Publications

The direct parametrisation method for invariant manifolds is a nonlinear reduction technique which derives nonlinear mappings and reduced-order dynamics that describe the evolution of dynamical systems along a low-dimensional invariant-based span of the phase space. It can be directly applied to finite element problems. When the development is performed using an arbitrary order asymptotic expansion, it provides an efficient reduced-order modeling strategy for geometrically nonlinear structures. It is here applied to the case of rotating structures featuring centrifugal effect. A rotating cantilever beam with large amplitude vibrations is first selected in order to highlight the main features of the method. Numerical results show that the method provides accurate reduced-order models (ROMs) for any rotation speed and vibration amplitude of interest with a single master mode, thus offering remarkable reduction in the computational burden. The hardening/softening transition of the fundamental flexural mode with increasing rotation speed is then investigated in detail and a ROM parametrised with respect to rotation speed and forcing frequencies is detailed. The method is then applied to a twisted plate model representative of a fan blade, showing how the technique can handle more complex structures. Hardening/softening transition is also investigated as well as interpolation of ROMs, highlighting the efficacy of the method.

This article addresses the measurement of the nonlinear modes of highly flexible structures vibrating at extreme amplitude, using a Phase-Locked Loop experimental continuation technique. By separating the motion into its conservative and dissipative parts, it is theoretically proven for the first time that phase resonance testing organically allows for measurement of the conservative nonlinear modes of a structure, whatever be its damping law, linear or nonlinear. This result is experimentally validated by measuring the first three nonlinear modes of a cantilever beam. Extreme amplitudes of motion (of the order of 120° of cross section rotation for the first mode) are reached for the first time, in air with atmospheric pressure condition, responsible for a strong nonlinear damping due to aeroelastic drag. The experimental backbone curves are validated through comparison to the conservative backbone curves obtained by numerical computations, with an excellent agreement. The classical trends of cantilever beams are recovered: a hardening effect on the first nonlinear mode and softening on the other modes. The nonlinear mode shapes are also measured and compared to their theoretical counterparts using camera capture. Finally, it is shown that the damping law can be estimated as a by-product of the phase resonance measurement of the conservative nonlinear modes. As an original result, the damping law is observed to be highly nonlinear, with quadratic and cubic evolutions as a function of the structure’s amplitude.

Selon un procédé de fabrication additive d’une pièce (2, 3, 4) par fusion laser de couches de poudre métallique, on utilise une poudre d’un alliage présentant une transformation de phase austénitique en phase martensitique à une température de transformation prédéterminée. On subdivise la pièce en au moins un premier et un deuxième volume (21, 22), on applique des premières conditions d’éclairement sur les zones destinées à former le premier volume (21) permettant d’obtenir un alliage avec une première température de transformation, on applique des deuxièmes conditions d’éclairement différentes des premières conditions d’éclairement sur les zones destinées à former le deuxième volume afin de modifier la composition chimique de l’alliage et d’obtenir une deuxième température de transformation dans le deuxième volume (22) différente de la première température de transformation. Figure pour l’abrégé : Fig. 1

ACTUATEUR AÉRODYNAMIQUE ACTIF EN AMF POUR ROUE DE VÉHICULE AUTOMOBILE La présente invention concerne un actuateur (12) pour pale (10) de roue de véhicule automobile, comprenant un fil métallique avec, successivement, un premier tronçon (12.1) s’étendant longitudinalement depuis une première extrémité (12.4) jusqu’à une zone intermédiaire (12.3) dudit fil métallique, et un deuxième tronçon (12.2) s’étendant longitudinalement depuis la zone intermédiaire jusqu’à une deuxième extrémité (12.5) dudit fil métallique, la zone intermédiaire étant apte à s’engager en rotation avec la pale et le premier tronçon étant à mémoire de forme de manière à pouvoir faire pivoter la pale suivant la température du fil métallique ; remarquable en ce que la zone intermédiaire est d’un seul tenant avec les premier et deuxième tronçons du fil métallique et forme un pliage dudit fil métallique. (Figure à publier avec l'abrégé : Figure 5)

Ensuring the structural integrity of solar photovoltaic modules is crucial to maintain power production efficiency and fulfill the anticipated product lifespan. Hence, implementing quality control procedures and structural health monitoring is necessary throughout the stages of manufacture and operation. The ultrasonic examination has some benefits compared to electroluminescence and infrared approaches, namely in identifying mechanical flaws in the front glass. The Lamb waves (LW) method is an auspicious inspection approach among ultrasonic-based methods. This is primarily attributed to its quicker measurement speed than the standard ultrasonic c-scan. The LW method offers an advantage in terms of its ability to provide long-range coverage. The predominant approach in LW inquiry often centers on using fundamental modes within the low-frequency range. Nevertheless, the findings of this investigation demonstrate that the higher-order mode exhibits superior effectiveness for the specific objective of this research, as it displays a higher level of sensitivity towards cracks in the front glass of the module. The current study ultimately showcases the use of the LW scan. A damage indication threshold is determined by the fraction of energy spectral density (ESD) associated with the crack-sensitive mode. This technology effectively produces a comprehensive map of the designated area by comparing the ESD values at various measurement positions with a predetermined threshold. This map provides precise indications of the existence of areas that are affected by cracks.

Power Electronics Converters (PEC) play a crucial role in the operation of many modern electrical systems and devices. Despite their widespread use, the lack of an efficient and cost-effective disassembly process can limit their repairability, refurbishability, remanufacturability and, ultimately, recyclability, thus hindering the circularity of products. In order to improve their circularity, it is important to assess their ease of disassembly. Therefore, this paper investigates the applicability of the “ease of Disassembly Metric” (eDiM), which is referenced in the material efficiency standards, Benelux repairability assessment method, and Repair Scoring System (RSS), to analyze the ease of disassembly of energy-related products. After identifying the limitations of the eDiM method, we refined and adapted it to make it more suitable for Printed Circuit Board (PCB)-based PEC, and thus propose a PCB-based disassemblability assessment method allowing the implementation of quantifiable requirements supporting their circularity. This standardized approach, at the PCB level, can improve the circularity of such products by facilitating design enhancements. With this approach, policymakers and designers can contribute more effectively to the transition to a circular economy in PCB electronics, particularly in the field of power electronics.

This paper introduces SmartSimVR, a ground-breaking research initiative focused on the development of a user-specific intelligent architecture for immersive virtual environments. The primary objective of this architecture is to address real-time artificial intelligence training and adapt the virtual environment based on the user's state or external parameters. In a case study centered around the detection of cybersickness, an undesirable side effect in immersive virtual environments, we employed this architecture in a driving simulator application. Leveraging the capabilities of this architecture enables the optimization of virtual reality experiences for individual users, resulting in increased comfort.

The rapid and relentless pace of technological advancement over recent years has had a profound impact on the realm of education. This dynamic transformation has paved the way for a host of new possibilities and innovations that are reshaping the educational landscape. One of the most noteworthy developments within this technological revolution is the advent of virtual and augmented realities. These immersive technologies have become pivotal in shaping the evolution of educational tools and systems across universities worldwide. For examples of this phenomenon, one can refer to recent works such as Sandyk et al. (2023) and Kontio et al. (2023). The "JENII project" is an example of initiative in the sphere of immersive education, which is being spearheaded by the Arts et Metiers Institute of Technology. This project is set on a course to revolutionize engineering education by designing a suite of immersive and interactive digital twins. While Engineering Learning Workplaces are not physically present, the immersion enabled by the technology, when coupled with a machine's digital twin, closely replicates the genuine interaction an engineering student would encounter in an industrial environment. Thus, within the framework of the Conceive-Design-Implement-Operate (CDIO) approach, these immersive digital twins are envisioned as virtual counterparts to the workplaces described in Standard 6. However, immersive digital twins are not static; instead, they offer the prospect of continuous optimization to provide engineering students with a dynamic learning experience. A important attribute of these digital twins is their potential to catalyze Active Learning, a fundamental component of CDIO (Standard 8). They offer students unfettered access to a set of realistic exercises, during both classroom sessions and independent study. These exercises are meticulously designed to simulate actions that students would undertake on actual machines, fostering a hands-on learning environment. What sets these digital twins apart is their ability to allow students to repeat exercises as many times as needed, replicating real-world scenarios. This affords a unique opportunity for students to refine their skills and gain mastery over complex engineering tasks.

As more of our lives are spent using electronic devices, it comes as a natural deduction that those digital tools could be used to maintain people’s health. Gamified exercise or exergames are indeed promising means to motivate the population to get physically active and even cognitively active if paired with the appropriate games. Considering the global concern of an aging population which could benefit from both physical and cognitive stimulation, these tools appear to be an encouraging solution to keep the population healthier over time. This scoping review reports on the digital tools used in publications between January 2015 and December 2023 regarding the physical and cognitive stimulation of healthy elderly people. The search was conducted in PubMed, Web of Science, and ScienceDirect databases. Of the 1579 publications retrieved, a total of 68 publications were analyzed in this review. A wide variety of digital tools were used in the corpus for the combined physical and cognitive stimulation of the elderly. These tools can be categorized into six types of hardware: pressure plates, optical motion capture, inertial motion capture, virtual reality, ergometers, and driving simulators. The apparition of publications using virtual reality and an increase in publications using inertial motion capture in 2020 could be an indicator that digital tools used for cognitive and physical stimulation of the elderly are evolving. Another finding is the wide variety in evaluation tools used to monitor the outcomes of each protocol. A standardization of the testing process might be needed in order to improve comparisons between experiments.

In modern manufacturing, machining remains a vital process for complex mechanical components. In particular, the aerospace industry extensively employs high-feed milling techniques to machine complex geometries from nickel-based superalloys. This study focuses on the analysis and modeling of high-feed milling for Inconel 718 in 2.5-axis machining. Its objective is to develop a generalized model of high-feed milling that enables the prediction of surface topography. The proposed model integrates crucial geometric parameters of the tool and its exact kinematic within the machine, along with tool and machine deflections caused by cutting forces. A key novelty of this research lies in its capability to determine surface topography and its quality based on a generalized model, representing significant progress in the field of high-feed milling. To validate the model, experimental efforts are measured to characterize the cutting forces and system deflections during machining. The developed approach demonstrates its ability to model surface topography and to predict surface roughness. It also highlights the influence of tool and machine deflection on surface quality. This research contributes to the advancement of the application of high-feed milling in aerospace manufacturing by enhancing machining capabilities and improving part quality.