Transient generation by a wide thermoelastic source at a solid surface

Bresse, L. F.; Hutchins, David A.

doi:10.1063/1.342956

Cited by 35 publications

(22 citation statements)

References 6 publications

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“…In some experiments, the specific time profile ofthe epicentral displacement generated by laser irradiation of a constraining layer consisting of a transparent material placed over the irradiated face of the target 17 has been clearly exhibited, but the analytical relation between the propagation of the longitudinal waves and the normal displacement at the epicenter has not been determined except for transparent layer having the same elastic and thermal properties that the metallic substrate 18,19 The normal displacement at the epicentre (Fig. 2a) was recorded for a metallic substrate and for a transparent coating on a metallic substrate using the contactless experimental arrangement of Fig.…”

Section: Methodsmentioning

confidence: 99%

Laser removal of oxide films: laser ultrasonics diagnostic

Oltra

Rosa

2002

SPIE Proceedings

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In the present work, the laser ultrasonics technique has been applied as diagnostic of the laser induced decohesion of coating. A modeling system consisting in a 304 stainless steel coated by a plasma sprayed layer was used to describe the basic measurements. These acoustic measurements were performed using an interferometric probe. It is concluded that this contactless technique can be used to follow the cleaning of oxidized materials.

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Section: Methodsmentioning

confidence: 99%

Laser removal of oxide films: laser ultrasonics diagnostic

Oltra

Rosa

2002

SPIE Proceedings

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“…Assuming the Lorentz force is decomposed spatially into N force components, the total displacement for these temporal delta force components is given by, where ⊗ denotes a convolution operation, ( ) f t is the temporal dependence of Lorentz force, ( , , 0, ) u t x y z δ = is the total displacement for these temporal delta force components of each circular source (piston or ring source), and is given by, with temporal dependence of delta function [11][12] . In same way, the solution to line coil can be deduced, but will not be given here due to limit space.…”

Section: Methodsmentioning

confidence: 99%

“…Due to the complexity of the problem, an analytical solution is only available for some simple uniform force distributions, such as uniform normal piston force and uniform radially acting ring force [1,3,[11][12] . Accordingly, transient field studies were carried out generally by the Finite Element Method (FEM) [7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

<title>Ultrasonic field modeling for arbitrary non-contact transducer source</title>

2005

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We present a model for transient ultrasonic wave generation by Electromagnetic Acoustical Transducers (EMATs). Analytical solutions are currently available only for few kinds of sources and our model combines these analytical solutions and numerical computation to predict the ultrasonic field generated by arbitrary sources. This model can be used to calculate bulk waves within samples as well as surface waves on sample surfaces with the advantages of explicit physical meaning and quick processing speed over pure numerical calculations such as the Finite Element Method (FEM). We use the model to explain how static and dynamic magnetic fields generate ultrasonic waves in a sample. We wish to characterize the EMAT source in detail in order to tailor sources for optimal configuration for specific NDE applications. A Michelson laser interferometer is used to measure out of plane surface displacement of sample, and results agree well with the modelling simulation. The modelling can be used for arbitrary source.

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“…34 In some experiments, the specific time profile of the epicentral displacement generated by laser irradiation of a constraining layer consisting of a transparent material placed over the irradiated face of the target, 35 or a polymer coating, 22 has been clearly exhibited, but the relation between the propagation of the waves and the normal displacement at the epicenter has not been determined except for transparent layers having the same elastic and thermal properties as the metallic substrate. 36,37 The aim of the present study is to propose an alternative method using laser ultrasonics devoted to assess the practical adhesion of transparent coatings. Subsequently, acoustic modeling is performed and this leads to the integrity interface characterization.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the coating–substrate adhesion by laser-ultrasonics: Modeling and experiments

Rosa

Oltra

Nadal

2002

Journal of Applied Physics

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The aim of the present study is to investigate a laser-ultrasonic method to determine the oxide-coating's adhesion strength on a metallic substrate. In order to demonstrate this method a completely contactless system is used, combining laser generation and detection of ultrasonic waves. A nanosecond pulsed Nd:YAG laser is used to irradiate the transparent oxide coatings, while the normal displacement of the rear surface of the metallic substrate is detected at the epicenter by a laser heterodyne interferometer. Increasing the laser beam energy, the generated acoustic wave forms are correlated with the thermoelastic regime, the fracture of the coating-substrate interface, and finally the expulsion of the coating. The generation of ultrasonic signals in the thermoelastic regime is described by a two-dimensional model suitable to calculate the in-and out-of-plane components of the mechanical displacement versus time. The values of the so-called practical adhesion found are in agreement with those obtained by classic contact techniques ͑tensile adhesion test, indentation, bending test͒. This work demonstrates the suitability of this quantitative and contactless test to evaluate the coating-substrate adhesion.

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Transient generation by a wide thermoelastic source at a solid surface

Cited by 35 publications

References 6 publications

Laser removal of oxide films: laser ultrasonics diagnostic

Laser removal of oxide films: laser ultrasonics diagnostic

<title>Ultrasonic field modeling for arbitrary non-contact transducer source</title>

Evaluation of the coating–substrate adhesion by laser-ultrasonics: Modeling and experiments

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