• Title/Summary/Keyword: Brake dynamometer

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Thermo-Elastic Analysis for Chattering Phenomenon of Automotive Disk Brake

  • Cho, Chongdu;Ahn, Sooick
    • Journal of Mechanical Science and Technology
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    • v.15 no.5
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    • pp.569-579
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    • 2001
  • This study investigates the effects of operating conditions on the chattering of an automotive disk brake by experimental and computational methods. Design factors, which cause chattering in automobiles, have attracted great attentions for long time; but they are not well understood yet. For this study, we construct a brake dynamometer for measuring the disk surface temperature during chattering, and propose an efficient hybrid algorithm (combining FFT-FEA and traditional FEA program) for analyzing the thermo-elastic behavior of three-dimensional brake system. We successfully measure the judder in a brake system via the dynamometer and efficiently simulate the contact pressure variation by the hybrid algorithm. The three-dimensional simulation of thermo-mechanical interactions on the automotive brake, showing the transient thermo-elastic instability phenomenon, is presented for the first time in this academic community. We also find from the experimental study that the disk bulk temperature strongly influences the brake chattering in the automotive disk brakes.

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A study on the characteristics of friction in automotive brake lining (자동차용 브레이크 라이닝의 마찰특성에 관한 연구)

  • 정화영
    • Journal of the korean Society of Automotive Engineers
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    • v.8 no.4
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    • pp.56-65
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    • 1986
  • This paper theoretically analyzed the relations between the out-put braking torque and the wheel cylinder pressure in the leading-trailing drum brake for heavy duty truck as the characteristics of friction in break lining, comparing with the results derived from full-scale inertial brake dynamometer test in actual braking condition to develop reliable brake system in extensive using conditions. The main results obtained are as follows; 1) The characteristic curve representing the relations between BEF (Brake Effectiveness Factor) and Friction coefficient derived from theoretical analysis are consistent with the experimental results of dynamometer test. 2) According to the results of dynamometer test, the friction coefficient of brake lining is subject to initial brake speed and the actual using temperature in brake system.

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A Study on the Thermal Behaviour of Automotive Disc Brakes Using FEA and Dynamometer (FEA와 다이나모메터를 이용한 자동차 디스크 브레이크의 열적 거동에 관한 연구)

  • 박범식;손영지;장성규;전언찬
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2000.10a
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    • pp.45-50
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    • 2000
  • While braking cars, a large amount of energy is taken into the brake system in a short period of time. This leads to some problems ; cracking of the disc, non-uniform wear of pad and disc, fade. Thus it is important to measure the contact thermal behaviour precisely between disc and pad. The measurements must be considered to design the brake system. The paper describes methods to analysis the problem of the thermal behavior on the ventilated disc with ANSYS-a program of FEA and a brake dynamometer. According to this way, the paper can present the error between the data by the dynamometer and the results of analysis by ANSYS.

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Braking Force Test Evaluation Dynamometer Development of Vehicle (차량용 브레이크 제동력 평가 다이나모미터 개발)

  • Kwon, Byeong-Heon;Yoon, Pil-Hwon;Lee, Seon-Bong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.5
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    • pp.56-65
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    • 2019
  • Recently, automobiles have been developed for safety and environmental reasons. Particularly, awareness of automobile safety is changing significantly. As a result, safety systems developed by ADAS have emerged. However, the period of mass production through ADAS development and test evaluation is long. Therefore, in this paper, we develop a brake dynamometer to shorten the time required for ADAS development and test evaluation. In addition, the developed brake dynamometer satisfies the international standard JIS D-0210, and the user can evaluate the braking force by selecting test conditions and test method for each mode of ADAS. We use the ACC, LKAS, and AEB scenarios proposed in previous studies to verify the reliability of the developed brake dynamometer. The developed brake dynamometer was verified by comparing the test values and the calculated values using theoretical formulas of the proposed ADAS mode based on previous studies. In addition, it is expected that the performance evaluation of brake parts for each ADAS mode will be possible in an environment where the vehicle test of ADAS is not possible in the future.

An Experimental Study on the Squeal Noise Generation due to Dynamic Instability of Brake Pad (브레이크 패드의 동적 불안정성에 따른 스퀼 소음 발생 원인의 실험적 연구)

  • Cho, Sangwoon;Lim, Byoungduk
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.5
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    • pp.520-526
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    • 2016
  • Squeal noise is a typical brake noise that is annoying to both passengers and pedestrians. Its frequency range is fairly wide from 1 kHz to 18 kHz, which can be distressful to people. The brake squeal noise occurs due to various mechanisms, such as the mode coupling of the brake system, self-excited vibration, unstable wear, and others. In this study, several parameters involved in the generation of a squeal noise are investigated experimentally by using a brake noise dynamometer. The speed, caliper pressure, torque, and friction coefficient are measured as functions of time on the dynamometer. The contact pressure and temperature distributions of the disc and the pad are also measured by using a thermal imaging camera and a pressure mapping system. As a result of the simultaneous measurement of the friction coefficient and squeal amplitude as functions of the velocity, it is found that the onset of the squeal may be predicted from the ${\mu}-v$ curve. It is also found that a non-uniform contact pressure causes instability and, in turn, a squeal. Based on the analysis results, design modifications of the pad are suggested for improved noise characteristics.

Friction Characteristics of Non-Asbestos Organic (NAO) and Low-Steel Friction Materials: The Comparative Study

  • Kim, Seoun Jin;Jang, Ho
    • KSTLE International Journal
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    • v.1 no.1
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    • pp.1-7
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    • 2000
  • Eviction characteristics of two typical friction materials (non-asbestos organic and low-steel friction materials) for an automotive brake system were investigated using an inertial brake dynamometer. In particular, the effect of sliding speed on friction coefficient was carefully investigated employing various test modes. The two friction materials were developed for commercial applications and were different mainly in the type and the amount of metallic ingredients in the friction material. The dynamometer test showed that the low-steel friction material was sensitive to the sliding speed exhibiting a negative $\mu$-v relation. On the other hand, the non-asbestos organic friction material was less sensitive to the sliding speed. The low steel friction materials with a negative $\mu$-v relation also induced larger vibration amplitude during brake applications.

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A Study on the Techniques of Simulation Test in Automotive Braking System (자동차 제동장치의 시뮬레이션 시험 기법에 관한 연구)

  • 민규식;김형섭
    • Journal of the Korean Society of Safety
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    • v.8 no.2
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    • pp.23-29
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    • 1993
  • In this study, the method of deciding simulation test conditions is developed by computer program compared to actual vehicle test as accurately as possible. These results of analytical test conditions are conformed by simulation test using the brake dynamometer by comparison with test results of actual vehicle. Results of simulation test by these analytical results show good agreement with the vehicle test results. The analytical simulation test conditions provide the input data to brake dynamometer which follows : - each test inertia corresponding to braking deceleration - test condition of input control : brake line pressure - test condition of output control : braking torque

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Development of Nondestructive System for Detecting the Cracks in KTX Brake Disk Using Rayleigh Wave (Rayleigh Wave를 이용한 KTX 제동 디스크의 균열 검측 시스템 개발)

  • Kim, Min Soo;Yeom, Yun Taek;Park, Jin-Hyun;Song, Sung Jing;Kim, Hak Joon;Kwon, Sung Duck;Lee, Ho Yong
    • Journal of the Korean Society for Nondestructive Testing
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    • v.37 no.1
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    • pp.29-36
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    • 2017
  • Recently, KTX (Korean Train Express) train stoppage accidents were mainly caused by malfunctioning equipment, aging and cracking of railway vehicles, crack breakages of brake disks, and breakages of brake disks. Breakage of brake disk can cause large-scale casualties such as high-speed collision and concern about derailment by hitting lower axle and wheel. Therefore, in this study, a brake disk with solid and ventilation type, which is the brake disk of a KTX train was modeled, and a dynamometer system was constructed to operate the disk. A Rayleigh wave was used to inspect the surface of the brake disk. An ultrasonic inspection module was developed for the brake disk by using a local immersion method due to the difficulty involved in ultrasonic inspection using an existing immersion method. In addition, the surface defects of the brake disk were evaluated using a dynamometer mock-up system and an ultrasonic inspection module of the brake disk.

Squeal Test Using Lab-Scale Brake Dynamometer for Pad Angle and Negative-slope (랩스케일 브레이크 다이나모 메터를 이용한 패드각도 및 음의 기울기에 따른 스퀼 소음 실험 연구)

  • Nam, Jae-Hyun;Cho, Byung-Jae;Kang, Jae-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.7
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    • pp.3158-3163
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    • 2013
  • In this study, squeal noise test was conducted by using the lab-scaled brake dynamometer. Squeal conditions with respect to the angle of the brake pads ($34^{\circ}30^{\circ}26^{\circ}$) and negative slope, were studied. Squeal frequency of the In-plane-like mode was confirmed by hammering test and finite element analysis. This Squeal mode was difficult to control by the pad angle variation. Also the squeal sound was found to be periodic signal which has higher harmonic components. Squeal noise is independent of the negative slope. It implies that squeal noise can reach the stick-slip oscillation.