Pierre-Yves Le Bas

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In acoustics, it is known that, for a given response signal at an arbitrary location, reciprocity and time reversal ͑TR͒ can be used to focus high levels of acoustic energy at that position. In solid media, elastic waves generally induce different disturbances in three directions. In this paper, both experimental and numerical wave propagation results for(More)
Reverse time migration (RTM) is a commonly employed imaging technique in seismic applications (e.g., to image reservoirs of oil). Its standard implementation cannot account for multiple scattering/reverberation. For this reason it has not yet found application in nondestructive evaluation (NDE). This paper applies RTM imaging to NDE applications in bounded(More)
An energy current imaging method is presented for use in locating sources of wave energy during the back propagation stage of the time reversal process. During the back propagation phase of an ideal time reversal experiment, wave energy coalesces from all angles of incidence to recreate the source event; after the recreation, wave energy diverges in every(More)
Time reversal is a proven technique for focusing wave energy in time and space. A known side effect of the process is the presence of temporal side lobes and spatial fringes, which can be undesirable depending upon the application. A deconvolution, also known as an inverse filter, technique has been developed to improve temporal compression of the focal(More)
This contribution provides fundamental support, and both experimental and numerical wave propagation results demonstrating the ability to use a scalar source, a three component detector and the reciprocal TR process to selectively focus different vector components, either individually or collectively. The principle is explained from an analytical point of(More)
This paper describes the principle behind a high amplitude non-contact acoustic source based on the principle of time reversal (TR), a process to focus energy at a point in space. By doing the TR in an air filled, hollow cavity and using a laser vibrometer in the calibration of the system, a non-contact source may be created. This source is proven to be(More)
An air-coupled ultrasonic transducer is created by bonding a bulk piezoelectric element onto the surface of a thick plate with a wedge of power-law profile. The wedge is used to improve the ultrasonic radiation efficiency. The power-law profile provides a smooth, impedance-matching transition for the mechanical energy to be transferred from the thick plate(More)
This Letter presents a series of time reversal experiments conducted on the surface of a fused silica glass block. Four different time reversal techniques are compared using three different imaging conditions. The techniques include two classical time reversal experiments: one with a pulse waveform source and one with an impulse response generated from a(More)
  • Marcel C. Remillieux, Brian E. Anderson, T. J. Ulrich, Pierre-Yves Le Bas, Michael R. Haberman, Jinying Zhu
  • 2014
The future of nondestructive testing lies in the ability to efficiently generate waves in structures without contact. Introduction Nondestructive testing (NDT) of structures and mechanical parts is increasingly receiving attention as the need to monitor the health of aging infrastructure and quality controls on the manufacturing of mechanical parts is(More)
Laboratory studies were performed in order to determine and enhance the possibility to localize microdamage based on a combination of classical time reversal techniques and nonlinear elastic wave response. The use of emitters having a more or less chaotic shape is investigated. Its benefit is clearly found in breaking the symmetry of the problem, leading to(More)