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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Statistical Analysis of Impacts of Surface Topography on Brake Squeal in Disc-Pad System</title>
      <link>https://trid.trb.org/View/1433551</link>
      <description><![CDATA[A disc-pad system is established to study impacts of surface topography on brake squeal from the perspective of statistical analysis. Firstly, surface topographies of brake disc and pad are precisely measured on the scale of micron and are statistically analyzed with a three-dimensional evaluation system. Secondly, the finite element model of brake disc and pad without surface topographies is created and verified through component free modal tests. Thereby the valid brake squeal model for complex modal analysis is built with ABAQUS. An effective method is developed to apply interface topographies to the smooth contact model, which consequently establishes sixty brake squeal models with topographies. Thirdly, impacts of surface topography on brake squeal are studied through comparison and statistical analysis of prediction results with and without topographies.         The analysis manifest that topography amplitudes and evaluation index deviations of brake pad far exceed those of the disc, indicating the surface of brake pad is relatively much rougher. Moreover, squeal prediction results confirm that surface topographies can both cause contact pressure variation and affect the randomness of brake squeal characteristics, namely, numbers and values of squeal frequencies. Additionally, contact interface topographies can cause system modal coupling states to change, which further affects squeal tendency and uncertainty. Meanwhile, statistical characteristics and variations of surface topographies demonstrate close correlation with those of brake squeals. Hence the consideration of surface topographies can effectively improve squeal prediction precision, and stochastic characteristics of brake squeal during tests can be well justified by the time-varying surface topography.       ]]></description>
      <pubDate>Tue, 27 Jun 2017 16:10:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1433551</guid>
    </item>
    <item>
      <title>Effect of pad shapes on high-frequency disc brake squeal</title>
      <link>https://trid.trb.org/View/1459556</link>
      <description><![CDATA[In this paper, a case study on reduction of high-frequency disc brake squeal by modification of pad shapes is presented. The aim is to give an intensive analysis on the phenomena of pad shape effects on disc high-frequency occurrence. For the analysis, a complete closed-loop coupled modal synthesis model is built. A series of analyses is performed, such as complex eigenvalue analysis, substructure modal composition analysis, substructure modal parameter sensitivity analysis, feed-in energy analysis, etc. The simulation analysis gives reasonable explanations of pad shape effects on high-frequency brake squeal occurrence.]]></description>
      <pubDate>Mon, 01 May 2017 09:37:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1459556</guid>
    </item>
    <item>
      <title>Tackling noise on multiple fronts</title>
      <link>https://trid.trb.org/View/1427182</link>
      <description><![CDATA[Germany's federal government has approved additional funding for a variety of mitigation measures to address railway noise, which is a strong political issue across the country, as well as commissioning action plans for the coming years. Various initiatives and strategies are discussed in this article.]]></description>
      <pubDate>Fri, 21 Oct 2016 16:32:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1427182</guid>
    </item>
    <item>
      <title>Experimental characterisation of railway wheel squeal occurring in large-radius curves</title>
      <link>https://trid.trb.org/View/1416976</link>
      <description><![CDATA[Tonal squeal noise (i.e. the high-amplitude singing of a railway wheel with pure tone components) is emitted by some trailing inner wagon wheels on heavy haul trains traversing 1000?m radius curves on the iron ore export line in South Africa. Field measurements have shown that the trailing inner wheels that squeal are subject to predominantly longitudinal creepage with little-to-no lateral creepage. The longitudinal creepage acting at the contact of the squealing wheels exceeds 1%, which supports the likelihood of creep saturation and subsequent squealing due to unsteady longitudinal creepage in the large-radius curves. Experimental modal analysis of the wheel types identified to be relevant to squeal has revealed that for each unstable frequency, two eigenmodes are likely to be important: one that has a large mode shape component at the wheel–rail contact in the circumferential direction and another that has a large mode shape component at the wheel–rail contact in the radial direction. A frictional self-excitation mechanism based on mode-coupling is favoured as being responsible for squeal excited in large-radius curves.]]></description>
      <pubDate>Thu, 28 Jul 2016 10:45:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/1416976</guid>
    </item>
    <item>
      <title>Experimental verification of differences in subjective annoyance responses using a jury test to compare the noise emissions of straight and curved sections of an urban railway</title>
      <link>https://trid.trb.org/View/1406545</link>
      <description><![CDATA[The urban railway, which has both ground-level and underground sections, is a major means of transportation in the city of Seoul. Environmental noise problems have been encountered in residential areas near the railway on ground-level sections. To assess the extent of this problem, many countries have adopted the method of A-weighted equivalent sound pressure level (LpAeq). However, it may be not reasonable to apply the same evaluation method on all sections of a railway, since the acoustic characteristics of railway noise are highly variable, and its effect on human psychology is complex. Thus, since each person reacts differently to noise, psychological approaches have been utilized to analyze the effects of noise. The aim of this study is to determine an appropriate method for the assessment of railway-generated noise. First, the characteristics of railway-generated noise on straight and curved sections of track were compared by looking at aspects such as the waveforms of the sound pressure and the characteristics of frequency patterns. After that, the subjective annoyance response was analyzed by performing a jury test and a survey in order to understand how people react differently to similar sounds on the two test sections of track.]]></description>
      <pubDate>Fri, 20 May 2016 15:54:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1406545</guid>
    </item>
    <item>
      <title>Analysis of automotive disc brake squeal considering damping and design modifications for pads and a disc</title>
      <link>https://trid.trb.org/View/1403343</link>
      <description><![CDATA[The squeal noise occurring from the disc brakes of passenger cars has been analyzed by using the complex eigenvalue method numerically. The contact between a disc and two pads was analytically modeled as many linear springs and dampers in an effort to develop the improved equation of motion derived on the basis of Lagrange’s equation and the assumed mode method. The finite element modal analysis results for disc brake components constitute an eigenvalue matrix in the analytical equation of motion. The complex eigenvalue analyses based on the equations of motion are able to examine the dynamic instability of a brake system, which is an onset of squeal, by considering the disc rotational effect. Numerical analyses showed that the modes unstable in an undamped analysis became stable in a damped case, which illustrates the important effect of damping on the squeal instability in a brake squeal simulation. Then several modified brake models were suggested and investigated how effectively they suppressed the occurrence of squeal noise. The brake parts such as a pad chamfer and a disc vane were modified and the influence of pad chamfer and vane shapes on squeal occurrence was proved to be significant. The numerical results showed that proper structural modification of a disc brake system can suppress the brake squeal to some extent.]]></description>
      <pubDate>Thu, 28 Apr 2016 14:42:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1403343</guid>
    </item>
    <item>
      <title>Development of the New Concept Steering Bogie</title>
      <link>https://trid.trb.org/View/1281195</link>
      <description><![CDATA[There are many problems in sharp curves negotiation such as large lateral force, squeal noises and excessive wear of wheel flange and rail gauge corner. To solve these problems, single axle steering bogie (proto type: FS576) has been developed by Tokyo Metro and Nippon Steel & Sumitomo Metal Corporation. The authors confirmed good curving performance by FS576 on the result of field test. Therefore, Tokyo Metro adopted this newly single axle steering bogie (production type: SC101) for new series 1000 in Ginza line. SC101 improves lateral force, noise level, and lateral acceleration of rail in passing curves. In this paper, the design concept and outline of steering bogie SC101 for series 1000 are described. And the curving performance of SC101 is evaluated based on the result of field test and commercial service.]]></description>
      <pubDate>Mon, 27 Jan 2014 10:45:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/1281195</guid>
    </item>
    <item>
      <title>Investigation of the effect of lateral adhesion and rolling speed on wheel squeal noise</title>
      <link>https://trid.trb.org/View/1262439</link>
      <description><![CDATA[In order to validate prediction models of wheel squeal, a rolling contact test rig is used to investigate fundamental squeal behaviour. The vibration characteristics of the wheel are investigated using analytical and finite element methods, and by experimental impact hammer analysis, respectively. Accordingly, the lateral resonant frequencies and mode shapes of the wheel are determined. A dominant mode is identified based on this as the primary peak in the sound spectrum of squeal and is used as an indicator of the occurrence and magnitude of squeal. The lateral creep curves and amplitudes of wheel vibration at various rolling speeds are measured using a strain gauge technique and predicted. A simplified model including the interaction between lateral force and transverse vibration of the dominant mode is developed, and the experimental and simulated results show the sound pressure level and vibration velocity of the wheel increases substantially as the angle of attack reaches and exceeds the value around 8 mrad. The phenomenon of double peaks in the sound spectrum of wheel squeal is also investigated. It is found that the cause of double peaks is due to the wheel rotation and the frequency divergence of double peaks increases with rolling speed as predicted theoretically.]]></description>
      <pubDate>Fri, 20 Sep 2013 16:31:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/1262439</guid>
    </item>
    <item>
      <title>Effects of Lining Thickness on Squeal in Drum Brake Assembly: Experimental Investigations</title>
      <link>https://trid.trb.org/View/925145</link>
      <description><![CDATA[This paper presents the effects of brake lining thickness due to wear on drum brake squeal. The brake lining will be worn out and subsequently its thickness will be reduced after a few number of braking applications. Hence the dynamic properties of the lining, such as its natural frequency, might be changed. This paper presents two different sets of brake lining, i.e., new and worn lining are used to investigate its effect on squeal generation. First, modal testing is performed to determine natural frequencies of those brake linings at free-free boundary condition. Later, squeal tests are carried out using a brake dynamometer and the squeal frequency is measured up to 10 kHz. Several squeal results are plotted over brake operating conditions to observe the influence of different lining thickness. In addition to these, squeal mechanisms, i.e., modal coupling due to closeness of the natural frequency between drum brake components and negative damping due to negative friction-velocity slope that contribute to the squeal generation are also investigated and discussed.]]></description>
      <pubDate>Mon, 16 Aug 2010 09:11:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/925145</guid>
    </item>
    <item>
      <title>Experimental and Theoretical Investigation of Railway Wheel Squeal</title>
      <link>https://trid.trb.org/View/809682</link>
      <description><![CDATA[The authors note that their paper offers new results from a project designed to develop a complete, validated model of curve squeal noise generation. The model accounts for friction characteristics and excitation caused by unstable forces between the wheel and rail, along with vehicle dynamic behavior. Also included in this model are both wheel and track dynamic response and acoustic radiation. The paper details descriptions of the twin disc rig and the test methods. These test methods involve a modified twin disc rig used to provide experimental data for the validation of the model and measurement of the lateral force and dynamic response of rollers experiencing varying amounts of lateral creepage during squealing. The authors note that while there are extant theories to predict creep forces and their relationship to creepages, most have not been verified using empirical methods that characterize the falling friction coefficient observed during unsteady squealing. To address this, an outline of the squeal model is also presented. Tests results are compared with the prediction from the squeal model and with available theories. Good agreement is shown.]]></description>
      <pubDate>Tue, 19 Jun 2007 08:28:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/809682</guid>
    </item>
    <item>
      <title>Introduction of Falling Friction Coefficients into Curving Calculations for Studying Curve Squeal Noise</title>
      <link>https://trid.trb.org/View/806119</link>
      <description><![CDATA[In this paper, a method of introducing falling friction coefficients into curving simulations for studying curve squeal noise is presented.  Generation of squeal at the wheel of a railway vehicle in a curve is caused by unstable vibration, caused in turn by a lateral wheel/rail force which reduces with increasing lateral creepage.  To model vehicle curve squeal, the wheel/rail tangential force in the curving simulation is calculated by a modified version of FASTSIM, which uses a sliding velocity-dependent friction characteristic.  Using the falling friction characteristics, a UK passenger vehicle is modelled with SIMPACK.  Curving behaviour is simulated for a range of curve radii and cant deficiencies.  The wheel/rail contact properties are then obtained to study the possibility of the occurrence of squeal using a frequency-domain method.  The methodology in this paper allows various curves, wheel/rail profiles, vehicle speeds and friction characteristics to be taken into account.]]></description>
      <pubDate>Wed, 25 Apr 2007 13:46:47 GMT</pubDate>
      <guid>https://trid.trb.org/View/806119</guid>
    </item>
    <item>
      <title>Acoustic Modelling of Railway Wheels and Acoustic Measurements to Determine Involved Eigenmodes in the Curve Squealing Phenomenon</title>
      <link>https://trid.trb.org/View/806122</link>
      <description><![CDATA[Curve squealing is an annoying noise phenomenon occurring when a train runs through a curve with a small radius.  To study this phenomenon, field measurements, laboratory measurements and acoustic calculations have been performed.  Measurements show that not every train produces curve squealing.  In addition, single locations - normally one or two - within the train are responsible for the squealing.  The principal sound sources are the wheels, producing a narrow band noise due to stick-slip excitation.  The sound emission of the rails has a minor importance.  Train speed, running direction and moisture on the rails influence the occurrence of the squealing, but also the characteristics of the single wheels are expected to have a large impact.  Acoustical simulations of the sound emission of a new wheel have been performed.  The results have been compared with laboratory measurements.]]></description>
      <pubDate>Wed, 25 Apr 2007 13:46:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/806122</guid>
    </item>
    <item>
      <title>Traction and Curving Behavior of a Railway Bogie</title>
      <link>https://trid.trb.org/View/806526</link>
      <description><![CDATA[In conventional railway systems, vehicles exert traction and must also negotiate curves.  The creep forces between a bogie and the track are shown here for a wide range of curve radii (300-1800 m), a wide range of applied traction (traction ratios of 0, 0.14 and 0.28) and for bogies of widely different yaw stiffness, which is the factor that most affects a bogie's curving performance.  Traction destroys the steering performance of any bogie, increasing the lateral displacement of the critical leading wheelset and also its angle of attack, thereby increasing the tendency for 'squeal' noise.  The resultant wheel/rail creep forces also typically increase and change orientation significantly.  There is a significant difference in creep force across both wheelsets, with slip occurring first at the leading wheel on the high rail.  For modest levels of applied traction, low yaw stiffness improves curving performance.  However, low yaw stiffness becomes ever less beneficial as traction increases.  Indeed, at levels of applied traction typical of modern locomotives, a bogie and the wheelsets within it behave essentially as a rigid bogie, regardless of the yaw stiffness.]]></description>
      <pubDate>Wed, 25 Apr 2007 13:46:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/806526</guid>
    </item>
    <item>
      <title>Sound Solution Works in Australia</title>
      <link>https://trid.trb.org/View/763700</link>
      <description><![CDATA[Australian train operators are using the Rail Squeal Acoustic Detection system (RailSQAD), a new acoustic system that identifies noisy wheelsets in a highly-populated residential Adelaide Hills region. RailSQAD was developed for the Australian Rail Track Corporation (ARTC) by the Adelaide-based specialist acoustic engineers Vipac Engineers and Scientists and is a joint initiative of ARTC, the Environmental Protection Authority, and train operators. The primary objective of RailSQAD is to reduce wheel squeal noise emissions throughout this region. RailSQAD is an advanced acoustic array system which can detect, record, and trend a range of train wheel/rail noise sources from both freight and passenger trains and then identify the noisy ones for removal and repair. One benefit of using RailSQAD is that it allows operators to use it as a preventive maintenance tool to achieve 25% reduction in wheel wear and 3% improvement in fuel economy. Another benefit is the removal of nearly 90% of rogue bogies from the Adelaide-Melbourne sector, which decreases maintenance and rail grinding costs. A third benefit lies in the reduced risk of derailment from rogue bogies.]]></description>
      <pubDate>Fri, 18 Nov 2005 13:39:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/763700</guid>
    </item>
    <item>
      <title>WHEEL SQUEAL CONTROL WITH KELTRACK LIQUID FRICTION MODIFIER AND PROTECTOR TRACKSIDE APPLICATION: THEORY AND PRACTICE</title>
      <link>https://trid.trb.org/View/700476</link>
      <description><![CDATA[Although the underlying mechanism for wheel squeal noise is well understood, an integrated abatement method addressing this cause has not previously been reported.  This study describes a practical experiment using a water-based liquid high positive friction modifier called Keltrack applied using a top of rail trackside applicator called Portec Protector.  This proprietary friction modifier and delivery equipment have been co-developed to provide an optimized system that significantly reduces wheel squeal in curves.  Wheels experiencing lateral creep in curves are subject to roll-slip oscillations as a result of the frictional characteristics of the interface layer between the wheel and rail.  These roll-slip oscillations are amplified in the wheel web, leading to the familiar squeal.  Providing a thin film of material between the wheel and rail with positive friction characteristics can greatly reduce the magnitude of these oscillations.  The friction control characteristics of Keltrack allow the material to be delivered to the top of both rails without compromising traction or braking.  Key equipment features include top of rail bar design optimized for accurate and precise delivery, and control system features.  The equipment is placed at the entrance to curves, and the friction modifier is carried down into the curve by the passing wheels. Application rate is optimized by control of the axle count between pump activations, and by the length of pump activation. The integrated system is now successfully controlling noise at more than 20 transit sites.  Two case studies are presenting to illustrate the effectiveness of this technology.  Typical sound level reduction is 10-15 dB, depending on the initial sound level.]]></description>
      <pubDate>Sat, 03 Apr 2004 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/700476</guid>
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