Showing papers in "Ultrasonics in 1989"

TL;DR: In this article, a laser-ultrasonic method to measure the acoustic velocities and the elastic constants of solid materials based on the crosscorrelation of successive echoes is presented.

TL;DR: In this paper, an amplitude spectrum technique for the measurement of the phase velocities of waves in media, which can be dispersive and attenuating is presented, where the variation of phase velocity with frequency is calculated from the longitudinal resonant frequencies, the corresponding mode numbers and the distance between the boundaries of the tested material.

TL;DR: In this paper, the authors discuss some potential industrial applications for laser ultrasound, illustrated by examples of recent laboratory demonstrations of its potential for nondestructive testing and materials characterization, where laser ultrasonic techniques are only likely to find industrial application where they answer a need that cannot be met by conventional transducers.

TL;DR: In this paper, an aluminum hemicylindrical sample has been irradiated with an array of laser lines, with each line acting as a source of acoustic waves, and detection of the generated ultrasonic waves was performed using both a wide-band stabilized Michelson interferometer and a 20 MHz piezoelectric transducer.

TL;DR: It is shown that all the characteristic features of experimental acoustic cavitation spectra occur in the spectrum of a single bubble affected by non-gradiental acoustic fields.

TL;DR: A selection of well established deconvolution techniques are assessed for operation in the ultrasonic environment and those algorithms which are best suited to particular ultrasonic applications and conditions are identified via a simulation approach, based around a linear systems model.

TL;DR: When a previously non-oscillating bubble is first insonated, its radial motion can contain transients as mentioned in this paper, which may enhance the violence of the volume pulsations.

TL;DR: In this article, the vibration system is analyzed in order to construct a high-speed ultrasonic motor with high efficiency, and the efficiency is markedly improved up to 86% and a maximum speed of 1 m s −1 is achieved.

TL;DR: In this paper, the authors have shown that transient excitation can cause the unstable growth and collapse of bubble nuclei, as well as enhancing the stable cavitation of larger bubbles.

TL;DR: In this paper, a model for studying the effects of defect surface roughness on ultrasonic signals is described, and the model contains many aspects of a real inspection system, giving predictions of interest to practical ultrasonic non-destructive testing.

TL;DR: In this article, a model of the reflection and transmission of longitudinal ultrasonic waves through a contact interface of solids is presented, in which the contact interface, in the form of a layer of weightless springs, is characterized by three parameters: unit contact stiffness, coefficient of viscous friction and coefficient of reradiation damping.

TL;DR: Water containing powders of MoS2 and WSe2 was sonicated under an argon-hydrogen atmosphere (1 MHz; 2 W cm−2) and transparent yellow or red solutions were obtained which contained colloids with two size distributions.

TL;DR: In this paper, the use of subsurface longitudinal waves (SSL), which can be effectively generated at the first critical angle, was explored for material characteristic analysis to determine certain elastic constants and also for inspection of sub-surface defects.

TL;DR: In this paper, the authors considered the problem of normal mode tracking using an ultrasonic immersion system and analyzed the optimum possibilities offered by a correlation method for time-of-flight measurements when mixing of the different modes is present.

TL;DR: Dow Corning 710 silicone fluid has been investigated to establish its suitability as a reference liquid for ultrasonic attenuation Measurements made in the megahertz frequency range with overall uncertainties of 4-5% at a confidence level of 95% are compared with previous values given in the literature as discussed by the authors.

TL;DR: In this paper, the reflection coefficients for a steel substrate with a polymer coating were made with different boundary conditions at an interface between the coating and the substrate and the results showed that double dips in the spectrum became single dips when the bonding became smooth.

TL;DR: A reflection mode proof-of-concept medical ultrasound imager based on time delay spectrometry based on TDS spread spectrum has been developed and tested and has a higher signal-to-noise ratio than pulse-echo systems which allows high resolution at greater depths.

TL;DR: This paper shows how, by using some simple concepts and straightforward experiments, reasonably complicated acoustic projectors can be designed and built by almost anyone with access to a machine shop and a test laboratory.

TL;DR: In this article, the design and operation of a laboratory ultrasonic imaging system that has been developed for characterizing delaminations in composite materials is described, and examples are presented of the system's successful application to a test specimen containing artificial defects and to a carbon fibre composite specimen containing damage induced by impact loading.

TL;DR: In this paper, theoretical values of ultrasonic velocity in binary liquid mixtures of propan-1-ol and butan- 1-ol with n -hexane, benzene, and acetone have been evaluated using Free Length Theory, Collision Factor Theory and Nomoto's relation.

TL;DR: In this paper, a passively mode-locked laser which produces picosecond energetic laser pulses for the generation of ultrasound is described, and a single pulse from this train, up to 8 mJ in 30 ps, was used to generate ultrasound in thin sheet material, such as 250 μm thick aluminium sheet.

TL;DR: A dependence of ultrasound's efficacy on the medium's temperature during insonation and a significant reduction of ultrasound efficacy in compromising cellular integrity in the presence of cysteamine are indicated.

TL;DR: Experimental results of ultrasound propagating in cold drawn wires of stainless steel and aluminium ranging in diameter from 0.25 to 1.21 mm are in close agreement with theoretical predictions as mentioned in this paper.

TL;DR: In this article, the authors describe the reflection and refraction of plane acoustic waves on a liquid-solid interface using the thermoviscous properties of the solid and show that the influence of thermal effects is very small and appears only for low and high values of the incident angles.

TL;DR: Results show that, under present experimental conditions, ultrasonic thickness measurements compare well with the micrometer actual thickness results, and can be used as a non-destructive tool for quantitative cortical bone thickness measurements.

TL;DR: An electrostatic curved phased array transducer for airborne ultrasonic imaging has been developed for use in a hybrid sensor system in the guidance control of an autonomous AGV.

TL;DR: In this article, an optical technique based on a combination of the theory of light diffraction by ultrasonic fields and tomography was proposed to distinguish between a perfect transducer and a transducers with a defect.

TL;DR: In this article, two acoustical techniques to measure sound velocities in solids under high static pressure are examined from both theoretical and experimental points of view, and the authors illustrate the elastic behavior of two perovskite crystals: RbCdF 3 and SrTiO 3.