【作者】 王正国；

【导师】 莫继良；

【作者基本信息】 西南交通大学 ， 机械设计及理论， 2013， 硕士

【摘要】 由摩擦引起的振动和噪声会严重影响设备的正常使用并导致噪声污染。长期以来,尖叫噪声问题始终未得到解决。近年来出现了许多关于界面特征对摩擦噪声影响的研究,但都进展不大。表面织构已被证明能有效改善界面的摩擦学性能,而关于表面织构对摩擦噪声影响的研究报道很少,因此开展表面织构对摩擦振动噪声影响的研究工作具有创新性,对探索表面织构控制摩擦噪声及减轻尖叫噪声的可能性具有重要意义。本文用电火花加工方法在列车制动盘蠕墨铸铁材料上制备出不同沟槽宽度和间距的沟槽型表面织构,并将其和光滑表面进行摩擦噪声对比试验,研究织构参数对摩擦噪声的影响,探讨了沟槽型表面织构影响摩擦振动噪声的机理。主要得到以下结论：(1)沟槽型表面织构的参数对摩擦噪声强度有重要影响。摩擦噪声随着沟槽宽度的增加而减小,随着沟槽间距的增加而增大。然而在沟槽型表面织构的所有参数中,沟槽间距和沟槽宽度比对摩擦尖叫噪声产生的影响最大,沟槽间距和沟槽宽度比为2：1的织构表面能明显降低摩擦尖叫噪声。(2)当系统产生摩擦噪声时,无论光滑表面还是织构表面,摩擦力都存在剧烈波动,相应时间内系统产生摩擦自激振动。产生摩擦噪声表面的摩擦力、振动加速度和噪声信号的主频都相同,并且和摩擦系统的某阶自然频率十分接近。此外,信号主频处,摩擦力和振动加速度、声压和振动加速度的相干性很高。这表明摩擦力主频与系统自然频率耦合,引起了摩擦系统的自激振动并对外发射出摩擦噪声。(3)对于沟槽型织构表面,球与沟槽碰击会产生摩擦力的波动,但这种波动的频率较低(远低于噪声的主频),作为不连续的激励,其不可能和摩擦系统的自然频率耦合并引起强烈的自激振动,相反,它的存在会打断摩擦界面连续的接触,扰乱摩擦系统的自激振动,抑制摩擦噪声的产生。(4)磨损表面的微凸体、犁沟、磨屑、粘着和剥落等摩擦界面特征是形成摩擦力高频成分的主要因素。而具有较合理的沟槽尺寸及分布的织构表面,可获得较好的排屑性能,磨损表面较为平整光滑,摩擦力波动高频成分减少,系统不容易产生尖叫噪声。(5)提出了沟槽型表面织构影响摩擦噪声的机理：对于沟槽型织构表面,摩擦界面的不平顺对摩擦力的影响因素主要包括两个部分：一为相对宏观的沟槽轮廓效应,即对磨球与沟槽棱角碰击所导致的摩擦力明显的波动,其可以抑制摩擦噪声的形成；另一部分为磨损表面(沟槽间平面)的微凸体、犁沟、磨屑、粘着和剥落等界面因素,其导致了摩擦力高频成分产生并最终形成摩擦噪声。影响摩擦力的这两部分界面因素共同作用且相互竞争,导致不同参数的织构表面具有明显不同的摩擦噪声特性。更多还原

【Abstract】 Friction-induced vibration and noise usually have significant influence on the regular operation of equipments and cause noise pollution. Squeal phenomenon has not yet been fully understood and solved until now. In recent years, many studies have been conducted to investigate the influence of topography characteristics on friction noise. However, little progress has been made. Surface texturing has been widely studied in the last two decades which can significantly improve the tribological properties of friction surfaces. However, there are very few reports on the correlation between textured-surface and friction noise. Therefore, it’s significant to conduct experimental test to study the influence of textured-surface on friction noise, which can lead to the specification of optimized surface texturing for controlling fiction noise and reducing squeal.In this work, groove-textured surfaces with different widths and pitches were manufactured on compacted graphite iron samples (brake disc material) by electromachining. The influence of groove-textured surface on friction noise and the difference between the groove-textured and original smooth surfaces in friction noise properties were studied. The mechanism of the effect of groove-textured surface on friction vibration and noise is discussed. Accordingly, the main conclusions can be drawn as following:(1) The geometrical parameters of the groove-textured surfaces had significant influence on the friction noise level, which was found to reduce with the increase of width and increase with the increase of pitch, respectively. However, the squeal generation was more influenced by the dimensional proportion of groove width to pitch, instead independently by groove width or pitch. Groove-textured surfaces with a specific dimensional proportion of groove width to pitch of1/2showed good potential in reducing and suppressing squeal.(2) All the friction force curves of the smooth and groove-textured surfaces exhibited significant fluctuation during the generation of friction noise, which corresponding to the self-excited vibration of friction system. The dominant frequencies of friction force, vibration acceleration and noise were the same which were closed to the natural frequency of the friction system. The coherence analysis results showed that the correlation coefficients between friction force and vibration accelerations and sound pressure at the dominant frequency were very high. Therefore, squeal was found to originate from the unstable vibratory response due to friction-induced vibration corresponding to mainly one natural frequency of the tribo-system. (3) For the groove-textured surfaces, the low-frequency wave-fluctuations of the friction force caused by counterface ball sliding across the grooves didn’t cause continuous unstable vibrations and the consequent squeal. Instead, the wave-fluctuations could help to disturb and suppress the generation of continuous high-frequency fluctuations of friction force and vibration accelerations which was considered as the major cause of squeal.(4) The generation of friction noise in this study can be mainly attributed to the high frequency components of the interface friction force, which were mainly resulted from the irregularities characteristics of the worn surface, such as asperity, ploughing, debris, adhesion and detachment. Groove-textured surface with specific geometry was found to allow an easier wear debris escape from the contact zones into the grooves, which would help to reduce the irregularities and high frequency components of the friction force, and consequently reduce the squeal tendencies.(5) The mechanism of the effect of groove-textured surface on friction vibration and noise can be addressed as following:the effect of irregularity of friction interface on friction force mainly consists of two parts for the groove-textured surfaces. On the one hand, macroscopic grooves that are produced by machining process can cause the low-frequency wave-fluctuations of the friction force when counterface ball sliding across the grooves, which suppress the generation of friction noise. On the other hand, microscopic irregularities of the worn surface on ridge, such as asperity, ploughing, debris, adhesion and detachment, will cause the high frequency components of the friction force and the consequent squeal generation. The interaction and competition of these two factors will lead to the significant different friction noise characteristics of the groove-textured surfaces having different geometrical parameters.更多还原