scholarly journals Computational study of wave propagation in materials with microstructure effect

2011 ◽  
Author(s):  
Αλέξιος Παπαχαραλαμπόπουλος
Keyword(s):  
Wave Propagation ◽  
Acoustic Waves ◽  
Lamb Waves ◽  
Computational Study ◽  
Interstitial Tissue ◽  
Isotropic Composite ◽  
Relaxation Functions ◽  
The Matrix ◽  
Microstructure Effect ◽  
Non Destructive

Fractures are common at human bones. So, a callus is formed and the procedureof osteogenesis is initiated. Medical doctors need to have a tool that allowsthem to evaluate the healing procedure without taking X-ray photos every week.Such a variety of tools can be provided by non-destructive inspection techniques.But rst, one has to create a model for predicting phenomena such as size-eectsand in particular dispersive acoustic waves propagation.Before this thesis, there has been made an attempt by (Vavva, 2009), topredict modal wave propagation with Mindlin's Form-II. Herein, for the rsttime there are presented dynamic solutions of this theory.To begin with, the bone is considered to be a dampless homogeneous (ortho)isotropic composite material, with interstitial tissue being the matrix andthe osteons being the bres. So, Mindlin's theory can be applied in this case.Next, a fundamental solution is obtained for Mindlin's Form-II of his gradientelasticity theory. In conjunction to an existing integral representation, there canbe obtained solutions using the Boundary Element Method. With the help of aconsidered Representative Volume Element, simulations have been conducted andresults are presented for the cases of P, S and Rayleigh waves, as well as guidedwaves in plates. The dispersion diagrams as given by Wigner-Ville representationsare compared to the theoretical ones. What is more, the validity and accuracy ofthe BEM code have been checked using analytical solutions of one-dimensionalproblems.Furthermore, relaxation functions from viscoelastic theories are consideredand are taken into account using the correspondence principle. So, both viscoelasticand gradient-visco-elastic models have been considered and the resultsof various cases (P, S, Rayleigh and Lamb waves) have been compared to theabove.Finally, since the present thesis has to do with information extracted fromdispersive wave propagation, some studies have been made and measures havebeen proposed for velocities and dispersion.All in all, this has been a work dealing with the fact that micro-structureaects the macro-behavior of a material concerning waves propagation and, inthe framework of Mindlin's Form-II, there have been extracted several conclusionsconcerning bone-like materials.

scholarly journals Application Of Guided Wave Propagation In Diagnostics Of Steel Bridge Components

2014 ◽  
Vol 60 (4) ◽  
pp. 493-516 ◽  
Author(s):  
M. Rucka ◽  
B. Zima ◽  
R. Kędra
Keyword(s):  
Wave Propagation ◽  
Lamb Waves ◽  
Guided Wave ◽  
Steel Bridge ◽  
Bolted Joint ◽  
Engineering Structures ◽  
Bolted Connection ◽  
Guided Wave Propagation ◽  
Non Destructive

AbstractEarly detection of potential defects and identification of their location are necessary to ensure safe, reliable and long-term use of engineering structures. Non-destructive diagnostic tests based on guided wave propagation are becoming more popular because of the possibility to inspect large areas during a single measurement with a small number of sensors. The aim of this study is the application of guided wave propagation in non-destructive diagnostics of steel bridges. The paper contains results of numerical analyses for a typical railway bridge. The ability of damage detection using guided Lamb waves was demonstrated on the example of a part of a plate girder as well as a bolted connection. In addition, laboratory tests were performed to investigate the practical application of wave propagation for a steel plate and a prestressed bolted joint.

Influence of the applied pressure of the transducer on the propagation speed of the ultrasonic wave in wood

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Edgar V.M. Carrasco ◽  
Rejane C. Alves ◽  
Mônica A. Smits ◽  
Vinnicius D. Pizzol ◽  
Ana Lucia C. Oliveira ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Applied Pressure ◽  
Pressure Gauge ◽  
Eucalyptus Grandis ◽  
Propagation Speed ◽  
Ultrasonic Waves ◽  
Ultrasonic Speed ◽  
Wave Propagation Speed ◽  
Propagation Technique ◽  
Non Destructive

Abstract The non-destructive wave propagation technique is used to estimate the wood’s modulus of elasticity. The propagation speed of ultrasonic waves is influenced by some factors, among them: the type of transducer used in the test, the form of coupling and the sensitivity of the transducers. The objective of the study was to evaluate the influence of the contact pressure of the transducers on the ultrasonic speed. Ninety-eight tests were carried out on specimens of the species Eucalyptus grandis, with dimensions of 120 × 120 × 50 mm. The calibration of the pressure exerted by the transducer was controlled by a pressure gauge using a previously calibrated load cell. The robust statistical analysis allowed to validate the experimental results and to obtain consistent conclusions. The results showed that the wave propagation speed is not influenced by the pressure exerted by the transducer.

scholarly journals Frequency-domain study of nonthermal gigahertz phonons reveals Fano coupling to charge carriers

2020 ◽  
Vol 6 (51) ◽  
pp. eabd4540
Author(s):  
Thomas Vasileiadis ◽  
Heng Zhang ◽  
Hai Wang ◽  
Mischa Bonn ◽  
George Fytas ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Acoustic Waves ◽  
Lamb Waves ◽  
Charge Carriers ◽  
Acoustic Phonons ◽  
Phonon Spectra ◽  
Electron Hole Plasma ◽  
Nonequilibrium Conditions ◽  
Microelectronic Components ◽  
Anti Stokes

Telecommunication devices exploit hypersonic gigahertz acoustic phonons to mediate signal processing with microwave radiation, and charge carriers to operate various microelectronic components. Potential interactions of hypersound with charge carriers can be revealed through frequency- and momentum-resolved studies of acoustic phonons in photoexcited semiconductors. Here, we present an all-optical method for excitation and frequency-, momentum-, and space-resolved detection of gigahertz acoustic waves in a spatially confined model semiconductor. Lamb waves are excited in a bare silicon membrane using femtosecond optical pulses and detected with frequency-domain micro-Brillouin light spectroscopy. The population of photoexcited gigahertz phonons displays a hundredfold enhancement as compared with thermal equilibrium. The phonon spectra reveal Stokes–anti-Stokes asymmetry due to propagation, and strongly asymmetric Fano resonances due to coupling between the electron-hole plasma and the photoexcited phonons. This work lays the foundation for studying hypersonic signals in nonequilibrium conditions and, more generally, phonon-dependent phenomena in photoexcited nanostructures.

scholarly journals Non-Invasive Testing of Physical Systems Using Topological Sensitivity

2021 ◽  
Vol 11 (3) ◽  
pp. 1341
Author(s):  
María Higuera ◽  
José M. Perales ◽  
María-Luisa Rapún ◽  
José M. Vega
Keyword(s):  
Lamb Waves ◽  
General Purpose ◽  
Mathematical Tool ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Topological Sensitivity ◽  
Physical Systems ◽  
Non Invasive ◽  
Active Infrared Thermography ◽  
Non Destructive

A review of available results on non-destructive testing of physical systems, using the concept of topological sensitivity, is presented. This mathematical tool estimates the sensitivity of a set of measurements in some given sensors, distributed along the system, to defects/flaws that produce a degradation of the system. Such degradation manifests itself on the properties of the system. The good performance of this general purpose post-processing method is reviewed and illustrated in some applications involving non-destructive testing. These applications include structural health monitoring, considering both elastodynamic ultrasonic guided Lamb waves and active infrared thermography. Related methods can also be used in other fields, such as diagnosis/prognosis of engineering devices, which is also considered.

Study of Porosity of Carbon Reinforced Plastic Composites Using Broadband Ultrasound Structuroscopy Techniques

2017 ◽  
Vol 755 ◽  
pp. 44-51
Author(s):  
Anton S. Bychkov ◽  
Alexander A. Karabutov ◽  
Elena V. Savateeva ◽  
Yulia G. Sokolovskaya ◽  
Vasily P. Zarubin ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Metal Matrix ◽  
Elastic Moduli ◽  
Epoxy Composites ◽  
Ultrasonic Spectroscopy ◽  
Isotropic Composite ◽  
Plastic Composites ◽  
Reinforced Plastic ◽  
Local Porosity ◽  
Longitudinal Acoustic Waves

Theoretical assessments are given for the use of the through-transition technique of broadband ultrasonic spectroscopy to determine porosity of heterogeneous materials. Experimental measurements of local porosity of composites using the through-transition technique are presented. Dependences of elastic moduli on the concentration of hardening particles and porosity of metal matrix isotropic composite found. Experimental relationship between the phase velocity of longitudinal acoustic waves and the power of structural noise in samples of graphite epoxy composites is obtained.

scholarly journals Study of Lamb Waves for Non-Destructive Testing Behind Screens

2018 ◽  
Vol 170 ◽  
pp. 03005 ◽  
Author(s):  
P. Kauffmann ◽  
M.-A. Ploix ◽  
J.-F. Chaix ◽  
C. Gueudré ◽  
G. Corneloup ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Lamb Waves ◽  
Nuclear Industry ◽  
Liquid Sodium ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Leaky Lamb Waves ◽  
Short Time ◽  
And Control ◽  
Non Destructive

The inspection and control of sodium-cooled fast reactors (SFR) is a major issue for the nuclear industry. Ultrasonic solutions are under study because of the opacity of liquid sodium. In this paper, the use of leaky Lamb waves is considered for non-destructive testing (NDT) on parallel and immersed structures assimilated as plates. The first phase of our approach involved studying the propagation properties of leaky Lamb waves. Equations that model the propagation of Lamb waves in an immersed plate were solved numerically. The phase velocity can be experimentally measured using a two dimensional Fourier transform. The group velocity can be experimentally measured using a short-time Fourier transform technique. Attenuation of leaky Lamb waves is mostly due to the re-emission of energy into the surrounding fluid, and it can be measured by these two techniques.

scholarly journals Overexpression of the Matrix Metalloproteinase Matrilysin Results in Premature Mammary Gland Differentiation and Male Infertility

1998 ◽  
Vol 9 (2) ◽  
pp. 421-435 ◽  
Author(s):  
Laura A. Rudolph-Owen ◽  
Paul Cannon ◽  
Lynn M. Matrisian
Keyword(s):  
Matrix Metalloproteinase ◽  
Transgenic Animals ◽  
Reproductive Organs ◽  
Mammary Development ◽  
Seminiferous Tubules ◽  
Interstitial Tissue ◽  
Wild Type ◽  
The Matrix

To examine the role of matrilysin (MAT), an epithelial cell-specific matrix metalloproteinase, in the normal development and function of reproductive tissues, we generated transgenic animals that overexpress MAT in several reproductive organs. Three distinct forms of human MAT (wild-type, active, and inactive) were placed under the control of the murine mammary tumor virus promoter/enhancer. Although wild-type, active, and inactive forms of the human MAT protein could be produced in an in vitro culture system, mutations of the MAT cDNA significantly decreased the efficiency with which the MAT protein was produced in vivo. Therefore, animals carrying the wild-type MAT transgene that expressed high levels of human MAT in vivo were further examined. Mammary glands from female transgenic animals were morphologically normal throughout mammary development, but displayed an increased ability to produce β-casein protein in virgin animals. In addition, beginning at approximately 8 mo of age, the testes of male transgenic animals became disorganized with apparent disintegration of interstitial tissue that normally surrounds the seminiferous tubules. The disruption of testis morphology was concurrent with the onset of infertility. These results suggest that overexpression of the matrix-degrading enzyme MAT alters the integrity of the extracellular matrix and thereby induces cellular differentiation and cellular destruction in a tissue-specific manner.

scholarly journals Investigation of acoustic fields in the arctic zone with uneven ice cover

2021 ◽  
Vol 254 ◽  
pp. 02007
Author(s):  
Vladimir Korochentsev ◽  
Сhen Wenjian ◽  
Victor Petrosyants ◽  
Tatiana Lobova ◽  
Julia Shpak
Keyword(s):  
Wave Propagation ◽  
Acoustic Waves ◽  
Signal Propagation ◽  
Ice Cover ◽  
Measuring System ◽  
The Arctic ◽  
Water Medium ◽  
Water Ice ◽  
Ice Surface ◽  
Hydraulic Generator

A mathematical model for elastic wave propagation in an ice cover with uneven relief (hummock) has been developed. The theoretical model is based on the application of “directed” Green’s functions. We obtained numerical results for different distances between radiating and receiving antennas installed inside the ice layer and in water medium. An information-measuring system was created to investigate elastic acoustic waves along ice surface based on electo-hydraulic generator. Experiments of high-frequency acoustic signal propagation from electro-hydraulic generator in water-ice-air system were carried out. We illustrated the model validity for the investigation of hydroacoustic wave propagation in real ice conditions.

Mathematical methods for the characterization of ultrasound in anisotropic materials

2000 ◽  
Vol 78 (9) ◽  
pp. 803-821 ◽  
Author(s):  
B O'Neill ◽  
R Gr. Maev
Keyword(s):  
Wave Propagation ◽  
Acoustic Waves ◽  
Asymptotic Theory ◽  
Anisotropic Materials ◽  
Bulk Wave ◽  
Mathematical Methods ◽  
Theoretical Methods ◽  
The Past ◽  
Fundamental Equations

Although the fundamental equations for the propagation of elastic and acoustic waves in anisotropic materials have not changed in more than a 100 years, the last few decades have seen a surge in interest in the topic. Much of this interest stems from the growing need for characterization of an increasing number of exotic materials. The intent of this paper is to review, for the benefit of beginning researchers in acoustics and ultrasonics, the fundamental phenomena related to elastic wave propagation in anisotropic media. We also present the most common and interesting theoretical methods developed over the past 20 years to model bulk wave propagation in such media. The methods discussed include plane wave superpositions, ray asymptotic theory, paraxial beams, and Green's functions. More peripheral issues, including anisotropic effects combined with various other exotic effects, are dealt with in the bibliography. PACS No.: 43.90

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