曲面保护高量程加速度传感器阻尼特性研究

Damping characteristics of a high g accelerometer with curved stop protection

利用有限元模拟方法,对一种高量程MEMS加速度计进行10万g正弦加速度脉冲下的动态冲击响应分析。首先,建立适用于该器件曲面阻尼的分段近似叠加理论模型;随后,采用ANSYS有限元模拟技术分别研究器件阻尼带隙宽度及其阻尼介质特性对器件动态冲击响应特性的影响。器件动态冲击响应实际上是受迫振动与传感器悬臂梁固有频率振动的叠加。当阻尼带隙较小时,输出结果表现为冲击载荷下的受迫振动响应;随着阻尼带隙变宽,悬臂梁固有频率振动渐突显,响应峰值电压也近线性增加,而峰值电压所对应时间则非线性减小。在其它条件相同情况下,阻尼介质粘滞系数越大,响应输出曲线越光滑,但其峰值电压也相应越低。在空气阻尼介质中,过载保护曲面的平移距离控制在0.5～0.65μm范围内,以获取较好的动态响应效果。

The dynamic response of a piezoresistive high g＇s Micro Electromechanical System （MEMS） accelerometer under a sine pulse of acceleration with 100,000 g＇s peak was simulated by using Finite Element Method （FEM）. Firstly, a multi-segments-plates-approximate model of curved surface damping suitable for this component was established. Subsequently, the effects of damping gap width and the characteristics of damping media on the dynamic shock response of component was studied with ANSYS FEM technology. Results show that the dynamic responses of component were in fact the superposition of the forced vibration with dynamic shock and vibration of cantilever in its inherent frequency. When the damping gap width was very small, output result behaved as the forced vibration under dynamic shock. With the increase of damping gap width, the vibration of cantilever became more outstanding and the peak output voltage increased linearly while the time corresponding to the peak output voltage decreased nonlinearly. Under the same conditions, with higher viscosity coefficient of damping media, the output response curve became smoother, besides the peak voltage became lower.Therefore, in air damping media, the damping gap width at the beam bottom should be controlled between 0.5 μm and 0.65μm to gain the best dynamic response.