Showing papers in "Ultrasonics in 2015"

TL;DR: This review addresses the microscopic mechanisms that are involved in the photogeneration processes of GHz-THz coherent acoustic phonons (CAP) induced by an ultrafast laser pulse, discussing the deformation potential mechanism, the thermoelasticity, the inverse piezoelectric effect and the electrostriction in condensed matter.

TL;DR: A variety of state-of-the-art MPT configurations and their applications will be reviewed along with the working principle of this transducer type.

TL;DR: An introduction to picosecond laser ultrasonics, a means by which gigahertz-terahertz ultrasonic waves can be generated and detected by ultrashort light pulses, which can be used to characterize materials with nanometer spatial resolution.

TL;DR: Experimental outcomes prove that typical micro-defects due to the layer-by-layer deposition process, such as near-surface and surface flaws in a single layer deposit, can be detected.

TL;DR: This paper develops a robust damage detection method based on singular value decomposition (SVD), and shows that the orthogonality of singular vectors ensures that the effect of damage and that of environmental and operational variations are separated into different singular vectors.

TL;DR: For large-scale production role-to-role fabrication has been shown reducing costs even more and investment costs and energy consumption are comparatively low and processes are very flexible enabling economic fabrication even for small- scale production.

TL;DR: The experimental results showed that when the elliptical vibration was applied in RUEM, a superior cutting process can be obtained compared with that in CG, including providing reduced cutting forces, an extended tool life, and improved surface integrity due to the intermittent material removal mechanism and the excellent chip removal conditions achieved.

TL;DR: Guided wavefield analysis methods for detection and quantification of crack damage in an aluminum plate are presented and simulation based studies show that spatial wavenumber imaging method is able to distinguish cracks of different severities.

TL;DR: Regression analysis showed a reliable linear correlation between UPV and compressive strength, which allows a reasonable estimation of the strength of Lecce stone by means of non-destructive testing methods such as the ultrasonic wave velocity.

TL;DR: Some of the useful properties of guided Lamb type waves are investigated, using analytical, numerical and experimental methods, in an effort to provide the knowledge base required for the development of viable structural health monitoring systems for composite structures.

TL;DR: The main features and utility of proposed d36 piezoelectric wafer for guided wave generation and detection in structural health monitoring are demonstrated.

TL;DR: A method for extracting the nonlinearity parameter β11 is proposed based on a nonlinear least squares curve-fitting algorithm that is tailored for Rayleigh wave measurements and improves upon conclusions drawn from previous analysis.

TL;DR: The methodology yields delamination size and correlates local wavenumber results from multiple excitation frequencies to theoretical dispersion curves in order to robustly determine the delamination ply depth.

TL;DR: The proposed technique has some advantage since knowledge about the undamaged scenario for the concrete medium is not necessary to assess its integrity, and is capable of creating clear images of the inspected region of interest.

TL;DR: The acoustic vibrations of single-metal and multi-material nanoparticles are studied by ultrafast pump-probe optical spectroscopy and the applicability of the continuous elastic model to the small size range, down to one nanometer, is discussed.

TL;DR: The agreement between sonomicrometry and speckle tracking demonstrates that carotid strain assessment by ultrasound speckled tracking is feasible and significantly reduces the likelihood of false positives in clinical ultrasound images.

TL;DR: A two-step hybrid technique is proposed in this paper for predicting acoustic source in anisotropic plates that always reduced the prediction error irrespective of whether the final prediction coincided with the actual source location or not.

TL;DR: This study demonstrated that the proposed method was able to automatically measure the pennation angle and fascicle length of GM ultrasound images, which made it feasible to investigate muscle-level mechanics more comprehensively in vivo.

TL;DR: The proposed non-contact hybrid system can effectively characterize the dispersive relation without knowledge of neither the materials characteristics nor the mathematical model and proved a high sensitivity of the air-coupled and laser ultrasound in characterizing Lamb wave dispersion in plate-like structures.

TL;DR: The obtained results indicate that the nonlocal effect decreases the resonance frequency except for the fundamental frequency of nanocantilever sensor, helpful to the design of micro/nanomechanical zeptogram-scale biosensor.

TL;DR: This study presents a nondestructive evaluation method based on guided ultrasonic waves (GUW) to quantify corrosion damage of prestressing steel strands by using dispersion curves, continuous wavelet transform, and wave velocity measurements.

TL;DR: The study of bandgap properties of a two-dimensional phononic crystal with the two resonators is studied and embedded in a homogenous matrix and results show that, the opening of the bandgaps is because of the local resonance and the scattering interaction between two resonator and matrix.

TL;DR: The optical theorem is extended and generalized in a cylindrical coordinates system for the case of 2D beams of arbitrary character as opposed to plane waves of infinite extent and reveals the presence of an interference scattering cross-section term describing the interaction between the diffracted Franz waves with the resonance elastic waves.

TL;DR: The proposed head phantom can be utilized as a very useful tool for evaluating ultrasonic protocols, thus minimizing the need for animal models and cadavers.

TL;DR: Diversity of acoustic streaming field in a 2D rectangular chamber with a traveling wave and using water as the acoustic medium is numerically investigated by the finite element method and it is found that the working frequency, the vibration excitation source length, and the distance and phase difference between two separated symmetric vibrationexcitation sources can cause the diversity in the acoustic streaming pattern.

TL;DR: Very good agreement between numerical and experimental results are found confirming the existence of the predicted band gaps in a phononic polyvinyl chloride (PVC) plate with a square lattice of cross-like holes.

TL;DR: A broad review of the literature surrounding the utilization of traditional mechanical transducers to generate ultrasound in arc welding is presented and various innovative concepts based on this method are presented, which allows the introduction of ultrasonic energy in the arc welding without the need of any auxiliary device of welding.

TL;DR: The applicability of a laser-ultrasonic procedure to improve the performances of train axle ultrasonic inspection is demonstrated, with the demonstration that the technique is suitable for the detection of surface defects purposely created on the train axle.

TL;DR: The first experimental observation of coherent acoustic phonon generated by the absorption of ultrashort light pulses in piezoelectric heterostructures is presented and some methods developed to realize customizable phonon generation are presented.

TL;DR: A new T-shape piezoelectric motor using the hybrid of two orthogonal longitudinal vibrations is proposed in this work, which exhibits merits of simple structure, easy to realize miniaturization,easy to be fabricated, and high power-to-weight ratio.