高速列车制动片摩擦块尺寸对制动噪声特性的影响

同一工况下,在制动摩擦噪声试验机上使用3种不同尺寸的圆形摩擦块进行制动摩擦噪声对比试验,通过对不同摩擦块尺寸状态下的界面噪声信号进行等效声压级分析和频谱分析,研究摩擦块尺寸对制动噪声特性的影响;对界面磨损形貌采用光学显微镜和二维轮廓仪进行分析,并计算出摩擦界面上的摩擦弧长,以揭示摩擦块尺寸对制动噪声行为的影响机制。结果表明:在试验条件下,摩擦面积相同时,大圆形摩擦块能有效地抑制制动噪声,而中圆形和小圆形摩擦块的制动噪声强度较大;相较于大圆形摩擦块,中圆形和小圆形摩擦块表面出现明显犁沟和剥落等"不平顺"磨损因素会造成高强度的尖叫噪声;大圆形摩擦块相比于中圆形和小圆形摩擦块的摩擦弧长较短,这也是造成大圆形摩擦块状态下制动噪声强度减弱的一个重要因素。     

约束对盘形制动摩擦噪声影响的有限元研究

建立了铁路车辆盘形制动装置的三维实体有限元模型,分别为该模型中的制动盘、闸片和夹钳等部件设置了不同的材料特性。利用线性弹簧力模拟制动摩擦面间的法向力,摩擦力取为线性弹簧力与摩擦因数的乘积。通过对系统有限元运动方程进行复特征值分析,根据复特征根实部为正值判断系统发生失稳的模态,这也是可能产生摩擦噪声的模态。仿真结果显示,系统的约束条件对摩擦噪声的形成有显著的影响。改变模型的约束条件,可以抑制制动系统的摩擦噪声发生趋势,说明通过优化设置约束条件来提高摩擦系统的运动稳定性从而抑制摩擦噪声的发生是可行的。     

[轮轨磨耗及预测]高速列车制动摩擦块切入端特征对制动界面特性的影响

在自行研制的高速列车制动缩比试验台上，对四种不同安装方向下的三角形摩擦块进行拖曳制动试验，研究了摩擦块的切入端特征对制动界面特性的影响,并采用有限元方法分析不同摩擦切入端特征下摩擦块的接触压力分布特点，探讨了摩擦块表面接触压力分布与其表面热分布、振动噪声特性的内在关联。结果表明：在摩擦制动过程中，摩擦块的切入端存在应力集中现象，尤其是当摩擦切入端是一个角的两条边时，摩擦切入端的角附近区域应力集中更为明显，从而引起制动系统产生高强度的振动噪声并导致摩擦块表面局部高温现象。     

CRH2盘形制动系统制动尖叫噪声研究

为了研究高速动车组的制动尖叫噪声,建立CRH2拖车盘形制动系统的摩擦耦合有限元模型,对其进行运动稳定性和制动自激振动的瞬态动力学分析,研究了摩擦因数、闸片以及制动盘弹性模量对制动系统尖叫噪声的影响。结果表明：随着摩擦因数μ的增大,盘形制动系统发生制动尖叫噪声的趋势增加;随着闸片弹性模量的增大,制动系统发生制动尖叫噪声的趋势增加,并且激发的噪声频率也明显变大;随着制动盘弹性模量增大,制动系统发生制动尖叫噪声的趋势先降低后增大。     

摩擦片偏磨引起的汽车制动低鸣噪声

建立后盘式制动器有限元模型,对其进行制动低鸣噪声的有限元复特征值分析。根据系统的负阻尼比预测系统出现制动噪声的趋势。利用该模型,研究摩擦片切向偏磨对制动噪声的影响。研究结果表明,切向偏磨是引起制动低鸣噪声的主要原因。当偏磨量大于0.5 mm时,系统的负阻尼比突变,说明发生制动低鸣噪声的可能性极大;同时该噪声的出现与制动压力、摩擦滑动方向、摩擦因数有特定的关系。该计算结果与噪声试验结果完全一致,为消除该制动低鸣噪声提供了理论依据和指导。     

在往复滑动条件下摩擦噪声发生时磨痕形貌的观察

为了进一步认识在有摩擦噪声期间磨痕形貌与噪声之间的关系，采用两种常用的铁路车辆制动闸瓦材料进行摩擦噪声试验。试验中测取了不同循环次数时摩擦振动三维加速度、噪声声压等动态信号，并提取了相应的磨痕形貌。通过对磨痕形貌的激光共焦扫描显微镜(OLS)、SEM及光学显微镜观察，研究了噪声出现区域的形貌变化。研究结果显示磨痕上有摩擦噪声区域的形貌与无摩擦噪声区域的形貌有一定差别。     

制动力对制动尖叫噪声及磨损特性的影响

在自行研制的新型摩擦制动噪声试验台上,采用锻钢制动盘和铜基粉末冶金制动片作为摩擦副,研究制动力对制动尖叫噪声特性和界面磨损特征的影响。结果表明:随着制动力的增大,摩擦系统不稳定振动加强,系统产生高强度制动尖叫噪声的倾向增强;制动力的增大导致摩擦界面磨损更加严重,黏着撕裂和剥落、犁削、磨屑堆积等"不平顺"因素对接触界面产生连续激励并加剧系统的不稳定振动,进一步诱导高强度制动尖叫噪声的产生。     

降低制动摩擦振动的制动器结构拓扑优化设计

本文建立起某车型盘式制动系统三维有限元模型,分析了该制动系统的摩擦振动噪声特性,并基于ABAQUS/Optimization模块对该制动系统进行结构拓扑优化设计,在满足轻量化的目标要求下改善摩擦振动噪声问题.结果表明:制动系统在摩擦力作用下可能出现四种振动模态,且产生频率为3632.4 Hz的振动噪声的倾向和强度最大.产生该频率摩擦振动噪声的原因是由于制动钳的第4阶模态频率与制动盘的第11阶模态频率非常接近,在摩擦力作用下容易产生共振.通过对制动钳进行结构拓扑优化设计,移除制动钳两侧区域的材料,使其在满足重量最小的目标前提下将第4阶模态频率降低到2804 Hz,从而避免与制动盘发生共振,且制动钳的重量减轻了17.1％.进一步采用复特征值分析对结构优化后的制动系统进行摩擦振动噪声特性预测,结果表明制动系统仅有两组相邻模态出现模态耦合现象,且原始制动系统出现的3632.4 Hz的振动噪声频率已经消失,制动系统摩擦振动噪声问题得到显著改善.     

摩擦材料性能对制动噪声(鸣音)的影响分析及对策

摩擦材料的摩擦系数是影响汽车制动系统的关键因素之一。制动摩擦片的摩擦系数的高低直接影响汽车的制动性能以及稳定性,并可能带来制动噪声(鸣音)。文中通过分析研究,提出了改善制动摩擦片噪声(鸣音)的解决途径与优化设计方案,研究结果有利于提高设计汽车盘式制动器的整体性能。     

高速列车制动摩擦块切入端特征对制动界面特性的影响

在自行研制的高速列车制动缩比试验台上,对四种不同安装方向下的三角形摩擦块进行拖曳制动试验,研究了摩擦块的切入端特征对制动界面特性的影响,并采用有限元方法分析不同摩擦切入端特征下摩擦块的接触压力分布特点,探讨了摩擦块表面接触压力分布与其表面热分布、振动噪声特性的内在关联.结果表明:在摩擦制动过程中,摩擦块的切入端存在应力...     

稳恒磁场作用下摩擦制动尖叫发生率及其预测分析

为了研究稳恒磁场作用下制动尖叫发生率随制动工况的变化规律,提出一种基于长短时记忆(LSTM)网络的摩擦制动尖叫发生率的预测模型。设计制动尖叫信号的测量方案,并开展大量的模拟制动试验;通过LSTM门控循环单元的深度学习网络,构建对不同制动工况下制动尖叫发生率的智能预测模型;通过预测模型及摩擦界面的微观特性分析稳恒磁场对制动尖叫行为的影响规律及机制。结果表明：建立的模型可以实现对制动尖叫发生率的准确预测;稳恒磁场可有效降低制动尖叫发生率,但当磁感应强度增大到一定阈值后,磁场对摩擦行为的影响程度趋于饱和,制动尖叫发生率也逐渐趋于稳定。研究结果为探索发展基于磁场的制动器制动尖叫主动抑制技术提供了理论基础和数据模型。     

闸片沟槽织构对盘式制动尖叫的影响

为研究制动闸片沟槽织构对盘式制动系统制动尖叫的影响,基于摩擦自激振动理论,建立盘式制动系统普通闸片和沟槽闸片有限元模型,采用复特征值分析法研究该盘式制动系统的摩擦自激振动特性。利用该有限元模型开展沟槽的宽度和深度的参数化分析,获得其对制动尖叫的影响规律。结果表明：制动闸片与制动盘间的摩擦自激振动是导致制动尖叫发生的主要原因,沟槽型闸片对抑制制动尖叫具有明显效果;当闸片沟槽深度在5~20 mm区间内,盘式制动系统的稳定性随沟槽深度的增大而呈现逐渐降低的趋势,表明沟槽深度越小,发生摩擦自激振动的可能性越小;在沟槽宽度5~20 mm范围内,随沟槽宽度的增大,盘式制动系统的稳定性先增大后降低,在沟槽宽度为10 mm时,系统发生制动噪声的可能达到最大。     

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

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 2 and 3 at Seoul Metro rolling stock on tracks. This paper was recommended for publication in revised form by Associate Editor Yeon June Kang Seong Keol Kim received his B.S. in Mechanical Design and Production Engineering from Seoul National University, Korea, in 1986. He then received his M.S. and Ph.D. degrees from Seoul National University in 1988 and 1994, respectively. Dr. Kim is currently an Assistant Professor at the School of Mechanical Design and Automation Engineering at Seoul National University of Technology in Seoul, Korea. Also, he works as an Executive Director of R&BD division of Seoul Technopark. Dr. Kim’s research interests include reliability of Micro System Packaging and mechanical vibration.     

鼓式制动器振动与啸叫的研究

对于干摩擦引 分析汽车制动啸叫噪声,提出了鼓式制动器啸叫时振动的特性仅取决于制动鼓和蹄征 的观战建立了一种三种解析模型,用以分析制动鼓的固有模态及其稳定性,判 断动器是否发生啸叫。理论分析和试验结果吻合良好,表明该方法具有足够的准确度和工程实用性。     

A numerical investigation into the squeal instability: Effect of damping

Between the NVH issues, brake squeal is a harmonic acoustic emission (between 1 and 20 kHz) caused by friction induced vibrations. The onset of squeal is due to an unstable behaviour of the system leading to limit cycle vibrations. A general approach used by several authors to determine the system instabilities is the CEA: Complex Eigenvalues Analysis. This work presents a numerical investigation into the squeal instability on a simplified disc-brake system addressed to analyse the effect of damping on the squeal instability.The mode lock-in instability is reproduced by a parametrical analysis. The relationship between the distribution of damping on the system components and the propensity of the brake to develop squeal is investigated. The numerical results are validated by the experimental ones, presented in a previous work. The behaviour of the system eigenvalues highlights that, while a homogenous distribution of damping stabilizes the system, a non-uniform repartition of damping can increase the squeal propensity.     

Evaluation of Disc Brake Materials for Squeal Reduction

A nontraditional evaluation tool is introduced to examine the effects of different materials, in practical applications, that are used in fabricating disc brake components for commonly used or special requirements such as heavy-duty performance and racing cars. As an extension to earlier finite element (FE) disc brake models, a detailed FE model of the whole disc brake corner that incorporates the wheel hub and steering knuckle is developed and validated using experimental modal analysis. Stability analysis of the disc brake corner using the finite element software ABAQUS is carried out to predict squeal occurrence also taking into account the negative and positive damping effects and friction material real surface to increase the accuracy of prediction. A Taguchi method–based design of experiment is used to better assess the contributions of different materials and its interaction effects for effective reduction of brake squeal. The results showed that the pad friction material contributes 56% to the total system instability (squeal generation). The rotor material contributes 22% of the system instability. Caliper and bracket materials participate 11 and 11%, respectively.     

踏面制动尖叫噪声的有限元分析

利用ABAQUS软件建立铁路货车车轮踏面制动系统有限元模型,对其进行制动摩擦尖叫噪声的有限元复特征值分析.根据复特征值实部的正负判断系统发生尖叫噪声的可能性,如果有实部为正的特征值,则可判断系统有发生尖叫噪声的趋势.在ABAQUS建模方法中,闸瓦与车轮之间的法向力根据接触计算确定,不需假设接触弹簧,可以方便处理非平面滑动接触尖叫噪声问题.利用该模型,研究滑动摩擦因数、闸瓦压力角、闸瓦压力和转动方向对尖叫噪声的影响.研究结果显示,闸瓦压力角对制动尖叫噪声有重要影响,当闸瓦压力角α=5°时,制动系统发生尖叫噪声的影响.研究结果显示,摩擦因数越大,系统发生尖叫噪声的趋势就越大;闸瓦压力越大,尖叫噪声发生的趋势就越大.车轮逆时针转动比顺时针转动更容易引起尖叫噪声.     

Disc brake squeal characterization through simplified test rigs

This paper presents a review of recent investigations on brake squeal noise carried out on simplified experimental rigs. The common theme of these works is that of approaching the study of squeal noise on experimental set-ups that are much simpler than commercial disc brakes, providing the possibility of repeatable measurements of squeal occurrence. As a consequence, it is possible to build consistent and robust models of the experimental apparatus to simulate the squeal events and to understand the physics behind squeal instabilities.