Propagation Velocity Of Elastic Waves Research Articles

Numerical Simulation and Experimental Verification of Quality Detection of Grouting in Pre-Stressed Pipelines Based on Transmission Wave Method

The quality of grouting in pre-stressed pipelines plays a critical role in ensuring the safety and durability of pre-stressed concrete bridges. In this study, the transmission wave method was proposed as a means to assess the quality of grouting in pre-stressed pipelines. The ABAQUS finite element simulation (FE simulation) method was used to study the propagation of hammer stress waves in pre-stressed pipes. A full-scale test was conducted to verify the numerical simulation using the AGI-BWG instrument system developed to detect the quality of grouting. The results show that the propagation speed of transmitted waves increases and the frequency shifts towards higher frequencies with an increase in void length within pre-stressed pipelines. This research suggests that the propagation velocity of elastic waves in pre-stressed pipelines serves as a key indicator of grouting quality. The transmission wave method, based on hammer signals, proves to be an effective tool for detecting the quality of grouting in pre-stressed pipelines.

Studies of interfacial wave properties during displacement with pure viscoelastic fluids in microchannels

In this study, new experimental data for the displacement of a Newtonian liquid by three pure viscoelastic (Boger) fluids with different relaxation times were obtained with imaging in a 500 μm microchannel. Results were compared against those from displacement using a Newtonian liquid. Small irregular waves were observed at the interface for the Newtonian displacement, while periodic instabilities were seen for all Boger fluid cases. The elastic Mach number (Ma), describing the ratio of the flow velocity with the elastic wave propagation velocity, was found to be the key parameter for correlating the wave properties in the case of Boger fluids. The amplitude of the wavy interface initially increased up to Ma = 0.5, before decreasing again. The frequency and the wave velocity increased monotonically with increasing Ma. For all configurations, a phase shift of π was found between the top and the bottom interfaces. Correlations from experimental data were developed for all wave properties. Based on these correlations, an empirical wave model was developed to describe the observed planar images and to reconstruct the three-dimensional waves, which resemble a helical structure.

Численное решение двумерной задачи определения скорости распространения сейсмических волн в неоднородных cредах с памятью

The numerical method for two-dimensional inverse dynamic seismic problem for a viscoelastic isotropic medium is presented. The system of differential equations of elasticity for isotropic medium of memory type is considered as a mathematical model. The unknown values are the displacement, the memory function of the medium (the kernel of the integral term) and the propagation velocity of elastic waves in a weakly horizontally inhomogeneous medium. Additional information for the inverse problem is the response displacement measured on the surface. The method is based on reducing the inverse problem to a system of Volterra-type integral equations and their sequential numerical implementation. The results of the study are analyzed and compared with the analytical solution. It is shown that the results are in satisfactory agreement.

On the evolution of artificially maturated hydrocarbon source rocks

The elastic moduli are a function of properties that could vary between samples and change during maturation. Consequently, the effects of organic matter maturation on the elastic wave velocities of organic-rich rocks are challenging to describe. This work analyzes the isolated maturation effects on the organic content, pore volume, microstructure, and propagation velocities of elastic waves. To avoid any initial rock heterogeneity, we prepared a series of homogeneous samples from a unique outcrop block collected on the Eagle Ford formation with mineral composition initially determined using X-ray diffraction. From the initial set, four samples were held in their original condition and four were artificially maturated by hydropyrolysis until transformation rates were up to 95%. Then, the evolution of the sample properties was examined using an association of LECO TOC, Rock-Eval pyrolysis, vitrinite reflectance, mercury intrusion porosimetry (MIP), and ultrasonic pulse propagation. In addition, scanning electron microscopy images registered the microstructure evolution. To evaluate the effects of maturation on pore geometry and the organic matter elastic moduli, we analyze the relationship between the measured quantities using a rock physics inclusion model with the unmeasured properties taken as fitting parameters. The hydropyrolysis maturation increases the vitrinite reflectance from the initial 0.55% to 1.34% on the most matured sample. A total organic carbon reduction from 4.2% to 2.1% and a porosity increase from 9.2% to 21% are associated with observed maturation. The geochemical characterization on cleaned samples reveals an initial increment of soluble organic matter followed by a monotonical reduction related to oil migration out of bulk volume. The measurement of wave propagation velocities as a function of confining pressure displays an increasing pressure sensitivity with a downward trend in both velocity moduli. The petrophysical analysis indicates that the porosity increases through organic matter consumption and pore creation. The rock physics diagnoses indicate a decrease in the pore aspect ratio with an increase in the elastic modulus of the organic matter with maturation.

Inhomogeneous waves propagation in double-porosity thermoelastic media

PurposeThe purpose of this study is to investigate the reflection of plane waves in a double-porosity (DP) thermoelastic medium.Design/methodology/approachTo derive the theoretical formulas for elastic wave propagation velocities through the potential decomposition of wave-governing equations. The boundary conditions have been designed to incorporate the unique characteristics of the surface pores, whether they are open or sealed. This approach provides a more accurate and realistic mathematical interpretation of the situation that would be encountered in the field. The reflection coefficients are obtained through a linear system of equations, which is solved using the Gauss elimination method.FindingsThe solutions obtained from the governing equations reveal the presence of five inhomogeneous plane waves, consisting of four coupled longitudinal waves and a single transverse wave. The energy ratios of reflected waves are determined for both open and sealed pores on the stress-free, the thermally insulated surface of DP thermoelastic medium. In addition, the energy ratios are compared for the cases of a DP medium and a DP thermoelastic medium.Originality/valueA numerical example is considered to investigate the effect of fluid type in inclusions, temperature and inhomogeneity on phase velocities and attenuation coefficients as a function of frequency. Finally, a sensitivity analysis is performed graphically to observe the effect of the various parameters on propagation characteristics, such as propagation/attenuation directions, phase shifts and energy ratios as a function of incident direction in double-porosity thermoelasticity medium.

LÍ THUYẾT BIẾN DẠNG ĐÀN HỒI CỦA MÀNG MỎNG HỢP KIM XEN KẼ NHỊ NGUYÊN LẬP PHƯƠNG TÂM KHỐI TỪ PHƯƠNG PHÁP THỐNG KÊ MÔMEN

The article presents the theory of elastic deformation and elastic wave propagation velocity of BCC binary interstitial alloy’s thin film based on the statistical moment method. Metal’s films and bulk interstitial alloys are specific cases of interstitial alloy’s films in this theory. The obtained theoretical results are applied to W and WSi films, where calculated results are compared with other calculations and experimental data.

Atomistic Investigation of Titanium Carbide Ti8C5 under Impact Loading

Titanium carbides attract attention from both academic and industry fields because of their intriguing mechanical properties and proven potential as appealing candidates in the variety of fields such as nanomechanics, nanoelectronics, energy storage and oil/water separation devices. A recent study revealed that the presence of Ti8C5 not only improves the impact strength of composites as coatings, but also possesses significant strengthening performance as an interlayer material in composites by forming strong bonding between different matrices, which sheds light on the design of impact protection composite materials. To further investigate the impact resistance and strengthening mechanism of Ti8C5, a pilot Molecular Dynamics (MD) study utilizing comb3 potential is carried out on a Ti8C5 nanosheet by subjecting it to hypervelocity impacts. The deformation behaviour of Ti8C5 and the related impact resist mechanisms are assessed in this research. At a low impact velocity ~0.5 km/s, the main resonance frequency of Ti8C5 is 11.9 GHz and its low Q factor (111.9) indicates a decent energy damping capability, which would eliminate the received energy in an interfacial reflection process and weaken the shock waves for Ti8C5 strengthened composites. As the impact velocity increases above the threshold of 1.8 km/s, Ti8C5 demonstrates brittle behaviour, which is signified by its insignificant out-of-plane deformation prior to crack initiation. When tracking atomic Von Mises stress distribution, the elastic wave propagation velocity of Ti8C5 is calculated to be 5.34 and 5.90 km/s for X and Y directions, respectively. These figures are inferior compared with graphene and copper, which indicate slower energy delocalization rates and thus less energy dissipation via deformation is expected prior to bond break. However, because of its relatively small mass density comparing with copper, Ti8C5 presents superior specific penetration. This study provides a fundamental understanding of the deformation and penetration mechanisms of titanium carbide nanosheets under impact, which is crucial in order to facilitate emerging impact protection applications for titanium carbide-related composites.

Atomistic Investigation of the Titanium Carbide MXenes under Impact Loading

2D Titanium carbide MXenes with a structural formula recognized as Tin+1Cn have attracted attention from both the academic and industry fields due to their intriguing mechanical properties and appealing potential in a variety of areas such as nano-electronic circuits/devices, bio sensors, energy storage and reinforcing material for composites. Based on mutli-body comb3 (third-generation Charge-Optimized Many-Body) potential, this work investigated the impact resistance of monolayer Tin+1Cn nanosheets (namely, Ti2C Ti3C2 and Ti4C3) under hypervelocity up to 7 km/s. The deformation behavior and the impact resist mechanisms of Tin+1Cn nanosheets were assessed. Penetration energy is found to positively correlate with the number of titanium atom layer (n). However, in tracking atomic Von Mises stress distribution, Ti2C exhibits the most significant elastic wave propagation velocity among the examined nanosheets, suggesting the highest energy delocalization rate and stronger energy dissipation via deformation prior to bond break. Consistently, Ti2C presents superior specific penetration energy due its Young’s-modulus-to-density ratio, followed by Ti3C2 and Ti4C3, suggesting an inverse correlation between the titanium atom layer number and specific penetration energy. This study provides a fundamental understanding of the deformation and penetration mechanisms of titanium carbide MXene nanosheets under impact, which could be beneficial to facilitating their emerging impact protection applications.

Substantiation of the specific energy intensity of drilling as a criterion characterizing the explosive destruction of rocks on the example of the Koktaszhal

Drilling and blasting operations are one of the most important components of the mining industry. Currently, further improvement and optimization of technological processes at mining enterprises are possible mainly due to the determination and constant monitoring of the mining and technological properties of the rock mass – their drillability, explosivity and exaviability. A prospective assessment of the explosivity of rocks in the massif, which is the basis for designing and calculating the parameters of the DBO, is currently possible only using the energy parameters of technological work. The article provides information on methods for studying the strength and elastic characteristics of rocks in natural occurrence. The results of the study of the relationship between the specific energy intensity of drilling and explosive destruction of rocks are presented. The correlation between the specific energy intensity of drilling and the propagation velocity of elastic longitudinal waves is also considered. A comparative analysis is carried out between the traditional calculation of the explosive index using the results of laboratory studies on the physical and mechanical properties of the rocks of the Koktaszhal deposit and the calculation of the explosive destruction index taking into account the energy parameters of drilling. The validity of the use of the specific energy intensity of drilling as a criterion characterizing the explosive destruction of rocks in the design of drilling and blasting operations is shown.

Joint two-step inversion of porosity and saturation based on the Biot/squirt model with multiphase fluids

It is of great importance to predict reservoir petrophysical properties, such as porosity and saturation based on elastic properties, including density and wave propagation velocity, through quantitative seismic interpretation. A joint two-step inversion (JoiTSI) method is proposed for predicting porosity and saturation with a forward petrophysical model. As the forward model, the Biot/squirt model with multiphase fluids (gas, oil, and water) describes the nonlinear relationships between petrophysical and elastic properties. The first step of the two-step inversion is to invert porosity and saturation via a semianalytical approximation approach. The second step is a joint inversion at high porosities where porosity and saturation are simultaneously optimized using a hybrid genetic algorithm. In these steps, maximum a posteriori estimations are performed based on normal prior distributions, where the posterior distributions may differ between two steps because of the potential variability in reservoir properties. The numerical tests indicate that this JoiTSI method is more efficient and more accurate than the traditional inversion methods. In addition, Poisson’s ratio, P-wave impedance, and S-wave impedance are found to give better inversion results than those based on more commonly used attributes (density, P-wave impedance, and S-wave impedance). In the oilfield seismic example, the inversion accuracy of porosity and saturation is verified by actual well logs, and the major oil and water layers are correctly identified.

An analytical Generalized Reciprocal Method (GRM) for near-surface seismic refraction investigations

Seismic refraction is one of the active seismic methods that work based on seismic waves that are refracted following the layers of the earth beneath the surface. Seismic refraction surveying is an important tool for determining the geometries and elastic wave propagation velocities of near-surface layer for oil bearing structures. Based on the data acquisition sketch obtained, the acquisition is carried out using the In-Line technique. There are two sources of vibration chosen, namely at the forward and reverse points, the distance between the 5-meter geophone and the distance between the source of the vibration and the geophone of 5 meters. The seismic data processing technique used in this study is the Generalized Reciprocal Method (GRM). This method determines the value of analysis, XY Optimum distance, time-depth analysis value, and depth. In interpreting seismic data, the calculation results that have been made are validated for accuracy using Software. From the research that has been done, it can be known as modeling subsurface structure. There are three layers, the first layer is 6 m-10m deep, while the second layer is 18m-22m deep. In the range of about 0m-20m, the first layer has a velocity of 507.74 m/s, the second layer has a velocity of 1420.43 m/s and the third layer has a velocity of 2522.30 m/s. In the range of about 20m-80m the first layer has a velocity of 550.12 m/s, the second layer has a velocity of 1575.11 m/s and the third layer has a velocity of 2607.45 m/s. In the range of about 80m-100m, the first layer has a velocity of 482.34 m/s, the second layer has a velocity of 1301.09 m/s and the third layer has a velocity of 2400.86 m/s.

In Vivo Human Corneal Shear-wave Optical Coherence Elastography.

SIGNIFICANCEA novel imaging technology, dynamic optical coherence elastography (OCE), was adapted for clinical noninvasive measurements of corneal biomechanics.PURPOSEDetermining corneal biomechanical properties is a long-standing challenge. Elasticity imaging methods have recently been developed and applied for clinical evaluation of soft tissues in cancer detection, atherosclerotic plaque evaluation, surgical guidance, and more. Here, we describe the use of dynamic OCE to characterize mechanical wave propagation in the human cornea in vivo, thus providing a method for clinical determination of corneal biomechanical properties.METHODSHigh-resolution phase-sensitive optical coherence tomography imaging was combined with microliter air-pulse tissue stimulation to perform dynamic elasticity measurements in 18 eyes of nine participants. Low-pressure (0.1 mmHg), spatiotemporally discreet (150 μm, 800 μs) tissue stimulation produced submicron-scale tissue deformations that were measured at multiple positions over a 1-mm2 area. Surface wave velocity was measured and used to determine tissue stiffness. Elastic wave propagation velocity was measured and evaluated as a function of IOP and central corneal thickness.RESULTSSubmicron corneal surface displacement amplitude (range, 0.005 to 0.5 μm) responses were measured with high sensitivity (0.24 nm). Corneal elastic wave velocity ranged from 2.4 to 4.2 m/s (mean, 3.5; 95% confidence interval, 3.2 to 3.8 m/s) and was correlated with central corneal thickness (r = 0.64, P < .001) and IOP (r = 0.52, P = .02).CONCLUSIONSPhase-sensitive optical coherence tomography imaging combined with microliter air-pulse mechanical tissue stimulation has sufficient detection sensitivity to observe submicron elastic wave propagation in corneal tissue. These measurements enable in vivo corneal stiffness determinations that will be further studied for use with disease detection and for monitoring clinical interventions.

Management of the dynamic properties of a base modified by deep soil mixing technology

Conversion of building properties is performed primarily to reduce the compressibility of the base and increase strength. However, in addition to changing the static properties of soils, it is necessary to take into account changes in dynamic properties, such as dynamic shear modulus, damping coefficient, velocity of elastic shear and longitudinal waves. Thus, it is possible to control the dynamic properties of the base by converting the construction properties of soils. In this paper, we consider the change in the velocity of shear waves in a base transformed by the technology of deep soil mixing (DSM). In the work, the influence of additional vertical stresses on the dynamic properties of the bases transformed using deep soil mixing technology was evaluated. As a parameter that allowed us to evaluate the dynamic properties, the propagation velocity of elastic shear waves was chosen. Shear wave velocity was estimated based on the results of triaxial tests using the method of low-amplitude torsional vibrations in a resonant column. The research results showed that at small values of axial strains, there is no significant increase in the velocity of shear waves, an increase in the speed of shear waves by two times with an increase in stress by 0.6 MPa.

Studies of the shear wave velocity in soil cement under the anisotropic stress state

Introduction. Deep soil mixing, that alters construction properties of foundations, allows to construct buildings and structures on the sites that have loose soils. As a rule, adverse geotechnical conditions are accompanied by dynamic forces that affect designed buildings and structures. The objective of these studies is to predict changes in mechanical properties of soils that follow the alteration of structural properties of a foundation. Soil cement is the focus of this study. Materials and methods. The findings of special laboratory tests of soil cement samples using the method of low amplitude torsional vibrations inside a resonant column in the anisotropic triaxial compression mode allowed to assess the effect of the supplementary vertical load on the velocity of shear elastic wave propagation. The co-authors present a description of the research method and provide an overview of the equipment used to conduct special laboratory tests. Tests were performed on undisturbed soil cement samples that had a natural water content. The anisotropic stress state of soil cement samples exposed to triaxial tests in the resonant column was caused by special behaviour features of the foundation. Results. In this study, laboratory tests had two stages. At the first stage, the effect of the vertical stress on the velocity of shear wave propagation was assessed. Correlation dependences between the shear wave velocity and the ratio of vertical and lateral stresses were obtained. At the second stage, shear wave propagation velocity values were identified at various combinations of lateral σ3 and vertical σ1 stresses. The results of the second stage are designated for the assessment of the effect of the anisotropic stress state and the projection of shear wave velocities at the stress levels anticipated on the site that will accommodate designed heavy structures. Conclusions. The findings allow to assess the effect of lateral and vertical stresses on changes of shear wave velocities in the triaxial compression mode. It was identified that at equal values of lateral stresses σ3, a 7-fold vertical stress σ1 increase leads to a 15 % increase in the shear wave velocity in soil cement Vs. At the same time, an increase in the ratio of vertical to lateral stresses σ1/σ3 by a factor of 15 causes an 11 % increase in the shear wave velocity. It is noted that the smaller the initial value of lateral stress σ3, the higher the rise in the shear wave velocity Vs in the course of testing. Correlation dependencies, presented in this study, can be used to assess the effect of the anisotropic state as the first approximation (for preliminary calculations) in the design of heavy structures on soil cement foundations.

Local Phase-Amplitude Joint Correction for Free Surface Velocity of Hopkinson Pressure Bar

The Hopkinson pressure bar is widely used to measure the reflected pressure of blast waves over a short distance. However, dispersion effects will occur when the elastic stress waves propagate in the pressure bar due to lateral inertia, and there will be errors between the signals obtained from the sensors and the actual loading. For the free surface velocity measured in our system, we developed a local phase-amplitude joint correction method to convert the measured velocity into the average reflected pressure of a shock wave at the impact end of the bar, considering factors such as propagation modes of the elastic wave, the frequency components’ time of arrival, velocity variation over the bar axis, and the stress–velocity relationship. Firstly, the Pochhammer–Chree frequency equation is calculated numerically, and the first to fourth orders of phase velocity, group velocity, normalized frequency, and propagation time curves of elastic wave propagation in 35CrMnSiA steel are obtained. Secondly, the phase and amplitude correction formulas for calculating average reflected pressure from center velocity are derived based on the propagation mode of the axial elastic wave in the pressure bar by analyzing the time-frequency combined spectrum obtained by short-time Fourier transform. Thirdly, a local phase-amplitude joint correction algorithm based on propagation mode is proposed in detail. The experimental tests and data analyses are carried out for eight sets of pressure bar. The results show that this method can identify the propagation mode of elastic waves in the bar intuitively and clearly. The first three orders of propagation modes are stimulated in the bar 04, while only the first order of propagation is stimulated in the other eight bars. The local phase-amplitude joint correction algorithm can avoid correcting the component of the non-axial elastic wave. The rising edge of the average stress curve on the impact surface of bar 01 and bar 04 is corrected from 4.13 μs and 4.09 μs to 2.70 μs, respectively.

Selective excitation of two-wave structure depending on crystal orientation under shock compression

Single crystals subjected to shock compression exhibit responses with distinct two-wave structures for certain crystal orientations. However, little is known to date regarding how the shock response depends on crystal orientation, and especially why the two-wave structure depends on the crystal orientation. In this work, molecular dynamics simulations of shock compressions in copper single crystals are performed to investigate the orientation dependence of shock responses and the corresponding deformation mechanisms. Four copper single crystals with [001], [011], [012], and [123] crystal orientations along the depth direction are investigated. The [011], [012], and [123] crystal orientations of copper single crystals show distinct two-wave structures in their shock responses, while such a two-wave structure in the shock response is not seen for those orientations having a [001] crystal orientation. The potential causes are analyzed by considering the propagation velocities of both elastic and plastic waves. We develop a technique for identifying twin structures in face-centered cubic crystals and this technique can effectively identify the twin structure. The morphology of shock-induced defects (e.g., dislocations and twins) shows the significant dependence of crystal orientation and the mechanisms behind these are discussed in detail. Finally, the Johnson-Cook constitutive model describing dynamic deformations at high temperatures and high strain rates is used to analyze the relationships between the shock responses and microscopic defects. The predictions of the Johnson-Cook constitutive model are consistent with the results of the molecular dynamics simulations.

Influence of Blasting Vibrations Generated by Tunnel Construction on an Existing Road

Tunnel excavations are commonly carried out using the drill and blast method, which may cause blast-induced damage to adjacent buildings. Peak particle velocity (PPV) is a widely used parameter for evaluating the damage of blasting vibration. However, accurately predicting PPV is difficult with traditional empirical predicting methods because their results are often different from actual conditions. In this study, attenuation formula of propagation velocity of elastic stress waves in elastomer is derived on the basis of stress wave theory. Moreover, the formula for predicting PPV is modified in the case of multihole and multistage blasting and then applied to Guanlinzi Tunnel, which downtraverses through National Highway 316. Results show that the modified formula obtains a small relative error between predicted and in situ monitoring PPVs and can properly reflect the propagation law of PPV under the condition of multihole and multistage blasting. This work has important application prospects and can provide a reference for similar excavation blasting and vibration control methods.

Non-destructive testing of multilayer medium by the method of velocity of elastic waves hodograph

The method of velocity of elastic waves hodograph, aimed at non-destructive testing of structurally heterogeneous composite materials and products based on them, as well as multilayer products and constructions, is considered.&#x0D; The theoretical basis for determining the propagation velocity of elastic waves in a multilayer medium by the hodograph method is given. Based on the studies, recommendations are given for determining the propagation velocity of elastic waves in each individual layer of a multilayer medium, which allows non-destructive testing of the physicomechanical characteristics of each layer of a multilayer medium.&#x0D; It is shown that in addition to simple multiple reflections in a homogeneous medium, in a multilayer medium with parallel interfaces consisting of two or more layers, complex types of multiple reflected waves and mixed waves (reflected-refracted and refracted-reflected) can arise.&#x0D; The main task of applying the low-frequency ultrasonic method is to determine the acoustic parameters of the propagation of elastic waves (velocities, amplitudes, spectra). The main methods for determining the elastic wave velocities are considered, based on the hodograph equation of the indicated reflected waves in a multilayer medium.

Generation mechanism of stress wave while milling aluminium 2219

ABSTRACTResidual stresses become a huge obstacle to improve the quality of precision manufacturing. They impact the static strength, fatigue strength, and corrosion resistance of the manufactured parts seriously. Complexity of the residual stresses initialising, generating, and redistributing still makes it difficult to efficiently control their distribution. In this paper, a new approach based on stress wave is proposed to reveal the propagation mechanism of residual stress in depth during the milling process. An elastic longitudinal wave and a plastic longitudinal wave equations are established. The analytic expression of the stress wave in the real domain is obtained by Laplace transformation and Laplace inverse transformation. The propagation of stress waves in two-dimensional milling is simulated with Finite Element Method (FEM). A simulation case study has been performed in order to demonstrate the practicality and effectiveness of the proposed approach. The simulation results show that the simulated elastic wave propagation velocity agrees well with the theoretical one. The peak value of the milling stress wave decreases with the unloading. The influence of cutting thickness on the decay rate is larger than that of cutting speed.

Acoustic Determination of Properties Possessed by Porous Titanium

To impart the optimal structure to a powder material and promote high mechanical properties, the production process is to be monitored at each step using nondestructive methods. Acoustic methods are believed to be promising in this respect. The parameters of acoustic fields are influenced by many factors that determine the structure and properties of powder materials. A relevant task is to improve acoustic methods for the identification and use of this influence. A model material is taken as an example to show the capabilities of a nondestructive acoustic method relying on integrated measurement of the propagation velocities of longitudinal, transverse, and rod elastic waves in studying the patterns peculiar to the powder structurization at the molding and sintering stages. The following problems that can be solved using this method are considered and experimentally confirmed: identify how the properties of the starting powders influence the characteristics of the final material, monitor the compaction and contact formation processes in the material, and identify features of these processes, which are manifested as uneven distribution of properties over the material and aftereffects and are stepwise. Additional criteria are proposed to increase the reliability and descriptiveness of the results. Analysis of the experimental data shows that the propagation velocities of bulk and rod elastic waves in different ways reflect the compaction and contact formation in powder materials. The differences are explained by the peculiarities of acoustic fields generated by various types of elastic waves.