Ultrasonics最新文献

Carbon steel and low alloy steel are pearlitic heat-resistant steels with a lamellar microstructure. There are good mechanical properties and are widely used in crucial components of high-temperature pressure. However, long-term service in high-temperature environments can easily lead to material degradation, including spheroidization, graphitization, and thermal aging. This study proposes a theoretical model of ultrasonic backscattering with a lamellar structure in pearlite areas. It analyzes the effects of different pearlite area ratios and interlamellar spacing on ultrasonic backscattering signals. A Voronoi diagram is used to constructs a two-dimensional finite element (FE) model of the lamellar structure, and the effects of different pearlite area ratio and interlamellar spacing on the backscattering signals are analyzed to verify the correctness of the theoretical model. By preparing spheroidization samples of various grades, the change values of pearlite area ratio and interlamellar spacing are measured. The backscattering signals of different spheroidization samples are collected through the ultrasonic testing experimental platform, and the root-mean-square (RMS) maximum values of the ultrasonic backscattering are extracted. The observed trend is consistent with the theoretical model, finite element method (FEM), and experimental. Compared with the experimental results, the model results have some errors, but can be used to evaluate the performance degradation of metallic materials with lamellar pearlite structure.

In recent years, the widespread application of laser ultrasonic (LU) devices for obtaining internal material information has been observed. However, this approach demands a significant amount of time to acquire complete wavefield data. Hence, there is a necessity to reduce the acquisition time. In this work, we propose a method based on physics-informed neural networks to decrease the required sampling measurements. We utilize sparse sampling of full experimental data as input data to reconstruct complete wavefield data. Specifically, we employ physics-informed neural networks to learn the propagation characteristics from the sparsely sampled data and partition the complete grid to reconstruct the full wavefield. We achieved 95% reconstruction accuracy using four hundredth of the total measurements. The proposed method can be utilized not only for sparse wavefield reconstruction in LU testing but also for other wavefield reconstructions, such as those required in online monitoring systems.

Non-invasive estimation of pressure differences using 2D synthetic aperture ultrasound imaging offers a precise, low-cost, and risk-free diagnostic tool. Unlike invasive techniques, this preserves natural blood flow and avoids the limitations of devices that occupy lumen space. This paper evaluates a previously published estimator, modified to incorporate Singular Value Decomposition (SVD) echo-cancellation, using data from ten healthy volunteers and one patient. It is hypothesized that the estimator will enable precise pressure differences from the common carotid artery with a coefficient of variation of approximately 10% over a 10-second data acquisition period. Here, precision is essential to demonstrate the method's consistency and its ability to differentiate between healthy and diseased arteries at the earliest possible stage. Data are acquired using a GE-9L-D, 5.2 MHz linear transducer connected to a Vantage 256 research scanner. The estimator was applied to the left common carotid artery of ten healthy volunteers, with precision being evaluated over the recorded heart cycles by using the coefficient of variation. Eight out of ten individuals showed precision below 10%, whereas two individuals showed precision above 20%. The best precision was attained by subject_03 with a coefficient of variation of 4.64% (16.1 Pa) and the worst precision was attained by subject 09 with a coefficient of variation of 23.3% (30.2 Pa). The average range of pressure differences across volunteers (from maximum positive to maximum negative pressure difference) was 297 Pa when measured across a 14 mm streamline. The corresponding average coefficient of variation was found to be 9.95% (24.6 Pa). A comparison of peak systolic velocities between the experimental scanner and the reference scanner demonstrates a strong positive linear correlation (R² = 0.76). The corresponding slope of the linear best fit is 0.95, indicating that the relationship between the two scanners is close to a one-to-one match, with the experimental scanner's measurements being slightly less than those of the reference scanner. Finally, data attained from a single patient example shows pressure differences ranging from -61.81 Pa to 1240.82 Pa with blood velocities as high as 1.73 m/s, which is significantly higher than seen in any of the healthy volunteers, supporting the likelihood of differentiating between stenosis grades in future studies. While this study is limited to 10 healthy volunteers and one patient, a different study design is needed to quantify the severity of stenosis and correlate it with pressure differences.

Steel precision matching parts are widely used in aerospace and automobiles. In order to ensure the stability of the system, the matching parts' mating surfaces, such as inner holes and outer shafts, are required to achieve nano-surface roughness and submicron-shape accuracy. Diamond-cutting technology is generally used for ultra-precision machining processes. However, it is not suitable for machining steel due to the active chemical reactions. Ultrasonic elliptical vibration cutting technology can significantly reduce the cutting heat to suppress the chemical wear of diamond tools. Consequently, this study proposes a novel simple theory-simulation design method for an ultrasonic elliptical vibration boring (UEVB) device. The device works in two six-order bending vibration modes, generating an elliptical tool motion in the plane determined by the nominal cutting direction and the cutting depth direction. Through the impedance test, frequency sweep test, and amplitude test, the test results of the device match well with the simulation results. The experimental results of cutting S136 steel show that the UEVB technology suppresses system chatter by 10 % and reduces surface roughness Ra by 72 % compared with common boring. Additionally, the tool has much light wear and the machined surface roughness is Ra 11.3 nm, which realizes the ultra-precision cutting of steel by diamond tools. Furthermore, the roundness of the processed hole, with a diameter of 30 mm, reaches 0.473 μm, which is significantly better than the highest standard grade G1 (0.5 μm). These results verify the feasibility of the proposed method.

Microwave surface and Lamb waves in a multilayered piezoelectric "Al-IDT/(Al_0.72Sc_0.28)N/(001)[110] diamond" structure designed as a SAW resonator were studied using both the experimental and modeling methods. In this structure, it is possible to generate Rayleigh, surface horizontal (SH_n) and Lamb waves simultaneously. The successful excitation of Lamb waves at operating frequencies up to 20 GHz has been obtained. We have developed a method for identifying mode types based on an analysis of the elastic displacement fields and the frequency dependences of the dispersive phase velocities of each wave, as the frequency increases. The experimental data on the frequency response is in close agreement with the calculated values. The influence of Pt film deposition on the shifts in the resonant frequency of Lamb wave modes has been studied in detail. Since the Pt film was deposited on the free surface of a diamond substrate, shifts in the resonant frequency of Rayleigh-type waves are absent, as expected. This serves as an additional indication to distinguish these types of waves from others. The effect of film deposition on the frequency response of Lamb waves could be taken into account when designing acoustoelectronic sensors that use this type of wave as an operational mode.

Shear Wave Elastography (SWE) is an imaging technique that detects shear waves generated by tissue excited by Acoustic Radiation Force (ARF), and characterizes the mechanical properties of soft tissue by analyzing the propagation velocity of shear wave. ARF induces a change in energy density through the nonlinear propagation of ultrasound waves, which drives the tissue to generate shear waves. However, the amplitude of shear waves generated by ARF is weak, and the shear waves are strongly attenuated in vivo. Furthermore, the shear waves are usually drowned out by noise at deep locations, which presents a challenge in the detection of shear waves and low signal-to-noise ratios. In this paper, we investigate the feasibility of applying the Chirp coded signal for shear wave excitation (Chirp-SWE) in ARF-based shear wave elastography. The use of Chirp coded excitation of push waveforms was employed to enhance the action of ARF, thereby effectively exciting shear waves. Comparative experiments were carried out with conventional sine long pulses (SWE) and the Barker coded signal (Barker-SWE). The analysis of theoretical and simulation results revealed that Chirp-SWE could increase the excitation energy by approximately 10% compared to conventional SWE and Barker-SWE. The results of the elastic phantom experiments demonstrated that the average peak axial particle velocity obtained by Chirp-SWE was approximately 30%-50% higher, which facilitated the formation of a more stable shear wave. Additionally, it exhibited a higher signal-to-noise ratio during elasticity measurements. The in vitro liver experiments further validated the feasibility of implementing Chirp-SWE in tissues. The results demonstrated the feasibility and advantages of Chirp coded excitation of push waveforms in improving shear wave elastography results. It is expected that this will enhance the accuracy and robustness of soft tissue elastography.

Detecting surface contamination on thin thermoformed polymer plates is a critical issue for various industrial applications. Lamb waves offer a promising solution, though their effectiveness is challenged by the strong attenuation and anisotropy of the polymer plates. This issue is addressed in the context of a calcium carbonate (CaCO₃) layer deposited on a polypropylene (PP) plate. First, the viscoelastic properties of the PP material are determined using a genetic algorithm inversion of data measured with a scanning laser vibrometer. Second, using a bi-layer plate model, the elastic properties and thickness of the CaCO₃ layer are estimated. Based on the model, the sensitivity analysis is performed, demonstrating considerable effectiveness of the A1 Lamb mode in detecting thin layers of CaCO₃ compared to Lamb modes A0 and S0. Finally, a direct application of this work is illustrated through in-situ monitoring of CaCO₃ contaminants using a straightforward inter-transducer measurement.

3D printing technology, also known as Additive Manufacturing (AM), has revolutionized object prototyping, offering a simple, cost-effective, and efficient approach to creating structures with diverse spatial features. However, the mechanical properties of 3D-printed structures are highly dependent on the material type and manufacturing technique employed. In this study, ultrasonic testing methods were used to comprehensively characterize standard samples produced using two popular printing techniques: material extrusion and vat photopolymerization. The investigation focuses on seven commonly used 3D printing polymer materials, namely nylon, PET-G, flexible polymer, polycarbonate, acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and photopolymer resin. Through ultrasonic testing, the mechanical parameters of objects made of different polymer materials were found. Some of these parameters are Young's modulus, shear modulus, acoustic impedance, and absorption. A comparative analysis of these parameters in different objects provides insights about their respective performance and behavior. This information may be useful to enhance the design and performance of ultrasonic lenses and lab-on-a-chip devices. Findings indicate that the vat photopolymerization printing process yields high-quality samples that exhibit minimal deviations in thickness, diameter, and surface parallelism. Moreover, microscopic analysis of the vat photopolymerization samples revealed low levels of porosity, which suggests that the material can be considered homogeneous. In contrast, the material extrusion samples showed significant porosity in the form of gaps between the deposited filaments, which had a direct impact on their mechanical and acoustic properties.

We demonstrate an integrated non-destructive inspection methodology that employs the nonlinear ultrasonics-based sideband peak counting (SPC) technique in conjunction with topological acoustics (TA) sensing to comprehensively characterize the acoustic response of steel plates that contain differing levels of damage. By combining the SPC technique and TA, increased sensitivity to defect/damage detection as well as the ability to spatially resolve the presence of defects was successfully established. Towards this end, using a Rockwell hardness indenter, steel plates were subject to one, three and five centrally located indentations respectively. The acoustic response of the plate as a function of number of indentations was examined at a frequency range between 50 kHz and 800 kHz, from which the change in a global geometric phase was evaluated. Here, geometric phase is a measure of the topological acoustic field response to the spatial locations of the indentations within the steel plates. The global geometric phase unambiguously showed an increase with increasing number of indentations. In addition, spatial variations in a 'local' geometric phase as well as spatial variations in the SPC-index (SPC-I) were also determined. Spatial variations in both the local geometric phase as well as the SPC-I were particularly significant across the indentations for frequencies below 300 kHz, and by combining the respective spatial variations in the SPC-I and geometric phase, the locations of the indentations were accurately identified. The developed SPC-TA nondestructive method represents a promising technique for detecting and evaluating defects in structural materials.

Ultrasound shear wave elastography (SWE) is widely used in clinical applications for non-invasive measurements of soft tissue viscoelasticity. The study of tissue viscoelasticity often involves the analysis of shear wave phase velocity dispersion curves, which show how the phase velocity varies with frequency or wavelength. In this study, we propose an alternative method to the two-dimensional Fourier transform (2D-FT) and Phase Gradient (PG) methods for shear wave phase velocity estimation. We introduce a new method called Point Limited Shear Wave Elastography (PL-SWE), which aims to reconstruct phase velocity dispersion curves using a minimal number of measurement points in the spatial domain (as few as two signals can be utilized). We investigated how the positioning of the first signal and the distance between selected signals affect the shear wave velocity dispersion estimation in PL-SWE. The effectiveness of this novel approach was evaluated through the analysis of analytical phantom data in viscoelastic media, along with experimental data from custom-made tissue-mimicking elastic and viscoelastic phantoms, and in vivo renal transplant data. A comparative analysis with the 2D-FT technique revealed that PL-SWE provided phase velocity dispersion curve estimates with root mean squared percentage error (RMSPE) values of less than 1.61% for analytical phantom data, 1.58% for elastic phantoms, 4.29% for viscoelastic phantoms and 7.68% for in vivo data, while utilizing significantly fewer signals compared to 2D-FT. The results demonstrate that the PL-SWE method also outperforms the PG method. For the viscoelastic phantoms, the mean RMSPE values using PL-SWE ranged from 2.61% to 4.29%, while the PG method produced RMSPE values between 3.56% and 15%. In the case of in vivo data, PL-SWE yielded RMSPE values between 7.01% and 7.68%, while PG results ranged from 17% to 418%. These findings highlight the superior accuracy and reliability of the PL-SWE method, particularly when compared to the PG approach. Our tests demonstrate that PL-SWE can effectively measure the phase velocity of both elastic and viscoelastic materials and tissues using a limited number of signals. Utilizing a minimal number of spatial measurement points could enable accurate assessments even in cases with restricted field of view, thereby expanding the applicability of SWE across various patient populations.