Showing papers in "Ultrasonics in 1996"

TL;DR: In this paper, the authors discuss the selection of an appropriate mode and its excitation and reception for the use of Lamb waves for the detection of delaminations in composite materials and corrosion in pipes.

TL;DR: Cort cortical bone is shown to be at least orthotropic in its material symmetry and the mechanical properties of cortical bone are more homogeneous along the length than around the circumference.

TL;DR: In this paper, a transducer model based on nonlinear piezoelectric constitutive equations was developed to describe the harmonic generation that occurs on current or velocity signal analysis when the transducers are driven at high voltage.

TL;DR: In this paper, an array of ten pulsed Nd: YAG lasers was constructed in order to study the effects of generating ultrasonic signals from a single laser source in the thermo-elastic regime.

TL;DR: This paper reviews contrast agents developed in the last decade, which are all based on free gas or encapsulated gas bubbles, and recommends three new contrast agents based on ultrasound specific contrast agents.

TL;DR: In this paper, a large aperture lens-less line-focus transducer for materials characterization is described, which can be used to characterize sample material properties by simultaneously measuring surface wave speeds and bulk wave transit times from which the thickness and anisotropy may be deduced.

TL;DR: In this article, eight acoustic signals were scattered from a single bubble to determine how easily and accurately they can, individually or together, measure the bubble size, and the results from the Characterisation of Bubbles Using Simulataneous Techniques (COBUST) were presented.

TL;DR: The use of mechanical resonances to test properties of materials is older than the industrial revolution as mentioned in this paper, and early documented cases of British railroad engineers tapping the wheels of a train and using the sound to detect cracks perhaps marks the first real use of resonance to test the integrity of high-performance alloys.

TL;DR: In this paper, an ultrasonic welding method for welding of metal and plastic materials has been proposed, and the welding method of using two vibration systems crossed at a right angle is effective, and 10 mm thick aluminum plates have been joined successfully.

TL;DR: In this article, both micromachined air-coupled capacitance transducers and piezoelectric air-Coupled devices have been used to form images of artificial graphite foil defects in a fiber-reinforced thermoplastic composite plate.

TL;DR: In this article, the loss in piezoelectric ceramics is described and a method of measuring the high-power characteristics is described for antiresonance frequency.

TL;DR: In this paper, a new scanning technique using leaky Lamb waves is presented to detect internal defects in a multilayered fiber-reinforced composite plate specimen (SCS-6 fibers in Ti-6Al-4V matrix).

TL;DR: In this article, a study of the simulated reflection of a wideband ultrasound shear wave from the solid/viscous fluid interface is presented, and various parameters affecting reflection factors including the material properties of the solid, fluid properties like density and viscosity, and the operating frequency are discussed.

TL;DR: In this paper, a theoretical model was developed which led to an approximate expression in closed form for the normal surface displacement of the Rayleigh wave in both time and frequency domain, and quantitative agreement was found for a parameter-free comparison between theory and experiment.

TL;DR: In this article, the role of stroke, suction, frequency, tissue type, and tip area have been examined with regard to tissue fragmentation rate in the ultrasonic surgical aspirator.

TL;DR: In this article, the amplitude and phase of the S0 mode Lamb wave and SH0 mode plate wave generated by the EMATs were measured while changing the static field strength to the sheets.

TL;DR: In this paper, the Gibbs surface excess concentration of the alcohol at the solution microbubble interface was found to be directly related to the reduction reaction, irrespective of the type or bulk solution concentration of alcohol.

TL;DR: In this article, reactive liquid rubbers are added to epoxy to obtain a heterogeneous polymer, which increases wave attenuation by both scattering and absorption, but the attenuation in this kind of material remains relatively low.

TL;DR: In this article, a fiber-optic hydrophone with a dielectric coating is presented that can be used for the characterization of both high energy acoustical pulses, such as shock waves, and low-intensity ultrasonic fields.

TL;DR: In this paper, a method is described to measure precisely the ultrasonic absorption coefficient α and sound velocity v3 of liquids between about 300 MHz and 5 GHz using a rod-shaped piezoelectric lithium niobate crystals.

TL;DR: In this article, the authors used gas-containing particles encapsulated in a shell to explain the acoustic properties of these particles, which differ from that of gas-bubbles, and showed how acoustic behaviour of such particles can be explained from their size and compressibility.

TL;DR: In this paper, the propagation characteristics of the longitudinal and torsional vibrations in the ultrasonic exponential horns and choosing the decay constant of the cross-sectional area of the Ultrasonic exponential solid horns were analyzed.

TL;DR: In this paper, the effect of the generation laser spot size, energy density, and total energy on the transfer of energy from the generator to the two lowest Lamb wave modes, a0 and s0, was investigated.

TL;DR: In this paper, an attenuation comparison of a polymer matrix with a composite constituted with the same polymer matrix reinforced with long fibers is presented. And the results of attenuation measurements are presented on both the polymer matrix and the unidirectional fiber-reinforced composite.

TL;DR: In this paper, a validated vibration characterisation strategy is proposed based on sensitivity analysis for improved vibration control of an ultrasonic metal forming process, and the result is a design procedure for improving the reliability of metal forming processes.

TL;DR: In this article, an innovative process based on using the Hilbert transform of the impulse response evaluated from the two signals is proposed to estimate the time delay between two received signals, where a pure delay is transformed in a hyperbola whose vertical asymptote is located at a time yielding to the unknown shift in time.

TL;DR: In this paper, the authors compared four models that describe the propagation of ultrasound through two-phase media and found that the Allegra and Hawley model gave the most thorough interpretation of acoustic propagation through a two-phase system.

TL;DR: In this article, the operation of an ultrasonic linear motor using Rayleigh waves was described, where four IDTs were arranged to excite the x-propagation wave and the y-propagate wave in both directions.

TL;DR: In this article, the spatial and frequency dependencies of the transmitted leaky waves have been measured for a variety of composite plates including aluminum-aramid and graphite-epoxy, and the results have been employed to deduce, with high precision, the transmission coefficient of the plate over the frequency and angular bandwidths covered by the measurements.

TL;DR: The purpose of this paper is to determine the error introduced by ultrasonic hydrophones used to measure current or proposed Mechanical and Cavitation Indices, assuming that the hydrophones meet bandwidth specifications contained in US and IEC measurement standards.