【作者】 陈光雄；

【导师】 周仲荣；

【作者基本信息】 西南交通大学 ， 机械设计及理论， 2002， 博士

【摘要】 在金属往复滑动条件下，对平面-平面接触和球面-平面接触滑动摩擦噪声现象进行了试验研究。使用电子扫描显微镜(SEM)、激光扫描显微镜(LSM)、光学显微镜和表面轮廓测量仪等设备对摩擦噪声发生的区域进行了详细的观察和分析，运用小波变换技术对摩擦噪声状态下的动力学变量进行了深层次的研究，应用MATLAB／SIMULINK语言对摩擦系统进行了振动动力学仿真，系统地研究了摩擦噪声的形成机理。 首先，对摩擦噪声试验系统进行了模态参数辨识，确定了噪声与振动的关系。研究结果表明，摩擦噪声的主频与摩擦部件振动的主频十分相近，噪声信号与振动信号在这些主频处的相干函数大于0.75-0.8，因而确认是摩擦部件的振动发射摩擦噪声。 其次，利用动力学和声学测量技术确定了摩擦噪声所发生的区域，在此基础上对磨痕上表面形貌进行了详细的对比分析，发现有噪声区域的形貌明显不同于没有噪声区域的形貌。有噪声磨痕形貌的特征是表面粗糙度比较大、存在不规则的犁沟、麻坑或粘着微凸体；而噪声消失后的磨痕形貌特征是表面粗糙度比较小、有微抛光作用发生。根据噪声与磨痕形貌的关系，本文提出了新的摩擦噪声形成机理：在不规则的犁沟和麻坑或粘着微凸体形成区域，摩擦力有动态成分。当动态摩擦力频率接近摩擦系统的自然频率时，系统就发生摩擦振动从而发射噪声。根据这个假设，从摩擦学的角度解释了摩擦噪声一般发生在摩擦系数比较大的区域的原因。当摩擦系数较大时，摩擦力组成分量中的犁削分量和微凸体变形分量的动态成分最强，摩擦噪声必首先发生在该区域。 通过改变往复滑动位移，试验了摩擦力-相对滑动速度负斜率对摩擦噪声形成的影响。结果表明，摩擦力-相对滑动速度负斜率并不总能引起摩擦噪声。试验发现，摩擦噪声既可以在摩擦力-相对滑动速度负斜率的区域发生，也可以在正的摩擦力-相对滑动速度斜率的区域发生。试验也显示在粘着-滑动发生的区域，噪声也不明显，这说明粘着-滑动现象也可能不是本试验条件下摩擦噪声形成的主要原因。 试验发现，有时发射摩擦噪声的振动首先在法向出现，当这个法向振动比较强时，相同或相近频率的切向振动才发生。这个现象否定摩擦噪声发生的两个机理：粘着-滑动机理和摩擦力-相对滑动速度负斜率机理，因为这两个机理描述的是切向发生的摩擦振动。 利用小波变换技术对测量的切向力、切向惯性力和法向振动加速度进行分解，对这些动力学变量之间的相互关系进行了深层次的研究。结果发现，在摩擦噪声发生的区域，摩擦力总是有动态成分。存在两种摩擦力动态成分形成机第11页 西南交通大学搏士研究生学位论文理：一个是山法向振动产生；另一个可能是出摩擦力组成分量的犁削和微凸体变形分量的不规则变化产生。第一种动态摩擦力形成机理可以作为摩擦噪声产生机理一模态耦合机理的证据，而后一种动态摩擦力形成机理否定了模态耦合机理。 最后，本文用M卅m沼IMULINK语言对摩擦系统的振动进行了数值仿真。用试验辨识的摩擦系统参数和实测的摩擦力数据对单自山度和二自出度振动模型进行了数值仿真，得出粘着－滑动机理和摩擦力－相对滑动速度负斜率机理不能引发摩擦振动的结论，在理论上验证了本文的试验结果。更多还原

【Abstract】 In the present dissertation, friction-induced noises emitted by a flat specimen rubbing against another flat specimen or a ball specimen under reciprocating sliding are studied. The detailed observation of the scars is conducted by means of a scanning electrical microscope (SEM), laser scanning microscope (LSM), optical microscope and profilometer. The dynamic state variables are analyzed in detail using the discrete wavelet transform. Moreover, a simulation of friction-induced vibration is also carried out using MATLAB/SIMULINK software.Firstly, the identification of the modal parameters of the friction testing system is performed. The correlation between the friction-induced noise and vibration under reciprocating sliding is verified. The result shows that analogous to those in unidirectional sliding conditions, the dominant frequencies of the friction-induced noise are very close to the dominant frequencies of the friction-induced vibration. It is found that coherence functions between these two signals are more than 0.75 - 0.8 at these dominant frequencies. Therefore, it is concluded that the friction-induced noise is emitted by the simultaneous vibration.Secondly, by means of the measurement of the vibration and associated noise, the area in the presence of the friction-induced noise is determined accurately. As a result, a comparative analysis on the topography of the scar surfaces with and without noise is performed in detail. The difference in topography between the two scars with and without noise is found clearly. It is also observed that at the same scar, the topography of the area with noise is different from that without noise. It is observed that the topography of the area with noise on a scar surface is characterized by larger surface roughness, plowing grooves, pits or adhesive joined asperities. While it is found that the topography of the scar after noise disappearance is characterized by a clear polished scar surface and a smaller surface roughness. According to the Suh’s theory of friction genesis and based on the change in topography with and without noise, it is assumed that the there is dynamic components of friction force in the area where uneven plowing grooves and pits or adhesive joined asperities are generated. It is considered that when the dominant frequencies of these dynamics components are close to the natural frequencies of the friction system, the system will show a resonant behavior and emit associated noise. The assumption may be used to explain why the occurrence of squeal is always accompanied with a larger coefficient of friction. It is because in the area with a larger coefficient of friction the dynamic friction components due to plowing and7ivasperities deformation are strongest.By imposing the displacement of reciprocating sliding, an influence of the friction-velocity slope on squeal generation is tested. The result shows that a negative friction-velocity slope can not always cause squeal. It is often observed that the squeal can also occur in the area with a positive friction-velocity slope. Moreover, it is also observed that in the area with a severe stick-slip motion the squeal and associated vibration are very weak. That may suggest that the squeal is not due to stick-slip motion.The test result also displays that sometimes the normal vibration associated with squeal firstly occurs prior to the tangential vibration. The tangential vibration does not occur until the normal vibration gets stronger. This phenomenon shows that stick-slip motion and negative friction-velocity slope are not responsible for the present squeal. It is because these two generation mechanisms of squeal only govern the tangential vibrations.The measured tangential force, tangential inertial force and normal vibration acceleration are decomposed using a discrete wavelet transform. The relation among these three dynamics state variables is investigated. The result displays that there is always a dynamic friction component in the presence of squeal. There are two forma更多还原