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It is challenging to apply deep learning in professional fields that lack big data support, especially in industrial nondestructive testings (NDT). To solve this problem, one feasible solution is to introduce the concept of NDT physics into a deep neural network to compensate for the network's poor predictive abilities when trained on small datasets. Therefore, we propose a physics-informed deep neural network, named GuwNet, using a unidirectional oblique-focusing (UOF) high-frequency, high-order shear horizontal guided wave electromagnetic acoustic transducer (EMAT) to quantify microcrack defects more accurately. We study the quantification principle of microcrack defects suitable for UOF-EMAT, and propose a network using physical knowledge regarding this theory including the network structure and loss functions design. Compared with traditional nonphysics-informed methods, the length, depth, and direction of the quantification errors are reduced to 0.127 mm, 0.279% dt, and 1.843', respectively, and the average quantification error is reduced by more than 80%

By using the characteristics of two disparate materials (BaTiO3 ceramic and PZT-5H ceramic) on SiO2 glass, we have analyzed shear horizontal wave (SH wave) propagation through a piezo-visco-elastic...

Present study primarily focuses on interpreting the propagation pattern of Shear horizontal (SH) wave in a piezo-composite layered cylinder. The structure consists of three concentric cylinders com...

A semi-empirical model was applied to estimate the frequency shift of a shear-horizontal surface-acoustic-wave (SH-SAW) biosensor for detecting a disease-related biomarker antigen transferrin receptor (CD71) in the sample. In the simulation to investigate its sensitivity, a shift of the SH-SAW resonant frequency occurred by applying an incremental surface mass density change on the surface. The semi-empirical model was proposed and developed by using the experimental and numerical results to relate the concentration of the biomarker to the frequency shift. Results indicated that the thickness of the SiO2 guiding layer affects the sensitivity of SH-SAW sensing, and the dependence is non-monotonically. The SH-SAW sensor was used for specific detection of biotin at a varied concentration. With the concentration of the targeted antigen in the range 0.4 ∼4.2 μg/mL, a typical exponential relation was found between the quantitative target and the frequency shift. Measurement results showed that the mass-loading effect of the antibody-antigen has a reliable response with a sensitivity of 0.94 kHz/(μg/mL). Effects of the sample flow rate on the antigen- antibody interaction and thus the frequency shift of the SH-SAW sensor were also evaluated. It is demonstrated that the proposed model provides a useful approach to analyze effectively the frequency shift dependence on the concentration and the flow rates of sensed molecules in a flow-type SH-SAW sensor.

The electromagnetic acoustic transducer (EMAT) is widely used in In-Line Inspection of gas pipeline. However, the transduction efficiency of the EMAT transmitter is lower compared with the traditional piezoelectric transducer and needs improving. To enhance the amplitude of the received signal, an improved periodic-permanent-magnet EMAT is provided as well as its construction method to generate shear horizontal guided waves propagating in the circumferential direction. By designing a racetrack coil and magnetic array with the same radian of the annular pipeline, the EMAT is more suitable to generate the circumferential wave in the pipeline. The performance of the EMAT transmitter has been assessed with the validated finite element model.

This article reports Lithium Niobate (LN) based shear horizontal (SH0) resonators utilizing suspended and solidly mounted structures for radio frequency (RF) applications. The solidly mounted SH0 structure (also termed guided SH0 structure) is advantageous in obtaining reduced temperature coefficient of frequency (TCF), reduced high frequency overtone spurious responses, and improved power handling. The demonstrated solidly mounted guided SH0 resonators exhibit a mechanical Q as high as 1316 around 950 MHz, and electromechanical coupling factor ( ${k} _{\mathrm {t}}^{\mathrm {2}}$ ) of around 21.8 % - resulting in a figure of merit ( $\mathrm {FoM}=k_{\mathrm {t}}^{\mathrm {2}}\cdot \mathrm {Q}$ ) of 288.

Early detection of incipient damage in structures through material degradation monitoring is a challenging and important topic. Nonlinear guided waves, through their interaction with material micro-defects, allow possible detection of structural damage at its early stage of initiations. This issue is investigated using both the second harmonic Lamb waves and the third harmonic shear horizontal waves in this article. A brief analysis first highlights the selection of the primary–secondary S0 Lamb wave mode pair and primary–tertiary SH0 mode pair from the perspective of cumulative high-order harmonic wave generation. Through a tactic design, an experiment is then conducted to compare the sensitivity of the third harmonic shear horizontal waves and the second harmonic Lamb waves to microstructural changes on the same plate subjected to a dedicated thermal heating treatment. The third harmonic shear horizontal waves are finally applied to monitor the microstructural changes and material degradation in a plate subjected to a thermal aging sequence, cross-checked by Vickers hardness tests. The experiment results demonstrate that the third harmonic shear horizontal waves indeed exhibit higher sensitivity to microstructural changes than the commonly used second harmonic Lamb waves. In addition, results demonstrate that the designed third harmonic shear horizontal wave–based system entails effective characterization of thermal aging–induced microstructural changes in metallic plates.

Based on the complex function method, shear horizontal wave scattering in the two-dimensional and approximately linear inhomogeneous medium is investigated analytically in this work. A new pair of ...

Structural-geomorphological analysis of the modern relief allowed us to reveal patterns in the newest structure of Western Taimyr and to show the significance of the shear horizontal displacements of structural forms, as well as the manifestation of previously formed thrusts on the relief in some areas. The neotectonic evolution of the Arctic region has been controlled by opening of the Eurasian Basin since the Oligocene. This resulted in the activation of the northeastern faults in the region with the same orientation as the transform faults of Gakkel Ridge spreading zone, which supports the active evolution of this region at the present stage.

Shear horizontal (SH) guided waves are commonly used in non-destructive evaluation and can be generated by permanent magnet electromagnetic acoustic transducers (PPM EMATs). PPM EMATs generate SH waves that propagate either forwards and backwards. This is often an undesired characteristic. Recently, we presented designs of PPM-like EMATs that generate SH waves in a single direction through the interference mechanism of two independent periodic sources of forces. In this paper, we present a line-source based analytical model to calculate the radiation pattern produced by multi-PPM EMATs and, in particular, by dual-PPM EMATs, which are able to generate SH waves in a single direction. The model was validated by computing the radiation pattern of a unidirectional side-shifted dual-PPM EMAT, showing good agreement with experimental and numerical results.

The paper demonstrates the design, analysis and of shear horizontal fundamental mode (SH0) resonator based on 36Y-cut Lithium Niobate (LiNbO 3 ) thin film. A spurious-free SH0 resonator response with a k t 2 of approximately 20.7% has been achieved at the wave propagating orientation of 0° in the 36Y-cut plane. Such a high electromechanical enables the large bandwidth of acoustic-based RF filters.

Since the Coronavirus disease 2019 (COVID-19) pandemic outbreak, many methods have been used to detect antigens or antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including viral culture, nucleic acid test, and immunoassay. The shear-horizontal surface acoustic wave (SH-SAW) biosensor is a novel pathogen detection platform with the advantages of high sensitivity and short detection time. The objective of this study is to develop a SH-SAW biosensor to detect the anti-SARS-CoV-2 nucleocapsid antibody. The rabbit sera collected from rabbits on different days after SARS-CoV-2 N protein injection were evaluated by SH-SAW biosensor and enzyme-linked immunosorbent assay (ELISA). The results showed that the SH-SAW biosensor achieved a high correlation coefficient (R = 0.9997) with different concentrations (34.375–1100 ng/mL) of the “spike-in” anti-N protein antibodies. Compared to ELISA, the SH-SAW biosensor has better sensitivity and can detect anti-N protein IgG signals earlier than ELISA on day 6 (p &lt, 0.05). Overall, in this study, we demonstrated that the SH-SAW biosensor is a promising platform for rapid in vitro diagnostic (IVD) testing, especially for antigen or antibody testing.

A model of a pre-stressed piezoactive structure with an inhomogeneous coating made of functionally graded material with a piecewise continuous change of properties is investigated. The linearized m...

In this article, the propagation of nonlinear shear horizontal waves for some comparisons between the heterogeneous and homogeneous plates is considered. It is assumed that one plate is made of up hyper-elastic, heterogeneous, isotropic, and generalized neo-Hookean materials, and the other consists of hyper-elastic, homogeneous, isotropic, and generalized neo-Hookean materials. Using the known solitary wave solutions, called bright and dark solitary wave solutions, to the nonlinear Schrodinger equation, these comparisons are made in terms of the heterogeneous and nonlinear effects. All numerical results, based on the asymptotic analyses in which the method of multiple scales is used, are graphically presented for the lowest dispersive symmetric branch of both dispersion relations.

In the last few years, researchers have paid more and more attention to Shear Horizontal (SH) waves propagation characteristics as new approach used for damage detection. In particular, the fundamental SH0 mode is interesting due to its non-dispersive characteristics and single-mode existence in a certain range of frequency. These features offer promising applicability for developing a new Structural Health Monitoring technique. In order to examine damage detection features of the SH0, it is necessary to first investigate it via numerical simulations. Thus, in this paper, a new modelling approach is developed, based on the Local Interaction Simulation Approach (LISA), which allows to selectively simulate the propagation of SH waves. Both linear and nonlinear material definitions are taken into consideration to investigate propagation features of the aforementioned waves. In the latter case, the Landau-Lifshitz model and the Green-Lagrange strain-displacement relation is used. Furthermore, a local type of nonlinearity, such as a crack, is introduced to the model as well. The high-order harmonics generation is investigated for various cases, depending on the particular presence of the nonlinearity source. Based on the simulation results, the influence of propagation distance on the magnitude of high-order harmonics is evaluated and a comparative analysis is carried out in order to distinguish the sources of the nonlinearity. Presented results demonstrate that LISA is a sufficient tool for the SH-wavefield analysis.

This paper introduces the wave interferences effects of staggering multiple rows of Periodically Permanent Magnets (PPM) in an Electromagnetic Acoustic Transducer (EMAT) configuration to achieve selective beam forming effects such as steering, focusing and de-focusing of guided ultrasonic waves. The shear horizontal (SH) guided ultrasonic wave in a metal plate was used to demonstrate these effects using numerical Finite Element Model (FEM) that were validated using experiments.

Determination of the depth of surface-opening (visible) cracks is of critical importance for evaluating the structural safety of concrete elements. Accurately determining the crack depth wi...

In this work, the scalability between frequency and electromechanical coupling factor ( $k_{t}^{2}$ ) is demonstrated by shear horizontal surface acoustic wave (SH-SAW) resonators based on lithium niobate on insulator (LNOI). The dispersive characteristic is observed from the simulation, and is later substantiated by the fabricated devices with various wavelengths. A high electromechanical coupling factor ( $k_{t}^{2}$ ) of 25.1% was recorded throughout the measurement at a normalized LN thickness of 0.25. Linear response was also disclosed under different input power, verifying the adoption of LNOI topology. Thus, the measured results unveil the potential usage of SH-SAW resonators for wideband applications in communication systems.

When shear horizontal ultrasonic guided waves interact with thickness discontinuities in plates, the reflected and transmitted wavefields can be composed of several modes due to mode conversion. It is known that in a plate with a symmetric discontinuity, with respect to the plate’s mid-plane, mode conversion is restricted to modes that share the same symmetry as the incident mode. In this paper, we use an analytical model based on the reciprocity principle and finite element analysis to investigate mode conversion due to the interaction with different types of discontinuity, namely, non-symmetric, symmetric and geometrically symmetric but with opposite boundary conditions, that is one side of the discontinuity free and the other rigidly fixed. We show that the reflected field due to interaction with the latter is virtually restricted to modes with the opposite symmetry of the incident one, acting as a symmetry inverter discontinuity. Unlike fully symmetric discontinuities, the effectiveness of a symmetry inverter discontinuity depends on the frequency. This was proved with aid of the analytical model for a full-depth discontinuity and verified for partial depth discontinuities. Finally, symmetry inversion of SH waves was experimentally verified in acrylic plates which were symmetrically machined and filled with steel in one side to mimic a fixed boundary condition.

On site monitoring of engine oil is required. The features of a shear horizontal surface acoustic wave (SH-SAW) sensor include simultaneous detection of mechanical and electrical properties of liquids (such as viscosity, relative permittivity, and conductivity) and loaded mass on the sensor surface. In this paper, the used engine oil extracted from a motorbike was measured using the SH-SAW sensor. The degradation factors of the used engine oil were experimentally discussed. Especially, the influences of the particles in the engine oil, heating effect, and water contained in the engine oil were considered by comparing the differences between new and used engine oils. The results indicate that the influence of the water contained in the engine oil is the primary cause of the degradation of the used engine oil.

For the purpose of providing transducers for long-term monitoring of wall thinning of critical pressure equipment in corrosion or high temperature environments, the optimal design methodology for tapered waveguide units was proposed in the present study. Firstly, the feasibility of the quasi-fundamental shear horizontal (SH0*) wave propagating in the tapered waveguide units was analyzed via numerical simulations, and the transmitting limitations of the non-dispersive SH0* wave were researched. Secondly, several tapered waveguide transducers with varying cross-sections to transmit pure SH0* wave were designed according to the numerical results. Experimental investigations were carried out, and the results were compared with waveguide transducers with a prismatic cross-section. It was found that the tapered waveguide units can transmit non-dispersive shear horizontal waves and suppress the wave attenuation at the same time. The experimental results agreed very well with the numerical simulations. Finally, high-temperature experiments were carried out, and the reliability of thickness measuring by the tapered waveguide transducers was validated. The errors between the measured and the true thicknesses were small. This work paves a solid foundation for the optimal design of tapered waveguide transducers for thickness monitoring of equipment in harsh environments.

A robotic nondestructive inspection system developed for stainless steel dry storage canisters containing spent nuclear fuel was tested on a range of mockups in order to assess different aspects of the system. The nondestructive inspection was designed to be able to interrogate 100% of the canister weld lines, even if much of the surface is inaccessible because it uses ultrasonic shear-horizontal waves in what is basically a pulse-echo mode. The guided waves are sent and received by electromagnetic acoustic transducers, which are noncontact as well as tolerant of elevated temperature and gamma radiation. The nondestructive inspection targets stress corrosion cracks in the heat-affected zone of welds. The mockups enable determining the reflection and transmission ratios associated with the welds, the detectability of closed crack-like flaws, the detectability of branched cracks, B-scans along a weld line at elevated temperature, and full robotic system deployment. The test results demonstrate that the robotic system meets its functional requirements.

In this chapter, we compare the nonlinear bright solitary shear horizontal (SH) waves in heterogeneous and homogeneous layers in terms of the heterogeneous effect. Each layer has finite thickness overlying a rigid substratum. We assume that the layers are made up of isotropic, hyper-elastic and generalized neo-Hookean (similarly, compressible or incompressible) materials. Moreover, one layer contains heterogeneous materials and another contains homogeneous materials. The existence of nonlinear bright solitary SH waves in such layers can be found in the literature. Therefore, we aim to overcome the difficulty of a comparison of two nonlinear analyzes for this paper. Besides a comparison part, we add a discussion on some materials in homogeneous media.

The propagation of shear horizontal (SH) surface waves in piezoelectric semi-infinite bodies is investigated theoretically. The surface stress exerting on the boundary is taken into account through...

Nondestructive inspection (NDI) is an integral part of structural integrity analyses of dry storage casks that house spent nuclear fuel. One significant concern for the structural integrity is stress corrosion cracking in the heat-affected zone of welds in the stainless steel canister that confines the spent fuel. In situ NDI methodology for detection of stress corrosion cracking is investigated, where the inspection uses a delivery robot because of the presence of the harsh environment and geometric constrains inside the cask protecting the canister. Shear horizontal (SH) guided waves that are sensitive to cracks oriented either perpendicular or parallel to the wave vector are used to locate welds and to detect cracks. SH waves are excited and received by electromagnetic acoustic transducers (EMATs) using noncontact ultrasonic transduction and pulse-echo mode. A laboratory-scale canister mock-up is fabricated and inspected using the proposed methodology to evaluate the ability of EMATs to excite and receive SH waves and to locate welds. The EMAT's capability to detect notches from various distances is evaluated on a plate containing 25%-through-thickness surface-breaking notches. Based on the results of the distances at which notch reflections are detectable, NDI coverage for spent nuclear fuel storage canisters is determined. Keywords: Dry Storage Cask, Electromagnetic Acoustic Transducers, Shear Horizontal Guided Waves, Stainless Steel Canister

The effects of functionally graded interlayers on dispersion relations of shear horizontal waves in layered piezoelectric/piezomagnetic cylinders are studied. First, the basic physical quantities of elastic waves in piezoelectric cylinder are derived by assuming that the SH waves propagate along the circumferential direction steadily. Then the transfer matrices of the functional graded interlayer and outer piezomagnetic cylinder are obtained by solving the state transfer equations with spatial-varying coefficients. Furthermore, making use of the electro-magnetic surface conditions of the outer cylinder, the dispersion relations for the shear horizontal waves in layered piezoelectric/piezomagnetic cylinders are obtained and the numerical results are shown graphically. Seven kinds of functionally graded interlayers and four kinds of electro-magnetic surface conditions are considered. It is found that the functionally graded interlayers have evident influences on the dispersion relations of shear horizontal waves in layered piezoelectric/piezomagnetic cylinders. The high order modes are more sensitive to the gradient interlayers while the low order modes are more sensitive to the electro-magnetic surface conditions.

In this work, the shear horizontal (SH) wave dispersion in two dissimilar nanolayers is investigated by using the surface elasticity theory in which the surface effects are featured by surface elastic constants. It is found that the SH wave dispersion shows distinct dependence on the nanolayer thickness as well as the surface elastic constants. The larger the surface elastic modulus and/or the smaller the thickness, the higher the phase velocity. In particular, as the wave frequency approaches zero, the analytical relation between the phase velocity in the first mode dispersion and the surface elastic constants is deduced. Thereby, a facile method is suggested to determine the surface elastic constants from the phase velocity of SH waves scattered in nanolayers.

A two-dimensional problem of shear horizontal (SH) waves scattering by a finite width planar elastic (piezoelectric) inclusion partially debonded from its surrounding elastic matrix is inve...

The guided waves (GW) are extensively used in the nondestructive testing (NDT) and structure health monitoring (SHM) of the large and complex structures. It enables to detect the defects up to few meters away from the transducers. However, the defects could occur at longer distances. In order to cover the test area of interest for the estimation of defects and to find the exact position of the transducers to be glued/ embedded, the directivity pattern of the transducers must be known. The aim of the presented work is to develop the 2D analytical model for the estimation of directivity patterns of the transducers at various frequencies and distances. The model was developed using the Huygens's principle of wave propagation distances with considering the known phase dispersive characteristics of the guided wave modes in the medium. The principle of modelling will work to plot the directivity pattern at any distance, at any excitation frequency and with any configuration and shape of the transducers. In order to demonstrate the model, the directivity patterns of P1-type macro-fiber composite (MFC) transducer in the generation of fundamental Lamb modes and shear horizontal mode at 300 mm from the center of MFC were obtained. The input signal used was 80 kHz, 3 period signal and propagation medium was Al plate of 2 mm thickness. The prediction about the position of where MFC transducer should be placed or glued on the object and selection of proper wave modes in order to estimate the defects in various materials is also discussed. The results were validated using finite element analysis (FEA) performed in ANSYS and further verified by the experimental analysis using low-frequency (LF) ultrasonic measurement system ULTRALAB , developed by Ultrasound Research Institute, Kaunas University of Technology. The proposed analytical model will not only facilitate to decide the position and number of transducers but also leads to choosing the configuration of transducer and wave modes suitable to be used for the inspection of defects.

Motivated by the unexpected appearance of shear horizontal Rayleigh surface waves, we investigate the mechanics of antiplane wave reflection and propagation in couple stress (CS) elastic materials. Surface waves arise by mode conversion at a free surface, whereby bulk travelling waves trigger inhomogeneous modes. Indeed, Rayleigh waves are perturbations of the travelling mode and stem from its reflection at grazing incidence. As is well known, they correspond to the real zeros of the Rayleigh function. Interestingly, we show that the same generating mechanism sustains a new inhomogeneous wave, corresponding to a purely imaginary zero of the Rayleigh function. This wave emerges from ‘reflection’ of a bulk standing mode: This produces a new type of Rayleigh-like wave that travels away from , as opposed to along, the free surface, with a speed lower than that of bulk shear waves. Besides, a third complex zero of the Rayleigh function may exist, which represents waves attenuating/exploding both along and away from the surface. Since none of these zeros correspond to leaky waves, a new classification of the Rayleigh zeros is proposed. Furthermore, we extend to CS elasticity Mindlin’s boundary conditions, by which partial waves are identified, whose interference lends Rayleigh–Lamb guided waves. Finally, asymptotic analysis in the thin-plate limit provides equivalent one-dimensional models.