Study On Identification Of Weld Crack Of Steel Structure Based On Electromagnetically Excitation Infrared Thermography

Weld surface crack in steel structures is the most common and dangerous damage forms,it often initiation in weld of stress concentration,Non-destructive testing and evaluation(NDT&E)is important to the safety and reliability of Weld in steel structures and equipment.The major advantage of pulsed eddy current Thermography is the potential in accurate non-contact inspection of a large with a short time and high efficiency excitation.Steel weld surface crack detection by Electromagnetically excitation Infrared thermography.This thesis analyze the influence of the weld surface by test and finite element simulation;following the achievements,a novel image fusion method using mathematical morphology and automatic region growing a method for surface crack detection based on comparability determination of 3D temperature surface is proposed,it has an important value of weld crack detection.The main contributions are:(1)Introduces the fundamentals of Electromagnetically excitation Infrared thermography technology.Through verified experiment and COMSOL Multiphysics finite element simulation,the effect of surface emisssivity,the weld reinforcement,rough surfaces of the weld,various crack and directions is considered,which provides fundamental support for the surface crack effectively identify and quantitative.(2)A novel image fusion method using mathematical morphology and automatic region growing is proposed to reduce the effect of emissivity variation and extract the crack.(3)A method for surface crack detection based on comparability determination of 3D temperature surface is proposed to quantitative identification of Weld surface crack characteristics.(4)The test platform is set up,design different welding structure with various crack and directions.It is verified that a novel image fusion method using mathematical morphology and automatic region growing,a method for surface crack detection based on comparability determination of 3D temperature surface.Through the above research,crack identification is comprehension verified in steel structures of weld surface crack recognition,the research on benefit pushes pulsed eddy current thermography development in the field of weld surface crack detection.