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Mohammad Hadi Hafezi, Tribikram Kundu
The interaction between surface wave and a surface breaking crack is studied using a novel fast modeling tool called peri-ultrasound that can model both linear and nonlinear ultrasonic response. This modeling approach is based on peridynamic theory. In this study, the surface wave is modeled by applying a triangular pulse excitation function on the surface of a large structure. The particle movements are simulated on both sides of the surface crack to investigate transmitted and reflected fields. This investigation shows that: (1) the computed amplitude spectra of the Rayleigh wave agrees with the experimental observation; and (2) the structure containing a surface breaking crack shows noticeable increase in its nonlinear behavior...
November 7, 2017: Ultrasonics
Emmanuel Nicolas, Samuel Callé, Stéphane Nicolle, David Mitton, Jean-Pierre Remenieras
The characterization of brain tissue is crucial to better understand neurological disorders. Mechanical characterization is an emerging tool in that field. The purpose of this work was to validate a transient ultrasound technique aimed at measuring dispersion of mechanical parameters of the brain tissue. The first part of this work was dedicated to the validation of that technique by comparing it with two proven rheology methods: a rotating plate rheometer, and a viscoelastic spectroscopy apparatus. Experiments were done on tissue mimicking gels...
November 4, 2017: Ultrasonics
Shyam Trivedi, Harshal B Nemade
The paper presents 3D finite element simulation and analysis of Love wave resonator with different guiding layer materials and investigation of the coupled resonance effect with ZnO nanorods on the device surface. Analytical estimation of phase velocity and mass sensitivity of Love wave device with SiO2, ZnO, gold, SU-8, and parylene-C as guiding layer materials is performed for comparative analysis. Simulations are carried out to study the variation in electromechanical coupling coefficient, displacement profile and frequency response of the Love wave resonator...
November 3, 2017: Ultrasonics
Mototaka Arakawa, Hiroshi Kanai, Kazuo Ishikawa, Ryo Nagaoka, Kazuto Kobayashi, Yoshifumi Saijo
Scanning acoustic microscopy (SAM) using impulsive signals is useful for characterization of biological tissues and cells. The operating center frequency of an ultrasonic device strongly depends on the performance characteristics of the device if the measurement is conducted by using impulsive signals. In this paper, a method for the design of ultrasonic devices for SAM using impulsive signals was developed. A new plane-wave model was introduced to calculate frequency characteristics of loss of ultrasonic devices by taking into account the conversion loss at the ultrasonic transducer, the transmission loss at the acoustic anti-reflection coating, and the propagation loss in the couplant...
November 2, 2017: Ultrasonics
J E Araújo, Hugo M Santos, Carlos Lodeiro, J L Capelo
No abstract text is available yet for this article.
October 28, 2017: Ultrasonics
Sunil Kishore Chakrapani, Alexander Howard, Daniel Barnard
The current article reports on the experimental study of the influence of surface roughness on the measurement of the acoustic nonlinearity parameter. The nonlinearity parameter was measured using contact piezoelectric transducers, which were calibrated using the reciprocity based technique. Aluminum and steel samples were chosen to study the influence of hardness of the sample on the measurement of the nonlinearity parameter. While, lower Ra value (average asperity height) aluminum samples were more susceptible to surface deformation and scratches from coupling the transducer to the sample, the same could not be observed for steel samples...
October 28, 2017: Ultrasonics
B D Zaitsev, A M Shikhabudinov, A A Teplykh, I A Borodina
The influence of the width of the gap between the free side of the piezoelectric lateral electric field excited resonator and the metal film placed on the dielectric plate on the frequencies of the parallel and series resonances was experimentally and theoretically studied. The measurements were carried out in the temperature range of 14-45 °C. It has been shown that the change of the gap width from 0 up to 3.5 mm leads to the change of the parallel resonant frequency on 1.3% at the constant temperature...
October 27, 2017: Ultrasonics
B D Zaitsev, A A Teplykh, A M Shikhabudinov, I A Borodina, V V Kisin, I V Sinev
The effect of a thin layer with the finite surface conductivity located near the lateral electric field excited resonator on its characteristics is studied theoretically and experimentally. It has been shown that for the fixed distance between the free side of the resonator and conducting layer with increasing the surface conductivity of the layer the resonant frequency of the parallel resonance remains initially practically constant, then sharply decreases in a certain range and then insignificantly changes...
October 26, 2017: Ultrasonics
Yingxiang Liu, Shengjun Shi, Chunhong Li, Weishan Chen, Liang Wang, Junkao Liu
A bi-directional standing wave linear piezoelectric ultrasonic actuator with four driving feet is proposed in this work. Two sandwich type transducers operated in longitudinal-bending hybrid modes are set parallelly. The working mode of the transducer is not simple hybrid vibrations of a longitudinal one and a bending one, but a special coupling vibration mode contained both longitudinal and bending components. Two transducers with the same structure and unsymmetrical boundary conditions are set parallelly to accomplish the bi-directional driving: the first transducer can push the runner forward, while the other one produces the backward driving...
October 26, 2017: Ultrasonics
G M Kvashnin, B P Sorokin, A S Novoselov
Finite Element Modeling of the peculiarities of the trapping energy phenomenon in application to the piezoelectric layered structure (PLS) "Al/(0 0 1) AlN/Mo/(1 0 0) diamond" has been fulfilled. The resonant properties of longitudinal bulk acoustic waves (BAW) as well as frequency dependence of impedance within the 1 - 6 GHz band have been studied. The investigation of distribution of elastic energy flow and elastic displacements in a PLS cross-section allowed us to obtain an important information on energy trapping (ET) in PLS...
October 25, 2017: Ultrasonics
Guang Yao, Deyuan Zhang, Daxi Geng, Xinggang Jiang
The electrosurgical electrode currently stands out as one of the most commonly used tools in minimally invasive surgery. In order to facilitate tissue cutting and accelerate wound healing, tissue adhesion to the electrosurgical electrode is considered as an extremely urgent problem to be solved. In this paper, a novel ultrasonic vibration assisted (UV-A) electrosurgical electrode is firstly proposed to overcome the problem of tissue sticking. The anti-adhesion effects were evaluated by measuring the adhesion force and the weight of tissue adhesion using the electrosurgical electrode with and without UV-A comparatively...
October 20, 2017: Ultrasonics
Xiaokai Xing, Chunbo Feng
In CO2 flooding, it is difficult to strip CO2 from the produced fluids through pressure release alone, which may erode the equipment following the separator. Experiments are conducted to study how ultrasound enhances desorption of CO2 from crude oil. An analysis of ultrasonic influence on the desorption rate and the percentage of CO2 desorbed reveals the phenomena and variation rules of desorption peaks, second peaks, oil bubbling and power threshold.
October 20, 2017: Ultrasonics
Qiuyan Wang, Wenxiang Zhao, Zhiqiang Liang, Xibin Wang, Tianfeng Zhou, Yongbo Wu, Li Jiao
The wear behaviors of grinding wheel have significant influence on the work-surface topography. However, a comprehensive and quantitative method is lacking for evaluating the wear conditions of grinding wheel. In this paper, a fractal analysis method is used to investigate the wear behavior of resin-bonded diamond wheel in Elliptical Ultrasonic Assisted Grinding (EUAG) of monocrystal sapphire, and a series of experiments on EUAG and conventional grinding (CG) are performed. The results show that the fractal dimension of grinding wheel topography is highly correlated to the wear behavior, i...
October 16, 2017: Ultrasonics
Jaesun Lee, Jan D Achenbach, Younho Cho
Guided waves can effectively be used for inspection of large scale structures. Surface corrosion is often found as major defect type in large scale structures such as pipelines. Guided wave interaction with surface corrosion can provide useful information for sizing and classification. In this paper, the elastodynamic reciprocity theorem is used to formulate and solve complicated scattering problems in a simple manner. The approach has already been applied to scattering of Rayleigh and Lamb waves by defects to produce closed form solutions of amplitude of scattered waves...
October 13, 2017: Ultrasonics
Fushi Bai, Kai-Alexander Saalbach, Yangyang Long, Jens Twiefel, Jörg Wallaschek
Ultrasonic cavitation peening is a novel surface treatment technology which utilizes the effect of cavitation bubble collapses to improve the properties of metal surfaces. In order to obtain high impact during ultrasonic cavitation peening, a small standoff distance between a sound radiator and a rigid reflector (the surface of treated specimen) is necessary. However, the effects of different standoff distances on the capability of ultrasonic cavitation peening are not yet clear. In this paper, a simplified model was developed to evaluate the cavitation capability at different standoff distances...
October 13, 2017: Ultrasonics
Zhihui Han, Hu Peng, Xiaoyan Zhao, Xun Chen, Putian Lu
Sector-scanning is a conventional scanning mode in ultrasound imaging, which can increase the area to observe. In three-dimensional (3D) ultrasound, freehand imaging system is usually used. This method uses a moving elevation focused one-dimensional (1D) transducer to construct a series of B-mode slice images, and then these B-mode slice images are combined to form a 3D volume image. When sector-scanning is used to acquire the B-mode slices, the elevation resolution is poor because of the elevation resolution of the probe and the interpolations between the slices...
October 12, 2017: Ultrasonics
Zhaohui Li, Cheng Chi
Large wideband two-dimensional (2-D) arrays are essential for high-resolution three-dimensional (3-D) ultrasound imaging. Since the tremendous element number of a full sampled large 2-D array is not affordable in any practical 3-D ultrasound imaging system, it is necessary to reduce the element number through sparse 2-D array design. Sparse array design requires that both the positions and weights of the array elements should be arbitrarily alterable. Hence a proper evaluation tool that can deal with arbitrary array is integral to optimizing the array structure and apodization function...
October 10, 2017: Ultrasonics
Shenxin Yin, Zhiwen Cui, Tribikram Kundu
A new sensor cluster orientation is proposed to localize an acoustic source in a plate from the time difference of arrival (TDOA) with the help of only four to eight sensors. This technique requires neither a priori knowledge of the plate material properties nor a dense array of sensors to localize the acoustic source in isotropic as well as anisotropic plates. It is achieved by placing four sensors in a cluster in the shape of letter "Z" over a small region of the plate and a second Z-shaped cluster at another location of the plate...
October 10, 2017: Ultrasonics
Guanjun Yin, Ting Zhang, Wei Wang, Yunhong Xin, Jianzhong Guo
We investigated the coupling effect in a pair of parallel acoustic cladded waveguides and extended the effect to obtain energy focusing in a specially structured waveguide of nested pipes. For the structure composed of two parallel waveguides, we simulated and verified that when an acoustic input wave propagates in one waveguide, the wave couples with the other and alternates between the two parallel waveguides with periodic amplitude and a well-defined coupling length. This length is related to the frequency of the input wave and the structure of the waveguide...
October 10, 2017: Ultrasonics
Manuel Webersen, Sarah Johannesmann, Julia Düchting, Leander Claes, Bernd Henning
Ultrasonic methods are widely established in the NDE/NDT community, where they are mostly used for the detection of flaws and structural damage in various components. A different goal, despite the similar technological approach, is non-destructive material characterization, i.e. the determination of parameters like Young's modulus. Only few works on this topic have considered materials with high damping and strong anisotropy, such as continuous-fiber reinforced plastics, but due to the increasing demand in the industry, appropriate methods are needed...
October 6, 2017: Ultrasonics
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