Laser vibrometry of air-coupled Lamb waves

2005 ◽  
Vol 47 (3) ◽  
pp. 123-128 ◽  
Author(s):  
Igor Solodov ◽  
Klaus Pfleiderer ◽  
Gerhard Busse
Keyword(s):  
Lamb Waves ◽  
Laser Vibrometry

2-Dimensional Visualizations of Lamb Waves Interaction With a Notch in a Bovine Cortical Tibia

2008 ◽  
Author(s):  
Manik Hapsara
Keyword(s):  
Lamb Waves ◽  
Optical Detection ◽  
Cortical Layer ◽  
Detection Technique ◽  
Scanning Laser ◽  
Laser Vibrometry ◽  
Waves Interaction ◽  
Scanning Laser Vibrometry

The objectives of this study are to observe the behavior of Lamb waves upon encountering a defect in a bone and to provide 2-d visualizations of the process. For this purposes, measurements were conducted using a non-contact optical detection technique, scanning laser vibrometry. This technique produces 2-d graphics of the Lamb waves in the cortical layer of the bone.

A comparison of 1D and 3D laser vibrometry measurements of Lamb waves

2010 ◽  
Author(s):  
Eric D. Swenson ◽  
Hoon Sohn ◽  
Steven E. Olson ◽  
Martin P. Desimio
Keyword(s):  
Lamb Waves ◽  
Laser Vibrometry

scholarly journals Damage detection in a composite wind turbine blade using 3D scanning laser vibrometry

2016 ◽  
Vol 231 (16) ◽  
pp. 3024-3041 ◽  
Author(s):  
Ryan Marks ◽  
Clare Gillam ◽  
Alastair Clarke ◽  
Joe Armstrong ◽  
Rhys Pullin
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Structural Integrity ◽  
Lamb Waves ◽  
Turbine Blades ◽  
3D Scanning ◽  
Scanning Laser ◽  
Laser Vibrometry ◽  
The Impact ◽  
Scanning Laser Vibrometry

As worldwide wind energy generation capacity grows, there is an increasing demand to ensure structural integrity of the turbine blades to maintain efficient and safe energy generation. Currently, traditional non-destructive testing methods and visual inspections are employed which require the turbine to be out-of-operation during the inspection periods, resulting in costly and lengthy downtime. This study experimentally investigates the potential for using Lamb waves to monitor the structural integrity of a composite wind turbine blade that has been subject to an impact representative of damage which occurs in service. 3D scanning laser vibrometry was used to measure Lamb waves excited at three different frequencies both prior to, and after, impact to identify settings for an optimal system. Signal processing techniques were applied to the datasets to successfully locate the damage and highlight regions on the structure where the Lamb wave was significantly influenced by the presence of the impact damage. Damage size resulting from the impact was found to correlate well with the laser vibrometry results. The study concluded that acousto-ultrasonic-based structural health monitoring systems have great potential for monitoring the structural integrity of wind turbine blades.

Laser Vibrometer Imaging of Delamination Interaction with Lamb Waves Using a Chirp Excitation Method

2017 ◽  
Vol 754 ◽  
pp. 375-378 ◽  
Author(s):  
Ifan Dafydd ◽  
Zahra Sharif Khodaei
Keyword(s):  
Guided Waves ◽  
Lamb Waves ◽  
Laser Doppler Vibrometer ◽  
Composite Panel ◽  
Chirp Signal ◽  
Laser Vibrometry ◽  
Post Processing ◽  
Frequency Range ◽  
Narrowband Signal ◽  
Excitation Method

One method that has shown great potential in visualising and characterising the interaction of guided waves with damage in composites is Laser Vibrometry. A Laser Doppler Vibrometer (LDV) can be used to produce 2D wavefield images of guided Lamb waves but a single scan is very time consuming and normally multiple scans are required at various frequencies in order to determine the best input signal. This paper demonstrates the use of a chirp excitation method requiring only a single scan and a post-processing algorithm to obtain results corresponding to any narrowband signal within the frequency range of the chirp signal. The method was used on an artificially delaminated composite panel and showed that the S0 mode, dominant at higher frequencies, mainly caused mode conversions whilst the A0 mode, dominant at lower frequencies, mainly caused a change in phase and amplitude across the delaminationOne method that has shown great potential in visualising and characterising the interaction of guided waves with damage in composites is Laser Vibrometry. A Laser Doppler Vibrometer (LDV) can be used to produce 2D wavefield images of guided Lamb waves but a single scan is very time consuming and normally multiple scans are required at various frequencies in order to determine the best input signal. This paper demonstrates the use of a chirp excitation method requiring only a single scan and a post-processing algorithm to obtain results corresponding to any narrowband signal within the frequency range of the chirp signal. The method was used on an artificially delaminated composite panel and showed that the S0 mode, dominant at higher frequencies, mainly caused mode conversions whilst the A0 mode, dominant at lower frequencies, mainly caused a change in phase and amplitude across the delamination.

USE OF LAMB WAVES TO DETECT DAMAGE TO METAL BEAMS

2017 ◽  
Author(s):  
Anorosval Pedro Leirias da Silva Jr ◽  
Paulo Rogério Novak
Keyword(s):  
Lamb Waves
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