MEMS微平面构件的空气阻尼效应研究

Study on the Squeezed Air-damping on MEMS Parallel Plates

对垂直于衬底表面运动的微平面构件产生的空气挤压阻尼进行研究。从非线性修正雷诺方程出发,计入稀薄气体效应,建立微平面空气挤压理论模型,用有限差分法进行求解。研究揭示了在谐振挤压运动周期内挤压膜的性能变化。研究发现,气体稀薄效应必须在理论分析模型中计入,否则,将高估空气阻尼的影响。微构件平面尺寸增大将增大挤压阻尼力,且阻尼力的增大速度大于微构件面积的增大速度。谐振频率的提高将显著增强空气阻尼效应。

Air damping of a planar micromechanical structure that oscillates in the normal direction to the substrate was investigated. Theoretical models influencing the squeeze film damping have been developed for the transversely oscillating plates. The air-film model has been derived from the modified nonlinear Reynolds equation, where the influences of the gas rarefaction were included. The performance of squeeze film such as the variation of the pressure distribution and the air damping load were analyzed. For the scale effects in MEMS, the theoretical analyses should include gas rarefaction. The traditional lubrication equation without gas rarefaction effects will overestimate the numerical results. With the microstructure size increasing, the squeeze damping effects rise. The increasing speed of damping load is faster than the increases of microplate's area. Under high frequency, the effects of squeeze damping are more significant.