| Overload parameters are important indicators for evaluating the working status of ammunition during launch and penetration.Accurate measurement of overload parameters is conducive to the development and optimization of kinetic energy damage ammunition,and is of great significance to the development of national defense.Serial-launched projectiles withstand complex propellant gas pressure in the bore and have limited space on the projectile.The warhead is repeatedly subjected to high shock and vibration and high overload during the penetration of multi-layer targets.Existing test systems are difficult to reliably measure the overload parameters of above-mentioned ammunition under serial launch and penetration environments.Therefore,it is necessary to develop miniaturized,high-performance,high-overload resistance on-board measurement system with good environmental adaptability.In order to improve the accuracy of the system’s measurement of overload parameters,the actual static and dynamic characteristics and working performance of the test system need to be assessed.A measurement result with measurement uncertainty has an essential reference value for ammunition design because uncertainty reflects the quality of test results.Therefore,it is necessary to research the experimental method of evaluating the static and dynamic characteristics of the measurement system,and research the uncertainty evaluation method of the measurement results.Based on the above considerations,this article combines theoretical analysis,numerical simulation,and experiment to research the launch and penetration overload measurement method,measurement system design method,system performance evaluation method,and measurement uncertainty evaluation method for typical ammunition(serial launch projectiles and penetration warhead).The main work of this paper is as follows:(1)Aiming at the problems that the typical ammunition withstands complex forces in harsh environments and its overload parameters are difficult to acquire,methods for launch and penetration overload parameters measurement are studied.Based on the analysis of the physical process of serial launch and multilayer target penetration,the interior ballistic model and squeeze simulation model of the serial-launched projectile,and the simulation model of multilayer penetration are established,respectively.The variation and characteristics of the acceleration,the bottom and the front pressure,and the squeezing resistance of the serial launched projectile,the penetration acceleration and the explosive stress are comprehensively analyzed.Based on the analysis of the testability of the parameters,the feasibility of the measurement method,and the peculiarities of the on-board measurement,storage measurement methods for the overload parameters of ammunition are proposed.The overall measurement schemes are designed.(2)In view of the limited space in the serial-launched projectiles and the overload parameters of the projectiles cannot be measured by standard sensors,a composite pressure sensor based on polyvinylidene fluoride(PVDF)piezoelectric film is designed.The working principle of the sensor in the state of static and transmission overload is analyzed,and the working model of the force-electric conversion of the sensor is deduced.The adaptability of the sensor to the in-bore environment is researched,and theoretical analysis and simulation methods are used to prove the sensor’s ability to suppress the impact stress of gunpowder particles as well as to seal propellant gas,and prove the sensor’s insensitivity to high thermal loads in the bore.The mathematical model of the sensor is established,and the influences of the sensor’s structural parameters on the static and dynamic characteristics is researched by numerical calculation.A method for optimizing sensor’s structure parameters combined with artificial neural network and genetic algorithm is proposed,which improves the natural frequency and nonlinearity of the sensor significantly.(3)Aiming at the problem of lack of reliable overload parameter measurement device for the two typical ammunitions,special measurement systems are designed,and some anti-overload methods for the systems are researched.The working software of the system based on negative delay internal trigger,real-time acquisition and storage,and data protection mechanism are designed.A control mechanism,which combines STM32,real-time clock and power management chip,is proposed to improve the reliability of the on-board measurement system.The installation and protection mechanical structures for the measurement systems are designed,and the rationality of the structure is verified based on finite element simulation.An anti-overload method of the measurement system is proposed based on circuit board structure design,vibration isolation buffer and potting protection,and the effectiveness of the anti-overload method is verified through theoretical analysis and finite element simulation.(4)Experimental methods are researched to verify the characteristics of the measurement system.Aiming at the problem that the piezoelectric composite pressure sensor is not suitable for static calibration,a quasi-static calibration method based on the falling weight device is proposed.The mechanical structure of the sensor and the calibration device are improved.The static characteristic parameters of the composite pressure measurement system such as sensitivity,linearity and repeatability are calculated based on the results from the calibration experiment.Aiming at the problem that the inertial force response of the composite sensor in an overload state affects the accuracy of pressure measurement,a theoretical model and a model based on generalized least squares system identification for inertial force correction are established respectively.An experimental method of acceleration loading based on artillery launch is proposed,which improves the accuracy of the system identification modeling.The inertial force correction results of the two models are compared and analyzed,and the correction effect of the system identification method is found to be better.The experimental research on the dynamic characteristics of the composite sensor based on the air shock tube is carried out.The amplitude-frequency characteristics and natural frequency of the sensor are obtained,which show that the dynamic characteristics of the sensor accomplish undistorted measurement of the dynamic pressure.An impact hammer loading experiment method is proposed to verify the performance of the penetration overload measurement system,which proves the effectiveness of the system to measure the explosive stress.(5)The assessment test and measurement uncertainty analysis of the measurement system are carried out.The structural strength and anti-overload capability of the measurement system are verified through the shooting experiment.The measurement result is compared with the auxiliary test result and the simulation result,and its correctness is verified.Based on the measurement models of pressure,acceleration,and explosive stress,suitable measurement uncertainty analysis models are established.The influencing factors of measurement uncertainty are analyzed,and GUM method and Monte Carlo method are selected reasonably,and the measurement uncertainty of overload parameters is evaluated. |
