Jing Zu

Research on a Novel Capacitive Pressure Sensor to Measure Chamber Pressures of Different Caliber Artilleries

The research and development on a novel capacitive pressure sensor with an elastic pressure-sensitive element are presented in this paper. As a coaxial cylinder capacitor converter, it uses a circuit cylinder as its stationary anode and the piezo gauges shell as its moveable cathode with the electrode distance of 0.5 mm. The devices principle and structure are given, and its mechanical characteristics are theoretically simulated by using the finite element software ANSYS. The read-out circuitry was developed. Various physical properties were experimentally tested. Results show that its capacitance is approximately linear to the subjected pressure. Its sensitivity is 0.0099 pF/Mpa, pressure measuring rang is 0-600 Mpa, By using the sensors shell as its elastic sensitive element, its volume is reduced and its applications are increased, thus it can be used to measure the chamber pressures of various different caliber guns. In addition, its lower cost is helpful to promoting its applications.

A Group of Inverse Filters Based on Stabilized Solutions of Fredholm Integral Equations of the First Kind

The main cause of dynamic errors is the sensors frequency response limitation. One way of solving this problem is designing an effective inverse filter. Since the problem is ill-conditioned, a small uncertainty in the measurement will cause large deviation in reconstructed signals. The amplified noise has to be suppressed at the sacrifice of biasing in estimation. Based on stabilized solutions of Fredholm integral equations of the first kind, the paper presents a group of inverse filters from which correcting dynamic characteristics of measurement systems can be selected or optimized to reduce dynamic errors. Compared with previous work, the method has advantage of generalization. So, it is more flexible in designing inverse filters.

Quasi-Static Calibration Method of a High-g Accelerometer

To solve the problem of resonance during quasi-static calibration of high-g accelerometers, we deduce the relationship between the minimum excitation pulse width and the resonant frequency of the calibrated accelerometer according to the second-order mathematical model of the accelerometer, and improve the quasi-static calibration theory. We establish a quasi-static calibration testing system, which uses a gas gun to generate high-g acceleration signals, and apply a laser interferometer to reproduce the impact acceleration. These signals are used to drive the calibrated accelerometer. By comparing the excitation acceleration signal and the output responses of the calibrated accelerometer to the excitation signals, the impact sensitivity of the calibrated accelerometer is obtained. As indicated by the calibration test results, this calibration system produces excitation acceleration signals with a pulse width of less than 1000 μs, and realize the quasi-static calibration of high-g accelerometers with a resonant frequency above 20 kHz when the calibration error was 3%.

Triaxial Acceleration Measurement for Oblique Penetration Into Concrete Target

To obtain accurate data of the motion parameters of a rigid projectile during the oblique penetration event, a triaxial acceleration measurement device (TAMD) was developed, and a method for the calibration of a high-g accelerometer was presented by using a Hopkinson bar and a grating laser Doppler interferometer. The buffer structure was designed, and the cushioning capacity of it was studied to improve the survivability of the multichannel data recorder. A set of penetration experiments with concrete targets that had average compressive strengths of 35 and 45 MPa was conducted to characterize the response of monolithic concrete targets to projectile impact. The 96-mm-diameter 630-mm-long ogive-nose projectiles were machined from 35CrMnSiA steel and designed to contain a TAMD in the tail of the cavity. The projectiles were launched by a 100-mm-diameter smooth-bore powder gun to striking velocities between 300 and 600 m/s, and impacted the concrete target at an oblique angle of 0°-30°. The acceleration during the launch and the triaxial deceleration during the penetration were successfully recorded by the TAMD. The measured penetration data and deceleration-time data were analyzed.

Implantation Dynamic Testing and Calibration Techniques

Implantation dynamic testing (or new concept dynamic testing) is the information acquisition science within severe conditions. A definition of implantation dynamic testing is presented. The implantation dynamic testing refers to a real-time live measurement of dynamic parameters of a moving object with the main part of the testing systems located within the object being tested or in the same practical environment. A set of mathematical expressions (i.e. the conditional functions) for dynamic testing is described. The main characteristics, the main substances studied and the areas of application are presented. Since the performance of testing systems in implantation dynamic testing are strongly affected by the environment forces, general calibration methods are virtually not applicable. This paper presents three layers of calibration techniques: calibrations in simulated application environments, calibrations of environment factors, and tracing calibrations of dynamic parameters (also called quasi-sigma calibration). The last one is useful in many applications.

Correction of Signal Distortion Resulting from Measurement Systems Limitation

Abstract: A generalized method for correcting dynamic characteristics of measurement systems is presented to reduce dynamic errors. The cause of dynamic errors is the sensors frequency response limitation. One way of solving this problem is to make use of deconvolution. Since problems are ill-conditioned, a small uncertainty in the measurement will cause large deviation in reconstructed signals. The amplified noise has to be suppressed at the sacrifice of biasing in estimation. In this paper, the problem of dynamic characteristics correction is taken as solving stabilized solutions of Fredholm integral equations. Simulation result shows the validity of the method. A practical application of the method in dynamic calibration and data processing are described.

The Miniature Internal Electronic Pressure Gauge and Dynamic Calibration Method

In order to measure the chamber pressure of small caliber artilleries, a miniature internal electronic pressure gauge is designed, which adopted low power technology and miniaturization technology and storage testing technology. The working principle and the hardware design process of the gauge are described. The gauge is an intelligent pressure sensor system. The gauge is powered by battery, low power consumption, easy handling, high precision, high accuracy, and high reliability and can be reused. The gauge is used to test weapon chamber pressure which caliber greater than 57mm Dynamic calibration method based on the testing environment is proposed, the chamber pressure generator is developed; it can simulate the environments of artillery firing. Dynamic calibration system is established, the whole structure and working principle of the system is introduced. The necessity of environmental factors calibration is analyzed. The test data show that the static sensitivity coefficients and dynamic sensitivity coefficients are different. The data of the pressure gauge that have been calibrated have better stability and high confidence level. Accurate and reliable test data provides the important basis for assessing artillery, charge structure and ballistic performance.

Electrothermal-Chemical Gun Chamber Pressure Measurement System Based on Digital Optical Fiber Transmission

There were problems of strong electromagnetic interfere (EMI) and floating of ground potential when the electrothermal-chemical gun (ETCG) was launched. EMI seriously affected the chamber pressure measurement, and affected the accurateness of data and the security of apparatus. The chamber pressure testing technology was put forward which adopted the field testing technique with digital storage and the digital optical fiber transmission technique. The on-site storage pressure gauge and multilayer electromagnetic shielding structure was designed. Test data real-time transmission and remote reappear are realized by using high speed digital optical transceiver module and optical fiber. This testing technology effectively solved the EMI problem, improved the reliability and safety of chamber pressure measurement. The test data provide a basis for research of interior ballistic properties of ETCG. This testing technology can be widely applied to the parameters measurement with strong electromagnetic interfere.

Shock Calibration of the High-g Triaxial Accelerometer

This paper describes the calibration of high-g triaxial piezoresistive accelerometer for studies of normal and oblique penetrations into concrete targets. In order to determine the dynamic sensitivity, shock calibration tests were performed using a Hopkinson bar at up to 80,000 g acceleration level and the laser-grating interferometer techniques. Comparisons with the conventional calibration methods places an importance on the transverse sensitivities, influence on the acceleration measurement is impossible to disregard. The experiment of projectile penetration of hard targets was performed. The result showed that the testing signal is more accurate than emulation signal. Agreement between theory and experiment is exhibited for the projectile residual velocity and penetration depths.

Triaxial Acceleration Measurement for Oblique Penetration of a Rigid Projectile into Concrete Target

In order to obtain accurate data of motion parameters of a rigid projectile during the oblique penetration event, a triaxial acceleration measurement device (TAMD) was developed and a unique calibration method was developed by using a pneumatic gun and two sets of grating laser Doppler interferometers. A set of penetration experiments into concrete targets with average compressive strengths of 35 and 45 MPa were conducted. The 96-mm-diameter, 630-mm-long, ogive-nose projectiles were machined from 35CrMnSiA steel and designed to contain a TAMD in the tail of the cavity. The projectiles were launched by a 100-mm-diameter, smooth-bore powder gun to striking velocities between 300 and 500 m/s and impacted the concrete target at an oblique angle of 0 to 30 degrees. The acceleration during the launch and the triaxial deceleration during the penetration were recorded successfully by the TAMD. When the oblique angle changed slightly with time, the single and double integrations of axial deceleration versus time revealed accurate concurrence with the measured striking velocity and the penetration depth, respectively.