The Effects of Grit Particle Size on Frictional Characteristics of Automotive Braking System

2011 ◽  
Vol 189-193 ◽  
pp. 3511-3516
Author(s):  
Mohd Kameil Abdul Hamid ◽  
Gwidon W. Stachowiak
Keyword(s):  
Particle Size ◽  
Friction Coefficient ◽  
Contact Area ◽  
Wear Debris ◽  
Silica Sand ◽  
Test Rig ◽  
Braking System ◽  
Hard Particles ◽  
Effective Contact

The effect of grit particle size on frictional characteristics was investigated using a vertically oriented brake test rig. Silica sand of grit sizes 50-180 µm, 180-355 µm and 355-500 µm were used in drag mode application. Results showed that the presence of hard particles from environment can influence the friction response significantly. Basically, once the hard particles enter the gap, the value and amplitude of friction coefficient tend to decrease. However, slight increase in friction with smaller particles was recorded due to more hard particles involved in mixing and changing the effective contact area. Better friction stability was related to the presence of smaller grit particles and compacted wear debris to form frictional film on the braking interface.

scholarly journals External Hard Particle Size Effect on Changes in Frictional Performance and Grit Embedment during Drag and Stop Mode Braking

2014 ◽  
Vol 66 (3) ◽  
Author(s):  
M. K. Abdul Hamid ◽  
A. R. Abu Bakar ◽  
G. W. Stachowiak
Keyword(s):  
Particle Size ◽  
Wear Debris ◽  
Particle Size Effect ◽  
Silica Sand ◽  
Brake Disc ◽  
Hard Particle ◽  
Hard Particles ◽  
Effective Contact ◽  
Frictional Performance ◽  
Friction Performance

The effects of silica sand of 50-180 µm, 180-355 µm and 355-500 µm on friction performance and grit embedment at brake disc and pad interface was investigated. Results showed that present of external hard particles caused higher friction coefficient due to higher number of smaller particles involved in mixing and changing the effective contact, while good friction stability was attributed to smaller grit particles and compacted wear debris. Grit embedment was greatly dependent on presence of compacted wear debris as most grits were embedded into compacted wear debris with embedment of 0.8% was observed for 50-180 µm, 2% for 180-355 µm and 3% for 355-500 µm.

Effects of External Hard Particles on Brake Friction Characteristics During Hard Braking

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
M. K. Abdul Hamid ◽  
G. W. Stachowiak
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Contact Area ◽  
Oscillation Amplitude ◽  
Stopping Time ◽  
Hard Particle ◽  
Friction Coefficients ◽  
Hard Particles ◽  
Effective Contact ◽  
Friction Oscillation

The effects of external hard particles on the friction coefficients and its oscillation amplitudes during hard braking were investigated. Silica sands of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient and the fluctuation of frictional oscillation amplitude. Different sliding speeds were applied and external hard particle of different size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficients increase with hard particle due to the rapid changes of the effective contact area and the abrasion mode. Some embedded particles operating in two body abrasion mode help to increase the disc surface roughness and influence the stopping time of the disc. The standard deviation values of friction oscillation amplitude however were stable due to more wear debris produced and get compacted to form friction films assisting friction and they tend to reduce at medium speeds because many contact plateaus and effective contact area started to stabilize.

Synchronous Observation With Friction Measurement Prior to and During Occurrence of Scuffing

2010 ◽  
Author(s):  
Kazuyuki Yagi ◽  
Joichi Sugimura ◽  
Seiji Kajita ◽  
Toshihide Ohmori ◽  
Atsushi Suzuki
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Wear Debris ◽  
Point Contact ◽  
The Other ◽  
Test Rig ◽  
Friction Measurement ◽  
Inlet Zone ◽  
Sapphire Disc ◽  
Ball On Disc

In the current work, scuffing phenomenon was investigated by a direct observation of a contact area. A ball-on-disc test rig was used, which produced a point contact area between a rotating sapphire disc and a stationary steel ball. Sequence of the friction and photograph in the contact area was synchronously obtained prior to and during occurrences of scuffing. Experiments were conducted in a dry condition and a lubricated condition with hexadecane. In the lubricated condition, wear debris accumulated in the inlet zone entered suddenly into the contact area to sharply increase the friction coefficient. On the other hand, macro plastic flow occurred in the whole contact area in the dry condition during a rapid increase in friction coefficient.

Effects of External Hard Particles on Brake Friction Characteristics During Hard Braking

2012 ◽  
Vol 58 (2) ◽  
Author(s):  
M. K. Abdul Hamid ◽  
G. W. Stachowiak
Keyword(s):  
Standard Deviation ◽  
Friction Coefficient ◽  
Contact Area ◽  
Oscillation Amplitude ◽  
Stopping Time ◽  
Hard Particle ◽  
Friction Coefficients ◽  
Hard Particles ◽  
Effective Contact ◽  
Friction Oscillation

The effects of external hard particles on the friction coefficients and its oscillation amplitudes during hard braking were investigated. Silica sands of the size between 180 to 355 μm were used during the experiments. The results were compared to the results obtained without the grit particles present in order to determine the change in friction coefficient and the fluctuation of frictional oscillation amplitude. Different sliding speeds were applied and external hard particle of different size is found to significantly affect the friction coefficient and standard deviation of friction oscillation amplitude values. The friction coefficients increase with hard particle due to the rapid changes of the effective contact area and the abrasion mode. Some embedded particles operating in two body abrasion mode help to increase the disc surface roughness and influence the stopping time of the disc. The standard deviation values of friction oscillation amplitude however were stable due to more wear debris produced and get compacted to form friction films assisting friction and they tend to reduce at medium speeds because many contact plateaus and effective contact area started to stabilize.

Effect of two-body and three-body microcontacts under dry friction on contact characteristics

2017 ◽  
Vol 232 (4) ◽  
pp. 706-719 ◽  
Author(s):  
Horng-Wen Wu ◽  
Yang-Yuan Chen
Keyword(s):  
Surface Roughness ◽  
Friction Coefficient ◽  
Contact Area ◽  
External Load ◽  
Wear Debris ◽  
Elastoplastic Deformation ◽  
Particle Diameter ◽  
Body Contact ◽  
Wide Range ◽  
Three Body

The wear debris generation is unavoidable between the contact interfaces of moving components. In three-body contact instances, friction and wear occur at these separate contact points. This paper discusses the characteristics of the three-body contact comprising the abrasive particle in the interface compared to the two-body contact. The results show that for the wear debris or foreign particles present in the interface of the three-body contact, as external load initially increases, the external load is fully borne by the contact characteristics of particle-to-surface. Until the external load rises to a particular critical external load, it enters the real three-body situation, and the critical external load thus increases with an increase in the ratio of particle diameter to surface roughness. For two contact surfaces, the summit deformation is the elastoplastic deformation in a wide range of external loads. As the external load is lower than the critical external load value of the three-body contact, the contact surface is under the particle-to-surface two-body contact, and the elastic deformation of surface peak has the largest proportion of contact area. When the external load is higher than the critical external load value, the elastoplastic deformation contact area quickly dominates, and the total contact area ratio approximates to the surface-to-surface two-body contact situation. In the range of engineering surface roughness (σ = 50–400 nm), at each external load and surface roughness, the total friction coefficient decreases with the increase in the ratio of particle diameter to surface roughness under the three-body contact, and this shows that the friction coefficient of surface-to-surface contact is larger than that of the sphere wear debris between the contact interface. At the same surface roughness, the friction coefficient may increase or decrease with an increase in the external load because it is determined by particle diameter. At the same ratio of particle diameter to surface roughness and external load, the friction coefficient increases with the decreasing surface roughness.

scholarly journals Relationship between the real contact behavior and tribological characteristics of cotton fabric

Friction ◽  
2020 ◽  
Author(s):  
Rongxin Chen ◽  
Jiaxin Ye ◽  
Wei Zhang ◽  
Jiang Wei ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Contact Area ◽  
Dynamic Change ◽  
Tribological Characteristics ◽  
Real Contact Area ◽  
Cotton Fibers ◽  
Friction Behavior ◽  
Contact Behavior ◽  
The Real ◽  
Real Contact

Abstract The tribological characteristics of cotton fibers play an important role in engineering and materials science, and real contact behavior is a significant aspect in the friction behavior of cotton fibers. In this study, the tribological characteristics of cotton fibers and their relationship with the real contact behavior are investigated through reciprocating linear tribotesting and real contact analysis. Results show that the friction coefficient decreases with a general increase in load or velocity, and the load and velocity exhibit a co-influence on the friction coefficient. The dynamic change in the real contact area is recorded clearly during the experiments and corresponds to the fluctuations observed in the friction coefficient. Moreover, the friction coefficient is positively correlated with the real contact area based on a quantitative analysis of the evolution of friction behavior and the real contact area at different loads and velocities. This correlation is evident at low velocities and medium load.

EXTERNAL PARTICLE SHAPE ANALYSIS AND ITS EFFECT ON TRIBOLOGICAL PERFORMANCE OF DISC BRAKE

2016 ◽  
Vol 78 (9) ◽  
Author(s):  
Ahmad Fawwaz Abdul Aziz ◽  
Mohd Kameil Abdul Hamid
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Particle Shape ◽  
Silica Sand ◽  
Variable Load ◽  
Shape Effect ◽  
Disc Brake ◽  
External Particle ◽  
The Road ◽  
Open Design

The open design of disc brake and its location close to the road surface may lead the road particles of various sizes and shapes to enter in between brake pads and disc rotor. This study presents an experimental approach to determine the particle shape effect on friction and wear characteristics of OEM disc brake under different operating condition. Two types of external particles which are road particles and silica sand with two range of size of 200 µm and 400 µm were used. Testing was conducted for variable load and sliding speed. Presence of external particle with various size and shape affect the wear rate, friction coefficient and surface topography of the brake pad. Smaller particle generated more wear. Moreover, the particles which have sharped shape or high angularity resulted in higher weight loss of the pad and contribute to greater formation of compacted wear debris. Wear rate and friction coefficient also increase with contact pressure.   

Friction Coefficient Variation Mechanism under Wet Condition in Disk Brake (Variation Mechanism Contributing Wet Wear Debris)

2016 ◽  
Vol 9 (3) ◽  
pp. 1227-1234 ◽  
Author(s):  
Tadayoshi Matsumori ◽  
Yoshitsugu Goto ◽  
Noboru Sugiura ◽  
Kenji Abe ◽  
Yoshihiro Osawa ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Wear Debris ◽  
Coefficient Variation ◽  
Disk Brake ◽  
Wet Condition ◽  
Variation Mechanism

scholarly journals Opening Material as the Possibility of Elimination Veining in Foundries

2016 ◽  
Vol 16 (3) ◽  
pp. 157-161 ◽  
Author(s):  
M. Hrubovčáková ◽  
I. Vasková ◽  
M. Benková ◽  
M. Conev
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Cast Iron ◽  
Granular Material ◽  
Surface Defects ◽  
Silica Sand ◽  
Iron Castings ◽  
Thermal Dilatation

Abstract The main bulk density representation in the molding material is opening material, refractory granular material with a particle size of 0.02 mm. It forms a shell molds and cores, and therefore in addition to activating the surface of the grain is one of the most important features angularity and particle size of grains. These last two features specify the porosity and therefore the permeability of the mixture, and thermal dilatation of tension from braking dilation, the thermal conductivity of the mixture and even largely affect the strength of molds and cores, and thus the surface quality of castings. [1] Today foundries, which use the cast iron for produce of casts, are struggling with surface defects on the casts. One of these defects are veining. They can be eliminated in several ways. Veining are foundry defects, which arise as a result of tensions generated at the interface of the mold and metal. This tension also arises due to abrupt thermal expansion of silica sand and is therefore in the development of veining on the surface of casts deal primarily influences and characteristics of the filler material – opening material in the production of iron castings.

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