COLUMBO : Multiscale characterization and controllability by laser-ultrasounds of WLAM components: toward a physics-based and machine learning enhanced online monitoring

Project summary

The industrial use of components manufactured using additive manufacturing (AM) processes has strong growth potential in various challenging fields such as aeronautics, automotive, medical or nuclear. The desire to produce structural parts implies that they are inevitably subjected to Non-Destructive Testing (NDT) and that it is essential to master the process during manufacturing to give the parts a microstructure with the characteristics that make them usable. Implementing an online NDT monitoring strategy would lead to more efficient and optimal control by acting on the AM parameters to avoid process drifts or by repelling defective parts as soon as possible. However, despite increasingly developed studies on the influence of AM parameters on the resulting microstructures, actual knowledge remains incomplete, particularly for the wire-laser process (WLAM), which is more recent and of which certain advantages arouse growing interest among industrials. The availability of an online NDT would allow a significant advance in AM.

COLUMBO aims to demonstrate the ultrasonic-laser (UL) controllability of WLAM parts by quantifying the material parameters that make these controls possible and by defining the detectable characteristic quantities, in order to prove the feasibility of an effective online monitoring strategy. Ultrasonic NDT methods, proven by their fundamental sensitivity to local mechanical characteristics, are methods of choice both for the flaws probing (heat-affected zones, microporosities or cracks) and for the multiscale characterization of microstructures. Besides, UL techniques allow contactless inspection in hostile environments, such as the AM. Finally, the use of Rayleigh waves seems well suited to successively control and characterize the deposited metal layer-by-layer. It is clear that the efficiency of such an NDT procedure can only be guaranteed subject to a relevant physical interpretation and optimal use of the data of the real-time online control data. However, the WLAM parts constitute a challenge because of the complex phenomena of ultrasonic diffusion linked to their very marked microstructures (surface roughness, porosities, entanglement of columnar/equiaxial grains), very different from those resulting from conventional metallurgical processes. The associated signals, potentially rich in information, are therefore complex to interpret. The scientific issue to be addressed is the mastery of the correlation between the WLAM parameters, the characteristics of the obtained microstructure and its ultrasonic signature.

COLUMBO proposes to meet this challenge by developing multiscale and multi-physics modelling/ simulations of the WLAM process and the ultrasound propagation, both by comparing with characterization data and experimental measurements. Thanks to the manufacturing/measurement/modelling complementarity between the five partners, the considered methodology consists of establishing a hybrid benchmark of the carefully chosen parts with a microstructure of increasing complexity and with sets of well-identified and classified WLAM parameters, to continuously advance the knowledge on involved phenomena, the modelling of underlying physical mechanisms, and the quantification of measurable quantities. The ultimate goal is an optimal exploitation of real-time in situ control data using simplified models with validated physical content, and based on machine learning (ML).

To achieve this ambitious and topical objective, COLUMBO brings together a consortium of five partners with skills that fulfil the entire chain of expertise required: from WLAM process modelling/simulation, to online testing of WLAM process, including ultrasound modelling/simulation and characterization (EBSD), towards inversion of data by ML. This complementarity with a fair balance between theoretical/numerical modelling and experimental validation constitutes the key point of the rigor and the success of COLUMBO.

Project description on the ANR website

Project description on the COLUMBO website (dedicated site)

Partners and funders

Project coordinator : Jérôme Laurent (LIST)

• ICMMO : Institut de chimie moléculaire et des matériaux d'orsay
• ARMINES CEMEF : Association pour la recherche et le développement des méthodes et processus industriels
• LURPA : Laboratoire universitaire de recherche en production automatisée
• CEA LIST : Laboratoire d'intégration des systèmes et des technologies
• MSSMAT : Laboratoire de mécanique des sols, structures et matériaux
• ANR : Agence nationale de la recherche