Effect of Matrix Alloying on Braking Performance of Copper-Based Brake Pad Under Continuous Emergency Braking

2020 ◽  
Vol 142 (8) ◽  
Author(s):  
Peng Zhang ◽  
Lin Zhang ◽  
Dongbin Wei ◽  
Xuanhui Qu
Keyword(s):  
Friction Coefficient ◽  
Friction Surface ◽  
High Speed ◽  
High Strength ◽  
Brake Pad ◽  
Braking Performance ◽  
Emergency Braking ◽  
Ni Content ◽  
Improved Stability ◽  
Braking Process

Abstract The continuous emergency braking performance of copper-based brake pads alloyed with different Ni contents were tested. The results showed that the copper-based brake pad with high Ni content exhibits improved stability of friction coefficient during the whole emergency braking process, which indicates that Ni helps to reduce the sensitivity of the brake pad to the change of braking conditions. Moreover, the fade phenomenon of friction coefficient is obviously alleviated as the increase in Ni content under high-pressure and high-speed braking conditions. The introduction of Ni enhances the plastic deformation resistance of friction surface and promotes the formation of high-strength mechanical mixed layer and thick tribo-oxide film. This stable tribo-film remained on the contact interface is responsible for the steady mean friction coefficient under different braking conditions. Excessive addition of Ni reduces the plasticity of the friction surface, leading to the change of the main wear mechanism from adhesive wear to delamination

Ti3AlC2 — A Soft Ceramic Exhibiting Low Friction Coefficient

2005 ◽  
Vol 475-479 ◽  
pp. 1251-1254 ◽  
Author(s):  
Hong Xiang Zhai ◽  
Zhen Ying Huang ◽  
Yang Zhou ◽  
Zhi Li Zhang ◽  
Shi Bo Li ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Friction Surface ◽  
High Speed ◽  
Low Carbon Steel ◽  
Normal Pressure ◽  
Aluminum Carbide ◽  
Low Carbon ◽  
Friction Behavior ◽  
Sliding Speed ◽  
Al And Fe Oxides

The friction behavior of a high-purity bulk titanium aluminum carbide (Ti3AlC2) material dryly sliding against low carbon steel was investigated. Tests were performed using a block-on-disk type high-speed friction tester under sliding speed of 20 m/s and 60 m/s, several normal pressures from 0.1 to 0.8 MPa. The results showed that the friction coefficient is as low as about 0.18 for sliding speed of 20 m/s and only 0.1 for 60 m/s, and that almost not changes with the normal pressure. The reason could be related with the presence of a surface layer on the friction surface. The layer was analyzed to consist of Ti, Al and Fe oxides, which played a lubricate part inducing the friction coefficient decrease on the friction surface.

scholarly journals Nonlinear Dynamic Analysis of Lifting Mechanism of an Electric Overhead Crane during Emergency Braking

2020 ◽  
Vol 10 (23) ◽  
pp. 8334
Author(s):  
Congmin Niu ◽  
Huajiang Ouyang
Keyword(s):  
High Speed ◽  
Virtual Work ◽  
Thermal Power ◽  
Nonlinear Dynamic Analysis ◽  
Maximum Load ◽  
Rigid Bodies ◽  
Dynamic Responses ◽  
Response Analysis ◽  
Emergency Braking ◽  
Braking Process

Mechanical brakes are essential for electric cranes when emergency braking occurs. This paper presents, for the first-time, a dynamic response analysis of emergency braking events of electrical cranes that has modelled crane components as flexible and rigid bodies. Based on the Hamilton principle, a nonlinear and non-smooth dynamic model is derived from a modified Lagrangian function and the virtual work of non-conservative forces. The dynamic responses of a 32-ton overhead travelling crane during the emergency braking process of its lifting mechanism with two service brakes determined by simulating realistic operations. The numerical results show that the loads acting on components of the crane during the braking process depend on the braking capacity and the action time of the mechanical brakes, as well as the magnitude and the initial position of the payload. When a dual-brake scheme of the lifting mechanism is adopted, the maximum load of the high-speed links and the maximum thermal power of the mechanical brake appear in the emergency braking process when one of the two brakes fails to work. In addition, it is found to be a false belief that the lower the initial speed, the lower the maximum loads acting on components of cranes become during the braking process.

Vibration Characteristics of Elastic Disc Brake Pad Device

2011 ◽  
Vol 101-102 ◽  
pp. 29-32 ◽  
Author(s):  
Ji Min Zhang ◽  
Kuan Yang
Keyword(s):  
Mathematical Model ◽  
Friction Force ◽  
Friction Surface ◽  
Railway Vehicle ◽  
Brake Disc ◽  
Disc Brake ◽  
Brake Pad ◽  
Braking Performance ◽  
Simulation Results ◽  
Elastic Disc

A new elastic disc brake pad device is designed. A mathematical model on railway vehicle elastic disc brake is established compared with the non-elastic brake pad by uni-wheel set braking simulation. The simulation results show that the elastic brake pad could guarantee the vehicle braking performance as same as the non-elastic brake pad. When the friction surface of the brake disc or pad has defects, the elastic brake pad can effectively reduce the vibration of the friction force between the brake pad and the brake disc. It has been proved that the correctness and rationality of the design. A new idea for the design and analysis of the disc brake system is provides.

Research on Adhesion and Non-Adhesion Braking Characteristics for High-Speed Train

2011 ◽  
Vol 121-126 ◽  
pp. 3437-3443
Author(s):  
Hai Jun Wang ◽  
Jing Zeng ◽  
Guang Bing Luo ◽  
Zhuan Hua Liu
Keyword(s):  
High Speed ◽  
The State ◽  
High Speed Train ◽  
Braking Performance ◽  
Area Method ◽  
Emergency Braking ◽  
Braking Distance

The emergency braking deceleration and braking distance of high-speed train were studied under the conditions of adhesion brake on dry and humid rail surfaces, and adhesion and non-adhesion composite brake on humid rail surface. The average emergency braking deceleration was calculated by the area-method. The results show that the braking performance is affected significantly by the wheel/rail adhesion state and the braking performance of high-speed train can be improved by applying the adhesion and non-adhesion composite brake in the state of humid rail surface.

Effect of Brake Pad Design On Friction and Wear with Hard Particle Present

2014 ◽  
Vol 71 (2) ◽  
Author(s):  
M.K. Abdul Hamid ◽  
N.I. Shasudin ◽  
A.R. Mat Lazim ◽  
A.R. Abu Bakar
Keyword(s):  
Friction And Wear ◽  
Load Condition ◽  
Hard Particle ◽  
Brake Pad ◽  
Braking Performance ◽  
Wear Analysis ◽  
Brake Performance ◽  
Friction Performance ◽  
Brake Dynamometer ◽  
Braking Process

Brake pad and disc design are important factors in ensuring excellent brake performance. But, particles from the environment can easily enter and interrupt the braking process and reduce braking performance. Friction depends on the design and surface properties of the pad and the disc. Wear happens in the brake system as the pad and disc try to withstand the braking force during the braking process.  An experiment using brake dynamometer is done in order to determine the design effects on friction and wear when hard particle are present during the braking process. The test used three different brake pad designs under medium sliding load condition. It is found that Design 2 with a middle line groove provides better and stable brake torque and friction performance compared to Design 1 and Design 3. Design 2 also gavethe smallestweight loss inthe wear analysis of the pad.

Tribological behaviors of precipitates reinforced Cr-Ni-Mo-V steel lubricated by water or water-silica mixture

2018 ◽  
Vol 70 (8) ◽  
pp. 1431-1436 ◽  
Author(s):  
Shuaishuai Zhu ◽  
Baosen Zhang ◽  
Zhixin Ba ◽  
Xiangyang Mao ◽  
Weijie Fei ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
High Speed ◽  
Brake Disc ◽  
Wear Properties ◽  
Fatigue Wear ◽  
Industrial Firms ◽  
Content Type ◽  
Liquid Cell ◽  
Braking Process ◽  
Worn Surface

Purpose This paper aims to investigate the friction and wear properties of Cr-Ni-Mo-V steel against 440C stainless steel under both water and water–silica mixture lubricant. Design/methodology/approach The Cr-Ni-Mo-V steel specimens were taken from a forged steel brake disc with the process of quenching at 900°C and tempering at 600°C. The tribological testing was performed using a contact configuration of ball-on-flat with a liquid cell according to the ASTM standard. Detailed examinations on the worn surface were analyzed using a scanning electron microscope. Findings The results indicate that the friction coefficient and friction damage of the steel sliding under water–silica mixture are higher than those under water. The friction coefficient decreases with increasing load and increases with the sliding speed for the two lubricants. The mass wear rate presents a rising trend with both sliding load and speed. The wear mechanisms of the Cr-Ni-Mo-V steel sliding under the two lubricants are oxidation wear, abrasive wear and fatigue wear. Research limitations/implications Because of the chosen tribological testing approach, the research results could not describe the tribological performance of the brake disc accurately during actual braking process of the high-speed train. Therefore, researchers are encouraged to test the proposed propositions further. Originality/value This study shows that the tribology behavior of the Cr-Ni-Mo-V steel with water or water–silica mixture lubrications helps the industrial firms and academicians to work on the wear of the brake disc in rainwater or wet environment.

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.

Tire ABS-Braking Prediction with Lab Tests and Friction Simulations

2015 ◽  
Vol 43 (4) ◽  
pp. 260-275 ◽  
Author(s):  
Pavel A. Ignatyev ◽  
Stefan Ripka ◽  
Norbert Mueller ◽  
Stefan Torbruegge ◽  
Burkhard Wies
Keyword(s):  
Traffic Safety ◽  
High Speed ◽  
High Performance ◽  
Viscous Friction ◽  
Optimal Level ◽  
Friction Test ◽  
Test Procedures ◽  
Braking Performance ◽  
Friction Measurements ◽  
Braking Process

ABSTRACT The invention and application of antilock braking systems (ABS) has resulted in a significant improvement of traffic safety and a reduction of stopping distance, especially on wet roads [1]. The reason for this success is rather clear: ABS is designed to steer the braking process in the most efficient way by keeping an optimal level of tire slip. At the same time, it must be clear that ABS uses braking forces generated in the tire footprint, and really good braking is possible only with high-performance tires. The best way to probe tire performance is to build tires and test them. This is, however, a long and an expensive procedure, so prediction of ABS performance based on results of some simple experiments is a very attractive supplement to the development process. Tire-braking performance is related to the friction of rubber on a surface. Relevant friction mechanisms can include adhesion, rubber hysteresis, and various kinds of viscous friction. All of these phenomena depend on the local sliding velocity, load, and temperature of tread rubber. Tire blocks pass the footprint area of a braking tire very rapidly, but their dynamics are indeed influenced by ABS. All of these aspects make the problem of ABS-braking prediction very intricate. In this publication, we present an approach for prediction of the ABS-braking performance. The approach links friction measurements conducted in laboratory to tire tests results. The friction of six specially designed compounds was measured on dry and wet surfaces using a high-speed linear friction test rig. Obtained experimental results are analyzed with the aid of rubber friction theory [2,3] involving both surface and rubber as input parameters. It is demonstrated that lab friction test procedures can be used for prediction of ABS wet braking performance.

Fade behaviour of copper-based brake pad during cyclic emergency braking at high speed and overload condition

Wear ◽  
2019 ◽  
Vol 428-429 ◽  
pp. 10-23 ◽  
Author(s):  
Peng Zhang ◽  
Lin Zhang ◽  
Kangxi Fu ◽  
Peifang Wu ◽  
Jingwu Cao ◽  
...  
Keyword(s):  
High Speed ◽  
Brake Pad ◽  
Emergency Braking
Sign in / Sign up

Export Citation Format

Share Document