Research On Acquisition Method And Low - Frequency Characteristics Of Working Characteristic Parameters Based On Quasi - Static Shock Wave Pressure Measurement System

Electromotive pressure measuring method has the feature of strong real-time, large quantity, and high accurate rate, which is used commonly in the shock wave pressure testing. ICP piezoelectric shock wave pressure sensors and high impedance output shock wave pressure sensor which is widely used in electromotive pressure measuring method. They have excellent dynamic characteristics, along with the problem of poor low-frequency characteristics. The testing environment of shock wave pressure is harsh. The explosion will cause parasitic effects of strong light, high temperature, vibration, etc. For this reason, some protective measures will be take appropriately. Protective measures lead to the equivalent mass, the equivalent stiffness of the sensing system changes. Obviously, relying on job parameters provided by the manufacturer is unable to meet the work requirements. It’s important to get work parameters and other indicators of test system through calibration. On the one hand, since the static calibration cannot be used in piezoelectric sensor system, and static calibration loading time is long and it will bring harm to expensive sensors. On the other hand, the shock tube is suitable for the calibration of high frequency, but it cannot meet the zero-frequency, low frequency of testing. Suitable for high frequency and shock tube as a representative of the dynamic calibration and cannot meet the requirements of zero-frequency, low frequency testing. To make up for the shortcomings of the above two types of calibration, quasi-static calibration emerged.This article described the "inter-comparison" quasi-static calibration method. It used "direct comparison" type quasi-static principle, analyzed the pressure pulse selection basis, set up the standard pressure monitoring system. Also, the article proposed accuracy requirements, discussed transfer method of shock wave pressure measuring system based on the "inter-comparison" quasi-static calibration. Quasi-static calibration experiment of typical shock wave pressure sensor has been done using the hydraulic drop hammer calibration device.Different pulse width signals have different effective bandwidth and different energy proportion. The sensitivity changes while the pulse width of the signal goes changing. The paper studied the variation of sensitivity under different pulse width and selected the appropriate sensitivity, analyzed the half sine pressure signal, selected the reasonable width. This measure avoid the trouble that getting sensitivity under every different pulse stimulation. It has improved the calibration efficiency and saved costs.Based on the static calibration experiment data, the paper obtained the sensitivity of the standard sensor. According to the quasi static calibration experiment data, we got the sensitivity, linearity and repeatability of the shock wave pressure sensor system. We analyed the uncertainty factors of the standard pressure monitoring system and the pressure measurement system of the shock wave, and evaluated the uncertainty. The article’s work has a certain value to the establishment of quasi static calibration system in shock wave pressure measurement.