Study On Calibration And Nonlinear Correction Technique Of Shell Apacitive Pressure Test Device

Shell capacitive pressure test device is a type of new testing system, being used toobtain fuel gas pressure-time curve of an artillery gun chamber. This system is smart, highsensitive and low power consumption. Shell material is used to be sensitive componentsunder outside pressure and capacitance values obtained by capacitive sensor is transferred tovoltage values and is stored in the SCM through test circuit.Test accuracy and reliability of shell capacitive pressure test device must be guaranteedin the harsh environmental conditions. In a consequence, simulation of bore pressuregenerator is selected to calibrate this pressure test device after several kinds of calibrationmethod are compared, and then some influencing factors in this calibration are analyzed. Theresult shows three standard pressure sensors in standard test system are proper to be used inthis calibration method as standard source. The impacts of calibration of pressure measuringdevice are negligible, caused by strain, thermal shock and acceleration cavity effect, etc.Based on the test conditions and data fusion theory, analysis of calibration data showsthat measuring error of the transformer is out of technical requirements.The cause of thisresult is mainly nonlinearity of sensor. And linear error of the result of data-fitting meets therequirements, after the causes of nonlinearity and some data-fitting methods are analyzed andcompared.Three points are mainly studied in this paper:a) Characteristics of the bore pressure signal are briefly described and the principleand design of shell capacitive pressure test device is introduced. Finite elementanalysis and the measured data are compared to come to the conclusion thatpractical application and theory is different.b) Pressure test device need to be calibrated in order to ensure the accuracy of testdata. In this paper simulation of bore pressure generator is selected to generatesimilar bore pressure signal acting on three standard sensor and shell capacitive pressure test device. These three sensors are regard as standard source to analyzepeak and rising edge of data collected by pressure test device.c) Pressure measuring device is bore pressure tester based on principle ofcapacitance sensor, so its nonlinearity could be main reason for inaccuracy ofdata. In the end, the reasons for nonlinear are analyzed detailly and non-linear iscorrected. The result proves that the revised data is meet the standardrequirement.