• (a) accommodate for modern testing  technologies,
• (b) improve the squeal noise evaluation matrixes for disc and drum brakes,
• (c) bring the document into the  new SAE format standard,
• (d) revise its formatting for clearer test sequences, and
• (e) improve and harmonize definitions,  noise evaluation, test setup and conditions, test inertia calculations, and data analysis with other SAE dynamometer test  procedures and recent standards and developments from the EKB/VDA working groups in Europe.

Lastly, this revision  uses lower final temperatures during the fade sections to better represent vehicle-level testing while offering a more severe  fade schedule as optional.

• (a)容纳现代测试技术,
• (b)提高盘式和鼓式制动器尖叫噪声评价矩阵,
• (c)将文档转换为新的SAE格式标准,
• (d)修改其格式清晰的测试序列,和
• (e)改进并协调定义、噪声评估、试验设置和条件、试验惯量计算和数据分析与其他SAE测功机试验程序以及欧洲EKB/VDA工作组的最新标准和发展。

最后，本修订使用较低的最终温度在褪色fade部分，以更好地代表车辆水平的测试，同时提供一个更严重的褪色fade时间表供选择。

• (a)  drag mode at low speed with a pressure application profile meant to induce instability and squeal noise, and
• (b)  deceleration braking at moderate speeds at constant brake pressure; a common approach in the U.S., emphasizing the  replication of vehicle road test.

The SAE J2521 combines both braking modes to satisfy the strong need for a global  standardization of squeal noise dynamometer tests. This procedure was first presented to the SAE working group in 1999.  This procedure owes much to the previous development of the AK procedures. This prior work is gratefully acknowledged.

• (a)低速拖曳模式和压力应用剖面，以产生不稳定和尖声噪声;
• (b)在恒制动压力下中速减速制动;这是美国常见的做法，强调车辆道路试验的复制。

SAE J2521结合了两种制动模式，以满足全球噪声测力计测试标准化的强烈需求。这一程序于1999年首次提交SAE工作组。这一程序在很大程度上归功于AK程序以前的发展。感谢您之前的工作。

• — Schedule A - standard: standard test sections with deceleration, drag, and forward/reverse sections at various  temperatures and speeds.
• — Schedule B - optional: noise during cold modules to assess noise propensity below 50 °C and at or below freezing  level of zero degrees (0 °C).
• — Schedule C - optional: noise after fade to assess the influence of high-temperature excursions on the noise  propensity of a given brake.

两种试验矩阵（圆盘和鼓形）都包括三个主要时间表：

• -附表A-标准：在各种温度和速度下带有减速、阻力和前进/后退部分的标准测试部分。
• -附表B-可选：冷模件期间的噪声，以评估低于50°C和零度（0°C）冰冻水平或以下的噪声倾向。
• -附表C-可选：衰减后的噪声，以评估高温偏移对给定制动器噪声倾向的影响，噪音倾向的一个给定的刹车。

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The SAE J2521 procedure is applicable to high frequency squeal noise occurrences for on-road passenger car and light trucks below 4,540 kg of GVWR. The procedure incorporates high temperature and low temperature test matrixes, but does not fully account for the effects of the environment on brake squeal. Much research is currently underway in this area and can potentially be incorporated in future revisions.

For the purposes of this test procedure, squeal is defined as peak noise levels equal to or above 70 dB(A) between 1.25 kHz and 16 kHz for tests using a full suspension corners or full axle assemblies, or between 2 kHz and 16 kHz for brakes not using a full suspension corner.

SAE J2521程序适用于额定车辆总重低于4540 kg的公路客车和轻型卡车的高频尖叫噪声。该程序包含了高温和低温测试矩阵，但没有充分考虑环境对制动尖叫的影响。目前在这方面正在进行许多研究，并有可能纳入今后的修订。

在本试验程序中，对于使用全悬挂转角或全轴总成的试验，尖叫声定义为1.25 kHz和16 kHz之间等于或高于70 dB（A）的峰值噪声级，对于不使用全悬挂转角的制动器，尖叫声定义为2 kHz和16 kHz之间的峰值噪声级。

2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. SAE J2789 Inertia Calculation for Single-Ended Dynamometer Testing

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SAE J2598汽车盘式刹车片固有频率和阻尼试验
SAE J2625汽车制动尖叫试验推荐规程
汽车制动噪声与振动标准术语
SAE J2933制动盘模态频率的验证
SAE J3001制动绝缘体阻尼测量程序IEC 61672-1电声学-声级计
-第1部分：规范IEC 61672-2电声学-声级计
-第2部分：模式评估试验IEC 61672-3电声学声级计
-第3部分：定期试验

3.1盘式制动器的表观摩擦：

根据公式1：式中：μ=盘式制动器的表观摩擦/无单位

3.2 DRUM BRAKE EFFECTIVENESS (C*) Per Equation 2:

Where: C* = effectiveness for drum brakes / unitless T = output torque / N·m p = brake pressure / kPa Threshold p = minimum pressure required to start developing braking torque. Unless otherwise indicated by the test requestor or measured as part of the project, use a zero value / kPa AP = total piston area acting on one side of the caliper for disc brakes; or total wheel cylinder area for drum brakes / mm2 eff r = radial distance from centerline of the piston to the axis of rotation for disc brakes; internal drum diameter divided by 2 for drum brakes, unless other dimensions are provided by the requestor / mm  = brake efficiency. Unless otherwise indicated by the test requestor or measured as part of the project, use 1 (100%) For dynamic brake applications calculate the average-by-distance friction coefficient or effectiveness value between t1 and t2 per item 8.1. For brake drag applications calculate the average-by-time friction coefficient or effectiveness value between t1 and t3 per item 8.2.

3.3 GROSS VEHICLE WEIGHT – GVWR

Maximum vehicle weight indicated by the manufacturer / kgf

3.4 BRAKING SPEED

Linear speed at the onset of the brake application during stops or snubs where the speed reduces during the brake application

3.5 DRAG SPEED

Linear speed at the onset of the brake application during drag events where the speed remains constant during the brake application

3.6 INITIAL BRAKE TEMPERATURE -

IBT Rotor or drum temperature at the start of the brake application / °C

3.7 TIRE DYNAMIC ROLLING RADIUS

Equivalent tire radius that will generate the Revolutions Per Mile (RPM) published by the tire manufacturer for the specific tire size per Equation 3. Use the tire dynamic rolling radius to calculate the dynamometer rotational speed for a given linear vehicle speed / mm π RPM RR    2 1 609 344 (Eq. 3) Where: RR = tire dynamic rolling radius / mm RPM = tire manufacturer specification for revolutions per mile and typically shown for the tire size on the manufacturer’s website

4.3 Control system capable of performing brake applications at constant pressure, pressure profiles, or constant deceleration (torque control)

4.3.1 Pressure ramp rate of at least 100 bar/s (see item 8.1) and a maximum pressure of at least 160 bar

4.3.2 Overshoot of less than 1 bar during dynamic brake applications

4.3.3 Average pressure control within 0.25 bar of target value (set-point) during pressure profiles

4.3.4 Deceleration control and overshoot within 0.5 m/s² of target value (set-point)

4.3能够在恒压、压力剖面或恒减速(扭矩控制)条件下进行制动应用的控制系统

4.3.1压力斜坡速率至少为100 bar/s(见8.1项)，最大压力至少为160 bar

4.3.2动态制动时超调小于1 bar

4.3.3压力剖面时平均压力控制在目标值(设定值)0.25 bar以内

4.3.4减速控制和过度在0.5 m / s²的目标值(设定值)

4.4 Cooling air system directed at the brake.

4.4.1 Control the air speed such that it will not be so high as to blow away wear debris or create noise above the background limit of 64 dB(A) above 900 Hz. The cooling air remains on during the brake events.

NOTE 1: The 64 dB(A) limit provides 6 dB(A) separation which is a 2:1 separation or half the threshold limit to detect noisy brake events above 70 dB(A)

NOTE 2: Depending upon the project, other threshold levels could be more appropriate, like brake noise evaluation for electric vehicles. In such cases, confirm with the test requestor and the testing facility.

4.4.2 Set up the duct outlet 300 to 400 mm away from the rotor outside diameter with air duct with a hydraulic diameter (200-300) mm. Adjust cooling air to 10 m/s (35 km/h) measured at the duct outlet; if needed, adjust to meet the background noise level from item 4.4.1.

NOTE 1: In cases where the above conditions cannot be achieved, define with the test requestor and document it on the final test report

NOTE 2: Alternatively, adjust cooling air flow between 1 000 to 2 000 m³/h while ensuring background noise level per 4.4.1

NOTE 3: Since the cooling air setup is a critical subsystem of the inertia dynamometer which effects test variability and test duration, ensure proper definitions and test conditions are defined for the test project. Measure airflow, assess cooling rates at specific temperatures and test speeds, review cycle times, and observe overall temperature regimes during the tests to better understand the conditions and effects on noise and friction behavior.

4.4.3 Optional - Environmental control system. Except for the cold modules below 25 °C, control brake cooling air temperature to 25 °C ± 5 °C, and relative humidity to 50 %RH ± 10 %RH - equivalent to 7.90 to 11.93 g/kg, or 9,24 to 13.86 g/m3 absolute humidity at sea level and 25 °C. Use a psychrometric chart to find acceptable air temperature and relative humidity combinations. During cold modules below the dew point of the environmental control system, control only the cooling air temperature. See Figure 1 for two typical setups of cooling air for disc brake assemblies. Document on the test report the actual cooling air orientation relative to the brake and the brake rotation.

NOTE 1: It is recommended during cold sections to set the cooling air temperature approximately 10 °C below the IBT

NOTE 2: In order to keep similar and consistent cooling behavior of the brake assembly (including noise insulators or shims) for the same project, in addition to keeping the cooling air setup the same, use the same fixture orientation (left- or right-hand) in agreement with the test requestor and the testing facility

4.4冷却空气系统针对刹车。

4.4.1控制空气速度，使其不会高到吹走磨损碎片或产生超过背景限制的噪音，即在900hz以上的64分贝(A)。在刹车过程中，冷却空气一直处于开启状态。

注1:64 dB(A)的限制提供了6 dB(A)的分离度，即2:1的分离度，或检测超过70 dB(A)的噪声制动事件的阈值限制的一半。

注2:根据项目不同，其他阈值水平可能更合适，如电动汽车的刹车噪声评估。在这种情况下，与测试请求者和测试机构进行确认。

4.4.2设置风道出口距转子外径300 ~ 400mm，风道液压直径为200 ~ 300mm，调节风道出口测得的冷却空气为10m /s (35km /h);如有需要，从第4.4.1项调整至背景噪音水平。

注1:如果无法达到上述条件，请使用测试请求者进行定义，并将其记录在最终的测试报告中

注2:另外,调整冷却气流之间的1 000到2 000 m³/ h同时确保每4.4.1的背景噪音水平

注3:由于冷却空气装置是惯性测功器的一个关键子系统，它影响测试的可变性和测试的持续时间，因此确保为测试项目定义了正确的定义和测试条件。测量气流，评估特定温度下的冷却速率和测试速度，检查循环时间，观察测试期间的整体温度状态，以更好地了解环境和对噪音和摩擦行为的影响。

 

4.4.3选配-环境控制系统。除25°C以下的冷模块外，控制制动冷却空气温度为25°C±5°C，相对湿度为50% RH±10% RH -相当于7.90 ~ 11.93 g/kg，或在海平面和25°C的绝对湿度为24 ~ 13.86 g/m3。使用干湿测量图找出可接受的空气温度和相对湿度组合。在冷模组露点以下的环境控制系统，只控制冷却空气的温度。请参阅图1，了解盘式制动器总成的两种典型的冷却空气设置。文件上的测试报告，实际冷却空气的方向相对于制动和制动旋转。

注1:建议在冷区将冷却空气温度设置在IBT以下约10℃

注2:为了保持类似的和一致的刹车装置的冷却行为(包括噪声绝缘体或垫片)同样的项目,除了保持冷却空气的设置相同,使用相同的夹具定位(左或右)在协议测试请求者和测试设备

4.5 Automatic data collection system capable of recording digitally the following channels at 50 Hz minimum:

4.5.1 Brake equivalent linear speed / km/h

4.5.2 Brake input pressure / kPa

4.5.3 Brake output torque / N·m

4.5.4 Calculated brake apparent friction or effectiveness per items 3.1 and 3.2 4.5.5 (optional) Brake fluid displacement / mm3

4.5自动数据收集系统，可以数码方式记录下列最低50hz的频道:

4.5.1制动等效线速度/ km/h

4.5.2制动输入压力/ kPa

4.5.3制动输出扭矩/ N·m

4.5.4根据3.1和3.2条款计算的制动表观摩擦或效率4.5.5(可选)制动液排量/ mm3

4.6 Automatic data collection system capable of recording the following channels at 10 Hz minimum:

4.6.1 Brake rotor or drum temperature / °C

4.6.2 (optional) Brake pad or brake shoe temperature / °C

4.6.3 Cooling air temperature, relative humidity (or absolute humidity), and speed (or airflow)

4.6自动数据收集系统，可在10赫兹以下的频率记录以下频道:

4.6.1制动转子或制动鼓温度/℃

4.6.2(可选)刹车片或闸瓦温度/℃

4.6.3冷却空气温度、相对湿度(或绝对湿度)、速度(或气流)

5.1 Build the test fixture using as much as feasible the actual vehicle suspension and axle components. The suspension components should be as complete as possible to the connection points with the vehicle structure. This includes all bushings, including those at the structural connection points. However, certain projects specify a fixture using the knuckle assembly only to mount the brake corner and to connect to the inertia dynamometer tailstock. Also, it may not always be possible to use the entire suspension corner. In such cases, use an undisturbed knuckle assembly to fabricate the test fixture.

NOTE 1: In order to minimize frequency coalescence between the fixture and the brake assembly, when feasible, prefill the fixture frame with a noise-absorbing material like play sand or similar.

NOTE 2: When requested, conduct Frequency Response Function (FRF) natural frequency, or mobility measurements on the main components (friction material, rotor or drum, caliper, caliper brackets, brake backing plate assembly for drum brakes, knuckle or axle-end, etc.) to characterize the natural frequencies of the test fixture and brake assembly combined. Conduct the FRF at multiple locations, directions, and with the brake pressure applied at the typical pressures expected during the test. This type of measurements requires special preparation and proper instructions in agreement with the test requestor. See SAE J2933 and SAE J2598 for reference and examples for brake pads and brake rotors.

NOTE 3: In order to minimize test results variability, for the same project, use the same fixture level and fixture design. Ideally, when requiring multiple fixtures for the same project, use the same source for fixture fabrication.

For L2 or L3 fixtures impose a preload to the corner assembly to replicate its normal (or specified) operating condition. This ensures proper alignment, compliance, and transmissibility within the assembly. The preferred method of loading is to use a single compliant tension element (or compression underneath the knuckle) acting vertically, but not restricting vibration in the vehicle longitudinal or lateral directions. Other methods to impose preloading include: a. A wheel-and-tire assembly riding on a roller of suitable size and geometry b. An external bearing assembly connected to the driveline rotating the brake rotor or drum - typically a constant velocity shaft c. Loading the assembly through a soft connector from underneath the knuckle or hub carrier When applying a preload with additional components (bearings or wheel-and-tire assemblies) verify with the test requestor the proper method to minimize background noise (like using tires with the treads machined) or special algorithms to compensate for any additional background noise during the data collection and data analysis.

5.1尽可能多的使用实际车辆悬架和车轴部件搭建试验夹具。悬挂部件应尽可能完整地与车辆结构的连接点连接。这包括所有衬套，包括结构连接点上的衬套。然而，某些项目指定夹具使用指关节总成只安装刹车角和连接到惯性测功器尾架。此外，它可能不总是可能使用整个悬挂角落。在这种情况下，使用不受干扰的转向节总成来制造测试夹具。

注1:为尽量减少夹具与制动总成之间的频率重合，在可行的情况下，应在夹具框架内预装吸音材料，如play sand或类似材料。

注2:根据要求，对主要部件(摩擦材料、转子或鼓、卡尺、卡尺支架、鼓式制动器衬板总成、转向节或轴端等)进行频响函数(FRF)固有频率或移动性测量，以表征测试夹具和制动器总成组合的固有频率。在多个位置、方向进行FRF，并在测试期间的典型压力下施加制动压力。这种类型的测量需要与测试请求者一致的特殊准备和适当的指示。参阅SAE J2933和SAE J2598，了解刹车片和刹车片转子的参考和示例。

注3:为了最小化测试结果的可变性，对于相同的项目，使用相同的夹具级别和夹具设计。理想情况下，当同一项目需要多个夹具时，应使用相同的夹具制造源。

对于L2或L3夹具施加一个预加载到角落大会复制其正常(或指定)的操作条件。这确保了正确的对准，顺从，和传播的大会。首选的加载方法是使用一个单一的顺从张力元件(或压缩下的指关节)垂直行动，但不限制振动的车辆纵向或横向方向。其他施加预压的方法包括:wheel-and-tire大会。骑在一个合适大小的辊和几何b。外部轴承装置连接到动力传动系统旋转刹车转子或鼓——通常一个恒定的速度加载大会通过软轴c。连接器在关节或中心载体应用预加载时附加组件(轴承或wheel-and-tire总成)验证与测试请求者适当的方法来减少背景噪音(如使用轮胎在数据收集和数据分析过程中补偿任何额外的背景噪声的特殊算法。

5.2 Specify for the project the method required to drive the brake corner (direct connection to the dynamometer shaft, spool-driver in combination with a constant velocity drive shaft, wheel center driver with constant velocity drive shaft, etc.) and the details regarding the driver material and design. See Figure 2. NOTE 1: The drive system and connection to the main dynamometer can significantly influence the noise propensity of a given brake and the dominant frequencies during the test. Document and use the same design and material for the same project as a best practice to reduce test-to-test and dyno-to-dyno variability. NOTE 2: When feasible or when indicated by the test requestor, the spool-driver design should mimic the interface and force distribution of a reference wheel design.

1. Constant velocity drive shaft

2. Spool-driver 3. Wheel center driver FIGURE 2 - BRAKE DRIVING SYSTEM (A) SPOOL DRIVER, (B) WHEEL CENTER DRIVER

5.2具体说明本项目制动角的驱动方式(与测力计轴直接连接，spou -driver与恒速传动轴结合，轮毂驱动与恒速传动轴结合等)及驱动材料、设计等细节。参见图2。注1:在测试过程中，驱动系统和与主功率计的连接可以显著地影响给定制动器的噪声倾向性和主导频率。记录并使用相同的设计和材料，作为减少测试到测试和动态到动态变化的最佳实践。注2:在可行的情况下，或在测试要求者指出的情况下，假脱机驱动器的设计应模拟参考轮设计的界面和力分布。

1. 恒速传动轴

2. Spool-driver 3。图2 -制动驱动系统(A)轴驱动器，(B)车轮中心驱动器

7.1 Temperature measurement

7.1.1 Unless otherwise specified by the test requestor, use new rotor and brake pads, or new drum and brake shoe linings for each test.

7.1.2 For brake rotors, install thermocouple at a depth of 1.0 mm on the outboard face near the centerline of the braking surface. NOTE: As an alternative method for measuring rotor temperature, and in agreement with the test requestor, use an infrared measurement on the outside diameter of the inboard face of the disc. When using infrared measurements apply the outside diameter of the rotor coat with a heat-resistant black non-reflective paint that will provide an emissivity consistent with that required by the infrared measurement system. Obtain the correct emissivity settings from the test requestor or using an agreed-upon method. When using this method - unless readily available for the rotor design - perform a trial test to establish the correlation of the infrared reading with the embedded thermocouple. At appropriate intervals during testing ensure dust or debris does not accumulate on the lens.

7.1.3 Optional - For brake pads, install one thermocouple at a depth of 2.0 mm near the center of the friction surface on each pad. For disc brake pads with grooves, install the thermocouple at least 4.0 mm from the groove edge on the leading side of the pad. For inboard pads on single piston calipers, install the thermocouple on the leading side, 3 to 4 mm from the piston outside diameter near the center of the friction surface

7.1温度测量

7.1.1除非试验要求另有规定，每次试验应使用新的转子和刹车片，或新的鼓和刹车片衬片。

7.1.2对于制动盘，在靠近制动面中心线的外侧面上安装深度为1.0 mm的热电偶。注:作为测量转子温度的另一种方法，在符合测试要求的情况下，对阀瓣内表面的外径进行红外测量。当使用红外测量时，在转子的外径上涂上一层耐热的黑色非反射漆，以提供与红外测量系统要求一致的发射率。从测试请求者或使用商定的方法获得正确的发射率设置。当使用这种方法时——除非转子设计中有现成的方法——进行试验，以建立红外读数与嵌入式热电偶的相关性。在测试期间适当的间隔确保灰尘或碎片不会积聚在镜头上。

7.1.3可选-对于刹车片，在每个刹车片摩擦面中心附近2.0 mm处安装一个热电偶。对于带有沟槽的盘式刹车片，将热电偶安装在距沟槽边缘至少4.0 mm的位置上。对于单活塞卡钳上的内板，将热电偶安装在前侧，离活塞外径3至4毫米，靠近摩擦面中心。

7.1.4 When conducting schedule C (including fade section), confirm with the test requestor the need and location for additional thermocouple on the backing plate or noise shim to monitor temperature

7.1.5 For brake drums, install thermocouple at a depth of 1.0 mm on the centerline of the braking surface.

7.1.6 Optional - For brake shoes, install a thermocouple at a depth of 1.0 mm near the center of the friction surface of the most heavily loaded shoe.

7.1.7 Use the same temperature measurement and location for the same project.

7.1.8 When using a different control thermocouple for the test, document and report on the final test report

7.1.9 The use of redundant temperature measurements can prevent accidental overheating due to thermocouple or wiring failure.

7.1.4在进行附表C(包括褪色部分)时，应与试验请求人确认是否需要在垫板或噪声垫片上安装额外的热电偶以监视温度

7.1.5制动鼓应在制动面中心线安装深度为1.0 mm的热电偶。

7.1.6可选-对于闸瓦，在最沉重的闸瓦摩擦面中心附近安装深度为1.0 mm的热电偶。

7.1.7对同一项目使用相同的温度测量和位置。

7.1.8当使用不同的控制热电偶进行测试时，记录并报告最终的测试报告

7.1.9使用冗余的温度测量可以防止热电偶或线路故障引起的意外过热。

7.3.1 Unless otherwise specified by the test requestor, use a microphone conforming to IEC 61672-1 Class 2 or better with a corresponding windscreen.

7.3.1除非试验请求人另有规定，否则应使用符合IEC 61672-1第2类或更好的麦克风，并配备相应的挡风玻璃。

7.3.2 Use a calibrator according to IEC 60942 of the same class of the microphone at 1 kHz, before and after the test.

7.3.2试验前和试验后，根据同等级传声器IEC 60942的规定，使用1khz的校准器。

7.3.3 Use a frequency analyzer and/or digital data acquisition system to record the sound spectrum in the time domain. The system must compute and record narrowband sound pressure spectra using the following parameters and capabilities:

7.3.3.1 500 to 20 000 Hz frequency bandwidth, with a frequency resolution of 25 Hz

7.3.3.2 Peak-hold averaging with 66.7 % overlap processing

7.3.3.3 Apply Hanning windowing to the time-based records

7.3.3.4 Anti-aliasing filtering

7.3.3.5 A–type signal weighting

7.3.3使用频率分析仪和/或数字数据采集系统记录时域内的声音频谱。该系统必须使用下列参数和能力计算和记录窄带声压谱:

7.3.3.1 500 ~ 20000 Hz的频率带宽，频率分辨率为25 Hz

7.3.3.2峰位保持平均，重叠处理66.7%

7.3.3.3对基于时间的记录应用汉宁窗口

7.3.3.4反锯齿过滤

7.3.3.5 a型信号加权

7.3.4 Measure the Sound Pressure Level (SPL) in dB(A) throughout the duration of each brake application for all sections.

7.3.5 Ensure the background noise level inside the test chamber with the cooling air system operating does not have peaks above 64 dB(A) above 900 Hz

7.3.6 Noise measurement duration (recording) is the same as the duration of the brake application for all sections; from t0 to t4 for dynamic and brake drag applications

7.3.7 Noise measurement period for analysis from t1 to t3 for dynamic and brake drag applications

7.3.8 Microphone information may be saved as peak hold spectra, time recordings, peak-hold history at fixed intervals, or peak dB(A) and corresponding frequency at fixed interval

7.3.9 Optional - Use accelerometers to validate noisy brake events. Define with the test requestor the quantity, location, and data validation technique prior to commence testing

7.3.4在每段制动过程中，测量各区段的声压级(SPL)，单位为dB(A)。

7.3.5保证运行冷却空气系统的试验室内的背景噪声水平的峰值不超过640db (A)，不超过900hz

7.3.6噪声测量持续时间(记录)与各段制动时间相同;从t0到t4适用于动态和制动阻力应用

7.3.7动态和制动阻力应用t1至t3期间的噪声测量分析

7.3.8麦克风信息可保存为固定时间间隔的峰保持谱、时间记录、峰保持历史或固定时间间隔的峰值dB(A)和相应频率

7.3.9可选-使用加速计验证有噪声的刹车事件。在开始测试之前，与测试请求者一起定义数量、位置和数据验证技术

7.4 For disc brakes, the assembled lateral run-out shall not to exceed 50 µm when measured on the outboard surface and 10 mm from the outside diameter.

7.4盘式制动器,组装侧摆不得超过50µm当测量外表面和外直径10毫米。

图4说明了用于描述制动应用程序的主要时间戳。
图4 -典型的制动应用时间戳
要达到目标压力或减速水平，在动态制动周期使用压力坡道率
150 bar/s±50 bar/s。

8.1.1 Time t0 Brake application initiation. At this time, the pressure starts to rise.

8.1.2 Time t1 Time at level reached. At this time, the brake reaches its target level for torque or pressure control. At time t1, the calculation of average by time and the average by distance begins.

8.1.3 Time t2 Time at the end of averages. At time t2 the inertia-dynamometer data acquisition system terminates the calculation of average by time and average by distance. Time t2 is the end of the stable portion of the brake application. t2 is defined as the time at which speed is 0.5 km/h above the release speed (t3).

8.1.4 Time t3 Time at release speed. At time t3, the inertia-dynamometer servo controller releases the brake (specified in 8.1.3).

8.1.5 Time t4 Time at brake pressure and torque lost. At time t4, pressure and torque are below the minimum thresholds. The inertiadynamometer considers the braking event complete.

8.1.1 t0制动启动时间。这时，压力开始上升。

时间t1时间到达水平面。此时，制动器达到扭矩或压力控制的目标水平。t1时刻开始计算时间平均值和距离平均值。

8.1.3乘以t2时间，取平均值。在t2时刻，惯性测力计数据采集系统终止了按时间平均和按距离平均的计算。时间t2是制动稳定部分的结束时间。t2定义为释放速度(t3)以上0.5 km/h的时间。

8.1.4时间t3时间放行速度。在t3时刻，惯性测力计伺服控制器释放制动(8.1.3中规定)。

8.1.5倍t4时间制动压力和扭矩损失。在t4时刻，压力和扭矩低于最小阀值。惯性测量计认为制动事件已经完成。

图5显示了在恒定制动速度下用于表征制动阻力的主要时间戳。

8.2.1 Time t0 Brake application initiation. At this time, the pressure starts to rise. The ramp rate from t0 to t1 should provide a rise time to the nominal pressure minus 2.5 bar of 0.5 s.

8.2.2 Time t1 Time at start of the 1 bar/s pressure profile - equal to 0.5 s. At time t1 brake pressure is equal to the nominal pressure minus 2.5 bar. At time t1, the calculation of average-by-time effectiveness begins. For the zero-bar pressure profile t1 equals 2.5 s. NOTE: 1 bar = 100 kPa = 0.1 MPa = 14.5 psi

8.2.3 Time t2 Time at the middle of the 1 bar/s profile - equal to 5.5 s. At time t2 brake pressure is equal to the nominal pressure plus 2.5 bar. For the zero-bar pressure profile t2 equals 5 s.

8.2.4 Time t3 Time at end of the 1 bar/s pressure profile - equal to 10.5 s. At time t3 brake pressure is again equal to the nominal pressure minus 2.5 bar. At time t3, the calculation of average-by-time effectiveness finishes. For the zero-bar pressure profile t3 equals 7.5 s.

8.2.5 Time t4 Time at brake pressure and torque lost - equal to 11 s. At time t4, pressure and torque are below the minimum thresholds. The inertia-dynamometer considers the braking event complete. For the zero-bar pressure profile t4 equals 10 s. The ramp rate from t3 to t4 should provide a pressure release time from the nominal pressure minus 2.5 bar down to zero of 0.5 s.

8.2.1 t0制动启动时间。这时，压力开始上升。从t0到t1的斜坡速率应该提供0.5秒的公称压力- 2.5巴的上升时间。

时间t1时间在1巴/秒压力剖面开始-等于0.5秒。t1时刻的制动压力等于公称压力减去2.5巴。在时间t1，开始计算平均时间效率。对于零压剖面t1等于2.5 s。注:1bar = 100kpa = 0.1 MPa = 14.5 psi

8.2.3 t2在1 bar/s剖面中间的时间-等于5.5 s。t2时刻的制动压力等于公称压力加2.5 bar。对于零压剖面t2等于5s。

8.2.4时间在1bar /s压力剖面结束时的t3时间-等于10.5 s。在t3时刻，制动压力再次等于公称压力- 2.5 bar。在时间t3时，平均时间有效性的计算完成。对于零压剖面，t3等于7.5秒。

8.2.5时间t4时间制动压力和扭矩损失-等于11秒。在t4时刻，压力和扭矩低于最小阀值。惯性功率计认为制动事件已经完成。零杆压力剖面t4为10s。从t3到t4的斜坡速率应该提供从公称压力- 2.5 bar到零0.5 s的压力释放时间。

8.3.1 Brake warm-up operation for dynamic or brake drag applications If the temperature decreases below the IBT for the next braking condition, warm up the brake by conducting brake drag operation at 50 km/h until the brake temperature is 5 °C above the IBT for the next normal brake application. Control brake pressure at 20 bar for disc brakes, and at 30 bar for drum brakes. Do not conduct brake warm-up for sections with an IBT at or below 30 °C. NOTE: In cases when a brake warm-up is required for sections with an IBT at or below 30 °C (e.g.: when restarting the test after a test interruption), conduct brake warm-ups at 25 km/h and control brake pressure at 10 bar for disc brakes, and at 15 bar for drum brakes

8.3.2 Brake warm-up during the fade schedules If the IBT is not obtained (see item 8.4), perform a brake drag apply at 80 km/h with a torque equivalent to 1.96 m/s² deceleration to warm-up the brake. The warm-up procedure should be applied for no more than 20 s. Conducts the noise evaluation only during the stops where the initial temperature matches those indicated for the corresponding schedule.

8.3.3 Brake cool down If the brake temperature is 5 °C or above the IBT of the next brake application, rotate the brake at 20 km/h until the brake cools down to within 5 °C of the IBT.

8.3.4 Cold temperature soak When conducting schedule B, cool down the test chamber to 10 °C below the IBT before initiating the brake soak period; see item 4.4.3.

如果下一制动工况的温度低于IBT，则通过以50km /h进行制动阻力操作来预热制动，直到下一正常制动工况的制动温度高于IBT 5℃为止。盘式制动器控制在20bar，鼓式制动器控制在30bar。对于IBT温度在30℃或以下的路段，不要进行刹车预热。制动热身时注意:在案例部分所需的IBT达到或者低于30°C(例如:当重新启动测试后测试中断),进行制动热身25 km / h和控制在10条盘式制动器制动压力,对鼓式制动器和15条

8.3.2制动热身期间消失时间表如果IBT不是获得(见8.4项),执行制动阻力在80 km / h扭矩相当于1.96 m / s²热身刹车减速。热身过程不应超过20秒。只在初始温度与相应进度表指示的温度相匹配的停站期间进行噪音评估。

如果下一个制动应用的制动温度为5°C或高于IBT，则以20公里/小时的速度旋转制动，直到制动冷却到IBT的5°C以内。

8.3.4冷浸温度当进行附录B时，在启动制动浸时间之前，将试验箱冷却到IBT温度以下10°C;4.4.3看到项。

The brake fade section is intended to heat up the brake in preparation for the post-fade friction and noise evaluation. The IBTs for each brake application during the fade operation uses a logarithmic temperature profile per Eq. 4. 1 1 5 1 ln(15) ( ) ln( ) IBT IBT IBT n IBTn     (Eq. 4) Where:

n = brake application number; between 1 and 15 n IBT = Initial brake temperature for the nth brake application / °C 1 IBT = Initial brake temperature for the first brake application / °C 15 IBT = Initial brake temperature for the last brake application / °C The different fade schedules for disc or drum and front or rear brakes are shown on Table 2 and depicted in Figure 7. The optional fade schedules are more severe and provide higher temperatures. Unless otherwise specified by the test requestor, conduct the standard fade schedule and keep it the same for a given project.

刹车减振部分是为了给刹车加热，为减振后的摩擦和噪声评估做准备。在渐退操作期间，每个制动应用的IBTs使用对数温度剖面，每个公式4。1 1 5 1 ln(15) ( ) ln( ) IBT IBT IBT n IBTn     (Eq. Where:

n =制动次数;1至15 n IBT =初始制动温度n制动/°C 1 IBT =第一制动初始制动温度/ 15°C IBT =初始制动温度在过去制动/°C盘的不同褪色时间表或鼓和前方或后方刹车是显示在表2和图7所示。可选的褪色时间表更严峻，并提供更高的温度。除非测试请求者另有规定，否则应执行标准的渐退计划，并对给定的项目保持相同的渐退计划。

由于实际测试项目评估多种选项下的刹车噪声(阀瓣或鼓、标准或可选的渐变色温度，以及冷模块期间的其他最低温度)，因此在指定(或比较)测试结果时，务必清楚地标识请求(或执行)的实际测试序列。使用以下术语来识别所执行的测试。盘式制动器见项目10.3，鼓式制动器见项目11.3。

Brake-axle-schedules(冷温度)(消失温度)地点:制动:阀瓣或鼓轴:前方(FA)或后方(RA)时间表:安排A, B, C和序列实际上要求或进行温度(冷):最低初始制动温度设定点在寒冷的模块(消失温度):最大初始制动温度在褪色模块;见表2

在每个测试矩阵中有三个时间表，它们可以在不同的模式下组合，在冷态和渐变色模块中有不同的温度。除非测试请求者指出，否则不要执行附录B或C，因为它们是可选部分——表5和表8上用(*)表示。例:disc- fa - abc(0)(450)表示:对盘式制动器、前轴、包括的所有模块(a、B、C)、在零摄氏度(0°C)下进行的冷模块、在最大IBT为450°C下进行的褪色模块进行的测试。

9.1 Before conducting schedule B confirm with the test requestor the lowest temperature and the temperature steps. Confirm with the test requestor any additional temperature steps or modifications to the standard temperatures.

9.2 Before conducting schedule C confirm with the test requestor the fade schedule per item 8.4.

9.1在实施附录B之前，与测试请求者确认最低温度和温度步骤。与测试请求者确认任何额外的温度步骤或对标准温度的修改。

9.2在实施计划C之前，与测试请求者确认每项8.4的褪色计划。

Table 3 indicates the number of brake applications with noise analysis for each option and the corresponding cumulative brake applications for disc brake tests (front or rear; standard or optional sections; schedules A, B, C, or combinations). The nomenclature to indicate the sections and the temperatures selected for the test is indicated on the second row:

12.1.1 Lower limit of 2 kHz when utilizing a knuckle fixture (L1); or 1.25 kHz when utilizing a full suspension corner (L2), or full axle (L3) fixtures;

12.1.2 Upper limit of 16 kHz

12.1.1使用转向节夹具(L1)时，2khz的下限;或使用全悬架转角(L2)或全轴(L3)装置时为1.25 kHz;

12.1.2 16 kHz的上限

至少有一个峰值大于或等于70分贝(A)在频率范围内,独立于最接近峰值至少150赫兹(或2.5%的峰值频率),和6 dB (A)高于平均噪声水平测量范围的±75赫兹(或±1.25%的频率)上方和下方的峰值水平

NOTE 1: the actual test report will include separate charts for the maximum peak and the three loudest peaks for all brake applications with sound pressure level equal to or greater than 70 dB(A)

NOTE 2: as only squeal noise is considered as part of the evaluation, the treatment of other types of noise that might occur during the test needs discussion and decision from the test requestor, prior to testing and generating the corresponding test report

注1:实际测试报告将包括所有制动应用中声压级等于或大于70db (A)的最大峰值和三个最大峰值的单独图表

注2:由于只将噪声作为评估的一部分，因此在测试过程中可能出现的其他类型的噪声的处理需要测试请求者在测试和生成相应的测试报告之前进行讨论和决策

为了系统地展示测试结果，将图表和表格结果合并为默认的和最小的测试报告结构和布局(见附录a)。

13.1 Use charts to provide graphical depiction of the different noisy brake events per item 12 in relationship with (or as a function of) brake temperature, pressure, speed, test history, and frequency.

13.2 Summary table of noisy brake events per item 12 and occurrence for different types of brake applications for each frequency range. See example in Table 9.

13.3 Optional - Digital pictures showing the cooling air setup, fixture design, and driving method.

13.4 Optional - Digital pictures showing the friction material, the brake rotor or drum, and the noise insulator (when applicable) at the end of the test.

13.1使用图表来提供每项12中不同的噪声制动事件与(或作为)制动温度、压力、速度、试验历史和频率的关系的图形化描述。

13.2在每个频率范围内，对于不同类型的刹车应用，每项12所对应的有噪声的刹车事件和发生情况的汇总表。参见表9中的示例。

13.3可选-显示冷却空气设置、夹具设计和驱动方式的数字图片。

13.4可选-试验结束时显示摩擦材料、制动转子或制动鼓、隔音材料(如适用)的数字图片。