High-resolution 3D phased-array imaging of fatigue cracks using piezoelectric and laser ultrasonic system (PLUS)

Self Cite

As a high-resolution 3D phased-array imaging method, a piezoelectric and laser ultrasonic system (PLUS) was proposed, which is a combination of a piezoelectric transmitter and an ultra-multiple scan of a laser Doppler vibrometer. Thus far, PLUS has used an identical mode for incident and scattered waves. On the other hand, the ultrasonic scattering phenomena can accompany the mode conversion, which may provide further information on defects. In this paper, we propose multi-mode PLUS to enhance its imaging capability and attain more robustness. After describing the principle of multi-mode PLUS, we validated the imaging algorithm and demonstrated the improvement in the image resolution using a dataset of simulated received waves for the longitudinal-wave incidence to scatterers. Furthermore, we experimentally demonstrated the efficacy of multi-mode PLUS in a specimen with branched stress corrosion cracking.

“…The experimental configuration for multi-mode PLUS is essentially the same as the single-mode PLUS, [39][40][41] as schematically illustrated in Fig. 1.…”

Section: Multi-mode Plusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multi-mode 3D ultrasonic phased array imaging method using piezoelectric and laser ultrasonic system (PLUS)

Ohara¹,

Ulrich²,

Remillieux³

et al. 2023

Self Cite

“…Subsequently, a specific design for the stacked thin-plate region is described. Although it follows the focal law in phased-array ultrasonic focusing, [22][23][24][25][26][27] it differs in unequal thickness. As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Phased array imaging has long been used for medical diagnosis and is widely used in various industrial fields. [22][23][24][25][26][27] This study investigates transverse-and longitudinal-wave focusing in an elastic medium by controlling the wave field propagating in a stacked thin-plate region using the characteristics of Lamb waves in thin plates, which can be theoretically predicted from the dispersion curves.…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic focusing using a stacked thin-plate region

Fukuchi

Hayashi

Mori

2023

This paper describes a stacked thin-plate region for focusing the transmitted waves. The region was designed to focus the wave field in the bulk medium by utilizing the dispersion nature of Lamb waves. The first numerical calculation proved that an incident plane wave changes the wavefront in a stacked thin-plate region because of the different phase velocities in plates with different thicknesses, and the resulting transmitted wave was focused at the target. Second, when a delayed longitudinal wave was applied to the edge of the stacked thin - plate region with identical thickness, the numerical calculations showed that the delayed wavefront of the S0 mode was preserved in the stacked plate region, and that the transmitted longitudinal wave was appropriately focused at the target. The focusing devise consisting of a stacked thin-plate structure is useful for the buffer for phased array inspection.

“…In order to detect fatigue damage at an early stage, it is necessary to detect changes in the dislocation structure, microcracks, and closed cracks associated with fatigue damage, which is however very difficult with general UT using linear ultrasonic waves. On the other hand, nonlinear ultrasonic methods [2][3][4][5][6][7][8][9] have been widely studied for many applications, including fatigue damage evaluation, since ultrasonic waves are distorted by material's nonlinearity related to lattice anharmonicity, 10) dislocations, 6,[11][12][13][14][15] microcracks, [16][17][18] and so on, resulting in nonlinear ultrasonic waves. Their measurements are thus expected to evaluate change in material microstructure due to fatigue damage.…”

Section: Introductionmentioning

confidence: 99%

Measurement of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers

Takishita,

Takamatsu,

Ogi

2024

We developed a method of nonlinear three-wave interaction using shear-vertical-wave point-focusing electromagnetic acoustic transducers (SV-wave PF-EMATs). EMATs can excite and detect ultrasonic waves without couplants through interaction between electromagnetic fields and solid mechanics and are generally unsuitable for the nonlinear ultrasound measurement due to their low signal conversion efficiency. However, our originally developed PF-EMAT can focus SV waves at a focal point in phase, achieving a large local displacement. Here, two PF-EMATs with different driving frequencies are placed facing each other so as to match their focal points, where the focused SV waves intersect to induce the third waves with the frequencies of the sum and difference of the incident frequencies through the nonlinear three-wave interaction. We demonstrate that the local nonlinearity can be measured by this method with EMATs and demonstrate its applicability to evaluation of fatigue damage in a fatigue crack initiation phase with aluminum alloy specimens.