Design And Implementation Of DCPD Crack Growth Rate Real-time Monitoring System

It is one of the important experiment to obtain the stress corrosion cracking growth rate in an autoclave simulated the high temperature and high pressure water environment of the nuclear power equipment in the nuclear structural materials selection and safety evaluation.Due to the particularity of autoclave environment,there are relatively few means to monitor crack growth rate in real-time,and Direct Current Potential Drop method(DCPD)is widely in the crack propagate monitor in this kind experiment.Crack growing monitoring instruments based DCPD method relies on import and it is very expensive.Adopting an independently designed crack growth rate monitoring system,based on the DC potential drop method,combined with weak signal amplification and anti-interference technology.The integrated system and localization of the crack growth rate real-time monitor in the autoclave environment based on the DCPD method were carried out in this paper.The main works and achievements are as follows:(1)Based on the analysis of the basic principle and application status of the DC potential drop technology,the main factors affecting the accuracy of crack growth monitoring were identified,and the scheme design of the crack growth rate real-time monitor system based on the flip DC potential drop technology was performed,as well as the hardware module selection and circuit.To design other work,building and gradually improve the monitoring system experimental platform.(2)The embedded system based on ARM and the software Labwindows/cvi based on STM32 are designed to build a crack monitoring system.Completed the hardware design of the circuit of the lower computer,including the minimum system circuit based on STM32F4,power supply circuit,weak signal detection circuit,communication circuit,signal source auxiliary circuit,etc.At the same time,using Keil MDK platform to write a test based on UCOSIII multitask real-time operating system Code,using Labwindows/cvi virtual instrument development platform to complete the software design and development of the host computer software,and realize the control of the test system by the host computer.(3)Based on the measured data of imported general-purpose instruments,the results of numerical simulation experiments and the measured data of the monitoring system developed in this paper,a reasonable interference suppression technology was researched and developed,and the digital filter technology was used to optimize the performance of the instrument and improve the reliability of the instrument and accuracy.(4)Developed a real-time crack growth rate monitor based on the flip-flop DC potential drop technology and performed laboratory calibration tests,and the machine could reach the microvolt level.For instance,the 0.5t-ct sample,the crack monitoring resolution could reach 0.1mm,it has met the testing needs of crack monitoring instruments.