A high-dispersion regime of the zero-order symmetric Lamb wave mode for ultrasonic nondestructive evaluation

2012 ◽  
Author(s):  
Li-Feng Ge
Keyword(s):  
Nondestructive Evaluation ◽  
Lamb Wave ◽  
Wave Mode ◽  
Zero Order ◽  
High Dispersion ◽  
Ultrasonic Nondestructive Evaluation ◽  
Dispersion Regime

scholarly journals Application of Air-Coupled Ultrasonic Arrays for Excitation of a Slow Antisymmetric Lamb Wave

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2636 ◽  
Author(s):  
Rymantas Kazys ◽  
Almantas Vilpisauskas ◽  
Justina Sestoke
Keyword(s):  
Lamb Wave ◽  
Guided Waves ◽  
Ultrasound Velocity ◽  
Optimization Procedure ◽  
Wave Mode ◽  
Zero Order ◽  
Air Gap ◽  
Thin Plates ◽  
Low Frequencies ◽  
Excitation Method

Air-coupled excitation and reception of ultrasonic guided waves is already used for non-destructive testing and evaluation (NDT & E). Usually for air-coupled NDT & E purposes the lowest zero-order antisymmetric Lamb wave mode A0 is used, because it is most sensitive to internal defects and thickness variations. The velocity of the A0 mode is reduced with a reducing frequency and at low frequencies may become slower than the ultrasound velocity in air. Such a wave is named a slow Lamb wave. The objective of this research was the development and investigation of an air-coupled excitation method of the slow zero-order antisymmetric Lamb wave based on application of a piezoceramic ultrasonic array. We have proposed to excite the A0 mode by a planar air-coupled phased array with rectangular elements. The array is matched to the wavelength of the A0 mode in the film. Performance of such an excitation method was investigated both theoretically and experimentally. Two excitation methods of the array were analysed: when all array elements were excited simultaneously or one by one with a proper delay. In order to reduce crosstalk between array elements via the air gap, we have proposed an optimization procedure based on additional shifts of electric excitation impulses of the array elements. For experimental verification of the proposed approach a prototype of the air-coupled eight element array made of Pz-29 piezoceramic strips was manufactured. Experimental validation confirmed the possibility of exciting the slow A0 Lamb wave mode through the air gap in thin plates and films.

Determining impact induced damage by lamb wave mode extracted by EMD method

Measurement ◽  
2015 ◽  
Vol 65 ◽  
pp. 120-128 ◽  
Author(s):  
Xu Baochun ◽  
Yuan Shenfang ◽  
Wang Mulan ◽  
Qiu Lei
Keyword(s):  
Lamb Wave ◽  
Wave Mode ◽  
Emd Method

scholarly journals Wave Propagation Analysis in Composite Laminates Containing a Delamination Using a Three-Dimensional Spectral Element Method

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Fucai Li ◽  
Haikuo Peng ◽  
Xuewei Sun ◽  
Jinfu Wang ◽  
Guang Meng
Keyword(s):  
Wave Propagation ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Composite Structures ◽  
Spectral Element Method ◽  
Three Dimensional ◽  
Spectral Element ◽  
Wave Mode ◽  
Diagonal Form ◽  
Element Method

A three-dimensional spectral element method (SEM) was developed for analysis of Lamb wave propagation in composite laminates containing a delamination. SEM is more efficient in simulating wave propagation in structures than conventional finite element method (FEM) because of its unique diagonal form of the mass matrix. Three types of composite laminates, namely, unidirectional-ply laminates, cross-ply laminates, and angle-ply laminates are modeled using three-dimensional spectral finite elements. Wave propagation characteristics in intact composite laminates are investigated, and the effectiveness of the method is validated by comparison of the simulation results with analytical solutions based on transfer matrix method. Different Lamb wave mode interactions with delamination are evaluated, and it is demonstrated that symmetric Lamb wave mode may be insensitive to delamination at certain interfaces of laminates while the antisymmetric mode is more suited for identification of delamination in composite structures.

Notice of Removal: Zero TCF resonator based on S0 Lamb wave mode in AlN thin plate films

2017 ◽  
Author(s):  
Mohammed Moutaouekkil ◽  
Abdelkrim Talbi ◽  
Omar Elmazria ◽  
El Houssaine El Boudouti ◽  
Philippe Pernod ◽  
...  
Keyword(s):  
Thin Plate ◽  
Lamb Wave ◽  
Wave Mode
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