全动舵面载荷测量的压电天平设计与误差分析

Design and error analysis of a piezoelectric balance for the measurement of aerodynamic loads on an all-movable rudder

关键词:  风洞天平  压电传感器  天平标定  解耦  等效作用点

Key words:  wind tunnel balance  piezoelectric sensor  balance calibration  decoupling  equivalent action point

摘要:

针对大载荷、狭窄安装空间的全动舵面气动载荷测量风洞试验，设计一种四支点三向力压电传感器并联式天平.选择压电石英作为天平的力敏元件，讨论四支点三向力传感器在其中的空间布局及其测量原理，研究并联式天平的标定方法，并对天平进行静态标定、复合加载试验.应用基于标定矩阵的求解矩阵广义逆的静态解耦算法进行解耦，从传感器等效作用点偏移的角度，利用ANSYS有限元软件分析并联式压电天平误差产生机理.实验结果表明：该天平的最大非线性误差和重复性误差分别为1.352%、1.019%，最大向间干扰系数为2.865%，复合加载对竖直力的测量精度影响较小，而对弯矩影响较为明显; 天平静态标定指标均满足测试精度要求，但不同加载方向及其大小对传感器间距的影响各异，复合加载时，间距影响相互叠加，使天平测量精度降低，此天平并不适用于多向载荷测量.

Abstract:

A three-direction piezoelectric sensor parallel-type balance with four supporting points was designed for the dynamic load measurement of the all-movable rudder which withstands high-load and installed in narrow space. The piezoelectric quartz was selected to be the force sensing element, the spatial layout and measuring principle of this three-direction force sensor with four supporting points were discussed and the calibration method of parallel balance was studied. Static calibration and compound loading test were carried on this parallel balance. The generalized inverse static decoupling algorithm based on the solution matrix of calibration matrix was used to decouple. From the view of equivalent application points' offset, the error generation mechanism of parallel piezoelectric balance was analyzed using ANSYS finite element software. The experimental results showed that the maximum nonlinear error and repeatability error of the balance were 1.352% and 1.019% respectively. The largest interference coefficient was 2.865%. The influence of composite load on vertical force measurement accuracy was less, yet on the bending moment was obvious. The balance static calibration indexes satisfied the test precision requirements. However, due to the different effects of different load on the range interval between sensors and the superimposed impacts of the composite loading time interval, the balance measurement accuracy was reduced and not satisfied multi-directional load measurement.