A method for crack sizing using Laser Doppler Vibrometer measurements of Surface Acoustic Waves.

The goal of non-destructive testing (NDT) is to determine the position and size of structural defects, in order to measure the quality and evaluate the safety of building materials. Most NDT techniques are rather complex, however, requiring specialized knowledge. In this article, we introduce an experimental method for crack detection that uses Surface Acoustic Waves (SAWs) and optical measurements. The method is tested on a steel beam engraved with slots of known depth. A simple model to determine the cracks size is also proposed. At the end of the article, we describe a possible application: fatigue crack sizing on a damaged slat track. This technique represents a first step toward a better understanding of the crack growth, especially in its early stages (preferably when the cracks can still be repaired) and when it is possible to assume a linear propagation of the crack front. The ultimate goal of this research program is to develop a useful method of monitoring aircraft components during fatigue testing.

[1]  Do Thompson,et al.  Ultrasonic surface wave propagation and interaction with surface defects on rail track head , 2006 .

[2]  Daniel Cernadas,et al.  Non-destructive testing of plates based on the visualisation of Lamb waves by double-pulsed TV holography , 2006 .

[3]  Krishnan Balasubramaniam,et al.  Sizing of surface-breaking cracks in complex geometry components by ultrasonic Time-of-Flight Diffraction (TOFD) technique , 2007 .

[4]  J. Rose.  Ultrasonic Waves in Solid Media , 1999 .

[5]  Patrick Guillaume,et al.  On-line monitoring of fatigue cracks using ultrasonic surface waves , 2003 .

[6]  Louis Cartz,et al.  Nondestructive Testing: Radiography, Ultrasonics, Liquid Penetrant, Magnetic Particle, Eddy Current , 1995 .

[7]  Jan D Achenbach.  Modeling for quantitative non-destructive evaluation. , 2002, Ultrasonics.

[8]  Steve Vanlanduit,et al.  Laser vibrometer measurements of SAWs for nondestructive testing , 2006, International Conference on Vibration Measurements by Laser Techniques: Advances and Applications.

[9]  W. Staszewski,et al.  Fatigue crack detection in metallic structures with Lamb waves and 3D laser vibrometry , 2007 .

[10]  Guirong Liu,et al.  Elastic waves in anisotropic laminates , 2001 .

[11]  I. A. Viktorov.  Rayleigh and Lamb Waves , 1967 .

[12]  R. Edwards,et al.  Depth gauging of defects using low frequency wideband Rayleigh waves. , 2006, Ultrasonics.

[13]  J.-Y. Kim,et al.  Nondestructive sizing and localization of internal microcracks in fatigue samples , 2007 .

[14]  R. Penrose.  A Generalized inverse for matrices , 1955 .

[15]  Jonathan J. Kaufman,et al.  New ultrasound system for bone assessment , 2004, SPIE Medical Imaging.

[16]  Ichiro Komura,et al.  Crack detection and sizing technique by ultrasonic and electromagnetic methods , 2001 .

[17]  Rajiv Tiwari,et al.  Development of a Technique to Locate and Quantify a Crack in a Beam Based on Modal Parameters , 2007 .

[18]  Fabrizio Scarpa,et al.  Structural health monitoring using scanning laser vibrometry: III. Lamb waves for fatigue crack detection , 2004 .

[19]  D. J. Ewins,et al.  Modal Testing: Theory and Practice , 1984 .

[20]  Kazushi Yamanaka,et al.  IN ACOUSTIC MICROSCOPY , 1982 .