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PEOPLE@HES-SO – Directory and Skills inventory

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Boillat Eric

Boillat Eric

Professeur HES associé

Main skills

Additive manufacturing

Process Improvement

Simulation de procédés

Lasers

Finite element modeling

  • Contact

  • Teaching

  • Publications

Main contract

Professeur HES associé

Desktop: R08 / A27

Haute école d'Ingénierie et de Gestion du Canton de Vaud
Route de Cheseaux 1, 1400 Yverdon-les-Bains, CH
HEIG-VD
BSc HES-SO en Ingénierie et gestion industrielles - Haute école d'Ingénierie et de Gestion du Canton de Vaud
  • Fabrication additive - Impression 3D
  • Procédés de micro-fabrication et applications

2025

Fast and accurate laser powder bed fusion metamodels predicting melt pool dimensions, effective laser absorptivity and lack of fusion defects
Scientific paper ArODES

Lucas Schlenger, Milad Hamidi Nasab, Giulio Masinelli, Eric Boillat, Jamasp Jhabvala, Toni Ivas, Claire Navarre, Reza Esmaeilzadeh, Jian Yang, Christian Leinenbach, Patrik Hoffmann, Kilian Wasmer, Roland E. Logé

Journal of Manufacturing Processes,  2025, 141, 1337-1353

Link to the publication

Summary:

The significant computational expenses associated with simulating the Laser Powder Bed Fusion (LPBF) process often restrict the insights gained from modeling endeavors to specific combinations of process parameters, hindering broader conclusions. In this study, we employ a classical Design of Experiments approach on results obtained by multiphase Finite Element simulations. Utilizing this framework, we derive quadratic metamodels for the dimensions of the melt pool, enabling predictions of melt pool width, depth, and length across a wide spectrum of processing conditions. Notably, our findings indicate that as few as 25 simulations can suffice to predict melt pool dimensions in conduction mode LPBF across varying laser power, velocity, initial temperature, and spot size parameters. Among other insights, the metamodels uncover and quantify the substantial influence of initial temperature (the local temperature of the volume preceding the laser interaction). Additionally, rare insights regarding the melt pool sensitivity towards the laser spot size are provided. Furthermore, our investigation delves into laser interactions with different phases (powder, liquid, solid) across diverse processing conditions to establish a net global absorption coefficient. These analyses underscore that, under conventional process conditions, most of the incident laser intensity falls onto the liquid phase during conduction mode LPBF simulations of 316L stainless steel and Ti-6Al-4V. However, the laser spot size significantly affects the laser intensity interacting with the liquid phase, warranting consideration of laser spot size dependent absorptivity values in part-scale models. Lastly, employing straightforward geometric simulations, we derive a full processing map predicting the occurrence of Lack of Fusion defects, based on calculated melt pool dimensions and the associated scanning strategy.

Additive manufacturing of a 3D-segmented plastic scintillator detector for tracking and calorimetry of elementary particles
Scientific paper ArODES

Tim Weber, Andrey Boyarintsev, Umut Kose, Botao Li, Davide Sgalaberna, Tetiana Sibilieva, Johannes Wüthrich, Siddartha Berns, Eric Boillat, Albert De Roeck, Till Dieminger, Matthew Franks, Boris Grynyov, Sylvain Hugon, Carsten Jaeschke, André Rubbia

Communications Engineering,  2025, 4, 1, 41

Link to the publication

Summary:

Plastic scintillators, segmented into small, optically isolated voxels, are used for detecting elementary particles and provide reliable particle identification with nanosecond time resolution. Building large detectors requires the production and precise alignment of millions of individual units, a process that is time-consuming, cost-intensive, and difficult to scale. Here, we introduce an additive manufacturing process chain capable of producing plastic-based scintillator detectors as a single, monolithic structure. Unlike previous manufacturing methods, this approach consolidates all production steps within one machine, creating a detector that integrates and precisely aligns its voxels into a unified structure. By combining fused deposition modeling with an injection process optimized for fabricating scintillation geometries, we produced an additively manufactured fine-granularity plastic scintillator detector with performance comparable to the state of the art, and demonstrated its capabilities for 3D tracking of elementary particles and energy-loss measurement. This work presents an efficient and economical production process for manufacturing plastic-based scintillator detectors, adaptable to various sizes and geometries.

Avoiding cracks in multi-material printing by combining laser powder bed fusion with metallic foils :
Scientific paper ArODES
application to Ti6Al4V-AlSi12 structures

Amir Mohammad Jamili, Jamasp Jhabvala, Steven Van Petegem, Daniel Weisz-Patrault, Eric Boillat, Jiri Nohava, Andaç Özsoy, Shruti Banait, Nicola Casati, Roland E. Logé

Additive Manufacturing,  2025, 97, 104615

Link to the publication

Summary:

Laser powder bed fusion (LPBF) as an additive manufacturing (AM) technology has emerged as a powerful platform for producing multi-material metallic structures. The main drawbacks of using metallic powders for multi-material printing are related to technical issues (i.e. powder contamination reducing the reusability of the powder) and interfacial defects. This paper attempts to demonstrate the advantages of using a combination of metallic powders and thin foils for printing light titanium-aluminum multi-material structures. An AlSi12 powder was printed using the conventional LPBF process and the behavior of the second material feedstock was investigated using both Ti6Al4V powders and foils. The printing process was simulated numerically using a finite element model (FEM), and characterized experimentally through operando X-Ray diffraction (XRD). For the powder-powder combination, cracking near the interface between the two alloys was considered as a combined effect of residual stresses and the presence of brittle intermetallic compounds (IMCs); both were investigated using nanoindentation. Replacing the Ti6Al4V powder by a foil resulted in a thinner layer of Ti-Al IMCs near the interface, and eliminated the large interfacial cracks. The results from FEM and CALPHAD thermodynamic simulations, supported by operando XRD, indicated that the increased thermal conductivity of the foil, compared to powders, led to heat transfer within the foil and to the underlying LPBF structure, prior to local melting. The new thermal regime produced a flawless interface between Ti6Al4V and AlSi12, due to reduced residual stresses in the plane normal to the building direction, and lower volumes of brittle IMCs. It is concluded that using foils instead of powders mitigates cracking and enhances microstructures near the interface, due to changes in thermal regime and alloys mixing patterns.

2023

3D printing of inorganic scintillator-based particle detectors
Scientific paper ArODES

T. Sibilieva, V. Alekseev, Sergey Barsuk, Siddartha Berns, Eric Boillat, I. Boiaryntseva, A. Boiaryntsev, A. Carbone, A. De Roeck, S. Dolan, T. Driuk, A. Gendotti, I. Gerasymov, B. Grynyov, Sylvain Hugon, U. Kose, O. Opolonin, A. Rubbia, D. Sgalaberna, M. Sibilyev, S. Tretyak, T. Weber, J. Wuthrich, X. Y. Zhao

Journal of Instrumentation,  2023, vol. 18, article no. P03007

Link to the publication

Summary:

Inorganic scintillators are widely used for scientific, industrial and medical applications. The development of 3D printing with inorganic scintillators would allow the fast creation of detector prototypes for the registration of ionizing radiation, such as alpha, beta and gamma particles in thin layers of active material, and X-ray radiation. This article reports on the technical work and scientific achievements that aimed at developing a new inorganic scintillation filament to be used for the 3D printing of composite scintillator materials: study and definition of the scintillator composition; development of the methods for the inorganic scintillator filament production and further implementation in the available 3D printing technologies; study of the impact of the different 3D printing modes on the material scintillation characteristics. Also, 3D-printed scintillators can be used to produce combined detectors for high-energy physics.

Augmentation de la durée de vie des pièces en titane issues de la fabrication additive
Professional paper ArODES

Cyril Ramseier, Siddartha Berns, Eric Boillat, Randoald Müller, Pierre-Antoine Gay, Oksana Banakh

Oberflächen POLYSURFACES,  64, 2023, 3, 5-7

Link to the publication

Summary:

La présence de défauts surfaciques (rugosité et fissures) ou internes (porosité, manque de fusion, etc.) sont les sources principales provoquant des défaillances dans les pièces métalliques fabriquées par L-PBF (Laser Powder Bed Fusion). Surtout si elles sont sujettes à des sollicitations mécaniques répétées. La résistance à la fatigue de ces composants peut être grandement améliorée en utilisant des traitements thermiques appropriés (HIP-High Isostatic Pressure, p. ex.) et des parachèvements surfaciques adaptés (électropolissage, p. ex.). Cette étude s'est focalisée sur le comportement de pièces industrielles en attachant autant d'importance à la microstructure, la porosité et à l'état de surface.

2022

Additive manufacturing of fine-granularity optically-isolated plastic scintillator elements
Scientific paper ArODES

Siddartha Berns, Eric Boillat, A. Boyarintsev, Stephen Dolan, Adamo Gendotti, Borys Grynyov, Sylvain Hugon, Umut Kose, S. Kovalchuk, B. Li, T. Sibilieva, Davide Sgalaberna, Thomas Weber, Johannes Wuthrich, X. Y. Zhao

Journal of Instrumentation,  2022

Link to the publication

Summary:

Plastic scintillator detectors are used in high energy physics as well as for diagnostic imaging in medicine, beam monitoring on hadron therapy, muon tomography, dosimetry and many security applications. To combine particle tracking and calorimetry it is necessary to build detectors with three-dimensional granularity, i.e. small voxels of scintillator optically isolated from each other. Recently, the 3DET collaboration demonstrated the possibility to 3D print polystyrene-based scintillators with a light output performance close to that obtained with standard production methods. In this article, after providing a further characterization of the developed scintillators, we show the first matrix of plastic scintillator cubes optically separated by a white reflector material entirely 3D printed with fused deposition modeling. This is a major milestone towards the 3D printing of the first real particle detector. A discussion of the results as well as the next steps in the R&D is also provided.

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