شماره ركورد كنفرانس :
4862
عنوان مقاله :
Detection and discrimination of symmetric and asymmetric defects by using ultrasonic guided waves
عنوان به زبان ديگر :
Detection and Discrimination of Symmetric and Asymmetric Defects by using Ultrasonic Guided Waves
پديدآورندگان :
Asgari Mojtaba mojtaba.asgari1991@gmail.com MSc studentc, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, , Honarvar Farhang honarvar@kntu.ac.ir Professor, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, , Eshraghi Mortaza eshraghimortaza@yahoo.com MSc studentc, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, , Tabatabaeipour Morteza s.m.tabatabaeipour@gmail.com Research Associate, Faculty of Mechanical Engineering K. N. Toosi University of Technology,
كليدواژه :
Ultrasonic guided waves , Longitudinal L(0,2) mode , Mode conversion , axisymmetric excitation.
عنوان كنفرانس :
پنجمين كنفرانس بين المللي آزمون هاي غير مخرب ايران
چكيده فارسي :
Several methods are currently being used for nondestructive evaluation of pipelines. In the last few years, ultra-sonic guided waves have received much attention as a tool for inspection of oil and gas pipelines. This is due to the capability of these waves in propagating over long distances with little energy loss. In this paper, the possibil-ity of detection of pipe defects, such as grooves and holes, is investigated using an array of angle-beam trans-ducers. Identification of guided wave modes is done by means of a 2-D FFT analysis. The analysis demon-strates that the asymmetric excitation leads to generation of longitudinal L(0,2) mode in addition to the undesir-able flexural modes that make the interpretation of results difficult. In order to eliminate the undesirable flexur-al modes and to increase the amplitude of the longitudinal L(0,2) mode, the pipes were excited by axisymmetric guided waves. The results showed that the axisymmetric discontinuities, e.g. axisymmetric grooves, can be dis-tinguished from asymmetric defects, e.g. a hole, by checking the mode conversions that take place in each case.
چكيده لاتين :
Several methods are currently being used for nondestructive evaluation of pipelines. In the last few years, ultra-sonic guided waves have received much attention as a tool for inspection of oil and gas pipelines. This is due to the capability of these waves in propagating over long distances with little energy loss. In this paper, the possibil-ity of detection of pipe defects, such as grooves and holes, is investigated using an array of angle-beam trans-ducers. Identification of guided wave modes is done by means of a 2-D FFT analysis. The analysis demon-strates that the asymmetric excitation leads to generation of longitudinal L(0,2) mode in addition to the undesir-able flexural modes that make the interpretation of results difficult. In order to eliminate the undesirable flexur-al modes and to increase the amplitude of the longitudinal L(0,2) mode, the pipes were excited by axisymmetric guided waves. The results showed that the axisymmetric discontinuities, e.g. axisymmetric grooves, can be dis-tinguished from asymmetric defects, e.g. a hole, by checking the mode conversions that take place in each case.
