Transverse Wave Speed Research Articles

Design of vibrational filters based on 3D lattice material elongated structure

This study examines the potential of elongated periodic three-dimensional lattice structures for the design of vibration filters using so-called absolute band gaps. These filters are generally obtained by modifying the total stiffness of the structure, which decreases the propagation velocity of all wave polarisations. With a view to optimisation, we are implementing an original structure consisting of interconnected 3D beams with a sinusoidal accordion shape to control the speed of longitudinal waves. In addition, a central junction in the shape of a deformed cross controls the speed of transverse waves. To calculate the propagation of elastic waves in such structures, we use spectral element methods that take into account the longitudinal, torsional and bending motions of three-dimensional beams. The dispersion curves are obtained by applying the Floquet-Bloch periodicity conditions. They are analysed by a detailed study of the wave motion and polarisation. Finally, the geometrical parameters of the lattice cell are optimised using a genetic algorithm to generate the widest absolute band gap at the lowest frequency.

Fabrication of acoustically and physically validated artificial stones to natural kidney stones under shock waves and laser lithotripsy

To present an efficient method for fabricating artificial kidney stones with acoustic and physical properties to assess their fragmentation efficiency under shock waves and laser lithotripsy for very hard stones. The mixture ratio of super-hard plaster and water was adjusted to produce artificial kidney stones for comparison with > 95% human genuine calcium oxalate monohydrate (COM) and uric acid (UA) stones. Acoustic and physical properties, such as wave speed, stone hardness, density, compressive strength, and stone-free rates under shock-wave and laser lithotripsy, were assessed. The longitudinal wave speed of artificial stones prepared at a plaster-to-water ratio of 15:3 closely matched that of COM stones. Similarly, the transverse wave speed of artificial stones prepared at a plaster-to-water ratio of 15:3 to 15:5 aligned with that of COM stones. Stone fragmentation using shock-wave of artificial stones with mixed ratios ranging from 15:3 to 15:5 resembled that of COM stones. The Vickers hardness was similar to that of artificial stones produced with a mixing ratio of 15:3, similar to that of COM stones, while that of artificial stones produced with a mixing ratio of 15:5 was similar to that of UA stones. Density-wise, artificial stones with mixing ratios of 15:4 and 15:5 resembled COM stones. Compressive strength test results did not confirm the similarity between natural and artificial stones. The stone fragmentation using laser showed that stones produced with higher moisture content at a mixing ratio of 15:6 were similar to COM stones. This novel method for fabricating artificial kidney stones could be used to provide reliable materials for lithotripsy research.

Multiple methods for acoustic emission source location in metal waveguides

Research on sound source location, which is widely used in engineering, is an important topic in acoustic emission (AE) technology. Traditional double-ended location methods have certain limitations, such as sound sources being located between two sensors, a single application scenario and possible time delays. In this study, three theoretically feasible location methods were proposed and experimentally verified based on AE propagation theory to test the accuracy of the AE source location and explore single/double-sensor line location in metal waveguides. The experiments measured the propagation speed of longitudinal and transverse waves in the waveguide and verified the feasibilities of the three acoustic source location methods based on waveform analysis, with waveform matching using the wave range and wave speed differences. The experimental results show a location error of less than 3% for the double-ended and double wave-speed methods and less than 6% for the double-waveguide and reflective-surface types.

Some physical properties of K2TlAsX6 (X = Cl, Br) and CsPbBr3 semiconducting compounds

Some physical properties of K2TlAsX6 (X = Cl, Br) double perovskite compounds have been predicted using the theoretical unit cell parameters and elastic constants computed by Munir et al. (Materials Science and Engineering B 298 (2023) 116830). At equilibrium the Debye temperatures of K2TlAsCl6 and K2TlAsBr6 materials were found to be 193.5 K and 159.6 K, respectively. Furthermore, the mass density, the longitudinal, transverse and mean acoustic wave speeds, the acoustic impedance and the Debye temperature of Cesium Lead Bromide (CsPbBr3) inorganic perovskite compound under high stress up to 15 GPa have been predicted using the theoretical unit cell parameters and elastic constants computed by Junaid Zaidi et al. (Materials Research Express, Vol. 9, No. 12, (2022) 125501). To the best of our knowledge, there is no any data in the literature that can be compared to the findings we’ve achieved on the Debye temperature of K2TlAsX6 (X = Cl, Br) and CsPbBr3 materials.

1256 Fabricating Artificial Kidney Stones of Different Physical Properties for Ex Vivo Experimentation

Abstract Introduction There have been several new technologies introduced recently for lithotripsy. The optimal settings of these devices are unknown for different kidney stone densities. This study aims to develop artificial kidney stones for ex vivo studies. Method BegoStone was prepared with a powder to water ratio (by weight) ranging from 15:3 to 15:6. The phantoms' acoustic properties were characterised by using an ultrasound transmission technique, from which the corresponding mechanical properties can calculated based on elastic wave theory. Results The measured parameters for BegoStone phantoms of different water contents were assessed with regard to longitudinal wave speed & density. If transverse wave speeds were measured then longitudinal acoustic impedance, transverse acoustic impedance, Young's modulus, bulk modulus, and shear modulus can be derived. Longitudinal (CL (m/s)) and density (ρ (Kg/m3)) of BegoStone phantoms with different powder to water ratios corresponded to the known properties reported in natural kidney stones (Calcium Oxalate Monohydrate, Brushite, Uric acid and Struvite). A BegoStone water ratio of 15:3 had similar properties to Calcium Oxalate Monohydrate, 15:4 to be similar to Brushite, 15:5 was similar to Uric acid, and 15:6 was similar to Struvite. Conclusions This BegoStone preparation method can be used to fabricate artificial stones with physical properties matched with those of natural kidney stones of various chemical compositions.

New Metric to Evaluate Cardiac Anisotropic Mechanics by Directional High-Frequency Ultrasound-Based Transverse Wave Elastography

The evaluation of cardiac anisotropic mechanics is important in the diagnosis of heart disease. However, other representative ultrasound imaging-based metrics, which are capable of quantitatively evaluating anisotropic cardiac mechanics, are insufficient for accurately diagnosing heart disease due to the influence of viscosity and geometry of cardiac tissues. In this study, we propose a new ultrasound imaging-based metric, maximum cosine similarity, for quantifying anisotropic mechanics of cardiac tissues by evaluating the periodicity of the transverse wave speeds depending on the measurement directions using ultrasound imaging. We developed a high-frequency ultrasound-based directional transverse wave imaging system to measure the transverse wave speed in multiple directions. The ultrasound imaging-based metric was validated by performing experiments on forty rats randomly assigned to four groups; three doxorubicin treatment groups received 10 mg/kg, 15 mg/kg, or 20 mg/kg doxorubicin, while the control group received 0.2 ml/kg saline. In each heart sample, the developed ultrasound imaging system allowed measuring transverse wave speeds in multiple directions, and the new metric was then calculated from 3D ultrasound transverse wave images to evaluate the degree of anisotropic mechanics of the heart sample. The results of the metric were compared with histopathological changes for validation. A decrease in the maximum cosine similarity value was observed in the doxorubicin treatment groups, with the degree of decrease depending on the dose. These results are consistent with the histopathological features, suggesting that our ultrasound imaging-based metric can quantify the anisotropic mechanics of cardiac tissues and potentially be used for the early diagnosis of heart disease.

Dynamic failure of composite strips under reverse ballistic impact

Mesoscale impact experiments on composite strips were conducted in this study to reveal the fundamental failure mechanisms of fiber-reinforced composites (FRCs) under transverse impact by different projectiles. The componential material of composite armor, S-2 glass/SC-15, was manufactured into a single ply and sectioned into strips. The strip specimens were first characterized by X-ray computed tomography and scanning electron microscopy (SEM). The impact experiments were performed using a light-gas gun, shooting the strip specimens to the static wedge-nose projectiles with different nose diameters of 4, 40, and 400 µm. A high-speed camera recorded the strip's failure process from the side. Such a reverse ballistic impact scheme enabled to focus the camera on the projectile nose where the strip was deformed and fractured so that the entire failure process was recorded in real time. These experiments identified three failure modes of the composite strip for each projectile type, defined by no, partial, and complete local failure by the impact loading. The critical velocity region was quantified, showing rising upper and lower boundaries corresponding to the projectile nose diameter. The experimental data were compared with theoretical predictions by Smith's theory. The transverse wave speed deviated from Smith's prediction as the projectile nose diameter decreased, demonstrating a possibly significant error when the pure-tension assumption is employed to model the composite's impact behavior by sharper projectiles. Besides, a sharper projectile was more likely to induce a smaller tent angle, indicating a larger local deformation, considered owing to the stress concentration at the projectile nose.

Linear, weakly nonlinear and fully nonlinear models for soft tissues: which ones provide the most reliable estimations of the stiffness?

Benign and malignant lesions in tissues or organs can be detected by elastographic investigations in which pathological regions are spotted from local alterations of the stiffness. As is known, the shear modulus provides a measure of the stiffness of an elastic material. Based on the classical theory of linear elasticity, an elastogram yields estimations of the linear shear modulus from measurements of the speed of small-amplitude transverse waves propagating in the medium tested. In this paper, we show that the estimation of the shear modulus can be improved significantly by employing the fourth-order weakly nonlinear theory of elasticity (FOE), and indicate how the stiffness can be assessed more precisely with the use of FOE. We discuss also why FOE provides more reliable results than the fully nonlinear theory of elasticity. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.

An analysis for unipole acoustic logging while drilling wavefields with varying eccentered collar positions

Abstract The unipole logging while drilling (LWD) tool is a recently developed acoustic logging tool that uses an azimuthal emitting source to generate acoustic waves in the borehole to measure the longitudinal and transverse wave speeds of the surrounding stratum. In this study, the unipole transmitter transducer is modeled as a surface force source, and the analytical solution for unipole LWD wavefield is derived. The received waveforms are composed of infinite-order contributions owing to the directivity of the excitation of the unipole source. Using up to eight lowest-order modes, the acoustic waveforms excited by the unipole are calculated in both soft and hard formations, and then slowness-time coherence and velocity dispersion analysis are performed. The pure mode waves are obtained using the mode wave decomposition method. The influence of tool eccentricity (off-center positioning) on the wavefields excited by the unipole transmitter is also discussed. Based on the addition theorem of the Bessel function, the analytical solution of the received waveforms when the tool is eccentered can be obtained. In soft and hard formations, the received waveforms with tool eccentricities of 0 to 90% are compared. Tool eccentricity has a smaller effect for the soft formation than the hard formation. The received waveforms on the side closest to the borehole wall are also affected most when the tool is off center, with a sharp increase in amplitude in the fast formation and a late arrival wave group in the soft formation. These conclusions are important for the design and data interpretation of a unipole LWD tool.

Numerical investigation on movement of triple points on oblique detonation surfaces

A normal detonation wave in a gaseous mixture is a transient, multidimensional structure containing triple points (TPs) that collide in pairs and then propagate oppositely. However, the TPs on an oblique detonation wave (ODW) almost propagate along the same direction in most studies. In this study, the reactive Euler equations coupled with a two-step induction–reaction kinetic model are used to solve a two-dimensional wedge-induced ODW. Two novel movement patterns are observed in most cases. Results show that the TPs of the ODW can propagate upstream and even stand on the wave surface. The movement patterns of TPs include downstream, upstream, and steady according to their propagation direction relative to the wedge. We find that the ratio of the post-ODW flow speed Uτ to the transverse wave speed UT dominates the TP movement types. When the speed ratio Uτ/UT is approximately equal to 1, the TPs can stand on the wave surface. Above unity, downstream TPs form, and upstream TPs correspond to a value smaller than 1. Furthermore, the inflow Mach number has little influence on UT, while Uτ changes significantly. This is largely due to the high sensitivity of the ODW angle to the inflow. The high heat release rate benefits upstream TPs, and steady TPs form under a large wedge angle. The results are confirmed by varying the inflow Mach number, wedge angle, and chemical parameters.

Magnetic and rotational effects on the reflection of inhomogeneous waves in a fiber-reinforced thermoelastic material

The problem of reflection of inhomogeneous plane waves from the free surface of a fiber-reinforced magneto-thermoelastic rotating material has been investigated. The phase speeds of quasi longitudinal, quasi transverse and quasi thermal waves are derived. The reflection coefficients and the energy ratios are obtained. The magnetic and rotational effects on the reflection coefficients and energy ratios are computed numerically and presented graphically. It is found that the magnetic field and rotation influence the reflection coefficients and energy ratios significantly. Critical angles are observed for incident quasi transverse wave. The sum of energy ratios has been verified to validate the problem.

Peculiarities of wave dynamics in the tether of a space tethered system

In this paper we analyze the wave's effects in the tether of a space tethered system. The space tethered system is considered as a “big” massive satellite or a spacecraft moving along a circular orbit and a smaller satellite (endmass) connected with the first one by flexible and stretchable long tether. A load can be transported along the tether from the big satellite to the endmass. The method of characteristics (wave method) for numerical solving of non-linear wave equations of motion of the tether is proposed. It allows to analyze the dynamics of the system as in the cases when velocity of the load is low (much less that speed of transverse waves) so for the cases when it is equal or greater then speed of transverse waves. We analyze and compare the trajectories of movement of parts of system and system configurations that were obtained by non-wave method when the process of the load transportation is practically non-wave with some results obtained by the wave method. Also we obtain some conditions between the parameters of the system such as endmass, mass of the tether, speed of transverse waves, which provide stable movement of the load along the tether. • Modeling of dynamics of the space tethered system taking into account wave processes in the tether is considered. • Whole system is designed to “clean off” space debris from orbits. • The proposed method can be effectively used to modeling space missions.

Specific Features of Using the Linearization Method for the Analysis of Low-Frequency Oscillations of a Towed System

The results of experiments and numerical calculations in the low-frequency range of oscillations of the power and geometric characteristics of a towed system (TS) are presented. The hypotheses used in the linear amplitude-frequency analysis are verified with the use of a discrete model. The limits of applicability of the finite-difference method for numerical TS simulation are determined on the basis of a continuous hyperbolic model that takes into account varying lengthwise tension and finite speed of longitudinal and transverse (configurational) waves. The total error of numerical simulation does not exceed 15–20%. There is a certain delay both in the angle of TS deflection from the vertical and in the maximum horizontal component of the tensile force at its root point. It may be one of the causes of breakage of TS in certain conditions of oscillations and at a certain towing speed, when the tugboat and the TS oscillate in antiphase.

Research on Two-dimensional Fabry-Perot Ultrasonic Sensing Technology

According to the laser interference method, a two-dimensional Fabry-Perot fiber optic sensor is used as the core, and the difference between the propagation speed of the ultrasonic transverse wave and the longitudinal wave in the solid medium is used to measure the ultrasonic wave propagating in the solid to realize the ultrasonic positioning. An F-P interference cavity is formed with a coated quartz film, the end face of the fiber end, and air. At the same time, the cantilever beam design can be used to simultaneously extract longitudinal ultrasonic waves based on Fabry-Perot cavity interference and transverse ultrasonic signals based on cantilever fibers in a solid rod-shaped acoustic waveguide. In this paper, the position of the ultrasonic wave is determined by the difference of the longitudinal and transverse ultrasonic wave speeds in the detected ultrasonic signals.

Critical Role of a Nanometer-Scale Microballoon Shell on Bulk Acoustic Properties of Doped Soft Matter.

A material's acoustic properties depend critically upon porosity. Doping a soft material with gas-filled microballoons permits a controlled variation of the porosity through a scalable fabrication process while generating well-tailored spherical cavities that are impermeable to liquids. However, evidence is lacking of how the nanometer-scale polymeric shell contributes to the overall effective material properties in the regime where the wavelength is comparable to the sample thickness. Here, we measure ultrasound transmission through a microballoon-doped soft material as a function of microballoon and impurity concentration, sample thickness, and frequency. The measured longitudinal wave speeds are an order of magnitude larger than those in similar systems where no shell is present, while the transverse wave speed is found to linearly increase with microballoon concentration, also in contrast to systems with no shell. Furthermore, we find the results are independent of the soft material's elastic moduli as well as a lesser contribution of the microballoon shell on material attenuation. The results are validated with a multiple scattering model and suggest the shell contributes significantly to the material's bulk acoustic properties despite its thickness being 4 orders of magnitude smaller than the acoustic wavelength. Our results demonstrate how a nanometer-scale interface between a gas cavity and a soft polymer can be used in the submicrometer design of acoustic materials, and are important for observations of such phenomena as strong interference effects in soft matter.

Noninvasive high-frequency acoustic microscopy for 3D visualization of microstructure and estimation of elastic properties during hydrolytic degradation of lactide and ε-caprolactone polymers

The monitoring of degradation processes' kinetics in polymers is one of the attractive possibilities of ultrasound technique applications that provide non-destructive imaging of polymers' internal microstructure and measurements of elastic properties. In this work, biodegradable polymers and copolymers based on L,L-lactide, D,L-lactide and ε-caprolactone have been studied at different stages of hydrolysis at 37 °C by high-frequency (100 and 200 MHz) ultrasound. The acoustic microscopy technique has been developed to reveal changes in the internal microstructure and bulk sound speed in polymer samples over a hydrolysis period of 25 weeks. Ultrasound imaging provides visualization of amorphous and crystalline phases, internal imperfections, variation in packing density, and other microstructural features. Acoustic images demonstrate nucleation, growth, and the changes in internal inhomogeneities in polymers during degradation accompanied by a decrease in the polymers' molecular weight. We associate the changes in the elastic properties (the speed of a longitudinal wave) with crystallinity variations in polymers during hydrothermal aging. The results of the ultrasound investigations are supplemented by gel permeation chromatography, differential scanning calorimetry, and wide-angle X-ray spectroscopy. Statement of SignificanceMonitoring the kinetics of degradation processes in polymers is one of the attractive possibilities of applying ultrasound techniques that provide non-destructive imaging of the polymers' internal microstructure and measurements of elastic properties. In this work, visualization of nucleation, growth, and evolution of internal inhomogeneities in the volume of polymers and variation of values of speed of longitudinal and transverse sound waves during hydrolysis are compared with measurements of molecular weight, density, data of DSC curves, and X-ray scattering analysis. We discuss several common phenomena that occur in the volume of poly(L-lactide) and poly(D,L-lactide) over the degradation process as well as improvement of elastic properties of the poly(ε -caprolactone) and poly(L-lactide-co-caprolactone) during hydrothermal aging.

Wave propagation in elastic–plastic material with voids

Constitutive relations and governing equations have been developed for an elastic–plastic material with voids having single slip-plane and direction. The plasticity of the material is considered through the dislocation of slip-plane. The propagation of unidirectional plane waves has been explored in an infinite elastic–plastic material with voids, and it has been found that there exist four basic waves consisting of three coupled elastic–plastic waves and a lone transverse wave. The speeds of propagation of all the coupled elastic–plastic waves are found to be affected by the plasticity and void parameters, in general, while the transverse wave is not affected by the plasticity and void parameters at all and travels with the speed of classical transverse waves. Out of the three coupled elastic–plastic waves, two waves are the counterpart of the waves existing in elastic materials with voids, while the third wave is new and has appeared due to the presence of plasticity in the material. One of the coupled elastic–plastic waves that is least affected by the plasticity faces a critical frequency, below which the wave is a nonpropagating wave. This critical frequency arises due to the presence of voids in the medium. The speed of various waves is computed for a specific model and the results that are obtained are presented graphically. At large frequencies, all the coupled elastic–plastic waves propagate with constant speeds, but at low frequencies, they propagate with speeds less than that of the longitudinal wave of classical elasticity. Several earlier known results have been recovered as special cases from the present formulation.

Optimization of soft armor: the response of single-ply para-aramid and ultra-high molecular weight polyethylene fabrics under ballistic impact

Typical soft armor systems are constructed of multiple layers of a single fabric type. This empirical research sought to begin optimization of these systems through hybridization, sequencing dissimilar armor fabrics to maximize their ballistic protective performance, by first investigating single plies with a spectrum of properties to determine their behavior and response to impact. Eight individual plain weave fabrics with varying yarns and thread counts were manufactured from para-aramid and ultra-high molecular weight polyethylene (UHMWPE) yarns and physical and ballistic characterizations were conducted. The ballistic impact tests established the specific energy absorption (SEA) of each fabric across a range of impact velocities (340–620 m·s–1) and the transverse displacement wave velocity across the rear of the fabric was found using digital image correlation. Low cover factor ( Cfab) fabrics (0.74–0.84) consistently showed faster transverse wave speed than the high Cfab fabrics (0.84–0.96) for any given yarn type. The relative SEA of the fabrics varied dependent on both the impact velocity and number of plies impacted. It was found that lower Cfab fabrics had the highest SEA, critical velocity and transverse wave velocity. UHMWPE fabrics were not considered suitable for a woven hybrid system as they had a significantly lower SEA compared to all the para-aramid fabrics. Results indicate that a hybrid system, when considered as a theoretical spaced system, would benefit from higher Cfab fabrics as rearward layers. However, transverse wave results suggest the lower response of these fabrics may inhibit lower Cfab fabrics at the front of a combined hybridized system.

Dispersion of Transverse Waves in Single-Wall Carbon Nanotubes

In this work we investigate the in?uence of initial stress on the transverse waves propagation in single-wall carbon nanotubes with small scale e?ects under ultrahigh frequency (above k = 1nm?1), using the nonlocal continuum theory. The phase and group velocities are derived in a simple way. The e?ects of wave numbers, scale coe?cients and initial stress parameter on phase and group velocity are analyzed. The results show that the dispersion properties of the transverse wave propagation in a single-wall carbon nanotube are induced by small scale e?ects, which cannot appear in classical models. Also, it is clear that the increase of the scale coe?cient and wave number could be strengthened by the dispersion degree of the phase and group velocity of transverse waves. In particular, the analysis shows that the compression initial stress in a single-wall carbon nanotube does not only a?ect the number of transverse wave speeds and the magnitude of transverse wave speeds, but also the critical value of the wave number at the wave speed changes. The e?ects of the initial stress and small scale on the transverse wave propagation in single-wall carbon nanotubes may result in some complex dynamic phenomena of terahertz sound waves propagation in the carbon nanotubes, which can be used as a useful reference for the designs of nanodrive devices, nanooscillators and nanosensors.

Relativistic effect inducing drag on fast-moving dislocation in discrete system

Phonon scattering, a dominant source of drag, is one of key issues to understand the dynamic behaviors of a dislocation. In this paper, it is found that a relativistic effect causes additional drag that is not ignorable when the dislocation's speed is comparable to the transverse shear wave speed. By considering the emission of lattice waves from the dislocation core, we theoretically derive an equation of dislocation motion wherein the relativistic effect is well considered in the frame of phonon scattering. Consequently, the relativistic drag force is characterized by two dimensionless constants that are newly defined in this study. Given that these constants depend on structural and oscillation properties of the dislocation core, a discrete nature of the core is well-reflected. Then, the solution of the equation, or the dislocation's speed, is compared with the result obtained by molecular dynamics simulation. Furthermore, the developed equation can explain a level-off behavior at high dislocation's speed by quantifying the relativistic drag force. Thus we can broaden our understanding of dislocation dynamics to fast-moving dislocations.