Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures

The nondestructive inspection of concrete structures is indispensable for ensuring the safety and reliability of aging infrastructures. Ultrasonic waves having a frequency of tens of kHz are frequently used to reduce the scattering attenuation due to coarse aggregates. Such low frequencies enable the measurement of the thickness of concrete structures and detection of layer-type defects, such as delamination, whereas it causes a lack of sensitivity to crack-type defects. In this paper, to realize the ultrasonic phased array (PA) imaging of crack-type defects, we fabricated a low-frequency (LF) array transducer with a center frequency of hundreds of kHz. To avoid the crosstalk between piezoelectric elements and dampen the vibration of each element, we adopted soft lead zirconate titanate (soft PZT) with a low mechanical quality factor. Subsequently, we optimized the geometry of each piezoelectric element using a finite element method to generate a short pulse. After validating the design in a fundamental experiment using a single-element transducer, we fabricated a 32-element array transducer with a center frequency of 350 kHz. To show the imaging capability of the LF array transducer, we applied it to a concrete specimen with a delamination. As a result, the PA with the LF array transducer clearly visualized the delamination, which could not be visualized using the PA with a 2.5 MHz array transducer. Furthermore, we applied it to a more challenging defect, a slit, which is sometimes used to simulate crack-type defects. As a result, the PA with the LF array transducer clearly visualized a slit of 1 mm width and 40 mm height in a concrete specimen. Thus, we demonstrated the usefulness of the LF array transducer for inspecting crack-type defects.

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Phased Array Ultrasonic Technique Parametric Evaluation for Composite Materials

Volume 13: Vibration, Acoustics and Wave Propagation ◽

10.1115/imece2014-36945 ◽

2014 ◽

Cited By ~ 1

Author(s):

Hossein Taheri ◽

Katrina M. Ladd ◽

Fereidoon Delfanian ◽

Jikai Du

Keyword(s):

Composite Materials ◽

Phased Array ◽

Composite Plates ◽

Single Element ◽

Bulk Wave ◽

Plate Wave ◽

High Attenuation ◽

Array Transducer ◽

General Improvement ◽

Aluminum Plates

A series of ultrasonic elements arranged in a phased array transducer can provide the capability to activate each element separately but in a programmed sequence. This will help the acoustic signal to be generated at desired focusing distances and anticipated angles for specific materials and structures. In case of composite material inspection, this characteristic of the phased array method can improve the undesirable effects of the high attenuation and anisotropic structure of composite materials on response signals. In this study different phased array probes and wedges which are commercially available were evaluated for their response signals’ characteristics. First, the capability and resolution of bulk wave generation were studied for each set of probe and wedge, and the response signals were compared to that of the conventional single element ultrasonic transducers for different thicknesses composite plates. Then the resolution of the response signals and their sensitivity to defect size were evaluated and compared to the single element transducers as well. Next, each phased array probe and wedge set was used to generate plate waves in aluminum plates based on plate wave propagation theory, probe and wedge physical properties and the definition of delay law. Results show a general improvement in response signals’ strength and resolution for phased array method in comparison to the single element transducers. Also some plate wave modes could be generated with optimized signal generation parameters in phased array system.

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DESIGN AND FABRICATION OF A 20 MHz ANNULAR ARRAY FOR MEDICAL ULTRASOUND

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545811500106 ◽

2012 ◽

Vol 05 (01) ◽

pp. 1150010

Author(s):

ZHENHUA HU ◽

JUE PENG

Keyword(s):

Focal Point ◽

Impedance Matching ◽

Center Frequency ◽

Depth Of Field ◽

Single Element ◽

Medical Ultrasound ◽

Annular Array ◽

Array Transducer ◽

Small Depth

Most high frequency (> 15 MHz) medical ultrasound systems are based on single element transducers mechanically scanned. These systems can provide images with excellent resolution. However, single element transducers are often limited by the fixed focal point and small depth of field. Annular arrays consisting of concentric rings of elements are focused electronically. These arrays are desirable to avoid the fixed focal point of the single element transducers and improve the depth of field. This paper reports the design, fabrication, and characterization of a 5-element equal-area annular array transducer. After electrical impedance matching, the average center frequency was 20 MHz and -6 dB bandwidths ranged from 34 to 42%. The ILs for the matched annuli ranged from 6.1 to 26.5 dB.

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Ultrasonic Inspection of a 9% Ni Steel Joint Welded with Ni-based Superalloy 625: Simulation and Experimentation

Metals ◽

10.3390/met8100787 ◽

2018 ◽

Vol 8 (10) ◽

pp. 787 ◽

Cited By ~ 3

Author(s):

João Payão Filho ◽

Elisa Passos ◽

Rodrigo Gonzaga ◽

Ramon Ferreira ◽

Daniel Santos ◽

...

Keyword(s):

Weld Metal ◽

Arc Welding ◽

Phased Array ◽

Computational Simulation ◽

Ultrasonic Inspection ◽

Low Frequency ◽

Experimental Tests ◽

Ultrasonic Waves ◽

Shielded Metal Arc Welding ◽

Scanning Angle

The ultrasonic inspection of thick-walled welded joint with austenitic weld metal has proven to be a challenge due to its anisotropic microstructure that can promote ultrasonic waves attenuation. This work aimed to optimize the phased array ultrasonic inspection of the thick-walled joint of a 9% Ni steel pipe welded with Ni-based superalloy 625. The development was carried out by CIVA numeric simulation to preview the beam behavior during the inspection of GTAW (Gas Tungsten Arc Welding)/SMAW (Shielded Metal Arc Welding) joint with anisotropic weld metal. To validate the simulation results, experimental tests were performed with a phased array transducer using longitudinal waves on a calibration block withdrawn from the joint. The configuration of low frequency (2.25 MHz), 16 active elements and a scanning angle of 48° ensured the inspection of the entire joint and the computational simulation proved to be essential for the success of the inspection.

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Catheter Ultrasound Phased-Array Transducers for Thermal Ablation: A Feasibility Study

Ultrasonic Imaging ◽

10.1177/016173460502700203 ◽

2005 ◽

Vol 27 (2) ◽

pp. 89-100 ◽

Cited By ~ 8

Author(s):

Kenneth L. Gentry ◽

Nasheer Sachedina ◽

Stephen W. Smith

Keyword(s):

Phased Array ◽

Pulse Repetition Frequency ◽

Heart Tissue ◽

Single Element ◽

Ultrasound Transducers ◽

3D Scanner ◽

Array Transducer ◽

Ultrasound Ablation ◽

Design And Testing ◽

Ultrasound Scanner

The feasibility of catheter single-element ultrasound transducers for cardiac ablation has been shown previously. We describe the design and testing of catheter-sized linear phased arrays transducers for ultrasound ablation. One array has 86 PZT-4 elements operating at 8 MHz and 5 MHz. The overall array size is 14.9 mm by 3.1 mm (10 Fr). The other array has 50 PZT-5 elements operating at 4 MHz and is 17 mm by 3.1 mm (10 Fr). In order to produce the intensity needed to create lesions in heart tissue, we modified a real-time, 3D scanner to produce 100 Vpp 256-cycle transmit pulses at a pulse repetition frequency of 14.1 kHz. This made it possible for the PZT-4 and PZT-5 transducers to produce ISPTA of 3.26 W/cm2 and 142 W/cm2, respectively. When driving the transducers at high duty factor, the transmit circuitry in the scanner was damaged. A mechanically-focused transducer with the same dimensions as the PZT-4 transducer was built. When transmitting continuously at 9 MHz, it produced an ISPTA of 29.3 W/cm2. This created a lesion 5 mm across and 5 mm deep in beef tissue while raising the focal temperature 23°C. Ablation is within the capabilities of a catheter phased array transducer integrated into a diagnostic ultrasound scanner.

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Application of Dual Focused Ultrasonic Phased Array Transducer in Two Orthogonal Cross-Sections for Inspection of Multi-Layered Composite Components of the Aircraft Fuselage

Materials ◽

10.3390/ma13071689 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1689 ◽

Cited By ~ 2

Author(s):

Renaldas Raišutis ◽

Olgirdas Tumšys

Keyword(s):

Spatial Resolution ◽

Cross Sections ◽

Phased Array ◽

Complex Geometry ◽

Ultrasonic Waves ◽

Internal Defect ◽

Flat Bottom ◽

Aircraft Fuselage ◽

Array Transducer ◽

Ultrasonic Phased Array

Our previous studies have shown that the application of the proposed technique of a dual focused ultrasonic beam in two orthogonal cross-sections in passive (elevation) and active (azimuth) apertures of linear ultrasonic phased array transducer (ULPAT) enhances the 3D spatial resolution in the case of the inspection of conventional defects (flat bottom holes) or measurement of thickness of multi-layered metal composites. The objective of this work is to apply the proposed technique to enhance the spatial resolution of the ULPAT in the cases of detection and sizing demonstration of internal defects possessing spatially complex geometry, and during the inspection of defective multi-layered thin composite components (e.g., GLARE) of the aircraft fuselage. The specially prepared aluminium specimen possessing an internal defect of complicated geometry (crescent-shaped) was investigated. The simulation results and experiments demonstrate the resolution enhancement, higher amplitude of the reflections (e.g., 2.5 times or +8 dB) and spatial improvement in the defect detection even in the case of the non-perpendicular incidence of ultrasonic waves to the complex geometry surface of the internal defect. During the experiments, the multi-layered GFRP-metal based composite sample GLARE 3-3/2 was investigated in the case of the single-side access to the surface of the sample. The internal artificial delamination type defect of 25 mm was detected with a higher accuracy. Compared to the limitations of conventional ULPAT, the relative error (32%) (at the −6 dB level) of lateral defect dimensions estimation was completely reduced.

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Phased-Array Transducer for Intracardiac Echocardiography Based on 1–3 Piezocomposite

Frontiers in Materials ◽

10.3389/fmats.2021.663926 ◽

2021 ◽

Vol 8 ◽

Author(s):

Zhile Han ◽

Ninghao Wang ◽

Zhangjian Li ◽

Xinle Zhu ◽

Youwei Chen ◽

...

Keyword(s):

Phased Array ◽

Lower Surface ◽

Intracardiac Echocardiography ◽

Circuit Board ◽

Center Frequency ◽

Array Transducer ◽

Ultrasonic Phased Array ◽

Single Use ◽

Compact Design ◽

Imaging Performance

In this study, an ultrasonic phased-array transducer was proposed, which could effectively improve the imaging performance by using 1–3 piezocomposite. The piezocomposite consists of PZT and epoxy, with a pitch of 70 μm, kerf of 20 μm, and thickness of 170 μm. The phased-array transducer has 64 elements; the size of each element is 85 μm × 1.3 mm; the pitch of the transducer is 100 μm; and the kerf between the elements is only 15 μm. To minimize the transducer size, the 1–3 composite uses an encase structure, which connects the upper surface of the composite directly to the flexible circuit board bonded to the lower surface as the ground electrode. The size of the final fabricated transducer is 2 mm × 7.4 mm, and the transducer is mounted on a 9 F (3 mm diameter) catheter, which can bend in four directions and is primarily used for intracardiac echocardiography (ICE). The acoustic and electrical properties of the transducer were tested, including impedance, echo sensitivity, center frequency (9 MHz), bandwidth (BW) (55%), and consistency. Finally, the wire phantom experiments were carried out to demonstrate the spatial resolutions and imaging performance. This study shows that this transducer with compact design and construction can bring higher performance for the single-use disposable ICE catheter.

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Analysis of Flaw Detection Sensitivity of Phased Array Ultrasonics in Austenitic Steel Welds According to Inspection Conditions

Sensors ◽

10.3390/s21010242 ◽

2021 ◽

Vol 21 (1) ◽

pp. 242

Author(s):

YoungLae Kim ◽

Sungjong Cho ◽

Ik Keun Park

Keyword(s):

Austenitic Steel ◽

Simulation Modeling ◽

Power Plants ◽

Phased Array ◽

Flaw Detection ◽

Wave Mode ◽

Ultrasonic Waves ◽

Detection Sensitivity ◽

Flaw Sensitivity ◽

Steel Welds

The anisotropy and inhomogeneity exhibited by austenitic steel in welds poses a challenge to nondestructive testing employing ultrasonic waves, which is predominantly utilized for the inspection of welds in power plants. In this study, we assess the reliability of phased array ultrasonic testing (PAUT) by analyzing the flaw detection sensitivity of ultrasonic beams in anisotropic welds, based on the inspection conditions. First, we simulated the sectorial scan technique, frequently employed for the inspection of actual welds, while taking into account the ultrasonic wave mode, frequency, and shape and position of a flaw. Subsequently, we analyzed the flaw sensitivity by comparing A-scan signals and S-scan results. The sensitivity analysis results confirmed the detection of all flaws by considering at least two inspection methods based on the shape and position of the flaw. Furthermore, we verified our model by performing an experiment under the same conditions as the simulation and found that the results were in agreement. Hence, we find that the simulation modeling technique proposed in this study can be utilized to develop suitable inspection conditions, according to the flaw characteristics or inspection environment.

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