High Frequency Guided Wave Natural Focusing Pipe Inspection With Frequency and Angle Tuning

2005 ◽  
Vol 128 (3) ◽  
pp. 433-438 ◽  
Author(s):  
Li Zhang ◽  
Brian J. Gavigan ◽  
Joseph L. Rose
Keyword(s):  
High Frequency ◽  
Length Change ◽  
Guided Wave ◽  
Detection Sensitivity ◽  
Frequency Variation ◽  
Axial Distance ◽  
Focal Points ◽  
Wave Interference ◽  
Ultrasonic Guided Wave ◽  
Wave Sensitivity

When ultrasonic guided wave nondestructive evaluation is used to inspect pipelines, partial loading of transducers around the circumference leads to a non-axisymmetric energy distribution. At particular axial distances and frequencies, the ultrasonic energy is naturally focused at some spots via constructive wave interference. This so-called “natural focusing” phenomenon can be used to improve guided wave sensitivity for a defect by impinging more energy onto it. However, defects located in other places can be missed, unless we can move the natural focusing points throughout the pipe. We have done this by frequency and circumferential angle tuning for specific circumferential loading lengths. In order to utilize the natural focusing phenomenon to enhance detection sensitivity, a frequency and angle tuning (FAT) technique is employed to extend the area that can be scanned by focal energy. It is observed that the natural focal points at a fixed axial distance move with frequency variation and circumferential excitation length change. In this paper, the natural focusing phenomenon with FAT is theoretically calculated and experimentally investigated. The results show that the natural focusing inspection technique can sufficiently inspect an entire pipe with FAT.

Long Range Guided Wave Natural Focusing Pipe Inspection

2006 ◽  
Author(s):  
Li Zhang ◽  
Joseph L. Rose ◽  
Jing Mu ◽  
Steven E. Owens
Keyword(s):  
Long Range ◽  
Length Change ◽  
Guided Wave ◽  
Detection Sensitivity ◽  
Frequency Variation ◽  
Axial Distance ◽  
Wave Interference ◽  
Ultrasonic Guided Wave ◽  
Inspection Data ◽  
Wave Sensitivity

Long range ultrasonic guided wave nondestructive evaluation can be used to inspect pipelines over fairly long distances. Partial loading of transducers around the circumference leads to a non-axisymmetric energy distribution. At particular axial distances and frequencies, the ultrasonic energy is naturally focused at some spots around the circumference via constructive wave interference. This so called “natural focusing” phenomenon can be used to improve guided wave sensitivity for a defect since more energy is sent to the defect. However, defects located in other places could possibly be missed, unless we can move the natural focusing points throughout the pipe. We have done this by frequency and circumferential angle tuning for specific circumferential loading lengths. In order to utilize the natural focusing phenomenon to enhance detection sensitivity, a frequency and angle tuning (FAT) technique is employed to extend the area that is scanned by focal energy. It is observed that the natural focal points at a fixed axial distance move with frequency variation and circumferential excitation length change. In this paper, the natural focusing phenomenon with FAT is theoretically calculated and experimentally investigated. The results show that the natural focusing inspection technique can sufficiently inspect an entire pipe with FAT. Some sample inspection data is compared by applying axisymmetric excitations, FAT, and phased array focusing.

Исследование применимости при контроле дефектов высокочастотных мод направленных волн с помощью фазированных решеток

2021 ◽  
pp. 27-34
Author(s):  
М.Дж. Ранджбар ◽  
Сина Содагар
Keyword(s):  
High Frequency ◽  
Phased Array ◽  
Surface Defects ◽  
Steel Plate ◽  
Small Diameter ◽  
Guided Wave ◽  
Scanning Method ◽  
Ultrasonic Guided Wave ◽  
Array Transducer ◽  
Ultrasonic Phased Array

An ultrasonic phased array scanning method was used for lamb wave evaluation of surface and in-depth defects in a steel plate. The ultrasonic guided wave modes resulting from a phased array transducer were modeled using finite element method. The experimental results showed that the high-frequency A0 mode gives acceptable sensitivity and resolution for small diameter through-thickness and surface defects. The sectorial scanning showed better axial resolution rather than spatial resolution.

scholarly journals Ultrasonic guided wave detection of U-shaped pipeline

2020 ◽  
Vol 309 ◽  
pp. 03035
Author(s):  
Longxiang Zhu ◽  
Guangming Kong ◽  
Haibing Zhang ◽  
Xiangyang Yu
Keyword(s):  
Density Distribution ◽  
Cross Section ◽  
Energy Flow ◽  
Guided Waves ◽  
Signal Amplitude ◽  
Guided Wave ◽  
Detection Sensitivity ◽  
Experimental Result ◽  
Flow Density ◽  
Ultrasonic Guided Wave

The guided waves in the elbow was analyzed using semi- analytical finite element method, which was used to calculate the dispersion curves, along with the vibration deformation and energy flow density distribution of the elbow cross-section. The L(0,1) mode guided wave was used to detect different defects in the U-shaped pipeline in experiment. The average experimental velocity of L(0,1) mode in U-shaped pipeline was between the theoretical velocities of the straight pipe and the elbow, due to the different velocities in the two parts. The detection sensitivity difference of L(0,1) mode guided wave to defects in intrados and extrados of the elbow was analyzed, the experimental result showed that the reflected signal amplitude of defect in extrados was significantly larger than the defect in intrados, which was consistent with the energy flow density distribution in elbow cross-section.

Ultrasonic unilateral double-position excitation lamb wave defect detection and quantification method for ground electrode of transmission tower

2021 ◽  
pp. 1-15
Author(s):  
Kuan Ye ◽  
Kai Zhou ◽  
Ren Zhigang ◽  
Ruizhe Zhang ◽  
Chunsheng Li ◽  
...  
Keyword(s):  
Guided Waves ◽  
Power Transmission ◽  
Geometric Model ◽  
Guided Wave ◽  
Quantization Error ◽  
Dispersion Function ◽  
Stable Operation ◽  
Transmission Tower ◽  
Ultrasonic Guided Wave ◽  
Transmission Towers

The power transmission tower’s ground electrode defect will affect its normal current dispersion function and threaten the power system’s safe and stable operation and even personal safety. Aiming at the problem that the buried grounding grid is difficult to be detected, this paper proposes a method for identifying the ground electrode defects of transmission towers based on single-side multi-point excited ultrasonic guided waves. The geometric model, ultrasonic excitation model, and physical model are established, and the feasibility of ultrasonic guided wave detection is verified through the simulation and experiment. In actual inspection, it is equally important to determine the specific location of the defect. Therefore, a multi-point excitation method is proposed to determine the defect’s actual position by combining the ultrasonic guided wave signals at different excitation positions. Besides, the precise quantification of flat steel grounding electrode defects is achieved through the feature extraction-neural network method. Field test results show that, compared with the commercial double-sided excitation transducer, the single-sided excitation transducer proposed in this paper has a lower defect quantization error in defect quantification. The average quantization error is reduced by approximately 76%.

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