Publications

At chatter onset, as many works show, vibrations magnitudes grow until the tool exits the continuous cutting. Another magnitude limitation mechanism, namely ploughing is investigated in the present contribution, in a harmonic balance + continuation framework.

A case of high magnitude chatter vibrations of a flexible tubular part is considered via dynamical modelling in time domain, in a delayed differential equation (DDE) framework. A ploughing term is introduced into the tool-workpiece interaction law. This term is based on a penalty-type law depending on the instant effective clearance angle. This ploughing interaction produces a vibration limiting mechanism featuring realistic maximum magnitudes, as compared to experimental measurements. It is also shown that in spite of interrupted surface pattern, the cut remains continuous under chatter. Furthermore, this model restitutes re-stabilisation at the exit of a stability lobe, with several instabilities occurring during the operation.

Background In professional rugby, injury prevention and player availability are major challenges. Sports analytics use data from trainings and matches to address these issues. This study leveraged comprehensive daily data from a professional rugby club to predict players' readiness for training. Using this metric helped assess its effectiveness in predicting intrinsic injuries and improving injury prevention strategies. Methods Models including logistic regression, decision trees, and Long Short-Term Memory-based neural networks, were evaluated for their predictive accuracy and ability to discern patterns indicative of injury risks or readiness for physical activities. Findings The study demonstrated that long-short term memory and convolutional one-dimension models outperform traditional machine learning methods in analyzing players' physical conditions. This approach may support earlier identification of injury risks and inform workload management. Using model evaluation and interpretability techniques, including Local Interpretable Model-Agnostic Explanations (LIME) module, the study provided a framework for sports scientists, coaches, and medical staff to mitigate injury risks and optimize training sessions. Interpretation As a preliminary exploration, this study paves the way for further research into the integration of machine learning and neural networks in sports science, promising transformative impacts on injury prevention strategies in rugby.

This study investigates the decomposition of retained austenite (RA) in tool steels for plastic molding in correlation with the alloy chemical composition and the tempering parameters. Two grades differing in their silicon content with initial mixed bainitic/martensitic microstructures were investigated using in situ synchrotron high-energy X-ray diffraction (HEXRD) during tempering in the 550 °C to 600 °C temperature range for one-hour holding time. Results indicated carbide formation during heating or isothermal holding; however, retained austenite remained untransformed up to the end of the tempering holding time in all investigated conditions for both grades. In situ HEXRD provides direct evidence of the transformation of retained austenite into fresh martensite on cooling from the tempering stage. This behavior is correlated to the evolution of carbon enrichment of retained austenite and the effect of silicon is discussed.

In machine-tools, geometrical defects are unavoidable. They can greatly affect the dimensional accuracy of the final workpiece if not corrected. Software compensation strategies are less expensive than mechanical adjustments and they provide great improvement in volumetric accuracy. In this study, different compensation methods are compared in a 3-axis milling applications: Numerical Controller (NC) internal compensation tables, modification of the programmed tool-path (G code) and modification of position feedback signals. The latter is the main purpose of this work, because it shows great potential and is not linked to one particular type of NC. It communicates with a custom software application that processes the position data and generates corrected signals according to a geometric model based on the rigid body assumption. The NC is then induced to perform volumetric error correction based on its default programming. The compensation methods are compared based on their ability to bring out or correct imposed geometric errors. The highlighted solution shows performances comparable to the G-code modification by correcting more than 96% of the imposed geometric errors without affecting the numerical chain from the program generation to its execution on the machine. It is also independent of the NC or the motors control cards.

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.

This work offers a detailed examination of the phase field approach for modeling brittle fracture, emphasizing its theoretical foundations, mathematical descriptions, and computational strategies. Central to our discussion is an in-depth analysis of strain energy decomposition methods integral to phase field models. We introduce an innovative technique using a cleavage plane based degradation that has shown promising results under various loading scenarios. We meticulously evaluate each method’s inherent limitations and challenges to highlight their respective advantages and drawbacks across different loading scenarios. This review aims not only to catalog existing knowledge but also to pave the way for future research directions in the application of phase field approach to fracture analysis.

A method of generating a machining program with a programming system comprising a programming module and a man-machine communication interface having a display surface and selection means. The method comprises : - displaying on the display surface an image illustrating a representation of a real part to be machined and a virtual model corresponding to the real part to be machined;- selecting in the image, using the selection means, at least one given virtual zone of the predetermined virtual model corresponding to a given real zone of the part to be machined and a desired machining intensity parameter for the selected virtual zone; then- generating the machining program comprising a machining intensity characteristic to be applied as a function of the selected parameter.

Procédé de génération d'un programme d'usinage avec un système de programmation comprenant un module de programmation et une interface de communication homme-machine comportant une surface d'affichage et des moyens de sélection. Le procédé comprend : - l'affichage sur la surface d'affichage d'une image illustrant une représentation d'une pièce réelle à usiner et d'un modèle virtuel correspondant à la pièce réelle à usiner ; - la sélection dans l'image, à l'aide des moyens de sélection, d'au moins une zone virtuelle donnée du modèle virtuel prédéterminé correspondant à une zone réelle donnée de la pièce à usiner et d'un paramètre d'intensité d'usinage souhaité pour la zone virtuelle sélectionnée ; puis - la génération du programme d'usinage comprenant une caractéristique d'intensité d'usinage à appliquer en fonction du paramètre sélectionné.

Dissipative components of tool-workpiece interaction are of major importance in cutting-related vibrations. At the macroscopic vibration scale, such dissipation is usually accounted for by additional generalized damping forces in the equation of motion of the system’s elastodynamics. A finer consideration at cutting edge scale would bring up a line-distributed force mostly of ploughing nature. These two scales are usually linked by analytical integration, involving simplifying kinematical assumptions. In the present work a comparative investigation is proposed, for a machining operation, considering both representations in a detailed time domain modeling framework. Tool’s cutting edges are represented in a discretized manner, i.e. split into numerous elementary cutters allowing for detailed tool-workpiece interaction force distribution. The matter removal process is modeled via dexel-based surface discretization coupled with finite element-based modal shapes, enabling a consistent machined surface generation representation. Finally, the equations of motion are formulated for modal degrees of freedom and solved by a time marching algorithm. Based on these analyses, the limitations of resulting process damping force terms representations are considered regarding vibrations and interaction force magnitudes.