LMA - Laboratoire de Mécanique et d’Acoustique

Theme Non Destructive Testing and Evaluation

Non Destructive Testing and Evaluation (NDTE) is addressed starting from the reality of the studied material (steel, concrete, composites, nuclear fuel) and their industrial applications (in-situ constraints). All NDTE techniques (ultrasound, X-ray, eddy current , thermography ... ) are considered before choosing a methodology of study. Research activities revolve mainly around the modeling of materials and appropriate experiments on samples representative of the issues. The ultrasonic waves are often preferred to monitor and characterize the materials; their propagation is studied in order to obtain the desired properties through signal analysis and inverse approaches.

Scientific objectives

Non Destructive Testing and Evaluation to characterize materials and structures ultrasonic waves involve an overall approach:

  • to describe the material at the ultrasound scale. The structure is a bounded medium with a defined geometry. It is made of a material in a given mechanical state (e.g. under stress or not) with specific physic -chemical properties (e.g. wet surface or not). Analytical or numerical models are developed for welding (MINA model), concrete (aggregates, porosity , cracks, ... ), the liquid sodium (gas, flows), composites, bonded assemblies ...
  • to take into account the interactions between the ultrasonic waves and materials described at the ultrasound scale (e.g. diffraction, single and multiple scattering, attenuation, noise structure, …). Nonlinear acoustics is often studied.
  • to perform experiments with specific devices and set-up (contact, immersion, air, multi-element , laser, ... ) and to analyze data with an original approach (in terms of imaging, signal processing and inverse problems ). Those are the essential steps to validate the models developed previously. The development of multi-technique approaches such as data fusion, structural health monitoring (SHM), is one of the preferred research topics.

Addressed studies

  • Security and life of nuclear reactors in operation or future development (generation IV reactors), as part of a long-term partnership with CEA Cadarache (France):
  • Improvement of diagnostic performance of the fused polycrystalline materials continuing previous work conducted by the LCND with EDF R&D and CEA about welded joints)
  • Development of knowledge of wave propagation in concrete to meet the needs of diagnostic civil engineering structures. Coherent and incoherent waves are used to characterize multiple scattering environments. All information carried by the " coda " in forward or backscattered signals is also analyzed. The nonlinear and time reversal acoustic methods are investigated to characterize the state of the concrete.
  • Ultrasound characterization of misalignments of fibers, fiber undulations, and folds in woven composites.
  • Acoustic methods to assess adhesion in bonded assemblies.

Socio-economic impact

Testing and characterizing materials are related to three main application areas :

  • Nuclear energy
  • Civil Engineering : structural Integrity
  • Aeronautics : structural composites

Developments often involve :

  • Cooperation with different networks: COFREND (French Confederation for Non Destructive Testing) AFGC (French Civil Engineering Association), MACS system (Control of Structural Bonded Joints)...
  • Collaborative projects: ACDC Analysis and capitalization for the Diagnosis of Constructions, ANR EVADEOS, ANR MOSAICS, ANR ISABEAU, PIA ENDE.

Collaborations

Academia

  • international collaborations :
    • Los Alamos National Laboratory (USA)
    • GDRE Wave Propagation in Complex Media for Quantitative and Non Destructive Evaluation
  • national collaborations :
    • INSA Lyon, INSA Toulouse (LMDC), GHyMAc (Univ. Bordeaux), Centrale Lille, LCPC Nantes

Agencies

  • CEA, SETRA

Industries

  • EDF, SAFRAN, Saint-Gobain ...

Members

Nathalie FAVRETTO-CRISTINI Dimitri KOMATITSCH Bruno LOMBARD Joseph MOYSAN Cédric Payan Sandrine RAKOTONARIVO