On Uncertainty in Friction Measurements
On Uncertainty in Friction Measurements
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DOI：
10.1002/pamm.201710019
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发表时间：
2017-12
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影响因子：
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通讯作者：
G. Ostermeyer;M. Mueller;T. Srisupattarawanit;A. Voelpel
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文献类型：
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作者：
G. Ostermeyer;M. Mueller;T. Srisupattarawanit;A. Voelpel
在机械工程领域，摩擦无处不在。它是能量损失和磨损的根本原因。另一个问题是与舒适性相关的摩擦引起的振动的发生。突出的例子是制动尖叫等 NVH 现象，德国汽车工业和学术界正在花费巨资进行调查，以确定其原因和潜在影响因素。为此，需要进行大量专门的测量，并使用不同复杂度的模型。所有这些测量和模型都有一个共同特征，即摩擦系数（COF）（定义为切向力与法向力之比）对系统的稳定性具有决定性影响。为了参数化宏观模型中的摩擦系数，必须进行测量。在这种情况下，通常使用一段时间内和不同加载程序的平均值。正如测量结果所示，摩擦系数实际上并不是恒定的，而是在不同时间尺度上受到边界层中复杂过程引起的高度动态的影响。因此，将摩擦系数视为稳态参数，甚至视为常数，可以大大降低摩擦系数。摩擦系数的巨大变化会导致所考虑模型的稳定性极限发生相应的变化。这种现象是在现实世界中观察到的，其中尖叫似乎具有非确定性行为。这表明摩擦系数建模存在不确定性。由于各种类型的不确定性（可变性、不完整性和不准确性），整个问题是一个多态不确定性的问题。本文重点关注摩擦系数的建模，并考虑到不确定性的各种原因。作者研究所通过多年对制动系统摩擦现象的研究获得的原始数据的选择将根据其不确定性特性进行评估和分类。 （© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA，魏因海姆）
In the fields of mechanical engineering, friction is ubiquitous. It is a fundamental cause of energy loss and wear. Another concern is the occurrence of comfort‐relevant friction induced vibrations. Prominent examples of this are NVH phenomena such as brake squeal, which is being investigated at great expense by the German automotive industry and academia, to determine its causes and potential influencing factors. For this purpose, numerous specialized measurements are performed, and models of varying complexity are used. All of these measurements and models have the common trait that the coefficient of friction (COF), defined as the ratio of the tangential force and normal force, has a decisive influence on the systems' stability. To parameterize the friction coefficient in macroscopic models, measurements must be performed. In this case, often an average value over time and over various loading procedures is used. As the measurements reveal, the coefficient of friction is in reality not constant, but is subject to a high degree of dynamics on various time scales, caused by complex processes in the boundary layer. A treatment of the coefficient of friction as a steady‐state parameter, or even as a constant, is thus a major reduction. The large variability of the coefficient of friction causes a corresponding variance in the stability limits of the models considered. This phenomenon is observed in the real world, where squealing seems to have a non‐deterministic behavior. This suggests uncertainties in the modeling of the friction coefficient. Due to the various types of uncertainty (variability, incompleteness and inaccuracy), the entire problem is a matter of polymorphic uncertainty. This paper focuses on the modeling of the friction coefficient, taking into account the various causes of uncertainty. Selections of raw data obtained at the authors institute throughout many years of research on friction phenomena in brake systems will be evaluated and classified with respect to its uncertainty properties. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)