Longitudinal Wave Velocity Measurements Research Articles

Quantitative Nondestructive Evaluation of Cold Spray Manufactured Aluminum Alloy 6061 and Copper Samples

Cold spray (CS) is a solid-state process for depositing thick layers of material via the successive high-velocity impact of powder particles onto a solid surface, which leads to high rates of deformation, interparticle bonding, and coating build-up. Although CS is finding commercial utilization in non-load-bearing repair and coating applications, clear nondestructive characterization procedures are necessary to realize its potential in load-bearing structural applications. In this study, the viability of electrical conductivity and through thickness ultrasound wave velocity measurement methods was studied to serve as a means for nondestructive quantitative measurement for quality control in CS and potentially other additive manufacturing (AM) methods. Eddy current, ultrasound, porosity, hardness, and uniaxial tensile strength tests were conducted on CS deposited layers of aluminum alloy 6061 and copper on aluminum alloy 6061 and commercially pure copper substrates, respectively. CS gas dynamic parameters were intentionally and systematically varied to result in corresponding discrete differences in mechanical properties of deposits. Ultrasound measurements of longitudinal wave velocity and eddy current electrical conductivity measurements showed good correlation with process conditions, microstructural characterization results, and destructive mechanical tests (hardness, tensile). The results of this work show that ultrasound wave velocity and electrical conductivity correlate well with increased particle impact velocity in CS deposited aluminum and copper blocks, which evidently show an incremental decrease in porosity, increase in hardness, and increase in tensile strength. The outlined ultrasound and eddy current nondestructive testing methods present effective means for quantitative assessment of cold spray deposited structures while intact with the substrate.

Static and Dynamic Mechanical Properties of Granite from Various Burial Depths

The exploitation of mineral resources is gradually shifting from shallow to deep targets. However, the corresponding basic theoretical research has not determined the differences in rock-mining engineering at different depths. In this paper, longitudinal wave velocity measurements, uniaxial compression tests, and dynamic impact tests were conducted on granite from various burial depths to reveal the static and dynamic mechanical properties of the rocks. The initial damage variables of the rock specimens decrease after a rapid increase with increasing burial depth. The stress–strain curves of the deep rocks for various strain rates can be divided into two modes. The relationships between the secant modulus, peak stress, elastic modulus, and burial depth basically follow a quadratic function. The rock failure patterns observed in the uniaxial compression tests are basically tensile. In the dynamic loading experiments at various strain rates, the failure pattern of the rock changes with burial depth, when the strain rate is small, from local instability to overall instability and back to local instability; while the strain rate increases, the failure pattern transforms into overall instability. In the dynamic impact experiments with different confining pressures, the rock only undergoes shear failure due to the restriction of the lateral deformation from the confining pressure. These research achievements could provide significant theoretical support for rockburst prevention at greater mining depths.

Influence of Heating on Tensile Physical-Mechanical Properties of Granite

Abstract Heating procedures dramatically influence the physical-mechanical properties of rock. In this paper, via both numerical simulation and laboratory experiments, we examine the influence of constant temperature period (CTP, from 0.5 to 5 h) and predetermined temperature (PDT, from room temperature to 1,000℃) on the tensile mechanical properties of the Qinling granite, China. Results indicate that: CTP has a significant impact on the tensile mechanical properties of granite. For different PDTs, the density, longitudinal wave velocity (LWV) and tensile strength (TS) of granite decrease with increasing CTP. When CTP reaches the constant temperature turning-point (CTT), heating has fully affected the granite samples. The variation in LWV and TS versus temperature can be divided into four stages: 25–200℃, 200–600℃, 600–800℃ and 800–1,000℃. LWV and TS are negatively related to temperature and are more sensitive to temperature at higher PDTs. In addition, TS is more sensitive to temperature than LWV when PDT increases. The effects of CTP and PDT on LWV are similar to that of TS. Since the measurement of LWV is lossless, researchers can safely determine the appropriate CTP or CTT for any PDT and predict the tensile mechanical properties of rock by LWV analysis.

2P1-7 Measurement of Longitudinal Wave Velocity in Newly Formed and Mature Bone in the GHz Range

2P1-7 Measurement of Longitudinal Wave Velocity in Newly Formed and Mature Bone in the GHz Range

Impacts of the petrophysical and diagenetic aspects on the geomechanical properties of the dolomitic sequence of Gebel El-Halal, Sinai, Egypt

The aim of this paper is to demonstrate the controlling effect of the mineral composition, the diagenetic history and the petrophysical properties on the geomechanical properties and durability of the dolomitic El-Halal Formation in its type section in North Sinai as well as its economic potential for construction purposes. The petrographic studies include descriptions of both the mineral composition and diagenetic processes, while the petrophysical studies measure the density, porosity, permeability and true formation resistivity factor. In addition, some geomechanical laboratory tests were conducted, including the petrographic description of the mineral composition and diagenetic processes, as well as the Schmidt Hammer number (SHV), point load index (IS50), uniaxial compressive strength (UCS), and ultrasonic longitudinal wave velocity measurements. Scanning electron microscopy was used to help in pore-type description (intergranular, vuggy, etc.). Based on lithologic changes and mineral composition, the El-Halal Formation can be subdivided into three informal members: (1) lower dolomitic limestone, (2) middle sandy dolostone and (3) upper dolostone member. Petrographically, the sequence consists of three dominant microfacies: (1) dolomitic mudstone microfacies (dolomitic micrite to dolomicrite), (2) dolowackestone (clayey to sandy dolomicrite), and (3) dolomudstone microfacies (dolosparite). The most diagnostic diagenetic processes are dolomitization, cementation by calcite, aggrading neomorphism and the creation of authigenic illite. In the study area, dolomitization has affected almost all the Cenomanian succession. The SHV, IS50, and UCS values of the samples indicate high-strength rocks. The present study indicates the dependence of the geomechanical properties on the petrophysical properties and the mineral composition of the studied rocks. Modeling the properties indicates a reliable correlation between the different parameters which can be applied for predicting and characterizing the dolomitic El-Halal Formation elsewhere. The results of the present investigation are useful for studying the geomechanical and petrophysical properties of similar dolomitic sequences and in ranking its potential as construction materials.

Combined laser ultrasonics, and Raman scattering in diamond anvil cell system operating in the transmission configuration

Recently it has been demonstrated that it is possible to detect both longitudinal and shear waves as well as measure their velocities for a non-transparent iron layer compressed in a diamond anvil cell (DAC) to pressures approaching 23 GPa by using laser ultrasonics (LU) technique. These experiments were conducted in the reflection configuration when point source and point receiver were located at the same side of the specimen. The purpose of the present study is to examine the generation and detection of the acoustical waves in the LU-DAC system operating in the transmission configuration. The experimental results obtained at 16.4 GPa presented in this article demonstrate that the LU-DAC technique can be applied for longitudinal wave velocity measurements in small specimens under high pressure in the transmission configuration.

Investigation of Stress and Temperature Effect on the Longitudinal Ultrasonic Waves in Polymers

This work aims at establishing the effect of stress and temperature on the velocity of ultrasonic longitudinal waves in typical engineering polymers, and evaluating the potential of ultrasonic stress measurement in the evaluation of residual stresses in polymer parts. In order to estimate the effect of material morphology, two amorphous and two semicrystalline polymers have been considered. A series of tests are implemented, to determine the acoustoelastic constants and temperature constant of materials, by using the designed transducer fixtures for in situ measurement of longitudinal wave velocity. As expected, the velocity changes linearly with stress and temperature, and the temperature effect is as important as the acoustoelastic effect. It shows that this kind of nondestructive method is a valuable quantitative tool to estimate the residual stress in polymer products, but the material temperature influence must be considered during the estimation.

Small strain stiffness anisotropy of natural sedimentary clays: review and a model

Very small strain stiffness anisotropy of sedimentary clays is investigated. First, a general formulation of transversely isotropic elastic model is summarised, followed by a description of its complete parameter identification using transversal and longitudinal wave velocity measurements. Then, an extensive experimental database from the literature is reviewed. A number of general trends in the anisotropy evolution is identified, based on which a model is developed describing the dependency of the ratio of in-plane and transversal very small strain shear moduli on the stress state and overconsolidation ratio. Subsequently, an empirical relation between the ratios of shear moduli and Young moduli is quantified. The most problematic tends to be the evaluation of Poisson ratios and evolution of stiffness anisotropy under general stress conditions. These issues remain to be investigated experimentally in future work.

Elastic Wave Measurement Technology and its Engineering Application

The velocity and amplitude of elastic wave in the rock mass are dependent on the physical and mechanical properties, as well as the structural and stress state of rock mass. The elastic wave testing technique has become one of the most important approaches in geological engineering and rock mechanics. In order to enhance the analysis and application of elastic wave testing technique, the present paper investigates the elastic wave propagation pattern both in laboratory and in field. The lab tests focus on wave velocity in rock mass and the field work focus on the measurement of longitudinal wave velocity by using double-service elastic wave test. The field tests also include the testing of the roadway surrounding rock loose circle on the edge of underground chamber construction site. The study profiles the rock mass’s elastic wave dynamic characteristics, clarifies the rock mass structures, assess the property of the rock mass surrounding the subway. All these are of great significance to the underground chamber and tunneling engineering design and construction.

Laboratory measurement of longitudinal wave velocity of artificial gas hydrate under different temperatures and pressures

The longitudinal wave velocity and attenuation measurements of artificial gas hydrate samples at a low temperature are reported. And the temperature and pressure dependence of longitudinal wave velocity is also investigated. In order to understand the acoustic properties of gas hydrate, the pure ice, the pure tetrahydrofuran (THF), the pure gas hydrate samples and sand sediment containing gas hydrate are measured at a low temperature between 0°C and −15°C. For the pure ice, the pure THF and the pure gas hydrate samples, whose density is 898 kg/m3, 895 kg/m3 and 475 kg/m3, the velocity of longitudinal wave is respectively 3574 m/s, 3428 m/s and 2439 m/s. For synthesized and compacted samples, the velocity of synthesized samples is lower than that of compacted samples. The velocities increase when the densities of the samples increase, while the attenuation decreases. Under the condition of low temperature, the results show that the velocity is slightly affected by the temperature. The results also show that wave velocities increase with the increase of piston pressures. For example, the velocity of one sample increases from 3049 up to 3337 m/s and the other increases from 2315 up to 2995 m/s. But wave velocity decreases from 3800 to 3546 m/s when the temperature increases from −15°C to 5°C and changes significantly close to the melting point. Formation conditions of the two samples are the same but with different conversion ratios of water. The results of the experiment are important for exploration of the gas hydrate resources and development of acoustic techniques.

Effect of Cooling Rate on the Longitudinal Modulus of Cu3Sn Phase of Ag-Sn-Cu Amalgam Alloy (Part II)

Cu 3 Sn is indeed the e phase in the Copper-Tin system, which is one of the main phase of High Copper Amalgam Alloy (Ag-Sn-Cu Alloy) and at present very little emphasis has been placed on the microstructure and the mechanical properties of Cu 3 Sn phase. In this study 3 castings of Cu-38.37 wt% Sn were produced. The casting specimens were subjected to different cooling rate conditions: as cast, air blown, and water quenched. The possible phases were identified by x-ray diffraction and the microstructure were examined on a metallurgy optical microscope. An ultrasonic equipment were utilized for longitudinal wave velocity measurements. Using this velocity the longitudinal modulus can be calculated. Phase identification on as cast, air blown and water quenched specimens indicated that the specimens consist of e (Cu 3 Sn) phase. The smaller and finer microstructure of Cu 3 Sn phase was produced from water quenched (faster cooling rate) specimen. However its longitudinal modulus is significantly lower than the longitudinal modulus of as cast and air blown specimens. Therefore it is still need further investigation in order to obtain the transversal wave velocity and the Young's modulus.

Analysis of ultrasonic velocity measurements on sintering zinc oxide

Abstract A technique is presented for accurate measurement of the longitudinal wave velocity up to 1050 °C in sintering powder compacts. The technique uses laser generation and contact detection of the ultrasonic signal. Representative results are presented for heating cycles performed upon sintering ZnO powder compacts, and upon a pre-sintered dense ZnO sample. The data demonstrate the capability for performing in-situ longitudinal wave velocity measurements at high temperatures, and in attenuative materials such as sintering ceramic powder compacts. In addition, the data demonstrate the sensitivity of ultrasonic velocity measurements to changes within the sintering compact which are not detectable by dimension measurement alone. A novel application of ultrasonic velocity measurements performed in-situ on sintering ZnO is presented. This application is based upon interpretation of longitudinal wave velocity measurements in the context of existing models treating surface area reduction during sintering. A previously observed correlation between the longitudinal wave ultrasonic velocity and the specific surface area facilitates this interpretation. The analysis yields an activation energy for surface area reduction in sintering ZnO which compares well with values reported in the literature.

Picosecond acoustic measurements of longitudinal wave velocity of submicron polymer films

We apply picosecond acoustic techniques to determine the longitudinal wave speed of submicron polymer films in the through-thickness dimension. The time-of-flight of an elastic wave propagating through the polymer film is measured using an optical pump/probe technique. The longitudinal wave speed in poly(methyl methacrylate) films of thickness ranging from 20 to 130 nm has been determined. A pronounced increase in longitudinal wave speed is observed for films of thickness less than 40 nm.

Ｂｉｏｔ‐Ｓｔｏｌｌ海底堆積物モデルの物理パラメータについての考察

The Biot-Stoll model, which treats sound propagation in porous saturated media, has been applied to analyze the sound propagation in marine sediments, and its usefulness has been shown. There are a lot of physical parameters in the Biot-Stoll model. In the physical parameters, shear modulus and bulk modulus of the frame of marine sediment are important, for investigating the sound propagation in marine sediment. But it seems that these study has not sufficiently done. In this study, the physical parameters of the Biot-Stoll model, especially shear modulus and bulk modulus of the frame are investigated. Shear wave and longitudinal wave velocity measurements in 12 kinds of dry beach sands are done. From the values, shear modulus, bulk modulus and Poisson's ratio of the frame are obtained.

Scattering-induced error in longitudinal wave velocity measurements

The scattering of an elastic longitudinal wave on reflection at a free-plane boundary is studied using the analytical solution for a two-dimensional wave field generated by strip surface stresses. The variation in the scattered field is calculated with various incident angles of the narrow beams and displayed in polar diagrams, which show a wide range of scattered strength. The calculated result reduces to the specular reflection of an infinite plane wave with an increase in the number of beams in the bundle. These results give the basis for estimating the experimental error due to the scattering of the first and second echoes launched by transducers of finite width. The scattering-induced error is well characterized by the ratio of the transducer width to the square root of the specimen thickness, both being normalized by the wavelength. As this ratio increases from zero, the error begins to increase, passes a peak, and then approaches a constant value. To minimize the error, the use of a transducer is suggested for which the nearfield length is at least four times the specimen thickness.

Measurement of Longitudinal Wave Velocity through Hardened Cement Paste

Longitudinal wave velocity was measured and related to the physical properties of hardened cement paste. Longitudinal wave, generated by pulse oscillator were propagated to the sample under compressed state from 0 to 15 kb at from room temperature to about 230°C.The samples of cement paste, composed by normal portland cement and fine quartz sand, were hydrated and cured, in water or, autoclaved by different steam pressures.The major factors, effecting the longitudinal wave velocity, are thought to be caused by the crystal structure of hydrated products, pore size distribution, and grain contacts.The results of graphic from represents that the compressional longitudinal wave velocity appears to increase linearly with decrease in porosity and seems to approach to the original value of the calcium silicate hydrates.