Reducing Curve Squeal Noise Using Composite Materials Based on Experimental Investigation

Yang Soo Yun,Jae-Chul Kim 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.9

Curve squeal noise is one of the greatest noise sources among railway noise when a vehicle is passing through the sharp radius curve. Furthermore, its high frequency and pure tone component cause a great deal of pain to residents around the track. Squeal noise is caused by lateral creep of wheel/rail contact point in curve. When railway vehicle passes through a sharp curve, negative friction under conditions of lateral creepage induces stick–slip oscillations, and these in turn induce resonance of the wheel web. Thus, wheel squeal noise is generated. In this study, laser cladding rail with composite material on the rail head was tested to prevent decrease of adhesion coefficient versus creepage. To make a composite rail specimen for test rig, composite material was cladded using high power diode laser. Four distinct types of composite material were processed to prepare rail disc specimens. To determine their effect on squeal noise reduction, adhesion coefficient and noise test were performed using a wheel / rail scale test rig. Lateral adhesion coefficient and squeal noise were also measured. Our results showed that steel rail disc had negative slope of adhesion coefficient and generated squeal noise in 2 kHz and 4 kHz. However, there was less or no negative slope when composite material rail specimen was used. Some cladded rail specimens had negative friction at higher degree of yaw angle than steel rail. Particularly, the specific test specimen exhibited excellent friction characteristic without decreasing the adhesion coefficient even when the yaw angle increased, and that specimen did not generate the squeal noise. Experimental results showed that it is possible to suppress the wheel squeal noise by changing the friction characteristics of the contact point by applying the composite material.

패드 마모를 고려한 브레이크 스퀼 노이즈 해석 및 시험에 관한 연구

김민석(Minsock Kim),최진호(Jinho Choi),김용석(Yongsuk Kim) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11

Brake noise is one of the biggest customer’s complaints, and the brake noise has widely frequency band from low frequency such as moan, groan, and grunt to high frequency squeal noise. Among them, the squeal noise is commonly generated with worn pad condition. This paper is focused on the high frequency squeal noise with worn pad condition. The squeal noise analysis of worn pad condition is difficult because accuracy of noise analysis is not good. Hence, the objective of this study is to find a consistency method of squeal noise analysis in worn pad condition. This study try to predict squeal noise in worn pad condition using complex eigenvalue method and try to correlate analysis with test. The squeal noise test was executed in worn pad condition. The analysis was considered pad wear pattern, anisotropic lining material property, pad thickness and other braking condition for accuracy of noise prediction. The analysis results shows good prediction and well correlate results. And noise test result was different new pad condition with worn pad condition.

Improvements for reduction of the brake squeal noise at Seoul metro rolling stock on tracks

김성걸 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.8

Experimental and theoretical methods were applied to find and understand the phenomenon of brake squeal noise of the Seoul Metro rolling stock on tracks. Generally, it is well known that brake squeal noise is strongly related to stick and slip between brake pad and disk. In most cases for rolling stock on tracks, trailer cars needed more particular attention through the tests, because they were the major sources of brake noise due to frictional braking. There are two types of rolling stocks in Seoul Metro: chopper and VVVF. Both types of rolling stocks for lines 1 and 3 in the Seoul Metro were used for experimental analyses. To study brake squeal noise under various braking conditions, dynamometer tests were performed at the S&T Brake, Co., which is one of major manufacturers of brake pads for rolling stock on tracks. For measuring brake squeal noise, acoustic tests were performed with a microphone in the Gunja depot. And modal tests for brake parts, which consisted of brake lining, brake lining pad, and back plates, were executed to obtain the natural frequencies related to the brake squeal noise. Also, modal tests of the whole brake assembly and lining block were performed at the heavy maintenance shop of the Gunja depot. The mode analysis using an ANSYS was simulated to determine the relations between the mechanisms of brake squeal noise. As the results of the tests and the simulations, it was found that specific natural frequencies of the brake parts affected squeal noise, and also, the reason to create squeal noise. Finally, improvements for reducing squeal noise were proposed, and applied to lines 2and 3 at Seoul Metro rolling stock on tracks.

축소 모델 실험장치를 이용한 철도 스킬소음의 특성에 대한 실험적 연구

김지용(J. Y. Kim),황동현(D. H. Hwang),이준헌(J. H. Lee),김관주(K. J. Kim),김재철(J. C. Kim) 한국도시철도학회 2015 한국도시철도학회논문집 Vol.3 No.4

Squeal noise is a harsh, high-pitched sound that occurs when railways are running at sharp curve tracks. The cause of squeal noise is known to be the transient lateral traction force between wheel and rail. Field measurements are too difficult to control the parameters. Thus, the scaled test rig should have been made in order to investigate the generating mechanism of squeal noise. The unique feature of our test rig, HSTR(Hongik Squeal Testing Rig), is that DOFs of its wheelset are as close to as those of the real railway. The attack angle and running speed of the rail roller are controlled in real time for simulating a transient characteristic of driving curve. The environment conditions, such as given axle load, running speed, and wheel’s yaw angle have been identified for generating squeal noise and the squeal noise itself has been measured. The relation between wheel creepage and creep force in lateral direction and the criteria for squeal noise have been investigated, which results has been verified by finite element method.

Experimental Study on Reduction of Curve Squeal Noise on Mountain Tram Wheels on Sharp Curves Using Lubricant

Teudom Kann,서승일,연재훈 한국철도학회 2023 한국철도학회논문집 Vol.26 No.2

Curve squeal noise is an intense tonal noise that occurs when a train goes through a narrow curve and is generated by the wheel contacting the rail. The squealing noise is an issue in mountain tram development projects. In this study, 1:7.5 scaled equipment is proposed to produce the squealing noise based on rolling speed, rolling direction, angle of attack, and preload ratio. Solid-stick lubricant is used as a mitigation method. The similarity law is applied and a finite element analysis code is used to compare the natural frequency of full-scale and small-scale results. The results show that the scaled equipment can generate squealing noise and that rolling backward direction has a higher possibility of generating squealing noise. Moreover, the frequency similarity approach is verified, and the solid stick lubricant is found to successfully mitigate the squealing noise even at high rolling speed and angle of attack.

摩擦面에서 發生되는 스퀼 騷音에 關한 硏究

한경,이민호,이준서,이해철,차경옥 明知大學校 産業技術硏究所 1999 産業技術硏究所論文集 Vol.18 No.-

There are various noises generated by friction. Among the rest, eliminating squeal noise generated during braking is an important task for the improvement of vehicle passenger's comport. The parameters affecting brake squeal noise are the material properties of the braking pad, the dynamic properties of the brake parts and the dimensions of the brake assembly etc. Also, the squeal noise changes its inherent form(i.e. its sound pressure level and its frequency) with the normal load and sliding speed. In this study, the characteristics of brake squeal noise generated by friction is analyzed experimentally. The experiment focused on the analysis of friction self-excited vibration and squeal noise level. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding speeds. and Friction self-excited vibration is raised the brake squeal noise.

유한요소해석을 이용한 스킬 소음 발생 예측

황동현(Donghyeon Hwang),김지용(Jiyong Kim),이준헌(Junheon Lee),김관주(Kwanju Kim),조성산(Sungsan Cho),김재철(Jaechul Kim) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10

스킬 소음은 차량의 곡선 주행시 차륜과 레일 사이의 횡방향 점착-미끄럼 운동에 의해서 발생하는 소음이다. 대표적 과도 특성을 나타내는 스킬 소음의 정확한 예측을 위해서는 발생원인 차륜과 레일간의 횡방향 접촉력의 정확한 파악이 요구된다. 이를 설명하기 위한 다양한 이론이 존재한다. 하지만 해당 이론들은 다양한 가정에 의하여 사용이 제한된다. 본 논문에서는 유한요소 해석법을 이용하여 가능한 가정에 의한 제약없이 스킬소음이 발생하는 조건을 판단할 수 있는 해석적 방법 개발을 목적으로 한다. 이를 위하여 스킬 소음이 발생하는 조건에서의 유한요소 모델을 작성하고, 접촉영역에서 발생하는 횡방향 접촉력을 예측하여 점착계수와 크리피지의 관계를 도출한다. 작성된 마찰특성 곡선을 이용하여 크리피지가 약 0.005 이상일 경우 스킬 소음 발생을 예상했다. Squeal noise occurs due to lateral stick-slip mechanism while negotiating curve track. It is necessary to estimate lateral creep force that represent unstable response for prediction of squeal noise. There are many theories to estimate contact force for 3D rolling contact problem. But most of them are limited by various assumptions. This paper aims to predict occurrence of squeal noise without limitation that concerning 3D rolling contact theories using finite element analysis. The relationship between adhesion coefficient and creepage was presented by calculating lateral creep force in the contact area. Occurrence of squeal noise was assessed by friction characteristic curve. Squeal noise was expected when creepage is over 0.005.

주행속도와 제동력의 변화에 의한 디스크 브레이크의 스퀼 소음에 미치는 영향

김정훈(J. H. Kim),김경훈(K. H. Kim),최명진(M. J. Choi) 한국정밀공학회 2006 한국정밀공학회 학술발표대회 논문집 Vol.2006 No.5월

Brake noise is classified according to frequency territory: judder, groan and squeal. Squeal noise of disk brake is a noise and self excited vibration with frequency of 1~10Khz caused by the friction force between the disk and the pad of the automobile. Passengers in a vehicle feel uncomfortable. It causes unstable characteristic to the brake system when you try to stop the vehicle. Thus this study aims to find in which conditions the vehicles are stable during the braking hour and find ways to decrease a squeal noise and the vibration by measuring various factors including squeal noise and self excited vibration between the pad and disk brake system during the braking hour. From the result the countermeasure for a squeal noise and a vibration decrease is established. Also the analyzed data is found to be useful and can be applied to the actual brake model.

모드 중첩 회피를 통한 스킬 소음 저감 사례

이기연(Ghiyoun Lee),이광호(Kwangho Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Squeal noise which is the majority of brake noise is divided into low frequency squeal and high frequency squeal. Generally, the low frequency squealing mechanism is a rotor axial direction mode that couples the pads, rotor and other components; while higher frequency squeal mainly exhibits a rotor tangential mode. In this paper, the low frequency squeal is pointed and some examples are exhibited to reduce noise by means of mode decoupling.

축소스킬소음시험장치의 진동 전달특성을 이용한 차륜/레일 접촉력 예측 방법에 관한 연구

이준헌(Jun-heon Lee),김지용(Ji-yong Kim),지은(Eun Ji),김대용(Daeyong Kim),김관주(Kwanju Kim) 한국철도학회 2015 한국철도학회 학술발표대회논문집 Vol.2015 No.10

스킬 소음은 곡선부에서 레일과 차륜 사이에 발생하는 순음의 소음이다. 차륜과 레일 사이의 접촉은 점착-미끄러짐(stick-slip)현상을 보이면서 스킬 소음이 발생한다고 알려져 있다. 이러한 스킬 소음의 발생 메커니즘을 규명하기 위해 차륜/레일 주파수별 접촉력의 특성을 알고자 했다. 이러한 스킬 소음을 실험실 조건에서 발생시키기 위하여 축소 스킬 소음 시험기를 이용하였다. 축소 스킬 소음 시험장치는 차륜과 레일 모두 회전하는 원판으로 이루어져 있어 접촉력을 측정하는 데 어려움이 있다. 접촉력을 구하기 위하여 레일 롤러를 지지하는 서브프레임 진동 데이터를 측정하고, 간접적인 방법으로 접촉력을 계산하였다. 계산된 접촉력을 이용하여 접촉점의 변위를 계산하고, 레이저 변위 센서를 이용해 측정된 변위와 비교하였다. Squeal noise is a monotonic, harsh sound when railways run on the curved tracks. Contact between the wheels and rails causes a stick-slip phenomenon, which generates squeal noise. In order to identify the mechanism of the squeal noise in the laboratory environments, the scaled test rig has been fabricated. The knowledge of contact forces between wheel- and rail-rollers is essential for investigating the squeal noise characteristics, however it is difficult to measure it. Contact forces are calculated indirectly by the acceleration of the sub-frame for supporting a rail roller and modal behavior of the sub-frame. The estimated displacement of the rail roller by the calculated force is compared with that of measured by laser displacement sensor.