To support the European Union’s 2050 climate neutrality goal and the 2019 European Green Deal, the industrial sector must reduce its environmental footprint, especially in high-energy manufacturing processes such as laser cutting. While fibre laser cutting is widely adopted for its efficiency, the literature remains focused on first-generation CO₂ lasers, and lacks multicriteria assessments integrating environmental, economic, and technical aspects. To address these gaps, this study proposes a framework based on an environmental analysis, which guides the identification and evaluation of concrete alternative production solutions. An environmental assessment of a fibre laser cutting process was conducted using the Product Environmental Footprint method. Results show that raw material consumption dominates climate change, followed by assist gas, electricity, and metal waste. Three alternative solutions were examined: internal nitrogen generation, compressed air, and a hybrid solution combining production with compressed air and nitrogen. Nitrogen generation doubled costs and was rejected. Compressed air offered the best environmental gain but had technical limits. The hybrid solution proved the most balanced. It reduced assist gas impact on climate change by 62

Laser cutting is an old and multi-physical process that was quickly adopted by the metallurgical industry. However, this fast industrialisation has had a significant impact on quality control. Several studies have been carried out to characterise and minimise different types of cutting defects. Reviews published between 2008 and 2022 highlight that research often focuses on single-criterion ___quality' approaches, aiming to minimise specific defects such as the Heat-Affected Zone, surface roughness, or kerf geometry. Consequently, efforts have been directed at optimising specific aspects of quality rather than adopting a complete approach. Furthermore, these reviews reveal that cutting quality can be enhanced through the careful selection of laser manufacturing parameters and part parameters. However, while parameters such as material and thickness have been investigated, the influence of part morphology on cutting quality remains underexplored.___ Although some studies have examined the effects of material and thickness, part morphology is often limited to simple segments with varying cutting lengths or angles. While other research has investigated the impact of angle size on cutting quality, no established method exists to systematically determine the influence of each part morphology on cutting quality.______ In response to this gap, the present study proposes to evaluate the criticality of cutting defects, as defined by existing standards, across various part morphologies using a method adapted from Failure Modes, Effects, and Criticality Analysis (FMECA). The objective is to develop a global approach that examines the influence of all morphologies on all types of cutting defects. An industrial application shows that cutting defects, particularly thermal ones, are strongly influenced by morphologies, while thickness affects them irregularly. Improvement priorities target critical defects shaped by both factors. Burrs and adherent slag are critical in angles and arcs, while segments, often used in studies, are less sensitive._________ These observations lead to the definition of design limits. This method offers a detailed analysis of the influence of design data on quality, providing practical tools for improving industrial processes._________

Laser cutting is an established, multi-physical process widely adopted by the metallurgical industry. However, this fast industrialisation has had a significant impact on quality control. Reviews from 2008 to 2022 primarily focus on single-criterion quality approaches, targeting defects like the Heat-Affected Zone, surface roughness, or kerf geometry, rather than adopting comprehensive methods. In addition, these studies show that cutting quality can be improved by selecting laser manufacturing parameters and part parameters such as thickness or material. However, the influence of part morphology remains underexplored. Following this observation, this study proposes a generic and complete method adapted from the Failure Modes, Effects and Criticality Analysis, allowing the evaluation of the criticality of all cutting defects in a part. It focuses on six laser cutting defects defined in an international standard and three types of morphology: arcs, angles and segments. The aim is to establish a holistic approach linking morphologies to all defect types. Industrial application reveals that thermal defects are highly influenced by morphology. Burrs and adherent slag are particularly critical in arcs and angles, while segments are less sensitive. This analysis establishes design limits and offers practical tools to improve industrial laser cutting through detailed quality assessments.

Part of the sealing function in the pneumatic system of the French high-speed train (TGV) is provided by elastomeric components, such as nitrile butadiene rubber (NBR) O-rings. Like most elastomers, NBRs are sensitive to thermo-oxidative aging. In the current application, aging results in a strong hardening of the O-rings, which alters the sealing function and impacts the lifetime of the mechanical pneumatic system. Therefore, understanding the origin of this aging, studying its effects on the mechanical properties, and modeling it are of a paramount importance in optimizing time in maintenance operations of the TGV. In a previous study, accelerated aging tests have been carried out with different NBR formulations at different times and temperatures. These tests enabled us to reproduce ex situ the hardening observed on the O-rings. Aging mechanisms have been identified and related to the aging conditions of the NBR formulations through different characterization techniques: infrared spectroscopy, swelling tests, X-ray fluorescence spectrometry, differential scanning calorimetry thermogravimetric analysis, and micro-hardness. To consider the effects of the mechanical loading on the aging process and the mechanical behavior of tested NBRs, mechanical spectroscopy (DMA) analyses have been carried out. The results obtained highlight how mechanical loadings impact the aging of these NBRs and quantify the effects of aging on their viscoelasticity. From the collected data, a hyperelastic model has finally been identified to simulate the behavior of O-rings by the finite element method. These first results lay the foundation of a selection methodology for O-rings used in the pneumatic system of the TGV.

This study sought to evaluate the biomechanical properties of the interface between the rotator cuff and the semicircular humeral ligament or rotator cable (RCa) using histological and biomechanical techniques. Out of 13 eligible cadaver specimens, 5 cadaver shoulders with an intact rotator cuff were included, 8 were excluded due to an injured rotator cuff. The histological study enables us to describe the capsule-tendon interface between the infraspinatus tendon (IST) or supraspinatus tendon (SST) and RCa, and to detect loose connective tissue layers to determine their precise location and measure their length along the interface. The biomechanical study sought to characterize and compare the mechanical strength of the IST-RCa versus SST-RCa interfaces. The average thickness of the RCa was 1.44 ± 0.20 mm. The histological study revealed a loose connective tissue layer at the IST-RCa interface, a finding not observed at the SST-RCa interface. The biomechanical study showed that the rigidity of the SST-RCa interface (72.10–2 N/mm) was 4.5 times higher than for the IST-RCa interface (16.10–2 N/mm) and the average maximum forces reached were 19.0 N and 10.6 N for the SST-RCa and IST- RCa interfaces, respectively. The IST-RCa interface consists of a loose connective tissue layer contrary to the SST-RCa interface. In parallel, two different groups in terms of the mechanical response were identified: the IST-RCa interface group had less rigidity and ruptured more quickly than the SST-RCa interface, therefore emerging as the most vulnerable interface and explaining a potential extension of rotator cuff tears.

The sealing function in the braking system of the French high-speed train (TGV) is provided by elastomeric components, such as nitrile butadiene rubber (NBR) O-rings. Like most elastomers, these seals are sensitive to thermo-oxidative aging. In the current application, aging results in a strong hardening of the O-rings that alters the sealing function and impacts the lifetime of the mechanical braking system. This places severe demands on maintenance operations. Therefore, understanding the origin of this aging and studying its effects on the material properties is of significant importance to limit train maintenance operations.In the present study, accelerated aging tests have been carried out with different NBR formulations at different temperatures. These tests allowed to reproduce ex-situ the hardening observed on the O-rings. Aging mechanisms were identified and related to the aging conditions of the NBR formulations through different characterization techniques: infrared spectroscopy, swelling tests, X-ray fluorescence spectrometry, differential scanning calorimetry, thermogravimetric analysis and micro-hardness.

Nitrile butadiene rubbers (NBR) are widely used in sealing applications, such as O-rings inside the pneumatic system of the French high-speed train (TGV). In this application, a strong hardening of the NBRs alters the sealing function. Predicting the evolution of the mechanical properties during service life, especially the material hardening, is therefore a strategic issue to optimize time in maintenance operations of the TGV's pneumatic system. The main goal of this study is to reproduce the aging observed on a train's pneumatic system by performing thermo-oxidative accelerated aging tests with different commercial nitrile rubbers at several temperatures and up to 2016 h. After achieving similar degradation to specimens aged on trains, aging mechanisms and effects have been investigated through different characterization techniques: infrared spectroscopy, swelling tests, X-ray fluorescence spectrometry, differential scanning calorimetry, thermogravimetric analysis, and micro-hardness measurements. The results obtained enabled us to identify and to relate aging mechanisms to aging conditions and to precisely determine and quantify the effects of physicochemical state evolution on the mechanical properties of each NBR considered. Extra crosslinks and oxidative functionalities form in the different elastomers, making them hard and brittle, and thus impacting the sealing function.

Over the past decades, Vascular Interventional Surgery Robots (VISR) have been developed to address the risks associated with X-rays used in minimally invasive vascular surgery procedures. Manipulation of over-the-wire catheters is necessary to perform complex surgery but requires high forces on the robot's end effector during rotational movements. The VISR under study mimics the physician's fingers by rolling the catheter between two planar surfaces to rotate it. In this study, an experimental set-up is used to replicate this grasping method, also used in other VISR [1, 2]. The parameters of the gripping surfaces are investigated to maximise the torque delivered to the catheter and minimise the forces required at the robot's end-effector. The implemented design of experiment (DOE) demonstrated that large and soft gripping surfaces could achieve this compromise. By adjusting these parameters, sufficient torque can be achieved on the catheter.

Nowadays the development of innovative processes is a major challenge for industries which want to prototype functional workpieces. Incremental sheet forming (ISF) is a good alternative for sheet metal prototyping to ensure flexibility, accuracy of the part produced, and cost effectiveness. A derived process, the Water Jet Incremental Sheet Forming (WJISF), has been undergoing development since 2001 and this paper purpose to give its state of the art. Different eclectic industrial fields could be concerned by WJISF process: automotive, micro-electronics, medical, and aerospace industry, for example. As the ISF process, the WJISF device needs a multi-axial machine, but it also needs a pressure pump with a sufficient flow rate and pressure. In an environmental point of view, this process can be seen as a "green" one giving that the water can be recycled and there is no lubricant. A general methodology has been defined to rigorously investigate this process and focus on researchers' teams, technological feasibility, numerical simulations, machine-tool uses, and real parts manufacturing. The study presented here provides summarizing evidence, especially technological windows, which give quick view of the actual knowledges and will help scientists and industrials to find WJISF parameters related to their needs. A lot of simple tests have been carried out with numerical and experimental comparisons. Nevertheless, few real parts have been manufactured, and the complex shape obtained by WJISF remains a scientific field to explore.

The hysteresis observed in the mechanical response of filled rubbers is classically assumed to be due to viscosity. In this study, a complete energy balance is carried out during cyclic deformation of a filled acrylonitrile-butadiene rubber. Results show that for the studied material, viscosity is not the preponderant contribution to the hysteresis loop: the mechanical energy brought to the material is not entirely dissipated into heat but a contrario is mainly used by the material to change its microstructure. Moreover, no significant hysteresis loop is observed in the unfilled material. Hence, the filler network stores elastic energy during its deformation, leading to a change in the internal energy. The higher the stretch applied, the higher the relative stored energy, but the higher the stretch rate applied, the lower the relative stored energy in the filler network. This has been evidenced by defining a ratio gamma(se) in terms of energy. As hysteresis loop in rubbers does not systematically mean that intrinsic dissipation is produced, predicting changes in temperature, and consequently the self-heating, is not possible from the mechanical response only. To conclude, this study presents the first estimation of stored energy in a filled rubber.

Abrasive water-jet manufacturing process can shape a lot of materials ranging from metals to glasses. It has a lot of advantages, as its low cutting forces, but remains quite difficult to control. Indeed, the process is leaded by the abrasive particle trajectories which depends on the water static pressure and many other parameters. The impact pressure on the work-piece is commonly modeled by a two Gaussian fit sum which are representative of the particles velocity distribution and the granulometry respectively. Today no studies based on discrete elements take into account the mixing chamber and the focal canon which are the two main steps of the abrasive water-jet tool constitution. In this preliminary work we propose to model the flow through the focal canon until the target impact by an original numeric granular approach. The Non-Smooth Contact Dynamics is an efficient method on a large range of simulation domains. In our case, we consider the water phase and the abrasive phase as two collections of distinct polydisperse elements. The masses are corrected and the contact interaction laws are adjusted to account for an equivalent fluid which similar mechanical properties. These two phases are mixed in a chamber and focalised through the canon, knowing water static pressure and abrasive mass rate. After the canon end the abrasive water-jet evolves in air and thus decelerates by friction. The tool-fluid adapts its geometric configuration from this kinetic energy decrease and impacts a target plane located at a known distance from the canon. Such a model is built on some classic process parameters as the water static pressure, the abrasive mass rate or the work-piece vs. canon distance, but it also naturally takes into account finer mechanical parameters as the abrasive granulometry or friction dissipation. Simulations gives interesting results of impact pressure distribution on the target work-piece with dynamic data of all the collection particles. More generally, this work final aim is to link elemental particle damage studies with a macroscopic wear prediction law.

HYPOTHESIS:Loading otoprotective drug into cochlear implant might change its mechanical properties, thus compromising atraumatic insertion. This study evaluated the effect of incorporation of dexamethasone (DXM) in the silicone of cochlear implant arrays on insertion forces.BACKGROUND:Local administration of DXM with embedded array can potentially reduce inflammation and fibrosis after cochlear implantation procedure to improve hearing preservation and reduce long-term impedances.METHODS:Four models of arrays have been tested: 0.5-mm distal diameter array (n = 5) used as a control, drug-free 0.4-mm distal diameter array (n = 5), 0.4-mm distal diameter array with 1% eluded DXM silicone (n = 5), and 0.4-mm distal diameter array with 10% eluded DXM silicone (n = 5). Via a motorized insertion bench, each array has been inserted into an artificial scala tympani model. The forces were recorded by a 6-axis force sensor. Each array was tested seven times for a total number of 140 insertions.RESULTS:During the first 10-mm insertion, no difference between the four models was observed. From 10- to 24-mm insertion, the 0.5-mm distal diameter array presented higher insertion forces than the drug-free 0.4-mm distal diameter arrays, with or without DXM. Friction forces for drug-free 0.4-mm distal diameter array and 0.4-mm distal diameter DXM eluded arrays were similar on all insertion lengths.CONCLUSION:Incorporation of DXM in silicone for cochlear implant design does not change electrode array insertion forces. It does not raise the risk of trauma during array insertion, making it suitable for long-term in situ administration to the cochlea.

La palpation de la chaîne ossiculaire est une étape délicate et indispensable de la chirurgie reconstructive de la chaîne tympano-ossiculaire. Afin de fournir un outil performant pour la formation et l’entrainement à cette microchirurgie, il est indispensable de transmettre un retour de forces crédible et stable. Or si les déformations peuvent être calculées à basse fréquence pour être réaliste (typiquement 30 Hz), le rendu haptique nécessite un rafraichissement de 1000 Hz. Cette différence complexifie le développement d’une simulation réaliste temps-réel. Ce travail est centré sur le développement d’un rendu haptique de qualité et sur son évaluation, pour la conception d’un simulateur de microchirurgie otologique. Un modèle mécanique de la chaine ossiculaire est développé dans le logiciel de simulation médical SOFA (Inria). Nous proposons une nouvelle méthode de rendu haptique, qui repose sur une méthode de préconditionnement et une approche désynchronisée du calcul des déformations et du retour haptique. Une interaction programmée entre un instrument chirurgical et la chaîne des osselets est réalisée afin d’évaluer la qualité du rendu haptique comparée au moteur physique. Enfin, une simulation temps-réel est réalisée permettant aux chirurgiens d’interagir avec la chaîne des osselets, tout en ressentant les forces appliquées sur les structures anatomiques. Lors de l’interaction programmée, les forces calculées par le moteur physique sont de 0,274 ± 0,021 N (n = 4) et de 0,270 ± 0,013 N (n = 4) par notre méthode de rendu haptique. Cette différence n’est pas significative (Student pairé) traduisant une correspondance entre les forces calculées à 48 Hz par la simulation et 1000 Hz par le rendu haptique. De plus, ces forces sont en accord avec les mesures expérimentales sur des rochers, lors de la palpation des osselets, variant de 0,098 à 0,655 N [Bergin et al., 2014, Otol Neurotol]. Lors de la simulation de la palpation, le taux de rafraichissement observé est de 48 Hz pour la simulation et de 1000 Hz pour l’haptique. Les chirurgiens sont capables d’interagir de manière réaliste et stable avec notre modèle mécanique de la chaîne des osselets. Un retour de forces est retransmis, à haute fréquence. Ces forces sont similaires à celles calculées par la simulation à basse fréquence, traduisant la bonne conservation du réalisme de la modélisation lors du rendu haptique. Il s’agit du premier simulateur virtuel permettant d’interagir de manière réaliste avec une chaîne ossiculaire et disposant d’un retour tactile. Soutien financier : Société Collin, Bagneux, France.

Cochlear implants are routinely manually inserted, with limited control of insertion forces. Controlling the quality of insertion during cochlear implantation, should reduce trauma to inner ear structures to enhance preoperative residual hearing preservation. This could participate to improvement of speech performances of implanted patients.We have set up a test bench comprising, artificial and anatomical models of scala tympani with cochlear implant insertion force measurements. Three intracochlear lesion sites have been identified: entry point into cochlea, 180 degrees region corresponding to first turn, and the end of the first turn. We have shown that manual insertion could generate peaks and jolts, contrary to motorized insertion which has smoother and a more predictable insertion profile. Insertion force analysis allows detecting abnormal insertions. In case of array progression blocking, or tip fold-over, a sudden rise of insertion forces is observed at the beginning of the insertion (< 10 mm) and its final peak is higher (0,3 to 0,6 N vs 0.15 N for a normal insertion).These results have led to the conception of a mechatronic tool allowing a force controlled cochlear array insertion. This tool embeds a linear actuator and a force sensor in serial. It could be an additional tool to help the surgeon to perform a less traumatic surgical procedure to enhance rehabilitation of neurosensory deafness with cochlear implants.

This paper is focus on the development of a haptic rendering method to simulate interactions with heterogeneous deformable materials, such as anatomical components. Indeed, the strong heterogeneities of the biological tissues involves numerical and real-time issues to simulate the deformations and the mechanical interactions between the organs and the surgical tools. In this paper, we propose a new haptic algorithm adapted to the modeling of heterogeneous biological tissues, based on non-linear finite element model. The central contribution is the use of a triple asynchronous approach: one loop at low rate, which computes a preconditionner that solves the numerical conditioning problems; a second at intermediate rate, to update the model of the biological simulation; and the haptic loop which provides the feedback to the user at high rate. Despite of the desynchronization, we show that the calculation of haptic forces remains accurate compared to the model. We apply our method to a challenging microsurgical intervention of the human middle ear. This surgery requires a delicate gesture in order to master the applied forces.

Afin de préserver au maximum les structures encore fonctionnelles de l'oreille interne lors de l'implantation cochléaire, il serait souhaitable de diminuer les forces de frictions. Le but de ce travail a été de comparer les forces d'insertions dans des pièces anatomiques avec trois techniques d'insertion : à l'aide de micro-pinces, avec un outil de guidage commercialisé, et avec un outil motorisé. Des os temporaux micro-disséquées ont été montés sur un capteur 6-axes afin d'enregistrer les forces d'insertion. Chaque os temporal a été inséré trois fois dans un ordre aléatoire avec chacune des trois techniques avec un implant cochléaire Hi-Focus 1 J (Advanced Bionics, Valencia, États-Unis). La somme des moments des forces, pic d'effort, dépassement de seuil > 0,1 N, doublement brusque de l'effort sur 0,1s, et dérivé de la courbe d'effort ont été analysés pour définir une nouvelle métrique. Une somme des moments des forces plus faible a été constatée lors de la 3e insertion comparativement aux 2 premières insertions dans les pièces anatomiques. Les résultats de la 3e insertion ont été exclus de l'étude. La somme des moments des forces était de 1,16 ± 0,505 N (moyenne ± DS, n = 10), 1,337 ± 0,408 N (n = 8), et 1,573 ± 0,764 N (n = 8) pour les insertions avec micro-pinces, outil guide et outil motorisé respectivement. Le pic d'effort était plus élevé avec l'outil guidé (p < 0,05). Le dépassement du seuil >0,1 N était plus fréquent avec l'insertion aux micro-pinces par rapport à l'utilisation de l'outil guidé (p < 0,005). Ces franchissements du seuil de 0,1 N sont diminués d'avantage à l'aide de l'outil motorisé. Les doublements de l'effort sur une période de 0,1 s et l'analyse du dérivé de la courbe ont constaté un profil d'effort avec moins d'à coup et plus régulier avec les outils guidés et motorisés. La somme des moments des forces était équivalente selon la technique utilisée. En revanche, un profil d'effort plus reproductible et prévisible était observé lors de l'utilisation d'un outil motorisé. L'utilisation de micro-pinces et de l'outil de guidage entraîne des à coup au cours de l'insertion en rapport avec une insertion en plusieurs étapes. Au contraire, une insertion avec l'outil motorisé est régulière avec une augmentation de l'effort uniquement à la fin de l'insertion. Les critères d'analyse, définis dans ce travail, permettent de proposer une métrique afin de comparer des profils d'effort utilisant des techniques d'insertion différentes. Ce travail a bénéficié du soutien de Advanced Bionics (Valencia, Etats-Unis).

Otological microsurgery is delicate and requires high dexterity in bad ergonomic conditions. To assist surgeons in these indications, a teleoperated system, called RobOtol, is developed. This robot enhances gesture accuracy and handiness and allows exploration of new procedures for middle ear surgery. To plan new procedures that exploit the capacities given by the robot, a surgical simulator is developed. The simulation reproduces with high fidelity the behavior of the anatomical structures and can also be used as a training tool for an easier control of the robot for surgeons. In the paper, we introduce the middle ear surgical simulation and then we perform virtually two challenging procedures with the robot. We show how interactive simulation can assist in analyzing the benefits of robotics in the case of complex manipulations or ergonomics studies and allow the development of innovative surgical procedures. New robot-based microsurgical procedures are investigated. The improvement offered by RobOtol is also evaluated and discussed.