Time reversal techniques in ultrasonic nondestructive testing of scattering media

Time reversal techniques are adaptive methods that can be used in nondestructive evaluation to improve flaw detection through inhomogeneous and scattering media. Two techniques are presented: the iterative time reversal process and the DORT (French acronym for decomposition of the time reversal operator) method. In pulse echo mode, iterative time reversal mirrors allow one to accurately control wave propagation and focus selectively on a defect reducing the speckle noise due to the microstructure contribution. The DORT method derives from the mathematical analysis of the iterative time reversal process. Unlike time reversal mirrors, it does not require programmable generators and allows the simultaneous detection and separation of several defects. These two procedures are presented and applied to detection in titanium billets where the grain structure renders detection difficult. Then, they are combined with the simulation code PASS (phased array simulation software) to form images of the samples.

[1]  M. Fink,et al.  Time reversal of ultrasonic fields. Il. Experimental results , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[2]  Ronald A. Roberts,et al.  Study of the effect of microstructure on ultrasonic signal attenuation , 2001 .

[3]  Mathias Fink,et al.  Decomposition of the time reversal operator: Detection and selective focusing on two scatterers , 1996 .

[4]  M. Fink,et al.  Time reversal processing in ultrasonic nondestructive testing , 1995, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[5]  Mathias Fink,et al.  Optimisation of time reversal processing in titanium inspections , 1996, 1996 IEEE Ultrasonics Symposium. Proceedings.

[6]  G. Papanicolaou,et al.  Imaging and time reversal in random media , 2001 .

[7]  Mathias Fink,et al.  The iterative time reversal process: Analysis of the convergence , 1995 .

[8]  Edward James Nieters,et al.  An improved methodology for the inspection of titanium alloys , 1996, 1996 IEEE Ultrasonics Symposium. Proceedings.

[9]  M. O’Donnell,et al.  Phase-aberration correction using signals from point reflectors and diffuse scatterers: basic principles , 1988, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[10]  Mathias Fink,et al.  Theory of the time-reversal process in solids , 1997 .

[11]  Jan Drewes Achenbach,et al.  A simple scheme for self-focusing of an array , 1995 .

[12]  Mathias Fink,et al.  Acoustic time-reversal mirrors , 2001 .

[13]  C. Prada,et al.  Ultrasonic nondestructive testing of scattering media using the decomposition of the time-reversal operator , 2002, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[14]  Mathias Fink,et al.  Eigenmodes of the time reversal operator: a solution to selective focusing in multiple-target media , 1994 .

[15]  M. Fink,et al.  Self focusing in inhomogeneous media with time reversal acoustic mirrors , 1989, Proceedings., IEEE Ultrasonics Symposium,.

[16]  Harpreet Wasan,et al.  An experimental study of microstructure-induced ultrasonic signal fluctuations in jet-engine titanium alloys , 2000 .

[17]  Mathias Fink,et al.  Separation of interfering acoustic scattered signals using the invariants of the time-reversal operator. Application to Lamb waves characterization , 1998 .

[18]  M. Fink,et al.  Time reversal of ultrasonic fields. I. Basic principles , 1992, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.