Elastic Pulse Research Articles

Objective Evaluation of Stellate Ganglion Block Effects Using Ultrasound Wave Intensity Technology: A Study on Hemodynamics.

Emerging evidence suggests that although Horner's syndrome manifests observable facial changes, it may not comprehensively evaluate the hemodynamic alterations associated with stellate ganglion block (SGB). This study endeavors to systematically evaluate the influence of SGB on the elasticity and flow velocity of the common carotid artery (CCA) and brachial artery utilizing ultrasound wave intensity analysis (usWIA). Particularly, it focuses on patients necessitating monitoring for its effects on specific organs or regions. Totally, we selected 33 patients, where only 31 patients (comprising 15 males and 16 females) were included between September 2020 to January 2022 after screening patients who require SGB treatment for painful disorders. The side on which the SGB was administered depended on the patient's painful side, 13 cases underwent left stellate ganglion block (LSGB), and 18 cases underwent right stellate ganglion block (RSGB). Wave intensity (WI) data were collected by usWIA on the CCA and brachial artery before the administration of SGB and after the manifestation of Horner's syndrome. We then compared the changes in these data pre- and post-SGB using SPSS 26.0. The results showed an increase in arterial compliance (AC) of the CCA and brachial artery on the blocked side after SGB (P < 0.05). In contrast, pressure-strain elastic modulus (EP) and arterial stiffness pulse wave velocity (PWVβ) decreased (for all P < 0.05). Furthermore, the minimum velocity (Vmin) of the CCA exhibited a significant increase (P < 0.01), while wave intensity pulse wave velocity (PWVwi) was significantly reduced (P < 0.01). In contrast, on the contralateral side of the CCA, EP and PWVβ increased after SGB (for all P < 0.05), while AC decreased (P < 0.05). SGB has been observed to enhance the elasticity and blood flow velocity of arteries within its innervated areas. In clinical practice, usWIA can serve as an objective measurement tool for assessing the impact of SGB on arterial elasticity and flow velocity in specific organs or regions. Furthermore, unilateral SGB has been noted to diminish the arterial elasticity of the CCA on the contralateral side.

The Effect of Age, Hypertension, and Overweight on Arterial Stiffness Assessed Using Carotid Wall Echo-Tracking in Childhood and Adolescence.

Arterial stiffness represents an independent predictor of the risk of subsequent cardiovascular events. Early identification of high-risk individuals is necessary for effective prevention and targeted interventions. Carotid wall echo-tracking is a modern method for an accurate evaluation of the structural and functional properties of carotid arteries. This study aimed to assess age and sex-specific reference values of the echo-tracking parameters of carotid stiffness in 400 healthy children and adolescents and to evaluate the potential early effect of elevated blood pressure and overweight in 69 overweight normotensives, 45 white coat hypertensives, and 44 essential hypertensives. Stiffness index β, pressure-strain elastic modulus (Ep), arterial compliance (AC), and pulse wave velocity β (PWV β) were evaluated using Aloka ProSound F75. Both white coat and essential hypertension were associated with impaired carotid wall properties with the greatest effect on Ep, followed by PWV β, index β, and AC. The excess weight showed a weaker effect on Ep and PWV β. This is the first study to compare the effects of white coat and essential hypertension on carotid arterial stiffness assessed using the echo-tracking technique in childhood and adolescence with direct application of pediatric reference values specific to age and sex.

Influence of rapidly time-varying boundary conditions on the control of two-dimensional elastic pulses in laminates

Influence of rapidly time-varying boundary conditions on the control of two-dimensional elastic pulses in laminates

Destruction of a magnesium alloy film in the condensed state by an ultrashort laser-driven shock wave

Laser-driven shock wave phenomena in a sub-micrometer Mg–4Al–2Zn alloy film are studied using spectral interferometry with spatial and temporal (1 ps) resolution. Upon irradiating the film through a glass substrate by 500 fs laser pulses, the ultrashort elastic compression pulses with the peak stress up to 4.6 GPa at a propagation distance of 0.5 μm were generated. Depending on the laser fluence, either spall fracture near the rear surface in the solid state or cavitation near the metal–glass interface in the liquid state was observed. The spall strength of the solid Mg alloy and the upper limit of the cavitation threshold in the melt at the strain rate of ∼109 s−1 were extracted from the free surface velocity history. The depth of fracture initiation was retrieved from the instant of the spall pulse exit, and the thickness of the molten layer was estimated to be 100–160 nm depending on laser fluence. The investigation of the residual morphology by scanning electron and atomic force microscopies revealed the presence of melting and nucleation within the irradiated area. The experimental findings are of interest for predicting the behavior of magnesium alloys in the condensed state at extremely high strain rates, for studying the physics of metastable states and for simulating the interaction of ultrashort laser pulses with thin film materials.

Hypersound tomography of graphitized layers buried into diamond matrix

Acoustic properties of buried graphitized layers in diamond formed by ion implantation followed by annealing were studied using the picosecond ultrasonic technique with spatial resolution. Two methods of elastic pulse generation were used: heating an aluminum film deposited on a diamond sample by femtosecond laser pulses and direct illumination of the graphitized layers by these pulses. We applied a multilayered model of the acousto-optical response to fit experimental results and estimate the distribution of the acoustical parameters (wave resistance, viscoelastic damping, and longitudinal sound speed) of the structures under study in depth. It was found that unique sets of spectral lines are present in the Fourier spectra of measured responses in regions with different internal structures. Mapping of the Fourier spectra made it possible to visualize regions with different internal structures. The combined use of depth profiling and mapping can serve as a tool for hypersound tomography.

The effects of carotid artery stiffness on cerebral small vessel disease and cognition

AbstractBackgroundCarotid artery stiffness is associated with cognitive impairment and dementia, however, the underlying mechanism remains unknown. We examined the association of carotid artery stiffness with cerebral small vessel disease (CSVD) markers, cognitive impairment, dementia with its subtypes, as well as cognitive performance.MethodIn this case‐control study, 272 subjects from a memory clinic underwent physical and medical evaluation along with carotid ultrasonography, 3T brain magnetic resonance imaging and detailed neuropsychological assessment. Carotid ultrasonography was conducted to assess arterial compliance (AC), pressure‐strain elastic modulus (Ep), β‐index, augmentation index (AI), and pulse wave velocity‐β (PWV‐β). Brain MRIs were graded for white matter hyperintensities (WMH), lacunes, and cerebral microbleeds (CMBs). Participants were classified as no cognitive impairment, cognitive impairment no dementia, as well as dementia and its subtypes; Alzheimer’s disease (AD) and vascular dementia (VaD). Cognition was assessed using NINDS–Canadian Stroke Network harmonization neuropsychological battery.ResultIncreased carotid β‐index (β = 0.73, P&lt;0.001), Ep (β = 0.86, P&lt;0.001), and PWV‐β (β = 0.83, P&lt;0.001) were independently associated with WMH. Ep (OR = 1.42, 95%CI = 1.05–1.93), and PWV‐β (OR = 1.43, 95%CI = 1.05–1.94) were associated with presence of lacunes. Ep was associated with AD (OR = 1.59, 95%CI = 1.01‐2.73) and VaD (OR = 2.23, 95%CI = 1.04‐5.94). Additionally, PWV‐β was associated with VaD (OR = 2.24, 95%CI = 1.07–5.62). All carotid artery stiffness measurements, except AI, were associated with worse performance in global cognition, visuomotor speed and memory after adjusting for age, sex, education, hypertension, diabetes, hyperlipidaemia, cardiovascular disease, and smoking. These associations became attenuated but remained significant with global cognition after adjusting for CSVD markers (β‐index; β = ‐0.27, P = 0.04), Ep; β = ‐0.30, P = 0.03), and PWV‐β; β = ‐0.32, P = 0.02).ConclusionCarotid artery stiffening is associated with WMH, lacunes, and etiologic subtypes of dementia. Carotid artery stiffening is also associated with global cognition independent of CSVD. Elevated carotid artery stiffness may help identify patients at risk for developing CSVD and dementia.

Mechanochemical Activation of Superradiance in Paramagnetic Polymer Composites.

The review examines the effect of radio-frequency superradiance during pulsed mechanochemical activation of polymer composites under high pressure. Mechanochemical activation is implemented in three modes: (a) rheological explosion of polymer composite under rapid uniaxial compression, when an elastic wave pulse occurs in a polymer composite sample and implements the physico-chemical transformations leading to the occurrence of a superradiance pulse; (b) parametric mode, when an elastic wave pulse is introduced from the outside through a waveguide into a composite sample; (c) the mode of rapid pressure release, which also leads to the occurrence of a superradiance pulse. Paramagnetic polymer composites-namely polystyrene-binuclear clusters Co(QH)2-O-Co(QH)2 or Mn(QH)2-O-Mn(QH)2, where QH is a ligand based on QH2-3,6-di-tert-butylpyrocatechin)-are considered as objects implementing such processes. These binuclear clusters exhibit the Dzyaloshinskii-Moriya effect, and polymer composites based on them exhibit multiferroic properties. A composite of a molecular magnet in polystyrene matrix (Eu(III)(SQ)3·bipy complex with four unpaired electrons on Eu(III) and on SQ ligands; SQ is 3,6-di-tert-butylquinolate paramagnetic ligand) is also considered. The binuclear clusters and europium complexes form 2D nano-objects in the polymer matrix with a diameter of 50-100 nm and a thickness of ~ 1-2 nm. The review considers the formalisms of Dicke, Lorentz, Landau-Lifshitz-Blombergen and Havriliak-Negami equations, which make it possible to conduct a time-frequency analysis of these processes, to obtain data on the relaxation processes of spin and charge density in objects responsible for the process of radio-frequency superradiation. It is also shown that the analysis of electron spin resonance data allows us to provide a probable quantum chemical scheme for the implementation of the radio-frequency superradiance process. The phenomenon of superradiation has a great deal of potential in such areas as energy-saving technologies, wireless power transmission and storage devices. The technique of studying fast mechanochemical processes considered in the review allows us to investigate the mechanisms of interaction of magnetic and electrical subsystems in multiferroics and molecular magnets, which expands the scientific base for the creation of new functional materials and enables the solving of related problems of condensed matter physics.

SPECTRAL-ACOUSTIC MONITORING OF DAMAGE IN POLYCRYSTALLINE MATERIALS BASED ON A SIMULATION-MECHANICAL MODEL

In this study, a modified simulation-mechanical model is developed for dispersed damage accumulation in a polycrystalline material based on continuum damage mechanics and physical mesomechanics. The main damaging factors are assumed to be the field of dispersed microcracks in the material and the field of internal stresses arising primarily from linear structural defects. The statistical limit state criterion of a material following from the proposed model is consistent with the known information about the failure conditions of brittle and ductile structural materials. The possible application of the limit state criterion is discussed for typical cases of failure and transition from elastic to elastic-plastic deformation of polycrystalline structural materials. The proposed spectral-acoustic method for material damage assessment is used to analyze elastic pulse propagation in the simulated medium. The existence of some acoustic effects in the damaged medium is substantiated, which can be useful for the instrumental assessment of material damage at any time during loading of a sample or service of a structural element. It is shown that the spectral-acoustic method can provide a basis for a technique of measuring the damage parameters included in the proposed model. Available experimental data confirm the correctness of the damage assessment approach for structural materials. Further experimental studies will develop methods for express monitoring of dispersed damage in metal structures subjected to thermomechanical loads.

Impact Excitation of Magnetic Oscillations by an Elastic Displacement Pulse

Impact Excitation of Magnetic Oscillations by an Elastic Displacement Pulse

Quantitative characterization of Q235B steel electrochemical corrosion by acoustic emission

The mechanism of dissolving acoustic source of Q235B corrosion anode metal is the basis of acoustic emission (AE) source identification and corrosion site evaluation and analysis. In this paper, the local mechanical energy release and the characteristics of radiated elastic wave pulse in the process of metal dissolution are analyzed by using the principles of corrosion dynamics, damage thermodynamic energy conversion, local mechanical energy release and radiation elastic wave pulse characteristics of metal dissolving process, and the theoretical analysis is verified by atomic first numerical method. Combined with AE and electrochemical testing technology, the mechanism of Q235B steel corrosion acoustic source is studied experimentally. The characteristics of the metal dissolved acoustic source are obtained, and the energy conversion value of anode metal in the process of dissolution is extracted. The quantitative characterization formula of the corrosion behavior of the AE is established, which provides a basis for the assessment of the severity of the corrosion state of Q235B steel.

Manual for Calibrating Sound Speed and Poisson’s Ratio of (Split) Hopkinson Bar via Dispersion Correction Using Excel® and Matlab® Templates

This manual presents a procedure to calibrate the one-dimensional sound speed (co) and Poisson’s ratio (ν) of a (split) Hopkinson bar using the open-source templates written in Excel® and Matlab® for dispersion correction. The Excel® template carries out the Fourier synthesis and one-time dispersion correction of a traveling elastic pulse under a given set of co and ν. The MATLAB® template performs the Fourier synthesis and iterative dispersion correction of a traveling elastic pulse for a range of co and ν sets. In the case of the iterative dispersion correction, a set of co and ν is assumed at each iteration step, and the sound speed vs. frequency (cdc vs. fdc) relationship necessary for dispersion correction is obtained under the assumed set by solving the Pochhammer–Chree equation. Subsequently, dispersion correction is carried out by using the cdc vs. fdc relationship. The co and ν values of the bar are determined in the iteration process when the dispersion-corrected pulse profiles are reasonably consistent with the measured ones at two travel distances (2103 and 4000 mm) in the bar. In the case of the experimental profile considered herein, the ν and co values were calibrated to six and four decimal places, respectively. The calibration algorithm is described with the tips for using the open-source templates, which are available online in a publicly accessible repository.

Sound Speed and Poisson’s Ratio Calibration of (Split) Hopkinson Bar via Iterative Dispersion Correction of Elastic Wave

AbstractA process of calibrating a one-dimensional sound speed (co) and Poisson’s ratio (ν) of a (split) Hopkinson bar is presented. This process consists of Fourier synthesis and iterative dispersion correction (time-domain phase shift) of the elastic pulse generated by the striker impact on a circular bar. At each iteration, a set of co and ν is assumed, and the sound speed versus frequency (cdc versus fdc) relationship under the assumed set is obtained using the Pochhammer–Chree equation solver developed herein for ground state excitation. Subsequently, each constituting wave of the overall elastic pulse is phase shifted (dispersion corrected) using the cdc–fdc relationship. The co and ν values of the bar are determined in the iteration process when the dispersion-corrected overall pulse profiles are reasonably consistent with the measured profiles at two travel distances in the bar. The observed consistency of the predicted (dispersion-corrected) wave profiles with the measured profiles is a mutually self-consistent verification of (i) the calibrated values of co and ν, and (ii) the combined theories of Fourier and Pochhammer–Chree. The contributions of the calibrated values of co and ν to contemporary bar technology are discussed, together with the physical significance of the tail part of a traveling wave according to the combined theories. A preprocessing template (in Excel®) and calibration platform (in matlab®) for the presented calibration process are openly available online in a public repository.

Nonlinear elastic metamaterials as pulse shaping devices for shock test applications

Metamaterials (MM) have become a very active research topic in numerous domains of engineering because of their promise to create structures and devices that can control wave propagation in ways that exceed the capabilities of conventional homogeneous and composite materials. Most research on acoustic and elastic MM has been focused on linear behavior. However, linear MM suffer from notable drawbacks, for example, (i) the effective material properties for the application of interest are often limited to narrow frequency bands, and (ii) they have limited usefulness in applications where nonlinearity is unavoidable or essential, e.g., shock testing or high-intensity focused ultrasound. Nonlinearity has therefore been explored to expand the palette of accessible dynamic response of synthetic materials. In this work, we investigate applications for nonlinear elastic MM as pulse shaping materials for shock testing. By using high-resolution finite element methods in concert with direct numerical simulations of reduced-order dynamic models, we examine the propagation of elastic pulses under the influence of various types of nonlinear elastic response and identify means to obtain them. These simulations demonstrate the potential for nonlinear elastic MM to significantly expand the space of accessible excitations for shock testing, using a relatively small number of design parameters.

Shock Excitation of the Magnetization Oscillations in a Magnetoelastic Medium by Complex-Shaped Elastic Pulses

Shock Excitation of the Magnetization Oscillations in a Magnetoelastic Medium by Complex-Shaped Elastic Pulses

A Pulse-Multiplication Proposal for MIRACLES, the Neutron TOF-Backscattering Instrument at the European Spallation Source

The fixed-energy window scan approach, for both elastic and inelastic modes, is a valuable tool to discriminate between motions activated when dynamical phase transitions occur in a sample as a function of time, temperature, pressure, electrical field or illumination. Considering that, on one hand, such variations can generate a weak signal, and on the other, high data throughput makes it possible to screen many samples during a beam time, pulse multiplication is an ideal strategy to optimize the intensity of the analyzed signal. To ensure this capability, a proposal for a future upgrade of MIRACLES, the neutron time-of-flight backscattering spectrometer at the European Spallation Source (ESS) under construction in Lund, is reported in this article. The concept for a new chopper layout relies on the extraction of several elastic pulses, ensuring an increase in the neutron total elastic intensity hitting the sample. This proposal can be extended to the inelastic counterpart. The premise is to maintain the original beamline layout without modification, either of the guide sections or of the current chopper layout of MIRACLES, thereby guaranteeing that minimal changes and impact will occur during the proposed upgrade. However, this also presents a significant challenge, namely, to achieve an efficient pulse multiplication within the width and the length of the guide and within the rising/decay time of the pulses. With the concept presented here, an increase in elastic intensity by a factor of 2.8 was obtained. This is analogous to performing elastic fixed window (EFW) measurements with an ESS source operating at 14 MW, widening considerably the performance capabilities of MIRACLES. The knowledge generated here is also valuable for the design of scientific instruments for the next generation of low-energy, accelerator-driven neutron sources.

Split Hopkinson bar tests on metaconcrete: modeling and numerical simulations

The work deals with the dynamic characterization of metaconcrete, a mechanical metamaterial with locally resonant inclusions and unconventional dynamic performance. Metaconcrete can be defined as an unusual concrete in which standard aggregates are partially replaced by engineered ones made of a rigid heavy core covered by a compliant layer. From a mechanical point of view, its mitigation properties are associated to the mechanical energy trapped by the inclusions when acted upon by an elastic pulse with a frequency content close to their own resonant frequencies. So far, a discrete number of experimental investigations have been performed but none of these consider the impulsive nature of blast and impact loadings and the direction of the incoming wave with respect to the inclusion orientation in case of a brittle matrix. The results of numerical simulations considering different configurations of engineered inclusions within a single metaconcrete unit are compared in terms of stress level attained as well as internal and kinetic energy involved. Metaconcrete can bring about disruptive applications in several fields of applied sciences, but for the technology to become firmly established a synergism between computational and experimental approaches is paramount.

Estimation of Possibilities of Using Fractal Dimension and Information Entropy of Elastic Waves for Assessment of Damage to Steel 20 at Low Cycle Fatigue

The paper presents the results of experimental studies of specimens made of steel 20 for low-cycle fatigue (cantilever bending). A fatigue curve was obtained for the material under study in the range of stress amplitudes from 210 to 380 MPa. In logarithmic coordinates, this dependence is linear. According to the research results, it has been shown that one of the structure-sensitive characteristics is the shape of an elastic wave pulse transmitted through the medium under study. To analyze the pulse shape of an elastic wave, an algorithm is proposed for assessing the damage of materials, using the values of the fractal dimension of the attractor and the information entropy in the process of fatigue loading. It was found that according to the obtained dependences, the process of fatigue damage accumulation can be conditionally divided into 2 phases. In the first phase, the entropy of the ultrasonic signal practically does not change and remains within the range of 0.05-0.1 nat. The fractal dimension of the attractor of the ultrasonic signal increases from 1.5 to 1.8. During the transition to the second phase, the maximum values of the fractal dimension of the attractor of the ultrasonic signal are observed, the values of which decrease in the second phase to 1.4 before the destruction of the sample. The information entropy values in the second phase increase monotonically up to 0.55 nat. Studies have shown that the obtained dependences practically do not change with a change in the stress amplitude. The results of studies at various stress amplitudes have shown that the characteristics of the fractal dimension of the attractor and the information entropy of elastic wave pulses that have passed through the zones of accumulated damage in the metal expand and supplement the capabilities of acoustic methods in the problems of assessing the performance of materials with low-cycle fatigue and make it possible to identify the stage of destruction of steel 20.

A non-linear elastic approach to study the effect of ambient humidity on sandstone

We demonstrate that strong elastic pump wave pulses soften sandstone more in humidified conditions than they do in dry conditions and that this effect is repeatable and reversible. We assess these changes via the non-linear interactions of a strong pump wave with a weaker probe wave. We find that there is an exponential time constant (τ≈13days) associated with this process that is independent of the amplitudes of the pump and the probe, the phase delay between the two waves (the time between transmission of the pump and probe waves), the sampling rate, and whether the sample is being dried or humidified. We demonstrate that the humidity-dependent differences in the amount of softening are induced by only a very small amount of absorbed water vapor and argue that this water is intercalated within clay particles. We also show that our pump–probe experiments detect these humidity-dependent differences in the amount of softening easily and repeatably using an experimental design that does not rely on resonance conditions. This means that, in principle, our experiments could be more easily generalized to other experimental geometries to investigate non-linear elastic properties in complex or irregular sample geometries. Our method and findings have potential relevance in oil and gas exploration, civil engineering, and understanding of the mechanism of earthquakes.

Crushed rock dust as filler material in concrete

Abstract In India, it is estimated that out of 125 million tones (Mt) of stone aggregate produced every year, 17.8 Mt is crushed rock dust (CRD) which is presently used for land filling causing environmental problems such as loss of fertility of soil. This paper deals with the use of CRD as filler material in producing concrete. Cement is replaced with five percentages (C30-0%, C31-10%, C32-20%, C33-30% and C34-40%) of CRD by weight. Dynamic elastic modulus (Ed) Workability, density, flexural strength, compressive strength and ultrasonic pulse velocity (UPV) are experimentally investigated. Additionally, Scanning Electron Microscope (SEM) analysis is done on C30 and CRD concrete, to observe the internal microstructure of concrete. From the results, it is seen that, workability of CRD and C30 concrete decreased with increase of CRD in concrete. Up to 20% CRD in concrete, no significant difference is observed on compressive strength. Flexural strength is improved for all the CRD replacement levels in concrete. Relations between compressive strength, UPV and Ed are presented. The use of CRD by up to 20% of cement showed the best performance than C30 and is supported by SEM analysis. The use of CRD by up to 20% by CRD reduces cement usage and thereby mitigating global warming.

On the calibration dependencies designing for concrete strength testing by sclerometric nondestructive metods

Sclerometric methods of testing concrete, in particular, the rebound hammer testing, retain their positions as the most common indirect methods for concrete strength determining in situ. They are used as a means for technological testing during the buildings construction, as well as during their inspection during maintenance. Indirect parameters of current sclerometric devices are usually point-values: the rebound index, the diameter and depth of the print, the duration of the indenter insertion process, and the maximum interaction force. However, the lack of an unambiguous relationship between these parameters and the strength of concrete leads to additional uncertainty of the test result, which is one of the problems of sclerometric methods of concrete control. The instability of the calibration dependencies of the method is also observed. Even strict compliance with the requirements of the procedure does not guarantee the repeatability of the obtained dependencies.The article considers the possibility of improving metrological indicators of calibration dependencies of sclerometric methods by introducing an additional parameter-concrete humidity. The possibility of combining two sclerometric methods – the elastic rebound method and the shock pulse method is also considered. Data were obtained on concrete samples with a curing time of 25..60 days. Two-parameter calibration dependencies, including concrete humidity as an additional parameter, allowed for all experimental series of samples to reduce the residual mean square deviation of the calibration dependence of elastic rebound and shock pulse methods by 10%..16%, and to consistently provide the minimum acceptable value of the correlation coefficient r = 0.7 for the studied concrete compositions. The influence of concrete heterogeneity on the readings of sclerometric test methods is considered.The developed method of constructing two-parameter calibration dependencies can be recommended for inclusion in the current standards governing the determination of the strength of concrete structures under construction.