低g值微惯性开关中阿基米德平面螺旋梁的设计

针对低g值微惯性开关对微弹簧的系统刚度达到(0.1~10)N/m数量级的要求,设计了一种阿基米德平面螺旋梁结构的微惯性开关。根据材料力学中的卡氏定理和线弹性理论,推导了阿基米德平面螺旋梁的弹性系数计算公式,并与ANSYS有限元仿真分析结果进行了对比。基于推导的弹性系数计算公式设计了一种三根阿基米德平面螺旋梁支撑的动作阈值5.5 gn 的微惯性开关,并采用SOI硅片以及玻璃－硅－玻璃键合技术进行了加工,在离心转台上对开关实际动作阈值进行测试,并将测试值与设计值进行对比。结果表明,采用推导到的阿基米德平面螺旋梁弹性系数计算公式计算结果与ANSYS仿真结果相近,基于推导的弹性系数计算公式设计的三根阿基米德平面螺旋梁支撑的微惯性开关动作阈值设计值与实测值相近,单根阿基米德平面螺旋梁弹性系数约0.8 N/m,能够满足低g值微惯性开关低刚度的要求,推导的弹性系数计算公式能够用于基于阿基米德平面螺旋梁的低g值微惯性开关的设计。

Design of Archimdes Planar Micro-springs Used in Low-g Micro Inertia Switch

Aimed at the micro￣spring with stiffness down to(0.1~10)N/m magnitude in low￣g micro inertia switch, a planar micro￣spring based on the Archimdes planar helical spring is designed. The elastic coefficient formula is derived with the Castigliano’s theory and the linear elasticity theory of material mechanics,and compared with the ANSYS finite element method simulation results. A micro inertia switch with acceleration threshold of 5.5 gn supported with three Archimdes planar micro￣springs is designed and fabricated based on SOI wafer and anodic bonding of glass￣silicon￣glass. Acceleration threshold of the fabricated micro inertia switch is measured with a centrifuge and compared with the designed value. The theoretically calculated results using the derived elastic coefficient formula agree well with the ANSYS simulation results,and acceleration threshold of the designed inertia switch agrees with the measurement results. The elastic coefficient of the designed and fabricated Archimdes planar helical spring is about 0.8 N/m. It conforms to the low stiffness requirement of low￣g micro inertia switch. The derived elastic coeffi￣cient formula can be used in the design of low￣g micro inertia switch with Archimdes planar helical springs.