流体环境中静电微悬臂梁的多场耦合仿真分析

Multi-physics Analysis of an Electrostatically Actuated Microcantilever in Viscous Fluids

微器件动力学特性通常受到周围粘性流体阻尼的强烈影响,在器件优化设计中,需要建立静电-结构-流体三场耦合模型才能细致考虑这些影响。为研究微开关在粘性流体介质中的动/静态特性和流体阻尼,建立以Navier-Stokes方程描述流体特性的静电微开关模型并进行数值分析;与相关文献结果比较验证了计算的正确性;得到了空气和去离子水介质中微开关的静/动态闭合电压、不同阶跃电压驱动下的闭合特性和流体阻尼力分布的情况。分析认为,微开关动/静态闭合电压的差异在介质粘性较大环境中较小,而在介质粘性较小环境中较大。

The dymamical behavior of MEMS devices is strongly affected by viscous fluid damping effects from the surrounding.These damping effects have to be carefully considered for the design and optimization.For predicting the hydrodynamic loading of an electrostatical device in viscous fluids,it is necessary to build an electrostatic-mechanical-fluidic coupled model,where the flows characteristics were described by Navier-Stokes equations.Comprehensive analyses of the static/dynamic closing behaviors of the microswitch in viscous fluids were performed.Compared with published work of other researchers available in the literature,the numerical model was validated.After that,the static/dynamic closing voltages of the microswitch in the air and deionized water were calculated.The transient behaviors of microswitch under different action voltages were also simulated, including the squeeze-film damping pressure distribution as well.The results show that the difference between the static and the dynamic pull-in voltage in the deionized water is smaller than that in air.