TY - GEN
T1 - Ultrasonic guided wave focusing beyond welds in a pipeline
AU - Zhang, Li
AU - Luo, Wei
AU - Rose, Joseph L.
N1 - Copyright:
Copyright 2011 Elsevier B.V., All rights reserved.
PY - 2006/3/6
Y1 - 2006/3/6
N2 - Ultrasonic guided wave inspection techniques are well-known for the inability to scan a long range axial distance of a pipe from a single transducer position. A phased array focusing technique was developed to improve the ultrasonic guided wave inspection results by concentrating the energy onto a defect. Focusing can increase the energy impinging onto the defects, reduce false alarm ratio, locate the defects, and enhance the propagation distance of the guided waves. An ultrasonic system with n (n>1) individual excitation channels is required to achieve phased array focusing. When phased array focusing was carried out, time delays and amplitude factors were applied to control the input signals for each excitation channel. Different from the time delays for bulk wave linear array focusing, the time delays and amplitude factors for guided wave array focusing are non-linear functions of the focal distance, the pipe size, excitation conditions, and the active frequency. A challenge of this technique is to focus beyond welds, defects, or other obstructions. The influence of axisymmetric welds is investigated with 3D FEM simulations and an experimental example. The theoretical analysis and experiments shows that although welds usually decrease the penetration energy, a limited number of welds rarely affects the phased array focal location.
AB - Ultrasonic guided wave inspection techniques are well-known for the inability to scan a long range axial distance of a pipe from a single transducer position. A phased array focusing technique was developed to improve the ultrasonic guided wave inspection results by concentrating the energy onto a defect. Focusing can increase the energy impinging onto the defects, reduce false alarm ratio, locate the defects, and enhance the propagation distance of the guided waves. An ultrasonic system with n (n>1) individual excitation channels is required to achieve phased array focusing. When phased array focusing was carried out, time delays and amplitude factors were applied to control the input signals for each excitation channel. Different from the time delays for bulk wave linear array focusing, the time delays and amplitude factors for guided wave array focusing are non-linear functions of the focal distance, the pipe size, excitation conditions, and the active frequency. A challenge of this technique is to focus beyond welds, defects, or other obstructions. The influence of axisymmetric welds is investigated with 3D FEM simulations and an experimental example. The theoretical analysis and experiments shows that although welds usually decrease the penetration energy, a limited number of welds rarely affects the phased array focal location.
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U2 - 10.1063/1.2184618
DO - 10.1063/1.2184618
M3 - Conference contribution
AN - SCOPUS:33845386321
SN - 0735403120
SN - 9780735403123
T3 - AIP Conference Proceedings
SP - 877
EP - 884
BT - Review of Progress in Quantitative Nondestructive Evaluation
T2 - Review of Progress in Quantitative Nondestructive
Y2 - 31 July 2005 through 5 August 2005
ER -