Design Of A Strain Measurement System For The Outer Wall Of The Gun Barrel Under High Overload Conditions

The Gun barrel is the core component of rapid-fire weapons such as artillery,and is critical to the performance and longevity of the entire system.Its main function is to launch the projectile to the bore at a certain velocity.Moreover,the movement parameters of the projectile in the bore of the Gun barrel are related to the velocity,energy and trajectory of the projectile,which are important parameters for the study of projectile firing accuracy.During operation the Gun barrel is subjected to high temperature,high pressure and other shock loads,resulting in one of the shortest life spans of the entire weapon system.Therefore,in order to ensure the safe operation of the gun,research on the remaining life of the Gun barrel and material improvement remains a key research direction.The strain data of the outer wall of the Gun barrel under the high overload environment when the projectile is fired provides data support for the study of the remaining life of the Gun barrel,material analysis and projectile motion parameters,so the study of the strain acquisition system of the outer wall of the Gun barrel is particularly important.This thesis analyzes the functional requirements and technical specifications of the strain acquisition system for the outer wall of the gun barrel under high overload environment,and completes the overall design and platform construction of the strain acquisition system for the outer wall of the gun barrel under high overload environment.In this system,the following aspects are mainly studied:1)The current status of research on gun characteristics based on Gun barrel strain and the current status of research on strain data-based acquisition system are analyzed.The current research progress of strain data-based Gun barrel life prediction,fault diagnosis and projectile bore motion parameters is mainly described,as well as the current research status of the main measurement methods of strain data-based acquisition system including contact measurement and non-contact measurement.The basic principle of strain signal acquisition technology based on resistive strain gauges is also introduced to provide theoretical support for system design;2)To realize the strain data acquisition on the outer wall of the Gun barrel,this thesis designs the strain measurement circuit for the resistive strain effect,which converts the change of resistance value into the analog voltage signal change.The signal conditioning circuit is also designed to amplify and isolate the voltage signal output from the strain measurement circuit.And in order to eliminate the influence of the curvature of the Gun barrel itself on the resistive strain gauge,the STM32+DAC is used to level the initial voltage of the acquisition system;3)In order to improve the synchronization of multi-channel strain acquisition and the overall performance of the system,the main controller is designed in the way of FPGA+ARM,which realizes the synchronous acquisition and caching of 40 channels of strain data by using the characteristics of FPGA hardware parallelism and rich number of user IO pin,and completes the storage and transmission of data and the command interaction with the upper computer by using the advantages of ARM’s high-performance and low-power easy-to-port operating system.command interaction with the host computer;4)The system software design is completed in modules,including two parts: the lower computer software and the upper computer software.In the lower computer part,the leveling software design of STM32;the multi-channel synchronous acquisition control,data caching and PCIe communication program design of FPGA;the embedded Linux system platform construction of master ARM and the PCIe communication,data storage and Ethernet communication program design based on embedded Linux system are completed respectively.For the upper computer part,the human-machine interface design of the upper computer is carried out in Lab VIEW platform using G language to realize the functions of data download,command interaction,local data storage and query,etc;5)After the above-mentioned study,the entire strain measurement system was built and a test platform was constructed to verify the functions and technical specifications of the system.The functions or performance indexes of the upper computer function,40-channel synchronization,sampling rate and micro-strain acquisition were tested separately to meet the requirements and expectations.