Study On Key Problems For Application Of Ultrasonic Actuator In Fuze Safety System

Ultrasonic actuator is a novel electromechanical energy converter based on the inverse epiezoelectric effect of piezoelectric materials.Compared with the traditional electromagnetic motor,the ultrasonic actuator has the merits of flexible design concept and compact structure;quick response;self-locking without power;low speed and large torque;excellent EMC characterstics.The development of ultrasonic actuator promotes the continuous development of related fields.Also,with the revolution in military affairs and changes in the war form,the fuze safety system has a trend towards inforamtion and miniaturization to satisfy the informatization and intelligence of the battlefield.The development of fuze technology can closely follow new technology development trends and continually innovates itself to form its own characteristics with excellent compatibility.Ultrasonic actuator is a good candidate as an actuator in the SAD(safety and arming device)due to its advanced design concept and unique operating mechanism.It can be practical for the improving the controllability of the muzzle safe distance,reversible changing of the fuze safe state and self locking,the realization of modularization and iuniversality of fuze.The design theory and method of ultrasonic actuator applied in the SAD must be further discussed because their research and applications are still in their initial stages by now.Especially,the higher requirement of ultrasonic motor are put forward due to the shock environment,one of the typical fuze environment.How to design a suitable ultrasonic motor for the SAD as well as the research of the performance changes of ultrasonic motor in shock environment have become an urgent problem.A dynamic model of rotary ultrasonic actuator in shock environment is established considering the typical environment of fuse.The failure modes of rotary ultrasonic actuator are summarized based on its structural characteristics.The dynamic behavior of ultrasonic actuator in different shock environment is studied.The impact test and protect experiment are conducted to analyze the influence of shock environment on mechanical characteristic of ultrasonic motor,which is the foundation of rotary ultrasonic actuator applied in the fuze safety system.An H-shaped ultrasonic actuator and the corsponding SAD are designed and proposed.The working mode and operating mechanism of the H-shaped ultrasonic actuator are analyzed.The finite element method is used to determine the structural size and operating frequency of the actuator.Finally,the impedance characteristics,vibration characteristics and mechanical output characteristics of the actuator are tested,which verifies the feasibility to apply it in fuze.The H-shaped ultrasonic actuator has the characteristics of simple,stable,particle and reliable.It can realize the state transition between safety state and arming state quickly,which is suitable for safety and arming device.The influence of shock environment on H-shaped ultrasonic actuator is studied.The stress distribution of H-shaped ultrasonic actuator in shock environment was analyzed with finite element method,and the performance of H-shaped ultrasonic actuator before and after shock was compared experimentally.Though the impact results in the performance decline of H-shaped ultrasonic actuator,the actuator can still work but by raising the voltage.The damage of H-shaped actuator in shock environment is analyzed qualitatively and quantitatively based on electro-mechanical impedance method.Take the resonant frequency,effective electromechanical coupling coefficient and equivalent electrical parameters as the research object to analyze the reasons of the performance degradation of the H-shaped piezoelectric actuator in shock environment.The result shows that the H-shaped ultrasonic actuator can withstand the shock environment generated by launching weapons compared with traditional ultrasonic actuator,making sure that safety and arming device can work normally.In order to utilize the single-electrode in piezoelectric element of ultrasonic actuator,a novel concept by extracting and analyzing the signal from single-electrode in ultrasonic actuator to realize fuze environmental identification is proposed.The theoretical model of single-electrode in shock environment is established by simplifying the stator.The experiment result shows that the output single from single-electroderesearch is in good linear relationship with the acceleration.The composition of single-electrode is analyzed and a suitable filter is designed to improve the linear putput characterstics of single-electrode in shock environment.The method further expands the function of single-electrode and can confirm the environment of fuze,providing a new method for fuze environment identification.This study verifies the feasibility and provides the research foundation of ultrasonic actuator applied in the fuze safety system.