Analysis of an internal crack of pressure pipeline using ESPI and shearography

In this study, shearography and ESPI have been used for quantitative analysis of an internal crack of pipeline and both of them have proved to be suitable to qualitatively detect inside crack. However, shearography needs several critical? factors including the amount of shearing, shearing direction and induced load for the quantitative evaluation of the inside crack. In this study, the factors were optimized for the quantitative analysis and the size of cracks has been determined. Although the critical? factors in shearography have been optimized, it is difficult to determine the factors exactly because they are related to the details of cracks. On the other hand, ESPI is independent of the details of a crack and only the induced load plays an important role. The out-of-plane displacement was measured under the optimized load and the measured results were numerically differentiated, which resulted in an equivalent to the shearogram. The size of cracks can be determined quantitatively without any detail of a crack.