Reseach And Design On Large-load Wind Tunnel Strain-gauge Balance Calibration Loading System

Wind Tunnel Strain-gauge Balance is an important and essential device in the wind tunnel testing,it can collect multiple kinds of data,just like the aircraft flight angles,design parameters of the streamline surface and airflow influence on flight control,provided key data for the aircraft designing.Before wind tunnel testing,for measurement performance of the strain gauge,it must be calibrated like the same as other sensors before used.Generally,wind tunnel strain-gauge balance calibration is processed by the special calibration device.The device is a set of complex M&E systems which involves many discipline and specialty,like mechanical.electrical and control engineering.The calibration accuracy will directly affect the aerodynamic load measurement accuracy of the aircraft model.Nowadays,in our country the full-scale value of the calibration devices are mostly below 70KN.However,with the continuous development of aerodynamics,the needing for large scale and even super-large scale strain-gauge calibration device became more urgent.So under this background,some researching and designing work on large-load wind tunnel strain-gauge balance calibration loading system was carried out in this paper.The main contents are as follows:(1)According to the design requirement and the performance,several important technique problems in the developing of six-component strain-gauge balance calibration loading system are discussed.The force application mechanism technical scheme,loading point arrangement technical scheme and pose measurement technical scheme are all defined.The overall three-dimensional structure design of the calibration loading system was finally completed.(2)Based on the leverage and wedge reinforce mechanism,by using Solid Works and MATLAB two kinds of single-branch loading mechanism are designed,which contained design of force transformation components and calculation and selection of the servo motor.The structural optimum design of the loading device was finished by means of ANSYS Workbench simulation optimization software.Finally proposed the loading device attitude measurement scheme,and analysed the work principle and the feasibility of the measuring equipments.(3)Taking the support frame as one research object.Based on the support frame bridge static analysis results,this paper used the finite element analysis software to choose the optimum steel beam configuration.Then taken the steel beam section parameters as design variables,the structure maximum deformation as optimization constraint to minimize the mass of whole structure.Finally,the modal analysis of the support frame column is carried out.According to the first eight modal frequencies and mode shapes,the dangerous resonant period is obtained.(4)The error source and composition of the whole system is analyzed.Two compensation methods were proposed for natural load error and final state error.According to the uncertainty theory of measurement,a mechanical model of the resistance Fx was established,then evaluation uncertainty measurement of each input variables was dealed with in a reasonable and quantify way.