Effects of array transducer inconsistencies on total focusing method imaging performance

Zhang, Jie; Drinkwater, Bruce W.; Wilcox, Paul D.

doi:10.1016/j.ndteint.2011.03.001

Cited by 43 publications

(21 citation statements)

References 15 publications

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“…API is a dimensionless measurement of the image resolution. The smaller the API value, the narrower the sound beam width and the better the imaging quality [30]. Conversely, the larger the API value is, the wider the ultrasonic beam width will be, which will easily cause aliasing of adjacent defect images and worsen the imaging quality.…”

Section: Comparison and Discussionmentioning

confidence: 99%

Sparse-TFM Imaging of Lamb Waves for the Near-Distance Defects in Plate-Like Structures

Zhang

Lin

Fan

et al. 2019

Metals

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The ultrasonic phased array total focusing method (TFM) has the advantages of high imaging resolution and high sensitivity to small defects. However, it has a long imaging time and cannot realize near-distance defect imaging, which limits its application for industrial detection. A sparse-TFM algorithm is adopted in this work to solve the problem regarding rapid imaging of near- distance defects in thin plates. Green’s function is reconstructed through the cross-correlation of the diffuse full matrix captured by the ultrasonic phased array. The reconstructed full matrix recovers near-distance scattering information submerged by noise. A sparse array is applied to TFM for rapid imaging. In order to improve the imaging resolution, the location of active array elements in the sparse array can be optimized using the genetic algorithm (GA). Experiments are conducted on three aluminium plates with near-distance defects. The experimental results confirm that the sparse-TFM algorithm of Lamb waves can be used for near-distance defects imaging, which increases the computational efficiency by keeping the imaging accuracy. This paper provides a theoretical guidance for Lamb wave non-destructive testing of the near-distance defects in plate-like structures.

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Section: Comparison and Discussionmentioning

confidence: 99%

Sparse-TFM Imaging of Lamb Waves for the Near-Distance Defects in Plate-Like Structures

Zhang

Lin

Fan

et al. 2019

Metals

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“…al. [26]. Other areas with which the embedded PLL method is applicable could include compensating for subtle changes in focal delays due to temperature, boundaries between materials, or to compensate for focal errors caused by non-ideal propagation in a medium.…”

Section: Discussionmentioning

confidence: 99%

Ultrasound array transmitter architecture with high timing resolution using embedded phase-locked loops

Smith

Cowell

Raiton

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-Coarse time quantization of delay profiles within ultrasound array systems can produce undesirable sidelobes in the radiated beam profile. The severity of these sidelobes is dependent upon the magnitude of phase quantization error -the deviation from ideal delay profiles to the achievable quantized case. This paper describes a method to improve inter channel delay accuracy without increasing system clock frequency by utilising embedded Phase-Locked Loop (PLL) components within commercial Field Programmable Gate Arrays (FPGAs). Precise delays are achieved by shifting the relative phases of embedded PLL output clocks in 208 ps steps. The described architecture can achieve the necessary inter element timing resolution required for driving ultrasound arrays up to 50 MHz. The applicability of the proposed method at higher frequencies is demonstrated by means of extrapolating experimental results obtained using a 5 MHz array transducer. Results indicate an increase in Transmit Dynamic Range (TDR) when using accurate delay profiles generated by the embedded PLL method described, as opposed to using delay profiles quantized to the system clock.

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“…The deflection beam and focus beam of a phased array are normally generated with a time delay, which ensures a larger detection region for the sample [35]. The phased array technique can measure the scattering matrix of the defects and extract their signal characteristics, but the specific inconsistency of each array element has been found to have a great influence on defect detection and imaging [36,37]. The angular distribution of a scattered field in a solid or saturated fluid has been discussed by many researchers [10,38].…”

Section: Introductionmentioning

confidence: 99%

Ultrasonic Scattered Field Distribution of One and Two Cylindrical Solids with Phased Array Technique

Liu

Wang

et al. 2019

Chin. J. Mech. Eng.

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The scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.

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Effects of array transducer inconsistencies on total focusing method imaging performance

Cited by 43 publications

References 15 publications

Sparse-TFM Imaging of Lamb Waves for the Near-Distance Defects in Plate-Like Structures

Sparse-TFM Imaging of Lamb Waves for the Near-Distance Defects in Plate-Like Structures

Ultrasound array transmitter architecture with high timing resolution using embedded phase-locked loops

Ultrasonic Scattered Field Distribution of One and Two Cylindrical Solids with Phased Array Technique

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