Research On Defect Detection Technology Of Pressure Equipment Based On Infrared Thermal Wave

With the development and progress of industrial production,the demands for safety production and operation have been improved.The pressure equipment which is widely used in industrial production is a major focus of security.As a new nondestructive testing technology,infrared thermal wave is becoming more and more widely concerned,studied and used in industrial manufacturing.However,the research on the surface defects and subsurface defects of the pressure equipment is not mature.For the detection of subsurface defect,a fast and efficient method of qualitative detection and quantitative analysis is urgent and meaningful.Surface defects have been studied by scholars,but the research on the visualization of defects is not enough.This paper is based on the infrared thermal wave.The characteristics of subsurface defects and surface defects are studied respectively,and their respective detection methods are proposed.The main contents of this paper are as follows:(1)Based on the theory of infrared thermal wave and the theory of finite element analysis,the thermal response simulation of subsurface defects and surface defects is carried out,which provides a theoretical basis for the detection of defects.(2)For the subsurface defects,the "logarithmic domain normalization method" quantitative detection and "time domain square root" qualitative analysis are proposed.First,subsurface defects are detected based on the "logarithmic domain normalization" method.Then,the quantitative analysis of the defect depth is carried out based on the "time domain square root" qualitative analysis method.According to the transmission characteristics of infrared thermal wave,the linear relationship between the defect depth and the difference zero point is obtained.(3)For the detection of surface defects,the "ICA thermal region separation algorithm" is adopted.First,the eddy current distribution and heat transfer characteristics are analyzed.Furthermore,the correlation of defect specimens is analyzed,and the weak correlation between defective area and non defective region is obtained through experiments.Based on the above mechanism,the problem is modeled,and a thermal region separation algorithm based on ICA is adopted.The algorithm of ICA thermal region separation includes the construction of observation matrix,albinism process and separation of independent regions.It can separate the different thermal response regions well.(4)In order to improve the effect of surface defect detection,a "PCNN thermal region fusion algorithm based on wavelet transform" is proposed.In order to fuse the thermal separation area from different contrast functions,a fusion algorithm based on PCNN is adopted.In order to improve the fusion effect,the low-frequency thermal region is extracted by wavelet transform.Finally,experiments verify the effectiveness of the "PCNN thermal region fusion algorithm based on wavelet transform".To sum up,the test method is designed for the surface defects and subsurface defects of the pressure equipment,and the experimental verification is carried out and the experimental results are basically consistent with the theory.Although the research conditions are limited,the types of defects discussed are limited,but the analysis theory and the method have reference value for other defects of the pressure equipment,so the research in this paper is of great significance.