

scholarly journals Thermoregulation in colonies of africanized and hybrids with Caucasian, Italian and Carniolan Apis mellifera honey bees

1999 ◽  
Vol 42 (4) ◽  
Author(s):  
Vagner de Alencar Arnaut de Toledo ◽  
Regina Helena Nogueira-Couto
Keyword(s):  
Apis Mellifera ◽  
Honey Bees ◽  
Maximum Temperature ◽  
Tropical Region ◽  
Internal Temperature ◽  
Africanized Honey Bees ◽  
Significant Difference ◽  
The Mean ◽  
One Year ◽  
Brood Nest

This experiment was carried out to study the internal temperature regulation of a colony of Africanized honey bees (AFR), compared with hybrid Caucasian (CAU), Italian (ITA), and Carniolan (CAR) bees, during the period of one year and different size hives located in a sub-tropical region. The instant internal temperature, 33.7 ± 1.5° C for the AFR, 33.5 ± 1.4° C for the CAU, 33.7 ± 1.5° C for the ITA and 33.8 ± 1.4° C for the CAR, did not show any significant difference (P>0.05). The maximum temperature (36.1 ± 2.3° C) was statistically different (P<0.05) from the minimum (27.6 ± 5.3° C). There was no difference (P>0.05) in the mean internal temperature, between the nucleus (31.7 ± 6.3° C) and the brood nest (32.1 ± 5.3° C) measured between two and four o'clock in the afternoon.

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