Publications

The European Agency for Safety and Health at Work (2010) states that 15-20% of workplace accidents are maintenance-related, and 10-15% of these incidents result in fatalities. Due to the specialized expertise and knowledge required for this task, maintenance activities induce significant occupational stress (Sugiharto, 2019). Recognizing the necessity of evaluating physical workload becomes imperative for enhancing performance and working conditions, aiming at effective anthropocentric design (Bernard et al., 2021). However, this is not the only workload that operators experience. Mental workload can adversely affect maintenance activities, potentially leading to human errors and posing serious threats to complex system safety. The succession of maintenance tasks, whether simple or complex, demands mental resources such as decision-making, memory, and attention. The link between physical and mental workload exists within the activity, the individual and the surrounding environment with which he interacts (Causse, 2010). Taking into account Human Factors & Ergonomics (HFE) during the design cycle allows for the anticipation and optimization of interactions between operators and system components in terms of maintainability. Poorly executed studies on intrinsic or extrinsic equipment maintainability can generate human errors, which can affect performance and the safety of operators and systems. For this reason, anticipating the assessment of these dimensions makes collaboration with the design office more effective, so that HFE recommendations can be better taken into account during the design cycle. To this end, simulating maintenance tasks in an immersive environment, utilizing digital simulation tools (Virtual Reality, Augmented Reality, Mixed Reality), and physical simulation (mock-up), encourages the exploration of the relationship between the user and the maintenance environment. However, in the field of maintainability, it seems that no certified method for measuring mental workload has yet been established. Multiple categories of measures exist to assess mental workload: subjective measures, objective measures of performance and physiological measures. Some categories provide a singular perspective on mental workload, while others offer a more detailed understanding of its dynamics (Cegarra & Chevalier, 2008). Optimizing the selection of mental workload measurement methods and associated tools requires consideration of the constraints of the maintenance activity. The combination of measurement methods is fundamental to understanding the origin, variations, and limitations of mental workload, ensuring a holistic understanding of participants' cognitive activities and facilitating interpretation.

In this paper, a novel method for computing the nonlinear dynamics of highly flexible slender structures in three dimensions (3D) is proposed. It is the extension to 3D of a previous work restricted to inplane (2D) deformations. It is based on the geometrically exact beam model, which is discretized with a finite-element method and solved entirely in the frequency domain with a harmonic balance method (HBM) coupled to an asymptotic numerical method (ANM) for continuation of periodic solutions. An important consideration is the parametrization of the rotations of the beam’s cross sections, much more demanding than in the 2D case. Here, the rotations are parametrized with quaternions, with the advantage of leading naturally to polynomial nonlinearities in the model, well suited for applying the ANM. Because of the HBM–ANM framework, this numerical strategy is capable of computing both the frequency response of the structure under periodic oscillations and its nonlinear modes (namely its backbone curves and deformed shapes in free conservative oscillations). To illustrate and validate this strategy, it is used to solve two 3D deformations test cases of the literature: a cantilever beam and a clamped–clamped beam subjected to one-to-one (1:1) internal resonance between two companion bending modes in the case of a nearly square cross section.

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.