Ultrasonic Measurement Method Research Articles

Method for ultrasonic vector velocity measurement

Method for ultrasonic vector velocity measurement

In-Process Measurement of Contact Pattern Variations in Rotating Main Bearing of Machine Tools Using Ultrasonic Waves Method.

It can be pointed out that characteristics of machine tool joints have a significant effect on the static, dynamic and thermal behavior of a machine tool as a whole. To clarify various characteristics of the joint, it is basically essential to evaluate the contact pressure and its distribution. With regard to the measurement of the static contact pressure of the joint, one of the authors has already proposed a method using ultrasonic waves. In contrast, the joint behavior in the machine work condition is not revealed as yet. In this study, therefore, an ultrasonic waves method for the in-process measurement of contact pattern variations has been proposed, and its characteristics have also been investigated. The objective of the study is the joint between the bearing and its housing in the main spindle system. The method has a remarkable feature in that it is continuously applicable in operation without changing the state of contact at the joint. From the experimental results, it is ascertained that the proposed method is available for detecting the contact pattern variations significantly influenced by the thermal expansion of the outer ring of the bearing.

An extended zero-crossing method for ultrasonic velocity measurements.

Sound speed that is the response of media to sound propagation provides important information to evaluate elastic characteristics quantitatively. It is desired to develop precise measurement technique of sound speed. Sound speed of media can be determined by measuring travel time of the sound traversing media when the distance between transmitter and receiver is known. The zero-crossing method is popular to measure the travel time using sound pulse. This method is useful in measuring sound speed of homogeneous medium. In homogeneous medium, the wave form of received signal is almost independent of the travel distance of the sound pulse. In inhomogeneous medium, the wave form of received signal is depend on the characteristics of media. The measured sound speed by the zero-crossing method means the speed of early received sound. In this paper, an extended zero-crossing method is proposed. In order to evaluate the time interval, some time range within pulse signal is considered for processing. It increases the reliability of measured sound speed, and is helpful to consider on the physical meaning of measured sound speed of inhomogeneous media.

Ultrasonic Measurement of Local Concentration of Cake on Microfiltration Membrane Using Polymer Transducer.

In order to understand the filtration mechanism in microfiltration, information concerning cake concentration is important because the cake reduces the permeation rate. In this work, an ultrasonic measurement method of local cake concentration on the microriltration membrane was developed by using a special array polymer transducer. This method was applied to microliltration both with suspensions of yeast and polystyrene particles to study the effect of solidity of solute on cake compression. As a result, it was found that the yeast cake was compressible but that of polystyrene particles incompressible.

Mesures des débits par méthode ultrasonore

Flow measurement using ultrasonic method Ultrasonic flow measurement methods have been widely used in industry since the 70's. Progress in the domain of electronic components performances lead to more precision concerning speed and flow measures, but it is necessary to master geometrical parameters of the establishment and the choice of the site. The possibility of installing sensors on a loaded pipe and the use of external sensors make this method economically interesting for large pipes.

An ultrasonic Doppler venous outflow method for the continuous measurement of cerebral blood flow in conscious sheep.

A pulsed ultrasonic Doppler venous outflow method was developed for the continuous measurement of global cerebral blood flow (CBF) in conscious sheep. The sheep were prepared under anesthesia with a "suture down"-style ultrasonic flow probe on the dorsal sagittal sinus placed via a trephine hole. Angiographic and dye studies showed that the dorsal sagittal sinus at the point of placement of the probe collected the majority of the blood from the cerebral hemispheres. Studies of the blood velocity profile across the sinus showed that the dimensions of the dorsal sagittal sinus changed minimally with changes in CBF in vivo. The velocity measurements were calibrated under anesthesia against an in vivo direct venous outflow method. Control CBF values for six sheep ranged from 31 to 53 ml/min for the area of brain described above; for two sheep in which the weight of the brain was determined, this gave total CBF values of approximately 34 and 30 ml min-1 100 g-1. The CBF measured varied in the expected manner with changes in the end-tidal CO2 concentration in expired breath and showed transient reductions with the barbiturate thiopentone and transient increases with the opiate alfentanil. It is concluded that the method is simple and accurate.

49935 Double through-transmission bulk wave method for ultrasonic phase velocity measurement and determination of elastic constants of composite materials : Rokhlin, S.I.; Wang, W. Journal of the Acoustics Society of America, vol. 91, no. 6, pp. 3303–3312 (Jun. 1992)

49935 Double through-transmission bulk wave method for ultrasonic phase velocity measurement and determination of elastic constants of composite materials : Rokhlin, S.I.; Wang, W. Journal of the Acoustics Society of America, vol. 91, no. 6, pp. 3303–3312 (Jun. 1992)

Ultrasonic and thermodynamic investigations of weakly interacting systems

Ultrasonic velocity measurement method has been used to investigate the interaction between weakly interacting systems in ternary systems. The equilibrium constant and heat of formation for acetone-methanol in carbon tetrachloride is 0.33 dm 3 mol −1 at 303.15 K and 14.2 kJ mol −1 respectively.

Determination of macro- and micromechanical and interfacial elastic properties of composites from ultrasonic data

A self-reference ultrasonic bulk wave method for nondestructive measurement of elastic properties of ceramic matrix composites has been developed. The method has the advantage of minimizing the effect of geometrical imperfection of the sample. The experiment has been done on silicon carbide (SiC) fiber-reinforced reaction-bonded silicon nitride (Si3N4) matrix composites. The composite elastic constants are extracted from the experimental phase velocities using a nonlinear optimization procedure to find the best fit between experimental data and the solutions of the Christoffel equation. The effect of individual constituents on the overall composite properties has been investigated. The effects of porosity on the matrix properties and water saturation of pores on the immersion ultrasonic measurements are taken into account using a micromechanical model for two-phase particulate composites. This model is validated by experimental data. A microstructural model for analysis of elastic properties of ceramic matrix composites and their interfaces from experimental data is introduced. The fiber and the interface are modeled by effective fibers with anisotropic properties and a perfect bond between fiber and matrix. The properties of the effective fibers are extracted from the measured composite elastic moduli using a nonlinear optimization procedure. Shear and longitudinal elastic moduli of 3-μm-thick carbon-rich coatings are determined using measured effective and estimated actual elastic properties of the fibers.

Double through-transmission bulk wave method for ultrasonic phase velocity measurement and determination of elastic constants of composite materials

This paper describes a modification of a nondestructive ultrasonic method for measurements of the phase velocity of bulk waves in arbitrary directions in generally anisotropic materials. In the conventional method the through-transmission technique is used for velocity measurements at a specified angle of incidence. When this angle is changed by rotation of the sample, the transmitted beam changes position, and so the position of the receiving transducer must be changed. This leads to experimental difficulties and loss of precision. In the double-transmission technique, the ultrasonic wave is reflected from reflector plates behind the sample and returns via the same path to the same position on the transmitter/receiver working in pulse-echo mode, which eliminates the necessity of readjusting the receiver position. It is also shown that for arbitrary direction of measurement in anisotropic materials, time-delay measurements give phase velocity regardless of the angle of deviation between phase and group velocities. The physical basis of this phenomenon is explained. An example of velocity measurement and elastic-constant determination is given for unidirectional graphite–epoxy composite. Stability of the nonlinear least-square algorithm used for reconstruction of the elastic constants from the velocity data is demonstrated by computer simulation on a synthetic set of data.

An improved system of HRB(high-resolution Bragg reflection) method for ultrasonic measurements up to 2.1GHz.

An improved system of HRB (high-resolution Bragg reflection) method was constructed and used for velocity and absorption measurements in toluene up to 2.1GHz. The results show a strong velocity dispersion around 8GHz, which is interpretted in terms of vibration-to-translation relaxation process of toluene molecules.

Taguchi methods and expert systems in fabrication design

Quality improvement is a key objective in meeting reduced costs and increased productivity. It has therefore become an integral part of many organisations' business strategy. In the Non-Destructive Testing (NDT) of welds, the quality of inspection results from a welded structure is closely linked to the parameters used in the test procedure adopted. The formulation of the optimum test parameters depends on the knowledge and experience of the NDT specialist and requires inputs of several different types of expert knowledge. This experience which the human experts have is usually heuristic, judgemental, subjective or intuitive in nature. Moreover, the optimum procedures usually differ from one job to another. Hence, the application of the design of experimental techniques, such as Taguchi's approach, can be used to identify optimum conditions which are robust against unwanted disturbances in the testing environment while providing an improved degree of sensitivity. Taguchi methods (Taguchi, System of Experimental Design, Unipub Krauss, 1987; Phillip, Taguchi Techniques for Quality Engineering, McGraw-Hill, 1988) which are aimed at reducing variability and cost, can be used to improve the sensitivity of ultrasonic measurement methods through the use of the Signal-to-Noise (SN) ratio as the quality characteristic of a measuring system. Traditionally, the quality of measuring systems has been evaluated on the basis of repeatability. Another important element associated with the quality of measurement systems is ‘sensitivity’, which is the ability to perceive and discriminate between two signals or samples to be measured. Parameter design in Taguchi methodology can be used to provide the human experts with a means of optimising inspection parameters. Therefore, knowledge-based systems incorporating heuristic algorithms, as well as analytical and empirical models provided by Taguchi methods can in turn provide human experts with support to further improve their decision making. This paper will describe how parameter design can be used to increase the efficiency of NDT procedures by providing robust inspection parameters for a knowledge-based expert system, an ongoing research program to enhance industrial quality.

Ultrasonic method for measurement of depth of surface opening flaw in solid mass

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Ultrasonic attenuation spectroscopy research for food dispersion measurement.

Theoretical research work has been done for understanding the principle of the ultrasonic absorption in food dispersion. Four ultrasonic attenuation measurement methods have been developed. These are the through transmission method, through transmission substitution method, pulse echo substitution method, and pulse echo method. The first three methods compare echoes collected from a reference material of known ultrasonic properties with that of the sample. The last method compares reflected echoes collected from measurements on the sample only. An ultrasonic attenuation spectroscopy system for the study of ultrasonic properties of food dispersion has been developed. The results of tests on castor oil are in good agreement with the literature values. Experiments on skimmed milk, semi-skimmed milk, full fat milk, and homogenized milk’s ultrasonic attenuation spectra have been performed. The results demonstrate the effects of both fat content and fat globule particle size on the ultrasonic attenuation characteristics of milk.

Semi-automatic (method) for ultrasonic measurement of texture

Semi-automatic (method) for ultrasonic measurement of texture

Measurement of cake thickness on membrane for microfiltration of yeast using ultrasonic polymer concave transducer.

An ultrasonic measurement method was applied to obtain information about the properties of cake formed on the membrane in microfiltration of suspensions of yeast. The microfiltration was carried out at low applied pressure in order to assess that the cake formed was incompressible. A spherically concave transducer made of piezoelectric films of a vinylidene fluoride-trifluoroethylene copolymer was adopted. The surface shape of the cake was found not to be flat by the reflection technique. An on-line method of measuring cake thickness was developed by using the transmission technique, and the results showed good agreement with data reported elsewhere.

Volumetric blood flow via time-domain correlation: experimental verification

A novel ultrasonic volumetric flow measurement method using time-domain correlation of consecutive pairs of echoes has been developed. An ultrasonic data acquisition system determined the time shift between a pair of range gated echoes by searching for the time shift with the maximum correlation between the RF sampled waveforms. Experiments with a 5-MHz transducer indicate that the standard deviation of the estimate of steady fluid velocity through 6-mm-diameter tubes is less than 10% of the mean. Experimentally, Sephadex (G-50; 20-80 mum dia.) particles in water and fresh porcine blood have been used as ultrasound scattering fluids. Two-dimensional (2-D) flow velocity can be estimated by slowly sweeping the ultrasonic beam across the blood vessel phantom. Volumetric flow through the vessel is estimated by integrating the 2-D flow velocity field and then is compared to hydrodynamic flow measurements to assess the overall experimental accuracy of the time-domain method. Flow rates from 50-500 ml/min have been estimated with an accuracy better than 10% under the idealized characteristics used in this study, which include straight circular thin-walled tubes, laminar axially-symmetric steady flow, and no intervening tissues.

Investigation of ultrasonic methods for residual stress measurement in metals : Swanson, G.D. Allied Corporation, Bendix Kansas City Division, Missouri (United States), BDX-613-3685, 18pp. (Feb. 1987)

Investigation of ultrasonic methods for residual stress measurement in metals : Swanson, G.D. Allied Corporation, Bendix Kansas City Division, Missouri (United States), BDX-613-3685, 18pp. (Feb. 1987)

Superposed pulse echo overlap method for ultrasonic sound velocity measurement

A superposed pulse echo overlap method is described as a method to determine ultrasonic sound velocity. This method has the advantages both of the pulse echo superposition and the pulse echo overlap methods; round-trip time of echoes through the specimen was determined by overlapping the superposed echoes on the oscilloscope. Accurate and quick measurements of sound velocity in solids and liquids become possible by this method.

Ultrasonic depth measurement apparatus and methods

Ultrasonic depth measurement apparatus and methods