Ho-Seob Chang

Residual Stress Measurement of Flat Welded Specimen by Electronic Speckle Pattern Interferometry

Abstract The size and distribution of welding residual stress and welding deformation in welding structures have an effect on various sorts of damage like brittle failure, fatigue failure and stress corrosion cracking. So, research for this problem is necessary continuously. In this study, non-destructive technique using laser electronic speckle pattern interferometry, plate of welding specimen according to the external load on the entire behavior of residual stress are presented measurement techniques. Once, welding specimen force tensile loading, using electronic speckle pattern interferometry is measured. welding specimen of base metal and weld zone measure strain from measured result, this using measure elastic modulus. In this study, electronic speckle pattern interferometry use weld zone and base metal parts of the strain differences using were presented in residual stress calculated value, This residual stress value ​were calculated by numerical calculation. Consequently, ​weld zone of modulus high approximately 3.7 fold beside base metal and this measured approximately 8.46 MPa.

Evaluation of Residual Stress on Pipe Welded Joints Using Laser Interferometry

Residual stresses that occur during the welding process, are the main cause of failure and defects in welded structures. This paper, presents the use of an electronic processing laser speckle interferometer to measure the residual stress of a welded pipe for a nuclear power plant. A tensile testing machine was used to evaluate a welded pipe that failed in compression. The inform plane deformation and modulus of elasticity of the base metal and welds were measured using an interferometer. Varying the load on the welded pipe had a larger effect on the deformation of the base metal the other properties of the base metal and welds. The elastic moduli of the base metal and weld of the welded pipe were 202.46 and 212.14 GPa, respectively, the residual stress was measured to be 6.29 MPa.

Method for Measuring Weld Temperature Using an Infrared Thermal Imaging Camera

In this paper, a method is tested to measure temperatures in high-temperature welds. Protective glass was installed between an infrared thermal imaging camera and a heat source, and temperature compensation was applied to the measuring instruments. When the temperature of halogen lamps was taken in real-time and measured by the thermal camera, the temperature was found to be almost invariant with the distance between the camera and heat source. The temperature range could be predicted, through correlations with the thickness of the protective glass and the measured distance. This study suggests that the temperature measurement of welds obtained by using an infrared thermal imaging camera is valid, through experimental testing of heat sources.

Defect Depth Measurement of Straight Pipe Specimen Using Shearography

Abstract In the nuclear industry, wall thinning defect of straight pipe occur the enormous loss in life evaluation and safety evaluation. To use non-destructive technique, we measure deformation, vibration, defect evaluation. But, this techniques are a weak that is the measurement of the wide area is difficult and the time is caught long. In the secondary side of nuclear power plants mostly used steel pipe, artificiality wall thinning defect make in the side and different thickness make to the each other. wall thinning defect part of deformation measure by using shearography. In addition, optical measurement through deformation, vibration, defect evaluation evaluate pipe and thickness defects of pressure vessel is to evaluate quantitatively. By shearography interferometry to measure the pipes internal wall thinning defect and the variation of pressure use the proposed technique, the quantitative defect is to evaluate the thickness of the surplus. The amount of deformation use thickness of surplus prediction of the actual thickness defect and approximately 7 percent error by ensure reliability. According to pressure the amount of deformation and the thickness of the surplus through DB construction, nuclear power plant pipe use wall thinning part soundness evaluation. In this study, pressure vessel of thickness defect measure proposed nuclear pipe of wall thinning defect prediction and integrity assessment technology development. As a basic research defected theory and experiment, pressure vessel of advanced stability and soundness and maintainability is expected to contribute foundation establishment.