이중 빛 전단간섭계와 적외선열화상을 이용한 결함검출

Abstract

As the industrial site of the contemporary society becomes more high precision and high-tech, there is an increased need on the non-contact and non-destructive method, and the finite defect and corrosion of facilities and materials of the industrial site bring vast industrial and economic losses. Nondestructive testing methods with the merits of rapid response, high resolution, and manifold applications have been taken an important role to the safety diagnosis in industrial fields. Nondestructive testing(NDT) methods based on optical metrology are such as Infrared Thermography, Holography, Electronic Speckle Pattern Interferometry(ESPI), Shearography. And those can be sufficient in demand of NDT technical advance direction of present time. Laser application techniques have been applied for displacement measurement technique based on interferometer, laser based ultrasonic testing, Holography, speckle correlation interferometry etc. Particularly, speckle correlation interferometry can get the surface displacement on large area with real time, high resolution and non-contact basis, which gives the advantages in vibration analysis, deformation analysis and non-destructive testing. With computer science and image processing technology, film-based speckle correlation interferometry evolves into ESPI and Shearography, which substitute the film-based by the digitalized with CCD camera, frame grabber etc. Shearography is can measure the first derivative of surface displacement and inspect object with whole-field and non-contact. This technique has introduced to the aerospace and nuclear industry for the non-destructive testing. Recently, the advantage of Shearography that is remarkably insensitive to environmental vibration is applied to measure the strain and deformation of an object. This study proposes new modified Shearogrpahy called dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. Infrared thermography is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. Infrared thermal imaging of object is different from that of a defect, in a heated metal with an internal defect, and then location and size of a defect can be measured by the analysis of thermal imaging pattern. Infrared thermography is possible to measure long distance, and there is an advantage of high resolution by development of measurement equipment. Thus this technique can be a kind of non-contact nondestructive evaluation to apply to industrial structures, automobile and airplane etc. In this paper, defect of nuclear energy pipe and composite material were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.