The Simulation And Experimental Research On Ultrasound Infrared Lock-in Thermography For Sheet Metal Defect

Sheet metal defects are one of the main reasons for the failure which leads todamaged. So using a kind of effective nondestructive testing technology to solvesuch problems is particularly important. Ultrasound infrared lock-in thermographywhich is based on the infrared nondestructive testing method is a kind of rising testmethods. It combines the acoustics, mechanics of elasticity, infrared physics andcomputer technology. This technology is expected to realize the sheet metal defectsquickly and accurately measure.According related researcher’s researching progress in ultrasound infraredlock-in thermography, this paper explains detection principle of this method，andanalyses the selective heating characteristics when ultrasonic incentive componentinternal defects. Then this paper used the basic principle of elastic theory, contactdynamics and heat transfer theory to analyze theoretically ultrasonic incentive forsheet metal contacting interface-type defects heat process. sound-mechanical-heatenergy coupling model, that ultrasonic incents contact interface defects of sheetmetal to get hot, is set.Secondly, using finite element software ANSYS, we establish the simulationmodel that the amplitude modulation ultrasonic incent surface crack defects of sheetmetal to heat. And according to relevant algorithm, we use MATLAB software toextract the amplitude and phase information of the simulation results. Through theabove work, we realize the ultrasound infrared lock-in thermography to detectsurface crack defects of sheet metal. Using the above simulation method, we get theinfluence of the test results in the different characteristics of the materials and thedifferent modulation ultrasonic incentive parameters such as loading positions,initial static pressure and modulation frequency.Finally, prefabricated surface crack defects of the sheet metal aresystematically tested by using the inspecting system of ULT. Not only the influenceof the test results influenced by the main test parameters is obtained, but also thesound-mechanical-heat energy coupling model and the simulation model areverified correctly. Further more, ultrasonic infrared lock-in thermography to detectsheet metal internal defects is researched on the simulation analysis and experiment.