Propagation Velocity Of Ultrasonic Waves Research Articles

Using artificial neural networks in estimating wood resistance

The purpose of this research was to evaluate the potential of Artificial Neural Networks in estimating the properties of wood resistance. In order to do so, a hybrid of eucalyptus (Eucalyptus urograndis) planted in the Northern Region of the State of Mato Grosso was selected and ten trees were collected. Then, four samples of each tree were removed, totaling 40 samples, which were later subjected to non-destructive testing of apparent density, ultrasonic wave propagation velocity, dynamic modulus of elasticity obtained by ultrasound, and Janka hardness. These properties were used as estimators of resistance and compressive strength parallel to fibers, and hardness. Multilayer Perceptron networks were also employed, training 100 of them for each of the evaluated parameters. The obtained results indicated that the use of Artificial Neural Networks is an efficient tool for predicting wood resistance.

Changes of Physical Properties of Silesian Granite Due to Heat Loading

Temperature affects both the physical and structural properties of rocks and there may even cause chemical changes of minerals. Rocks are more or less inhomogeneous material, so that during testing the same rock samples taken from one location the measured values of physical properties can vary on large scattering between test specimens. To eliminate the influence of inhomogeneity of rock, we analyzed the effect of heat loading (up to 700˚ C) on the same specimens. For this reason we have used in our research particularly non-destructive testing methods – determination of bulk density, measuring of longitudinal ultrasonic wave propagation velocity, thermal conductivity and volumetric heat capacity. Besides the physical characteristics determined in the same specimen before and after tempering gas permeability and thermal expansion untempered and tempered test specimens was determined. Hg porosity and total porosity of untempered and tempered specimens were found, too. As model material was chosen so-called Silesian granite from Nový lom quarry (Žulová pluton, Czech Republic), which has been previously tested, and over macroscopically homogeneous character the variances in the measured parameters were found. Hg and total porosity and gas permeability increase with increasing temperature. The bulk density, the ultrasonic wave propagation velocity and thermal conductivity decrease with increasing temperature. The most sensitive parameters are ultrasonic wave velocity, thermal conductivity and permeability.

Analysis of structural integrity of a non-completed 28 year-old building in the city of Patos de Minas (MG)

Factors such as durability and performance must be the guideline in the design of any building, since most of the pathological manifestations that affect the buildings are associated with construction stages, from project design to use of the structure, severely influencing the useful life of structure. This work aims to diagnose the pathological manifestations of the current reinforced concrete structures in the urban environment, through a case study. The inspections were carried out in an anonymous non-completed building in Patos de Minas (MG), with an estimated age of 28 years. It was carried out the diagnosis of the main pathological manifestations and prognosis of the analyzed system. It used to inspections in the field—visual and detailed—and laboratory tests, such as measurement of propagation velocity of ultrasonic waves, reinforcement locate (scan), rebound hammer test, compressive strength test, Brazilian disk test, capillary water absorption test and carbonation depth measurement test. The pathological manifestations found in the concrete structure analyzed were cracking, peeling, carbonation and reinforcement corrosion. The value of rebound and ultrasonic pulse velocity obtained were relatively high (around 58 rebound and velocity of 4000 m/s), due to advanced carbonation (average across 30 mm). Already water absorption by capillary found in the laboratory was high too (in the range from 6105.17 to 30181.64 g/m2). Due to the high degree of deterioration, corrective or recovery measures are not applicable.

National Primary Standard for the Units of the Propagation Velocities and Damping Coefficient of Ultrasonic Waves in Solids Get 189-2014

Improvements in the National Primary Standard for the Units of the Propagation Velocities of Longitudinal, Shear, and Surface Ultrasonic Waves in Solids are discussed. A new standard apparatus for reproduction of the unit of the damping coefficient for longitudinal ultrasonic waves is described. It is based on contactless capacitive methods for generating ultrasonic waves and pulse-echo and resonance measurement techniques for receiving them. The metrological characteristics of the National Primary Standard for the Units of the Propagation Velocities and Damping Coefficient of Ultrasonic Waves in Solids, GET 189-2014, are given.

Hysteresis of ultrasound velocity in pork lard and water during a thermal cycle

Today, quick measurement methods, including methods of determination of food composition, are becoming increasingly important. The answer to the growing need is a non-destructive and very quick ultrasonic method. To determine the composition of a material with this method, it is necessary to determine the velocity of ultrasonic wave propagation in individual ingredients, which may vary depending on whether the material is cooled down or heated up, i.e. its hysteresis. The aim of this study was to determine if hysteresis occurs in ground meat during a thermal cycle.The key ingredients of ground meat are proteins, fat and water. Since there is currently no method available to obtain protein in a form allowing acoustic measurements thereof, samples of pork fat and process water were analyzed. The thermal cycle involved cooling down and heating the samples in a temperature range of 10–40 °C. The measurements were performed by the transition method, using two heads of ultrasonic l-wave with a frequency of 2 MHz. The occurrence of hysteresis during the thermal cycle within the analyzed temperature range was confirmed in lard samples, while in the case of water, hysteresis proved to be negligibly low. To minimize the uncertainty of the quantification of the composition of ground meat by the ultrasonic method the industrial applications must provide for the hysteresis of ultrasound velocity in fat.

An experimental method to measure the layer thickness and wave velocity of copper–steel composite board without interface echo

Thickness of each medium layer and velocity of ultrasonic wave propagation in each medium layer of the two-layer composite medium were measured simultaneously based on the method to collect phase information from continuous echo signals on front surface and undersurface. Such measurement was implemented under no interface echo and fixed total thickness of the testpiece. The method can be applied to any two kinds of two-layer composite medium. The paper only used a 35mm thick copper–steel composite board as an experimental example. Calculated results demonstrated that measuring errors of both thickness and velocity of ultrasonic wave propagation are smaller than 0.2%, indicating the effectiveness of the proposed measurement method.

Comparison of modelling using regression techniques and an artificial neural network for obtaining the static modulus of elasticity of Pinus radiata D. Don. timber by ultrasound

Abstract The traditional regression method was compared with an artificial neural network for obtaining the static modulus of elasticity (MOEstatic) of Pinus radiata timber using the dynamic modulus of elasticity determined by ultrasound in the first case and ultrasonic wave propagation velocity in the second case. Whereas the regression model is capable of explaining 70% of the variability of the samples at best, the artificial neural network can explain 80%, indicating that this type of tool improves the estimate of MOEstatic when it is obtained using the ultrasonic technique.

Acoustic Nondestructive Testing of Silicon Carbide/Graphite Composite

The relation between the structure and acoustic parameters for silicon carbide/graphite composite is shown. The effect of the composition and density of the composite and the size of the structural component of silicon on the propagation velocity and damping of the longitudinal ultrasonic wave at frequency 1, 4, and 5 MHz is determined. The results obtained can serve as a basis for testing the quality of the parts in tribocoupling units.

Об ультразвуковом контроле заготовок и изделий из углерод-углеродных композиционных материалов

Introduction. Carbon-carbon composite products feature high strength at temperatures up to 3000 C, resistance to aggressive environments, mechanical reliability and relatively low density. Up to now, there are no NDT established procedures for assessing the quality of composite products and their compliance with the technical requirements. Nowadays composites know-how can not guarantee the specified requirements. The paper provides the estimation of the composites ultrasonic testing equipment and procedure. Method. Subjected to studies were samples made a) in compliance with the required production technology, b) to ensure low mechanical properties, c) to ensure wrong frame geometry. An electronic module and transducers were developed so that a shadow method of sample examination in 3 orthogonal planes could be used. Subjected to studies were samples made a) in compliance with the required production technology, b) to ensure low mechanical properties, c) to ensure wrong frame geometry. An electronic module and transducers were developed so that a shadow method of sample examination in 3 orthogonal planes could be used. Results. The paper provides an analysis of relations between ultrasonic wave propagation velocity, signal amplitude, and the spectral maximum. It has been shown that a 200-500 kHz signal is appropriate to test all available samples, whereas a 400-500 kHz signal provides more information on the product and its defects. Defective samples shift the spectrum maximum to lower frequencies which can be used as the product rejection criterion. Possible directions in the further studies to improve the measurement accuracy have been emphasized. Conclusions. The findings show good opening for the carbon-carbon composites acoustic NDT.

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The article presents the methodology of characterization research of samples from prospective horizons for the exploitation of shale gas from Polish part of the Baltic Basin. High-resolution computed microtomography (μCT) and ultrasonic technique were used for the analysis. The resulting pixel size of μCT image for larger samples were 25 microns, while for small fragments of samples pixel size were 5 microns. In ultrasonic tests, fissures had a dominant impact on acoustic waves propagation. Extensive fissures surface resulted in attenuation of ultrasonic waves. Based on the μCT analysis, percentage content of fissures in the samples (average 0.82%) were determined. Furthermore a cross-section of specimens revealed the internal structure and morphology of fissures. Dynamic parameters of Young’s modulus (range 22÷57 GPa) and Poisson’s ratio (0.21÷0.40) were calculated, by converting the process of propagation velocity of ultrasonic waves through the samples. Results indicate the suitability of the use of ultrasonic analysis and μCT as complementary tests.

EFFECT OF SANDSTONE ANISOTROPY ON ITS HEAT AND MOISTURE TRANSPORT PROPERTIES

Each type of natural stone has its own geological history, formation conditions, different chemical and mineralogical composition, which influence its possible anisotropy. Knowledge in the natural stones anisotropy represents crucial information for the process of stone quarrying, its correct usage and arrangement in building applications. Because of anisotropy, many natural stones exhibit different heat and moisture transport properties in various directions. The main goal of this study is to analyse several anisotropy indices and their effect on heat transport and capillary absorption. For the experimental determination of the anisotropy effect, five types of sandstone coming from different operating quarries in the Czech Republic are chosen. These materials are often used for restoration of culture heritage monuments as well as for other building applications where they are used as facing slabs, facade panels, decoration stones, paving, etc. For basic characterization of studied materials, determination of their bulk density, matrix density and total open porosity is done. Chemical composition of particular sandstones is analysed by X-Ray Fluorescence. Anisotropy is examined by the non-destructive measurement of velocity of ultrasonic wave propagation. On the basis of ultrasound testing data, the relative anisotropy, total anisotropy and anisotropy coefficient are calculated. Then, the measurement of thermal conductivity and thermal diffusivity in various directions of samples orientation is carried out. The obtained results reveal significant differences between the parameters characterizing the heat transport in various directions, whereas these values are in accordance with the indices of anisotropy. Capillary water transport is described by water absorption coefficient measured using a sorption experiment, which is performed for distilled water and 1M NaCl water solution. The measured data confirm the effect of anisotropy which is qualitatively the same as for the heat transport parameters. Summarizing the obtained results, it can be concluded that the anisotropy of sandstone should always be considered in planning the restoration works on the architectural heritage, in order to ensure compatibility between the original and replacement material. DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7202

Error Determination in the Measurement of Propagation Velocity of Longitudinal Ultrasonic Waves by the Immersion Method

The effect of an adsorbed gas layer at the solid-liquid interface on the measurement results for propagation velocity of longitudinal ultrasonic waves in samples using an immersion method has been studied theoretically and experimentally. The systematic component of the immersion method error was determined by comparison with data obtained using a non-contact measuring method.

Influence of Measurement Position, Tree Diameter, and Bulk Wood Density on Models that Predict Wave Propagation Velocity in Logs According to the Velocity in Trees

Abstract The propagation velocity of ultrasonic waves from measurements in trees is numerically different from the velocity obtained from measurements in logs, even in freshly felled logs, and the latter velocity is better correlated with the quality of the wood. The differences can be explained by the basic and fundamental aspects of wave propagation; however, these aspects are difficult to consider in practical applications. Thus, the present study examined parameters that are more easily obtained in the field and considered to provide an equivalent log velocity based on living tree velocities. The results indicate that base logs are better correlated with the velocities measured in trees, because the measurement in trees is performed at the stem base. However, the inclusion of the diameter at breast height (DBH) can produce a model with the same prediction accuracy as that of logs obtained from the whole tree. The inclusion of the green density does not improve estimations of the velocity of logs using the velocity obtained for the tree. Considering that DBH is a parameter often used in forest management, this result can be useful for improving the accuracy of wood-quality predictions from acoustic trials in standing forests.

Application of the dusty plasma method for preparation of diamond ceramics

Diamond particles 3–7μm in size sustained in plasma in a high-dispersion state were coated with cobalt by magnetron sputtering. The relative concentration of cobalt in obtained powders was 2–3 mass. %. Sintering the diamond powders with the cobalt coating under the pressure of 8GPa and the temperatures of 2000–2100K resulted in the production of homogeneous specimens having the density of 3.6±0.1gcm−3. The produced diamond compacts demonstrated high values of the ultrasonic wave propagation velocity and elastic moduli.

National Primary Standard for the Units of the Propagation Velocities of Longitudinal, Shear, and Surface Ultrasonic Waves in Solids

Improvements in the national standard for the unit of the propagation velocity of longitudinal ultrasonic waves in solids are examined. The measurement techniques and standard measures for velocity are described. The composition and metrological characteristics of the new standard are discussed. In accordance with the scientific and technical program "Standards of Russia" and the steps planned for the intro- duction of the national primary standard for the unit of the propagation velocity of longitudinal ultrasonic waves in solids, GET 189-2010 (1), work has been under way at the Far Eastern Branch of the All-Russia Research Institute of Physicotech- nical and Radio Measurements (VNIIFTRI) during 2010-2012 to improve the standard, including the development and intro- duction of two new standards facilities as part of the standard for measuring the propagation velocities of shear and surface ultrasonic waves in solids. Thus, the new national primary standard GET 189-2012 ensures the uniformity of measurements of the propagation velocities of the main types of acoustic waves in solids. This standard is at the top of the national verifi- cation scheme for means of measuring the propagation velocity of ultrasonic waves in solids, which establishes the order of transfer of reproduced units to working standards and means of measurement. The need for measurements of the propagation parameters of ultrasonic waves in solids arises from fundamental, as well as applied research. The propagation parameters of ultrasonic waves are used in fundamental research for calculating the elastic constants and moduli of elasticity - the most important characteristics of solids (2). These parameters are also need- ed for determining the physical and mechanical characteristics, as well as the endurance properties of solids, and are of the greatest importance for creating new materials, and in developing techniques for producing and using these in technology and industry. However, the demand for measurements of the propagation velocity of ultrasonic waves is primarily related to the need to ensure the uniformity of measurements in the area of nondestructive testing of the quality of materials and work pieces using acoustic methods and means of measurement. An analysis of Russian and foreign literature in this area shows that the most promising approach for the develop- ment of original standard means of measurement in solid-state acoustics is the use of contactless methods for generating and receiving ultrasonic waves: optical and capacitive (3-8). Optical methods form the basis of the standard GET 189-2012. The standard laser-interference system for measuring the propagation velocity of longitudinal ultrasonic waves in the standard GET 189-2010 (1) serves as the basis for creating the unified standard facility for reproduction of the units of the prop-

Compressive strength of calcium aluminate mortar determined by ultrasonic non-destructive test method

The early-age hydration of a number of calcium aluminate cement pastes and mortar materials was investigated using compressive strength and ultrasonic through-transmission measurements. Ultrasonic signals obtained were successfully described in the temporal domain by a single Gaussian wave packet equation giving five characteristic parameters – amplitude A, angular frequency ω, phase shift, wave centre arrival time and signal width. The group velocity of ultrasonic wave propagation (vG) is suggested to be a more sound parameter characterising the material under study than the generally employed ultrasound velocity determined from the ‘time of flight' parameter. The combination of parameters AωρvG showed a linear correlation with the measured compressive strengths for all the samples tested. The physical meaning of the AωρvG group of parameters is given and its application is further discussed in relation to other testing procedures.

Estimativa da deterioração da madeira de assoalho de prédio histórico por meio de ondas ultrassônicas

Esse trabalho apresentou como objetivo detectar o grau externo de deterioração da madeira de Araucaria angustifolia (Bert.) O. Kuntze utilizada na confecção de assoalho. Para isso, foram testados os métodos visuais, por meio de notas, e o método não destrutivo baseado na propagação de ondas ultrassônicas. Comparando-se a velocidade de propagação de ondas ultrassônicas na madeira sadia e na madeira atacada verificou-se que as mesmas diferenciavam entre si ao nível de 5% de erro. Verificou-se também que o aumento na proporção de ataque na madeira apresentou-se inversamente proporcional à velocidade de propagação da onda. Uma vez que as amostras foram avaliadas apenas nas suas faces superficiais, fazem-se necessários estudos adicionais a fim de avaliar a influência dos defeitos internos das peças de madeira na velocidade ultrassônica.

Interferometric determination of the high-intensity laser-pulse-material interaction site

We developed a method that accurately determines an unknown position of the high-intensity laser-pulse-material interaction site on the front side of a plate. It is based on interferometric measurements of a normal displacement at known positions on the plate’s rear side. The displacement is caused by reflections of various pulsed-laser-induced mechanical waves. We have superseded the long-established time-of-flight approach with the improved, triple-echo method. To accurately locate the origin of the laser-induced ultrasound on the plate with a known thickness, we only need to detect the arrivals of the first three consecutive mode unconverted waves. Our method works without knowing the propagation velocities of various ultrasonic waves and additionally solves some time-related drawbacks of the conventional time-of-flight approach. The relative uncertainty of the measured source-receiver separations obtained with the presented method is less than 0.01.

Behavior of ultrasonic waves in wood with presence of holes

This work aimed to analyze the pattern of variation in wave lengths in presence of wood holes and to develop a model capable of describing the process. To attain that end, wood pieces were used from species pequiá (Aspidosperma desmanthum), on which circular and linear artificial holes were made and gradually enlarged. Ultrasonic tests were performed using USLab equipment and 45 kHz transducers. Measurements were taken first on the intact piece and then after each stage of artificial hole enlargement. Results demonstrated that propagation velocities of ultrasonic waves are affected by presence of holes and also that reduction in velocity is caused by changes in wave path, since waves tend to deviate from empty space and travel through matter. The circular hole type had a slightly stronger influence on velocity reduction than the linear hole type. Variation in velocity as a function of increasing percentage of hollow space relative to the intact piece can be represented by a linear model.

National primary standard for the unit of the propagation velocity of ultrasonic waves in solids

The results of creating a national standard for the unit of the propagation velocity of ultrasonic waves in solids are discussed. The structure of the standard and its metrological characteristics are described.