Analysis of Nano-Dynamic Behaviors and Complete and Stable Tracking Conditions for Contact Slider

分析了1自由度接触滑块和2自由度三自由度接触滑块的弹跳振动和动态接触力，并通过实验研究验证了数值分析结果的有效性。研究了悬臂梁支承的接触滑块摩擦自激振动现象，明确了稳定跟踪条件。研究结果如下：(a) 1-DOF滑块模型分析为了减小1-DOF接触滑块的弹跳振动，使其完全跟踪磁盘表面，需要10^5N/m左右的低接触刚度，0.1左右的高接触阻尼，较小的滑块质量和较小的静载荷。(b)基础实验当滑块载荷较大时，其弹跳振动始终较低。在铅接触滑块中，质量越小，反弹振动越小。然而，对于某些玻璃滑块，由于惯性效应的增加，较大的质量可以减少弹跳振动。几乎所有的实验结果在质量上都与理论一致。(c) 2-DOF滑块模型分析低接触刚度和高接触阻尼对于减少弹跳振动很重要，并且可以避免低模态的影响。将滑块作为单自由度模型进行分析，使前后空气支承刚度比高。(d)摩擦自激振动分析：当梁的横向频率和角频率接近时，滑块变得不稳定，当支承点和接触点位于滑块质量中心位置后方时，滑块可以稳定。

I analyzed bouncing vibrations and dynamic contact force of a 1-DOF contact slider and a 2-DOF tripad contact slider which has two air bearing pads and one contact pad at the trailing edge, and then showed the validity of the results obtained from these numerical analysis by an experimental study. I also investigated friction-induced self-excited vibration phenomena of contact slider supported by a cantilever beam and clarified stable tracking conditions. The results from these studies are summarized as follows :(a) 1-DOF slider model analysisIn order to decrease the bouncing vibration of 1-DOF contact slider and make it track on disk surface completely, low contact stiffness in the order of 10^5N/m, high contact damping of about 0.1, small slider mass and small static load are necessary.(b) Basic experimentThe bouncing vibration are always low when the slider load is high. In the lead contact sliders, the bouncing vibrations are smaller for smaller mass. However, in the case of some glass sliders, a large mass can reduce the bouncing vibrations because of the increase in the inertia effect. Almost all experimental results qualitatively agree with the theoretical ones.(c) 2-DOF slider model analysisLow contact stiffness and high contact damping are important in reducing bouncing vibrations and that the effects of a lower-mode can be avoided. The slider will be analyzed as a single-DOF model by making the rear to front air boaring stiffness ratio high.(d) Friction-induced self-excited vibration analysisThe slider became unstable when the lateral and the angular frequencies of the beam were close to each other and that the slider could be stabilized it the supporting and the contact points were located at the rear of the slider mass center position.