Mr. Loic De Roumilly, Ultrasonics and Automatic Techniques Group Leader at EDF, kindly accepted to answer a few questions for us.

What is your role at EDF? For how long have you been doing this job?

I have been working at EDF for 3 years as the Ultrasonics and Automatic Techniques Group Leader in the department of NDT (Non Destructive Testing) engineering. Like three other teams of the same size, the goal of my group (composed of ten people) is to develop, or supervise the development by industrial partners of NDT processes, and present them to an expert commission in order to get them qualified. These processes are destined to be deployed on EDF’s existing nuclear fleet, or on the future EPR (European Pressurized Reactor) in Flamanville.

Since when heve you been using the CIVA software? (How did you discover the software?)

Before joining EDF, I worked 9 years in the NDT department of the CEA in Saclay. Thus, as soon as I arrived in the Control Methods department, in September 2000, I started using CIVA (version 5 at the time). It is thanks to the simulation I did on this software that I took my first steps in NDT, before being confronted a few months later to the experimental reality. I had the chance to work closely with the modelers, who helped me to understand the models of the software and, at the same time, ultrasonic physics.
I used CIVA software to evaluate performances of industrial NDT processes and, during the course of these studies, I was given the opportunity to compare simulation and experiment for the common fonctionalities and for the more sophisticated models alike, starting at the development stage. Then, in the context of industrial partnerships (linked to the GERIM platform), I was asked to write down specifications for advanced functionalities and evaluate the developed tools.

What are the contributions of CIVA in your activity?

The use of simulation in the qualification process activity is very frequent, either by my group, by the qualification department, or by our industrial partners: upstream, for feasibility and process conception, during the development phase, but also when implementing NDT on site.

More precisely, for feasibility, design or development, CIVA allows to quantify the impact of influent parameters arising from the component’s geometry (or its attenuation), transductors and defects. Furthermore, for “conventional” qualifications, CIVA enables the evaluation of the performances of the process in terms of sensibility, which means determining the size of reflector of a given form, detectable above the notation threshold. Simulation allows us to limit considerably the number of trials (and the number of mock ups and associated artificial defects). Thus, ultrasonic qualification dossiers are based for large part on simulation. However, we try on a local level to validate our simulations with experimental results.

To qualify an NDT process, a performance sheet is created. Some of these include illustrations of the performances. These illustrations can be carried out on mock ups. Others, for many dossiers, are obtained using CIVA simulations.

Finally, when a process is implemented as an expertise, for example when it is carried out beyond the scope of its qualification, the EDF expert may use CIVA simulations to complete and confirm his analysis before giving an opinion.
Besides, in collaboration with the CEA, EDF carries out developments, and capitalizes them in the CIVA software platform: the ATHENA module, for finite elements calculations, wich will soon be available in the commercial version of CIVA, is an example.

Would you recommend CIVA to potential users?

Definitely. It is difficult not to use simulation today, and the use of CIVA can only be encouraged, considering the variety of configurations it can handle and the tools it offers. However, simulation – whichever software is used for it – must be used with a physical and critical sense: the contribution of simulation is much greater when you know precisely what you are expecting from it.

Which are, in your opinion, the improvements which would make CIVA more appropriate for the requirements of the industrial sector?

CIVA can simulate a huge number of configurations, but the stake of simulation in the field of qualification processes is to provide reliable information. The software has been well trialed over many years of its use in many industrial sectors, but the validation works already being carried out must be encouraged, to help users to better identify the domains of validity of the models they use.
Besides, to narrow the gap between simulation and reality, efforts could be made in allowing users to define their parameters more easily, in a more intuitive way, closer to real experiments.
But this is an art form in itself to make a tool intuitive while maintaining the technical level required to handle canonical configurations and subtle expertise cases alike.

• Launch the WidgeNDT (requires Java to run)

Multiple options and parameters are offered through pointers, making this tool fully interactive. For example, you can adjust the propagation velocity in each medium, and select a desired refraction angle for a specific mode (L or T). The tool will display the required incidence angle according to the Snell / Descartes’ laws.

The incident propagation medium can be either a semi infinite plane, corresponding to an immersied probe configuration, or limited to a coupling wedge between the transducer and the piece, describing a contact probe configuration.

In the case of an immersed probe, it is assumed that the coupling medium is water at a certain temperature adjustable through a pointer. The waves’ velocity in water is then modified by any change of this temperature.

In the case of a contact probe, you can adjust the velocity in the wedge using a speed cursor.

The transducer length, the sound path in the incident medium, the dimensions and position of the probe wedge are adjustable either through the parameters pointers, or by dragging the blue dots with the mouse.

Beyond this interactive calculator for Snell / Descartes’ laws, you can choose to simply represent a central ray from the center of the transducer, or to switch to “beam” mode, or to consider a plane or focused crystal. Let the choices offered guide you to build a realistic configuration.

Finally, you can see a marker at a given propagation time, along the paths corresponding to the L and T propagation modes. Then, you can visualize on the different paths an acquisition time gate, defined by a start time and a duration.

The video below illustrates how this WidgeNDT works:

Feel free to play with this tool, inform people around you of its existence, and share with us your comments and critics!

• Launch the WidgeNDT (requires Java to run)

The properties of the propagation medium are adjustable through horizontal pointers: the waves’ velocity in the incidental isotropic medium, and the stiffness tensor’s coefficients in the anisotropic medium.

Thus, depending on the selected incidence angle, the possible propagation modes’ velocities are displayed. The graphic also illustrates the phase direction (propagation direction) through a dotted lined arrow, and the energy direction (group velocity) through a full half-line.

An animation on the variation of the incidence angle may be launched by clicking on the “Play” button in the bottom left corner of the page, triggering a dynamic drawing of the slowness curves associated with the propagation modes existing in the anisotropic medium in a defined observation plane (the angle of this observation plane may also be adjusted through a pointer).

The video below illustrates how this WidgeNDT works:

Feel free to play with this tool, inform people around you of its existence, and share with us your comments and critics!

• Launch the WidgeNDT (requires Java to run)

The transducer is represented by a set of little elements, each emitting a spherical wave. These different spherical waves may be emitted all at once, or at a timed interval, the timing between the emission of these waves from one element to another being called a “delay”. Thus, the set of delays applied to each element is a “delay law” or “focus law”, and allows to change the direction and nature of the beam.

This WidgeNDT offers an animation of the spherical waves emitted by each element, taking into account the defined delay law, either by clicking on the “Play” button in the bottom left corner of the window, or by manipulating the horizontal animation pointer.

The delay law may be adjusted manually through the vertical pointers on top of each element, or automatically by using the appropriate option. In automatic mode, a delay law may be applied, which can steer the wavefront emitted by the sensor, or focus this wavefront on a point, adjustable with the mouse.

The video below illustrates how this WidgeNDT works:

Feel free to play with this tool, inform people around you of its existence, and share with us your comments and critics!

Under this section, you will find some free tools that may well prove helpful in your NDT day to day life.

Please enjoy our WidgeNDT and let us know your feedback. We would like to improve our contribution to easing your professional activities!

• Phased Array principle
• Slowness curves
• Snell’s law

• CIVA GW Release note

Probes

A wide range of UT probes, standard and advanced designs can be handled:

• Contact (with or without wedge)
• Single element or phased-array probes (see Phased Arrays section)
• Encircling or encircled probes for pipe inspection
• Different types of solicitations (shear or longitudinal vibration)
• Different configurations (Pulse-Echo, Pitch-Catch transmission or Pitch-Catch reflection)

Specimens

Plate-like and pipe-like structures can be handled by Civa as waveguides. Specimens may be homogeneous or heterogeneous, taking into account a coating for example. Each medium should be isotropic and linear attenuation laws may be considered for L-waves and T-waves:

Phased-Arrays Settings

CIVA allows defining delay laws on different kinds of probes: linear on plates, linear or matrix on pipes:

• Independent definition of emitting or receiving elements
• Variable aperture at emission or reception, for size or position

Delay laws are manually defined for each element.

Flaws

Simulation takes into account a flaw perpendicular to the waveguide, rectangular on a plate, sectorial on a pipe, and determine its interaction with the incident guided wave.

Results

Modes computation

A first module computes the dispersion curves associated to the specimen in a given frequency range.
Modal displacements and constraints are computed for each mode at each frequency of the frequency range.

• Application: selection of the working frequency range and visualization of the properties of the modes selected for the testing

Field computation

A second module allows simulating the ultrasonic beam radiated in different cross-sections of the specimen. The modal repartition of the emitted energy is displayed versus the frequency in the bandwidth of the probe.
The displacement and constraints are determined in a time range, which makes possible the visualisation of the propagation of the different waves at each cross-section.

• Application: design of specific probes dedicated to guided waves inspection, optimization of the ability for a sensor to select a given mode

Defect response

This module simulates the beam/flaw interaction and predicts the amplitude, waveform and time of fligth of the different types of echoes: incident, reflected and converted.

• Application: simulation of a complete guided waves testing

Dr. Nicolas Dominguez, CIVA Project Manager at the CEA, kindly visited us and accepted to answer a few questions.

How did you end up doing this job at the CEA? (What has your career been? How did the opportunity show up? Why did you accept to take this job?)

I started my career as a space antenna engineer at Alcatel Space. There, I developed design and performance prediction tools for phased-array antennas for telecommunication by satellites. The telecom crisis in 2001 pushed me toward aeronautics and AIRBUS, which I joined to complete a PhD thesis on ultrasonic Non Destructive Testing of porosity in composite materials. Following my thesis, I joined the Common Research Center of EADS, later renamed EADS Innovation Works (IW). At EADS IW, I was in charge of NDT modeling activities. I have of course kept on working on flaw characterization in composite structures, but I also worked on aeronautic structure maintenance, through the development of Eddy Current NDT methods and low-cost POD (Probability of Detection) approaches using simulation.
EADS and the CEA have a long standing collaborative agreement, they even have a framework agreement on CIVA. The success encountered with collaborations on common projects, the good relationship, the skills and projects complementarity have all worked on bringing EADS, the CEA and myself closer to each other. Subsequently to these fruitful partnerships, EADS agreed on putting me at the disposal of the CEA as CIVA Project Manager. It is a huge challenge I wanted to take up for what CIVA represents (the worldwide reference in the NDT simulation and expertise market), and for the very strong applicative potential of CIVA. The explosion of calculation capacities announced over the past 15 years as the element that would make possible intensive use of simulation codes is now a reality. Happy coincidence, over the same last 15 years, CIVA’s models have gained in maturity and efficiency, which now opens a huge applicative field, going from determination of POD with the aide of simulation, to optimal design of testing configuration on coverage area criteria, to X-Ray tomography simulation to improve reconstruction performances…
From a human perspective, it is also a great adventure to pilot a project gathering, to this day, around thirty engineers on the « development » part and sixty engineers in charge of studies based on CIVA.

Why did you use CIVA at EADS? (In which framework? Since when?)

Aeronautics is an industrial sector which has to constantly combine cutting-edge technologies and strong quality expectations because it involves human lives. This creates an environment favoring the integration of new techniques requiring modeling to be efficient. In the NDT field, the implementation of ultrasonic phased-array inspections is the historical example at EADS which has benefitted from the possibilities of simulation – calculation of delay laws, associated field calculations. Today, CIVA is used to assist the conception of specific probes and anticipate performance of detection (smallest detectable flaw and/or POD).
At EADS IW, CIVA has also become a tool that brings improvement to NDT methods and concepts. In the R&D field, many uses of simulation are under consideration to improve techniques and diagnosis, but I can’t tell you more…

What are your plans for the future of CIVA? (More NDT techniques simulated? More precision in simulation? An easier to use software?)

Without mentioning the improvements we are continuously making on the models, which are the heart of CIVA, I directed development towards increasing the accessibility of the possibilities offered by CIVA. Today, CIVA users are essentially experts, R&D engineers and researchers, which represent a very small part of the NDT community. This is due, on the first hand, to the interest these populations have in modeling and to their role in the company, and on the other hand, let’s be honest, to definitions of simulation that are sometimes overly complex. Someone able to set up an acquisition configuration should be able to do the same in a CIVA simulation!
This is the way things work: at first everything is complex, it is hard to think simple. As the tools mature, hindsight on their use and the development efforts bring intuitiveness.
Industries, employees and CIVA have a lot to win in this. CIVA is a tool that pulls people up, it involves the interest of its users, through the understanding it brings and the accuracy it requires in terms of configurations definition. CIVA forces the user to be precise with inspection configurations. A well-thought and mastered configuration is more efficient, quicker. It is better to make a mistake in front of your computer when you still have time than in front of the process when you have to take the parts out…
In parallel, we keep expanding the range of techniques offered in CIVA, notably with the release, in December 2011, of the first version of the CIVA X-Ray Tomography module and the release planned for April 2012 of the Guided Waves module.

How do you manage to assess the needs of CIVA users? (Through pools? Are you constantly listening to the market? …)

I have been, as an EADS engineer, one of the representatives of a part of the market, which I consequently know very well. I am constantly being approached and reaching out to my acquaintances in the EADS group to keep in touch with the needs in aeronautics. For other industrial areas (nuclear industry, petrochemical industry, civil engineering…), which I am less familiar with, I rely on the experience and feedback of my colleagues at the CEA and EXTENDE whose contributions are at the heart of CIVA improvement requests. Moreover, the participation of the “CIVA team” and EXTENDE in the major events in the NDT field, conferences, workshops, allows us to keep in close contact with the needs of the users, an essential element for the success of future CIVA versions.

Real examples are given on the back page for each application case:

• Kontrolle der Überprüfbarkeit vor der Herstellung

• Optimierung Ihrer Röntgenprüfungen

• Auswahl und Entwicklung eines Sensors bzw. einer Strahlenquelle

• Beurteilung der Auswirkungen von Verschlechterungsfaktoren

• Ausbildung und Schulung Ihrer Teams

• Validierung eines Prüfverfahrens

• Simulation der Durchführung einer Prüfung

• Optimierung Ihrer Qualifizierungsverfahren

• Steigerung der Zuverlässigkeit Ihrer POD-Kurven

• Steigerung der Diagnosezuverlässigkeit

Application cases are also available in the following languages :

• 中文 | English | Español | Français | Italiano | 한국의 | Português

Dr. Michele Carboni, researcher and CIVA user at the Department of Mechanical Engineering of the University Politecnico di Milano, kindly accepted to answer our questions.

When did you become a CIVA user?

I started to work with CIVA with version 8.1 in 2006.

For which type of activities do you use CIVA?

Being part of the academic staff of the Department of Mechanical Engineering at Politecnico di Milano (Italy), I’m mainly interested in research topics related to the NDT field and my use of CIVA greatly reflects this situation. Since I’m also responsible for the course on “Experimental Mechanics and NDT” held for our Master of Science students, some important applications of CIVA regard also teaching.

What convinced you to use simulation?

This is an interesting question. In the last ten years, a need for completing and supporting experimental results with numerical simulations arose in the NDT community. This is due to the very expensive costs that sometimes the experimental campaigns require. I started to use and research about NDT simulation in order to bring my contribution to this new way of thinking.

What did it change for you?

It gave me the possibility to add to my usual researches and methodologies new perspectives and new tools. I have to say that I’m very satisfied with the opportunity that simulation gives me in understanding and interpreting some experimental results I get during tests. Moreover, I was also able to get good predictions of experimental results.

Could you give us an overview on the research projects you are involved in?

My main research topic is structural integrity. I started in 1997, studying and researching fatigue and fracture mechanics as an MSc student, and I went on in my PhD thesis too. In 2006, I began to have also interest in NDT. I had the possibility to participate and work in the frame of different regional, national (Italian) and European projects. Most of them dealt with the structural integrity of railway axles. At the moment, I’m working on the “Probability of Detection” and “Model-Assisted Probability of Detection” curves for the ultrasonic inspection of railway axles, and on the application of Eddy Currents inspection to the detection of corrosion-fatigue damage on railway axles.

In which applications has simulation been particularly beneficial to your work?

For sure in the last topics I mentioned in the previous question. The “Model-Assisted Probability of Detection” approach is expressly based on the idea to mix experiments and numerical results, so simulations are of fundamental importance. I also found very useful to use simulation to understand the behaviour of Eddy Currents on a multiple-cracked body, like a fatigue-corroded railway axle.

What additional features would you like to be implemented in CIVA?

More flexibility on some aspects of the POD and the ET modules, because sometimes they do not allow to represent the physical problem I would like to simulate.

ASAP aims at enhancing security assembly control during manufacturing, thanks to the use of a non destructive testing system inside the plant, which will deliver a reliable, quick and simple view of the spot weld integrity.

The project will set a new phased-array ultrasonic control method with an innovative but simple-to-use aspect, combining sensor, device, and real-time algorithms developments fully integrated in the equipment.

The expected result is to implement a new equipment dedicated to the quality control people in the plant, and able to adapt instantaneously to the external geometry of the spot weld.

To this end, the following locks will be overcame:

• Development of an ultrasonic sensor small regarding the size of the controlled surface
• Development and implementation of real-time adaptive algorithms
• Integration of an automated diagnosis for plant control
• Correlation between NDT criteria and mechanical resistance of spot welds
• Macroscopic modelization to predict spot weld crash resistance

The ASAP consortium is composed of the following partners:

The project will last 3 years (2011-2014) and represents a total investment of 2026,9k€. The project is supported by the ANR (Agence Nationale de la Recherche) for an amount of 844,6k€.

Motivations for this project:

When a road accident happens, the structure of the vehicle is designed to absorb a part of the energy released by the shock, the objective being to protect as much as possible the occupants of the vehicle. The quality of the assembly, and more particularly the spot welds, is a key stake to ensure the absorption of the energy by deformation of the parts and rupture of fusible points.

Moreover, being subject to a high competitiveness and in the context of respect for the environment, the automotive insutry must innovate to offer technological breakthroughs, and also to optimize the conception and the fabrication of the vehicles.

The weight lightening of the vehicles is one of the keys to answering to these stakes, knowing that such a technical orientation must put up with excellence performances regarding automotive security.

The desired level of mastery requires the use of an ambitious quality insurance approach. This approach relies on a quality of control up to this this ambition, and on the acquisition of a stronger expertise in this field. However, carrying out non-destructive inspection methods remains difficult, because the profile of the spot welds shows a variability typical of the industrial process.

This difficulty results in significant control times, and a long to acquire expertise level and know-how, making it hard to deal with skill availability.

ASAP will answer these challenges by developing a new methodology in non destructive testing, allowing an optimized monitoring of the assemblies. The objective of ASAP will be to study and develop a new phase-array ultrasonic method.

One of the innovations of the project will be to implement within this instrumentation dedicated algorithms, allowing to adapt in real-time to the complex geometry of the spot weld, to improve the performances of detection, and to have an automatic interpretation of the quality of the spot weld without need for expertise.

In addition, a big part of the project will be devoted to the development and the reliability of a macroscopic model of dynamic behavior of the spot welds. This model, coupled with the simulation tools of the non-destructive testing method, will make possible the validation and the optimization of the methodology for a large range of characteristic parameters of the assemblies and spot welds.

The expertise of the ASAP consortium in complementary fields of research will make possible to lead, at the end of the project, to the creation of the first apparatus of the market ensuring reliable, fast and simple evaluation of the quality of the spot welds.