新型悬丝约束支撑微纳测头的变刚度特性分析

针对传统微纳测量装置在测量过程中测头支撑机构刚度不可变化的问题,设计了一种基于悬丝约束支撑的变刚度微纳测头。利用压电装置驱动柔顺导向机构产生位移,以改变悬丝所受的轴向张紧力。基于应力刚化原理改变悬丝的横向刚度,进而改变测头支撑机构的整体刚度,以获得具有变刚度性能的新型微纳测头。根据测头支撑机构在测量过程中刚度的变化,分别建立刚性和柔性模式下微纳测头Z向和横向的刚度理论模型。根据有限元仿真和刚度理论模型,分别得到测头刚度随悬丝端面受力的变化曲线。对比测头刚度的仿真值和理论值,得到测头Z向和横向刚度的平均相对误差分别为2.41%和4.72%,结果表明理论模型具有较高的准确性。研究成果为该类型测头的变刚度控制奠定了前期理论基础。

Variable stiffness characteristic analysis of a novel micro-nano probe with wire constraint suspension

To address the problem that the stiffness of the probe support mechanism cannot be changed during the measurement process using traditional micro-nano measuring device, a micro-nano probe with variable stiffness was designed based on the constraint support of suspension wire. The piezoelectric device was employed to drive the compliant guide mechanism which produces a displacement. Thus the axial tension of the suspension wire was changed. Based on the principle of stress stiffening, the transverse stiffness of the suspension wire was changed, and the overall stiffness of the probe support mechanism was varied to obtain a novel micro-nano probe with variable stiffness performance. According to the variation of the stiffness of the probe support mechanism during the measurement process, the theoretical model of the Z-direction and the transverse stiffness of the micro-nano probe were established in the rigid and flexible modes, respectively. Based on the finite element simulation and the established theoretical stiffness model, the curve of the stiffness change of probe versus the terminal force applied on the suspension wire was obtained. With comparing the simulated and theoretical values of the probe stiffness, the average relative errors of the Z-direction and the transverse stiffness of the probe were 2.41 % and 4.72 %, respectively. It indicates that the theoretical model had a high accuracy. The research results laid a preliminary theoretical foundation for the variable stiffness control of this type probe.