Clarification of Contact Dynamic Characteristics and Perfect Contact Sliding Condition of Tri-pad Contact Slider with Air Bearing System

1. 滑块与圆盘表面的接触动力学特性及设计条件（单自由度模型）从理论上推导了单自由度滑块在随机波浪形圆盘表面上的完美接触滑动条件，并通过数值模拟和实验验证了其有效性。在此基础上，推导出滑块和盘的表面设计条件，以实现完美的接触滑动和耐磨性。三垫滑块的设计条件（二自由度模型）数值模拟了三垫滑块在改变设计参数时的接触滑动能力。结果表明，如果使滑块与标准偏差为1nm的圆盘表面波浪度处于完美接触滑动状态，接触压力将达到数MPa。由于目前允许的接触压力为几kPa，使用寿命为5年，几乎不可能同时满足完美的接触滑动和耐磨条件。因此，将计算范围扩大到滑块与圆盘表面间歇性接触的近接触状态是有待解决的问题。三垫滑块的三自由度数值模拟通过数值分析滑块的横摇振动对滑块间距变化的影响，发现即使左右气轴承刚度比为0.8（最坏情况），横摇振动的影响也可以忽略。三垫滑块的实验研究我们制作了一个实验装置，可以通过将环境压力降低到0.1大气压以下来测量滑块在近接触和接触状态下的动态行为。我们观察到多峰共振现象，从近接触到接触，主共振频率降低。

1. Contact Dynamics Characteristics and Design Condition of a Slider and Disk Surface (Single-DOF Model)We theoretically derived the perfect contact sliding condition of a single-DOF slider over random wavy disk surface and verified its validity by numerical simulations and experiments. Then, we derived the design conditions of slider and disk surface both for perfect contact sliding and wear durability.2. Design Conditions of Tri-pad Slider (2-DOF Model)We numerically simulated the contact sliding ability of tri-pad sliders, changing design parameters. As a result, it was found that if we make the slider be in perfect contact sliding with disk surface waviness whose standard deviation is 1nm, the contact pressure becomes several MPa. Since the current allowable contact pressure is several kPa for the life time of 5 years, it is almost impossible to satisfy both perfect contact sliding and wear durability condition. Thus, it is the remained subject to expand the calculation range to near contact regime, in which the slider contacts with disk surface intermittently.3. 3-DOF Numerical Simulation of Tri-pad SlidersWe numerically analyzed the effects of roll vibration of the slider on the spacing variation and found that the effect of roll vibration can be neglected even if the ratio of right and left air bearing stiffness is 0.8 (the worst case).4. Experimental Study of Tri-pad SlidersWe manufactured experimental set up which can measure slider dynamic behavior in near contact and contact regimes by reducing ambient pressure to less than 0.1 atmospheric pressure. We observed multiple peak resonance phenomena and decrease of the main resonance frequency from near contact to contact regime.