Arts et Métiers

Objective To evaluate the pulse characteristics and the risk of fiber fracture (ROF) of the novel hybrid Thulium: Yttrium-Aluminium-Garnet (Tm: YAG) laser generator (RevoLix™ HTL, OmniGuide, USA). Materials and methods The RevoLix HTL laser was characterized using single-use 200 μm and 272 μm core-diameter fibers. Pulse characteristics (pulse profile, duration, and peak power (PP)), were assessed using the 272 μm fiber, employing a wattmeter and a photodiode. The ROF was evaluated using both 200 μm and 272 μm fibers, after 5 min of continuous laser activation (CLA) at five decreasing fiber bend radii (1, 0.9, 0.75, 0.6, and 0.45 cm). Pulse shape, duration, and PP were studied across three effect settings (50%, 75%, and 100%) with energy levels ranging from 0.5 to 1 J and 5 to 50 Hz frequencies. Each experiment was repeated three times. Results The RevoLix HTL exhibited a near-rectangular pulse profile consistent across all tested settings. At 100% effect, pulse durations ranged from 1,102 µs (30 Hz/0.5 J) to 2,182 µs (10 Hz/1 J), while PP ranged from 381 W (40 Hz/0.5 J) to 565 W (15 Hz/1 J). At 75% and 50% effects, pulse durations ranged from 1,138 µs (30 Hz/0.5 J) to 3,043.67 µs (40 Hz/1 J), while PP ranged from 325 W (29 Hz/0.5 J) to 473 W (40 Hz/0.8 J). Across all conditions, pulse energy remained consistent regardless of the effect value. A total of 39 settings were evaluated, and no fiber fractures were observed, even at a bend radius of 0.45 cm. Conclusion The RevoLix HTL laser provides a uniform pulse profile, stable PP, and robust fiber safety under various settings. These findings highlight its potential as a reliable and safe tool for lithotripsy. Further clinical studies are warranted to validate these results in vivo.

Objective The determination of the mid-sagittal plane (MSP) on three-dimensional (3D) head imaging is key to the assessment of facial asymmetry. The aim of this study was to evaluate the reliability of an automated landmark-based MSP to quantify mandibular asymmetry on head computed tomography (CT) scans. Materials and methods A dataset of 368 CT scans, including orthognathic surgery patients, was automatically annotated with 3D cephalometric landmarks via a previously published deep learning-based method. Five of these landmarks were used to automatically construct an MSP orthogonal to the Frankfurt horizontal plane. The reliability of automatic MSP construction was compared with the reliability of manual MSP construction based on 6 manual localizations by 3 experienced operators on 19 randomly selected CT scans. The mandibular asymmetry of the 368 CT scans with respect to the MSP was calculated and compared with clinical expert judgment. Results The construction of the MSP was found to be highly reliable, both manually and automatically. The manual reproducibility 95% limit of agreement was less than 1 mm for -y translation and less than 1.1° for -x and -z rotation, and the automatic measurement lied within the confidence interval of the manual method. The automatic MSP construction was shown to be clinically relevant, with the mandibular asymmetry measures being consistent with the expertly assessed levels of asymmetry. Conclusion The proposed automatic landmark-based MSP construction was found to be as reliable as manual construction and clinically relevant in assessing the mandibular asymmetry of 368 head CT scans. Clinical relevance Once implemented in a clinical software, fully automated landmark-based MSP construction could be clinically used to assess mandibular asymmetry on head CT scans.

This article presents the architecture of MemorIA, an integrative system that combines existing AI technologies into a coherent educational framework for creating interactive historical agents, with the aim of fostering students' learning interest. MemorIA generates animated digital portraits of historical figures, synchronizing facial expressions with synthesized speech to enable natural conversations with students. The system leverages NVIDIA Audio2Face for real‐time facial animation with first‐order motion model for portrait manipulation, achieving fluid interaction through low‐latency audio‐visual streaming. To assess our architecture in a field situation, we conducted a pilot study in middle school history classes, where students and teachers engaged in direct conversation with a virtual Julius Caesar during Roman history lessons. Students asked questions about ancient Rome, receiving contextually appropriate responses. While qualitative feedback suggests a positive trend toward increased student participation, some weaknesses and ethical considerations emerged. Based on this assessment, we discuss implementation challenges, suggest architectural improvements, and explore potential applications across various disciplines.

Additive manufacturing (AM) processes rely heavily on the geometric intricacies of parts being produced. Variations in the geometry of sequentially printed layers can introduce defects, arising from the complex interactions between geometry, process parameters, and materials. To mitigate these errors, it is critical to identify key geometric features and track their evolution in terms of both location and timing throughout the design and manufac- turing stages. This paper presents a novel method to describe shape in the context of AM, emphasizing the importance of layer-wise material deposition. Mereotopology, a framework for qualitatively describing the relationships between parts and wholes, is employed to pro- vide insights into the spatial, temporal, and spatio-temporal relationships inherent in AM processes. This formalism is particularly suited for shapes where precise dimensions may be indeterminate but where relational descriptions can still offer valuable information. The proposed theory integrates spatio-temporal evolution based on mereotopological principles and is applied to benchmark cases in AM. Additionally, a methodology for visualizing the generated descriptions is provided, along with a detailed case study. The paper concludes with a discussion on the strengths and limitations of this theory in comparison to existing approaches for describing four-dimensional objects. Graphical abstract

Hot‐forged wheel bearing hubs are manufactured using a complicated fabrication process chain to obtain the desired microstructure and mechanical properties in different zones that experience varying local stress states. The different process steps modify the surface roughness and the residual stresses distribution and therefore affect the fatigue behavior of the component. This study focuses on the effects of the shot‐blasting and the induction hardening stages on the fatigue failure mechanisms and aims to propose an appropriate fatigue design method. Fatigue tests are performed on industrial components and on conventional material specimens to evaluate the influence of the surface roughness and the residual stresses on the fatigue strength. The relaxation of residual stresses, caused by the heat treatment and the cyclic loading during fatigue testing, is shown to annihilate the positive effect of shot‐blasting, and the fatigue strength decreases because of the detrimental surface roughness, created by shot‐blasting. Different multiaxial fatigue criteria are tested to take into account the manufacturing process operations.

The composition of the mold atmosphere plays a critical role in mold-metal interactions during steel casting and is a root cause of certain casting defects. However, studying this atmosphere is challenging due to technical difficulties in extracting gases from sand molds and the harsh conditions of the metal casting process. Most of the studies realized in the field uses gas chromatography and mass spectrometry technics to investigate atmosphere in a foundry mold. Single-gas sensors, being readily available nowadays, present a cost-effective alternative to aforementioned technics. In this paper, we present an innovative gas analysis system designed for real-time, in-situ monitoring of the mold atmosphere. This system has been developed in collaboration between ENSAM Cluny (LaBoMaP) and the industrial partner Safe Metal. The paper presents the design, fabrication, operation and validation of an in-house foundry gas analyzer. Issues regarding gas sampling from a sand mold are discussed. The measurements with the analyzer were confronted with a reference gas mixture as well as with the foundry gas samples analyzed by μGC method.

This critical review examines advances in preprocessing and remelting processes for aluminium alloy chip recycling, emphasizing pre-treatment and remelting techniques that improve both resource recovery and material quality. Pre-treatment strategies, particularly cleaning methods and compaction are critically evaluated. Various cleaning methods, including centrifugation, ultrasonic solvent washing, extraction, and distillation are compared based on their ability to remove residual cutting fluids. Cold compaction, which augments chip density to approximately 2.5 g/cm³, significantly curtails oxidation losses and enhances metal recovery. During remelting, NaCl-KCl-based fluxes with limited fluoride additions (e.g., 3–7 wt% Na₃AlF₆) disrupt oxide networks but require careful dosage control to minimize furnace corrosion and environmental hazards. Moreover, mechanical stirring combined with suitable melting temperatures reduces porosity while enhancing melt purity. Future research should prioritize the development of low-energy cleaning methods, flux composition optimization, and scalable production techniques to further advance sustainable aluminium recycling.

Residual stresses are recognized as a critical factor influencing the mechanical performance and structural integrity of additively manufactured parts, particularly in nickel-based superalloys. Although the contour method and strain tomography have been applied independently for residual stress evaluation of such materials, a direct comparison of their reconstructions in laser powder bed fusion fabricated specimens has not been reported. In this study, both techniques were employed on identically produced specimens of CM247LC superalloy, and a strong qualitative agreement in residual elastic strain distributions was observed. Using the contour method, tensile residual stresses up to +1300 MPa were identified near the specimen edges, while compressive stresses approaching − 600 MPa were found in the central regions. Strain tomography, based on synchrotron X-ray diffraction, was used to non-destructively reconstruct internal residual elastic strain fields, revealing consistent trends and capturing localized variations aligned with the contour method. Through this integrated approach, a complete validation of stress reconstruction was achieved, and new insights into the stress evolution of laser powder bed fusion manufactured CM247LC were provided. The findings demonstrate how the complementary strengths of these techniques can be leveraged for improved residual stress characterization in high-performance superalloy parts.

This work is a numerical study of a transitional shock wave boundary layer interaction (SWBLI). The main goal is to improve our understanding of the well-known low-frequency SWBLI unsteadiness and especially the suspected role of triadic interactions in the underlying physical mechanism. To this end, a direct numerical simulation is performed using a high-order finite-volume scheme equipped with a suitable shock capturing procedure. The resulting database is then extensively post-processed in order to extract the main dynamical features of the interaction zone dynamics (involved characteristic frequencies, characteristics of the vortical structures, etc.). The dynamical organisation and space–time evolution of the flow at dominant frequencies are then further characterised by mean of an spectral proper orthogonal decomposition analysis. In order to study the role of triadic interactions occurring in the interaction region, a bispectral mode decomposition analysis is applied to the database. It allows us to extract the significant triadic interactions, their location and the resulting physical spatial modes. Strong triadic interactions are detected in the downstream part of the separation bubble whose role on the low-frequency unsteadiness is characterised. All the results of the various analyses are then discussed and integrated to formulate a possible mechanism fuelling low-frequency SWBLI unsteadiness.

The purpose of this research is the prediction of the natural frequencies of nanospheres radial vibrations. An innovative analytical method, based strain theory, is introduced to explore the influence of small-scale effects on the radial vibrations of nanospheres. To address the scale effects, three second-gradient models were devised, incorporating variations with negative and positive signs, as well as an inertial gradient. The derived natural frequency equations extend the classical continuum model initially proposed by Lamb. This study highlights the impact of the gradient model on the vibrational behavior of nanospheres. The key numerical findings indicate that the second-gradient model with a negative sign is physically unrealistic, whereas the model with a positive sign, though more realistic, exhibits instability. To address this instability, a second gradient model with inertia gradient is proposed. Moreover, the derived frequency equations are essential for analyzing the impact of scale effects on the natural frequencies of nanospheres radial. Ultimately, the findings play a vital role in interpreting experimental Raman spectra.

Geometric errors in a machine tool structure are mainly responsible for the volumetric error in the workspace. They occur at the attachment of each link between axis joints, but also along each axis in their joint frame. Reducing the impact of these errors is a key factor in guaranteeing the functional requirements of high value-added parts. Unlike mechanical correction, software compensation strategies are often chosen for their ease of implementation and versatile nature. In this study, a correction method by modifying the position measurement in real time is introduced and compared to compensation tables. The reaction response of the numerical controller (NC) to the modification of its position feedback is studied, and a 5-axis machining experiment to validate the proposed solution is performed. The principle of the experiment is to impose a virtual volumetric error in the workspace by modifying a machining program, then to test separately the ability of compensation tables and the proposed method to correct the chosen virtual geometric errors. The aim is to obtain a corrected workpiece similar to the one machined with a nominal program. In this way, it is not necessary to identify the geometric errors of the machine’s structure to test the performance of software compensation methods. The machined workpieces feature geometries that are easy to control, but the tool paths generated to produce them were complex enough to challenge the compensation methods. The ability of the proposed solution to correct the virtual volumetric error introduced by a modified machining program is evaluated at 98%. Indeed, roundness measurements show that over 99% of the added error has been corrected, with residuals lower than 5 µm. Furthermore, the joint trajectories monitored during machining are studied through a contouring error estimation. Nominal and compensated trajectories are 98% similar with the proposed solution, compared with 35% for compensation tables.

This study investigates the effect of additive manufacturing process parameters on the surface characteristics and performances of titanium Ti6Al4V, used for orthopedic implants. Parts were manufactured by selective laser melting, using a variety of volumetric energy densities, ranging from 58 to 152 J/mm³. Through a rigorous optimization of process parameters coupled with optical examinations of porosity distribution and morphology, a volumetric energy density of 58 J/mm³ was identified as an optimal manufacturing condition that resulted in extremely high densities of 99.8% in Ti6Al4V titanium alloy. X-ray diffraction measurements revealed the development of anisotropic residual stress states, characterized by elevated tensile stresses oriented along the build direction. Phase analysis results indicate a predominant martensitic acicular α′ structure, resulting from the rapid heating and cooling kinetics intrinsic to additive manufacturing, with a minor residual prior-β phase. Optical examinations reveal a microstructural transition from equiaxed prior-β grains to a columnar structure correlated with an increase in scanning speed (decrease in volume energy density). Corrosion tests were performed in Ringer’s solution at 37 °C to simulate physiological conditions. It has been established that the presence of elongated pores combined with high tensile residual stresses can significantly compromise the corrosion resistance of additively manufactured parts. Minimizing porosity, through optimized SLM process parameters, significantly improved corrosion resistance. This resulted in a continuous and dense passive film, reducing the corrosion rate by 72%, from 22 to 6 µm/year. These findings enable prosthesis manufacturers to enhance additively manufactured implant performances, extending their longevity.

IQueryn this study, the mechanical and tribological performance as well as the machinability of aluminium parts obtained by solid chip recycling were investigated and compared with the reference material. These aluminium billets were obtained using the stir consolidation friction technique, which consists of compacting chips from machined parts and rotating a cylindrical tool at different speeds. Different rotation speeds were used to produce the parts that were characterised. Chemical composition, microstructure, microhardness, machinability, friction and wear properties, and mechanical properties using the small punch test were measured and compared with the reference material. It was found that the microstructure of the recycled materials differed from that of the reference material. The latter has a microstructure of long grains oriented in the longitudinal direction, whereas the recycled materials have a microstructure of equiaxed fine grains, a microstructural evolution synonymous with dynamic recrystallisation. Hardness is more or less the same for recycled and reference materials and remains constant throughout the depth. The evolution of the coefficient of friction is similar but with a lower value for the recycled material in the stable part, whilst wear is lower by a factor of 2 for the sample obtained at 2000 rpm compared to the reference material. Finally, the sample obtained at 2000 rpm has a mechanical strength 25% lower than the reference material but with the same ductility.

In this paper, the dynamic behavior of a unidirectional S2-glass fiber-reinforced epoxy composite is reviewed through experimental tests conducted by Klosak et al. 2021, focusing on the effects of temperature and strain rate. Initially, comprehensive experimental analyses were performed to understand how these factors influence the composite’s mechanical properties. Building on this detailed analysis, a numerical model is proposed to study the composite’s behavior under dynamic loading conditions, such as impact and perforation. This model is innovative as it incorporates temperature effects on both the elastic properties and the material’s strength and damage characteristics. A function defining temperature sensitivity is introduced to capture these effects accurately. The Hashin failure criteria 1980 was employed to model damage initiation and evolution on time. The numerical model’s integration of strong temperature dependence allows it to replicate experimental measurements and the observed mode I failure patterns. Additionally, the model estimates the forces and rupture time associated with the epoxy matrix’s ductility. A comparative analysis is also provided, where specimens composed entirely of epoxy matrix are examined. The results demonstrate the model’s capability to accurately predict the dynamic response and failure modes of the composite, This work highlights the critical interplay between temperature, strain rate, and material behavior under dynamic loading and for a large range of temperatures.

In Virtual Environment (VE), haptic interaction plays an important role in delivering both tactile and kinesthetic sensations, enabling users to perceive the physical properties of virtual objects. These sensory inputs have diverse applications in areas such as medical training, virtual reality (VR) gaming, education, etc. This analytical review aims to provide a comprehensive overview of haptic technologies for fluid interaction developed in the past twenty years. A total of 59 studies meeting the inclusion criteria were identified and examined. The review thoroughly discusses relevant papers on haptic rendering methods as well as haptic devices designed for fluid interaction. In addition, an analytical point of view is presented from four key aspects, including fluid simulation methods, haptic feedback modalities, evaluation approaches, and applications. Finally, this paper highlights the current research gaps and outlines future directions to advance the development of reliable and accurate haptic techniques for interaction with fluids.

With today‘s trend toward mass customization, fast and efficient reconfiguration of manufacturing systems is essential. New artificial intelligence and robotics developments play a key role in optimizing these processes. AI-driven reconfigurations are becoming increasingly effective because of real-time data from digital twins and intuitive interaction through extended reality. This article presents an approach that integrates digital twins and extended reality in a reconfigurable manufacturing use case, laying the foundation for AI-driven optimization. It highlights potential industrial benefits, such as increased flexibility and reduced downtime, and provides an outlook on future developments.