Directivity profiles of ultrasonic guided wave phased arrays for multilayer composite plates

2009 ◽  
Author(s):  
Fei Yan ◽  
Cliff J. Lissenden ◽  
Joseph L. Rose
Keyword(s):  
Phased Arrays ◽  
Composite Plates ◽  
Guided Wave ◽  
Multilayer Composite ◽  
Ultrasonic Guided Wave

Time delay comb transducers for aircraft inspection

2009 ◽  
Vol 113 (1144) ◽  
pp. 417-427 ◽  
Author(s):  
F. Yan ◽  
J. L. Rose
Keyword(s):  
Time Delay ◽  
Material Properties ◽  
Poynting Vector ◽  
Composite Plates ◽  
Guided Wave ◽  
Plate Structures ◽  
Reinforced Composite ◽  
Ultrasonic Guided Wave ◽  
Wave Technique ◽  
Skew Angles

Abstract An ultrasonic guided wave technique based on time delay comb transducers is introduced for aircraft inspection. It is demonstrated that for isotropic plate structures the time delay comb transducers with appropriate excitation are capable of performing discontinuity detections without knowing the precise isotropic material properties of the objects being inspected. Fibre-reinforced composite plates are also considered. The wave skew effects are investigated using both the slowness curve and the Poynting vector. A composite inspection technique that takes advantage of the skew effects is proposed. Using time delay comb transducers to excite the guided wave modes with different skew angles, the proposed technique is capable of scanning the composite plate in different directions without moving or rotating the transducers. By contrast with the applications in the isotropic cases, knowledge of the material properties and other necessary information that is needed to produce dispersion curves is generally required. Experimental results are provided as a validation of the proposed techniques.

EXPERIMENTAL NON-CONTACT EVALUATION OF DELAMINATION IN CFRP COMPOSITE PLATES BY LASER GENERATION/AIR-COUPLED DETECTION ULTRASONIC SYSTEM

2008 ◽  
Vol 22 (11) ◽  
pp. 827-832
Author(s):  
SEUNG-JOON LEE ◽  
JOON-HYUN LEE ◽  
JOON-HYUNG BYUN
Keyword(s):  
Composite Plates ◽  
Guided Wave ◽  
Laser Generation ◽  
Near Surface ◽  
Fiber Placement ◽  
Ultrasonic Guided Wave ◽  
Cfrp Composite ◽  
Automated Fiber Placement ◽  
Surface Delamination ◽  
532 Nm

The objective of this research is to develop non-contact and real time inspection technique based on laser generated ultrasound for evaluating near-surface delamination in Carbon/Epoxy composite fabricated from automated fiber placement system. In this study, A hybrid laser generation/air-coupled detection ultrasonic system for detection and visualization of delamination in composite plates with simulated delamination of the area of 20 mm × 20 mm between the first and the second layer. Optical fiberized Nd :YAG pulse laser (532 nm, 32 mJ) with linear slit array is used to generate ultrasonic guided wave in unidirectional CFRP specimen (24 plies, 2.85 mm thickness). The characteristic of time domain waveform and frequency spectrum of guided wave is discussed. Two- dimensional images are obtained from these characteristics. The convergence of received signal using the pitch-catch and the scattering-reflection technique is discussed.

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%.

scholarly journals Phase-delayed laser diode array allows ultrasonic guided wave mode selection and tuning

2013 ◽  
Vol 113 (14) ◽  
pp. 144904 ◽  
Author(s):  
Pasi Karppinen ◽  
Ari Salmi ◽  
Petro Moilanen ◽  
Timo Karppinen ◽  
Zuomin Zhao ◽  
...  
Keyword(s):  
Laser Diode ◽  
Mode Selection ◽  
Wave Mode ◽  
Guided Wave ◽  
Diode Array ◽  
Laser Diode Array ◽  
Ultrasonic Guided Wave
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