Vahan Baronian

Atomic Energy and Alternative Energies Commission | CEA · Centre d'Etudes de Saclay

L’utilisation des ondes guidées pour inspecter des structures élancées s’est intensifiée ces dernières années. Compte tenu de leur nature multimodale et dispersive, le développement d’outils de simulation s’est révélé crucial pour mieux comprendre les phénomènes de génération, propagation et mesure des ondes guidées, afin d’optimiser de potentielle...

We are interested here in applying the Linear Sampling Method to the context of Non Destructive Testing for waveguides. Specifically the Linear Sampling Method [1] in its modal form [2] is adapted to image defects in an elastic waveguide from realistic scattering data, that is data coming from sources and receivers on the surface of the waveguide i...

This paper presents an application of the linear sampling method to ultrasonic non destructive testing of an elastic waveguide. In particular, the NDT context implies that both the solicitations and the measurements are located on the surface of the waveguide and are given in the time domain. Our strategy consists in using a modal formulation of th...

Structural Health Monitoring (SHM) is a thematic derived from Non Destructive Evaluation (NDE) based on the integration of sensors onto or into a structure in order to monitor its health without disturbing its regular operating cycle. Guided wave based SHM relies on the propagation of guided waves in plate-like or extruded structures. Using piezoel...

We consider the time-harmonic problem of the diffraction of an incident propagative mode by a localized defect, in an infinite straight isotropic elastic waveguide. We propose several iterative algorithms to compute an approximate solution of the problem, using a classical finite element discretization in a small area around the perturbation, and a...

This paper deals with an inverse scattering problem in an acoustic waveguide. The data consist of time domain signals given by sources and receivers located on the boundary of the waveguide. After transforming the data to the frequency domain, the obstacle is then recovered by using a modal formulation of the Linear Sampling Method. The impact of m...

We consider the time-harmonic problem of the diffraction of an incident propagative mode by a localized defect, in an infinite elastic waveguide. We propose several iterative algorithms to compute an approximate solution of the problem, using a classical finite element discretization in a small area around the perturbation, and a modal expansion in...

Ultrasonic guided wave techniques are seen as suitable candidates for the inspection of welded structures within sodium cooled fast reactors (SFR), as the long range propagation of guided waves without amplitude attenuation can overcome the accessibility problem due to the liquid sodium. In the context of the development of the Advanced Sodium Test...

Elastic guided waves (GW) are used to inspect pipeworks in various industries. Modelling tools for simulating GW inspection are necessary to understand complex scattering phenomena occurring at specific features (welds, elbows, junctions...). In pipeworks, straight pipes coexist with elbows. GW propagation in the former cases is well-known, but is...

Models for guided wave inspection are developed at CEA-LIST in the CIVA software platform. They are based on a numerical approach combining a modal description in regular parts of waveguides (plates, pipes, or guides of arbitrary crosssection like rails) and a Finite Element (FE) computation, in the vicinity of flaws or guide irregularities. It ena...

Models for ultrasonic guided wave NDT are developed at CEA LIST and integrated into the CIVA platform. Models already available in CIVA 11 GWT deal with plates, cylinders, guides of arbitrary cross section, possibly multilayered. Mode computation, radiated field from different type of transducers (contact with or without wedge, surrounding or surro...

The well-established semi-analytic finite element (SAFE) method for predicting guided wave propagation in straight guides is extended to deal with curved pipes using curvilinear coordinates system, following developments by Treyssède and Laguerre [J. Sound Vib. 329 1702-16 (2010)] for helical wires. The modal solution in the elbow can be obtained a...

To support the development of in-service inspection methods for the Advanced Sodium Test Reactor for Industrial Demonstration (ASTRID) project led by the French Atomic Energy Commission (CEA), several tools that allow situations specific to Sodium cooled Fast Reactors (SFR) to be modeled have been implemented in the CIVA software and exploited. Th...

Guided waves (GW) are used to inspect pipeworks in various industries. Specific features of pipeworks lead to complex scattering phenomena. Simulations tools able to handle such a complexity must be developed to help interpretation and to optimize testing configurations. They must handle both long range propagation and local scattering phenomena. H...

In-service inspection of sodium fast reactors requires the development of non-destructive techniques adapted to the hot and opaque sodium environment and the complex accessibility of the reactor pressure vessel. As the French Atomic Energy Commission is leading the development of the Advanced Sodium Test Reactor for Industrial Demonstration (ASTRID...

A hybrid numerical method coupling a modal description in regular parts of the waveguides and a Finite Element computation in the vicinity of guide perturbations has been developed several years ago. This approach enables the simulation of complex defects interaction and the computation of the wave field generated by a source located inside the wav...

Models for ultrasonic guided wave NDT are developed at CEA LIST and integrated into the CIVA platform. Models already available in CIVA 10 deal with plates and cylindrical guides, possibly multilayered. Mode computation, radiated field from different type of transducers (contact with or without wedge, surrounding or surrounded arrays in pipes) and...

Nondestructive testing of aerospace structures often requires their immobilization. Structural health monitoring (SHM) using guided waves (GW) can overcome this. GW propagate at long range but are diffracted by stiffeners present on typical structures. Optimally positioning sensors implies to determine the number of stiffeners GW can go through whi...

A problem of guided wave propagation and scattering has been submitted to the QNDE 2011 benchmark session. It is concerned with the scattering of guided waves emitted and received by two EMAT transducers positioned on either side of a stiffener over a plate made of aluminum alloy. The problem in hand requires the computation of cases of oblique inc...

The use of Guided Waves (GW) is a potentially attractive solution to inspect large structures from a single measurement point thanks to the capability of these waves to propagate over large distances. However, the multimodal and dispersive nature of GW makes it difficult to analyze and interpret the signals. This has motivated the development at CE...

Nondestructive testing of aerospace structures often requires their immobilization or disassembly. Structural health monitoring (SHM) can overcome these problems; the use of guided elastic waves (GW) in SHM is of great interest, because they propagate long distance in the structure thickness. Structures being stiffened, optimally positioning sensor...

Two previously proposed formulations to simulate nondestructive inspection by guided waves (GW) are extended to deal with (possibly multiple) scattering by several discontinuities or defects. They hybridize models for transducer diffraction effect (radiation, reception), for scattering by local discontinuities (by a finite element technique with sp...

This work concerns the numerical finite element computation, in the frequency domain, of the diffracted wave produced by a defect (crack, inclusion, perturbation of the boundaries, etc.) located in a 3D infinite elastic waveguide. The objective is to use modal representations to build transparent conditions on some artificial boundaries of the comp...

In a structure that guides elastic waves, a discontinuity (defect, shape variation) causes scattering (reflection, partial extinction or mode conversion). Two modal formulations have been developed to link separate models dealing with the calculation of the modal decomposition, with the generation and reception of guided waves (GW), with their scat...

En vue de simuler une expérience de contrôle non destructif par ondes ultrasonores guidées, on considère un guide élastique 2D (une plaque) ou 3D (une barre) qui comporte un défaut (fissure, hétérogénéité locale due à une soudure etc...). L'objectif est de résoudre numériquement le problème de la diffraction d'un mode du guide par le défaut. Nous n...

Bonded composite patches are an attractive solution to repair cracked or corroded airframe structures because of their advantages compared to traditional riveted doublers. However, certification issues limit the application of this technology. We present here the development of a SHM system for detecting disbonds between the patch and the structure...

The potentiality of guided ultrasonic waves in nondestructive testing is currently investigated. Indeed, guided waves can allow a rapid inspection of large areas and of non accessible parts of particular structures like plates or pipes, compared to conventional techniques. This work concerns the numerical finite element computation, in the frequenc...