Caractérisation du comportement mécanique d'un composite (tissu de verre/résine époxyde) à différentes périodes de vieillissement hygrothermiques

Characterization of the mechanical behaviour of composite (woven fabric glass/epoxy resin) at different times during hygrothermal ageingThis paper considers the analysis of the mechanical behaviour of a laminate constituted of 12 layers of glass fiber fabric/epoxy resin conditioned at different relative humidities of 0, 60 and 96 % at 60 °C. The analysing of the experimental results obtained of hygrothermal ageing on the mechanical response has permited to show that the influence of the moisture concentration on the ultimate mechanical properties becomes significant and  important  for the composite conditioned at relative humidity of 96 % to the periods I and II (state of saturation and ageing)

Identification method of structural defects in glass fiber fabric/epoxy resin laminate

We present the experimental methods proposed for the identification of structural defects of the laminate constituted of 12 layers of glass fiber fabric/epoxy resin. Two techniques of control were used to analyze the principal structural defects (local or global disorientation). The first technique provides a superficial observation (macroscopic analysis) of the superior and lower surfaces of each layer, while the second one ensures internal observation (microscopic analysis) of the different layers after pyrolysis of the matrix (delamination of the laminate).Описано експериментальні методи для ідентифікації структурних дефектів у 12-шаровому ламінаті на основі скловолокнистої тканини й епоксидної смоли. Для аналізу основних структурних дефектів (локальна або глобальна дезорієнтація) використовували два методи. Один метод забезпечує дослідження (макроаналіз) верхньої і нижньої поверхней кожного шару, інший - внутрішнє дослідження (мікроаналіз) кожного шару після піролізу матриці (деламінації ламінату).Описаны экспериментальные методы для идентификации структурных дефектов в 12-слойном ламинате на основе стекловолокнистой ткани и эпоксидной смолы. Для анализа основных структурных дефектов (локальная или глобальная дезориентация) использовались два метода. Один метод обеспечивает исследование (макроанализ) верхней и нижней поверхностей каждого слоя, другой - внутреннее исследование (микроанализ) каждого слоя после пиролиза матрицы (деламинации ламината)

Modeling of the mechanical behavior of composite at different relative humidities

The moisture diffusion and mechanical response in shear of a laminate constituted of 12 layers of glass fabric fiber/epoxy resin were evaluated. The experimental analysis of the moisture absorption of the specimens conditioned at different relative humidities, 0, 60, and 96% RH at 60°C was to determine the two parameters characteristic of the Fick diffusion law (the diffusion coefficient D and the maximum quantity of water of saturation Mm) which admits the reversibility of the phenomenon. The analysis of the mechanical response in shear of the specimens oriented at 45° tested in uniaxial tension at constant imposed displacement rates, has permitted to show that the influence of the moisture concentration for the composite is very important at 96% RH. The proposed simple model permits to specify the influence of water absorption on the mechanical behavior in shear.Для дванадцятишаруватого ламіната з матрицею з епоксидної смоли і скловолокон досліджено закономірності абсорбції вологи і механічної поведінки в умовах зсуву. Експериментальні дослідження абсорбції вологи зразками з ламіната за різних значень вологості повітря (0, 60 і 96%) при температурі 60°C дозволили визначити два параметри (коефіцієнт дифузії D і максимальну кількість вологи при насиченні M m), що характеризують закон дифузії Фіка, який припускає зворотність процесу. Аналіз механічної поведінки при зсуві, що забезпечується одновісним розтягом ламіната з волокнами, орієнтованими під кутом 45° до осі розтягу, при постійних швидкостях переміщення показав, що при вологості 96% концентрація вологи в композиті грає особливо важливу роль. Запропоновано просту модель, яка дозволяє описати вплив абсорбції вологи на механічну поведінку ламіната при зсуві.Для 12-слоистого ламината с матрицей из эпоксидной смолы и стекловолокон исследованы закономерности абсорбции влаги и механического поведения в условиях сдвига. Экспериментальные исследования абсорбции влаги образцами из ламината при различных значениях влажности воздуха (0, 60 и 96%) при температуре 6WC позволили определить два параметра (коэффициент диффузии D и максимальное количество влаги при насыщении Mm), характеризующих закон диффузии Фика, который предполагает обратимость процесса. Анализ механического поведения при сдвиге, обеспечиваемом одноосным растяжением ламината с волокнами, ориентированными под углом 45° к оси растяжения, при постоянных скоростях перемещения показал, что при влажности 96% концентрация влаги в композите играет особенно важную роль. Предложена простая модель, позволяющая описать влияние абсорбции влаги на механическое поведение ламината при сдвиге

Ecological and economical mortars made with dune sand and cements in combination with local mineral additions

 Messaoudene Ibrahim1,2, Jauberthie Raoul1, Molez Laurent1, Naceri Abdelghani2(1. Mechanical and Civil Engineering Laboratory, INSA – 35043, Rennes, France;2. Geomaterials Laboratory, MSILA University - 28000, Algeria) Abstract: The aim of this study is to formulate and characterize, with different methods, mortars prepared with dune sand and Algerian clinker in combination with several admixtures, natural additions or industrial by-products as pozzolan, granulated blast furnace slag and marble powder.  Mineralogical and chemical compositions of the initial products were studied with X-ray diffraction (XRD), SEM, EDX and X fluorescence (XRF).  Grain size distribution of anhydrous cements and additions (absolute density, Blaine specific surface (SSB) and laser granulometry) were carried out.  Mortar strengths are acceptable at 28 days: between 5 and 6 MPa in bending test and between 28 and 41 MPa in compressive test.  These resistances improve clearly to reach high performances after one year: between 7 and 9 MPa in flexural test and between 43 and 61 MPa in compressive test.  The microstructure was studied using SEM coupled with microanalysis EDX; these observations explained the increase mechanical strength.  Results showed that it is possible to obtain mortars with high mechanical performances in long-term and, ecological and especially economic advantages with a good formulation of those mortars containing dune sand and additive cements (binary, ternary or quaternary) with super plasticizer adjuvant.Keywords: mix design, characterization, pozzolan, slag, marble, dune sand Algeria Citation: Messaoudene Ibrahim, Jauberthie Raoul, Molez Laurent, and Naceri Abdelghani.  Ecological and economical mortars made with dune sand and cements in combination with local mineral additions.  Agric Eng Int: CIGR Journal, 2010, 12(3): 38-47.  &nbsp

A comparative performance analysis based on artificial intelligence techniques applied to three-phase induction motor drives

In this work, we introduced a new robust hybrid control to an induction motor (IM), based on the theory of fuzzy logic and variable structure with sliding-mode control (SMC). As the variations of both control system parameters and operating conditions occur, the conventional control methods may not be satisfied further. Fuzzy tuning schemes are employed to improve control performance and to reduce chattering in the sliding mode. The combination of these two theories has given high performance and fast dynamic response with no overshoot. As it is very robust, it is insensitive to process parameters variation and external disturbances

Effect of Industrial By-products Fillers on the Properties of Blended Cements in Sulphate Environments

International audienceIn previous studies, we have investigated the durability of normal concrete in various sulphates environments. The contribution of this study is the addition of industrial by-products fillers: granulated blast furnace slag and marble powder. These two fillers do not need any calorific energy compared to clinker manufacturing. From an environmental perspective, no more carbon dioxide is produce when these two materials are used. Furthermore, slag and powder marble are waste that should be stocked in adapted landfills. Samples of normal mortar were exposed for 12 months to two sulphate environments: ammonium sulphate and sulphuric acid at two concentrations (0.05 and 0.25 mol/L). The evolution of crystalline phases is analyzed by XRD and minerals are observed by SEM, microanalysis (EDS linked to SEM) confirms their chemical composition. These determinations involve both the superficial formations that internal training due to conservation bath. For a low concentration of suphate (0.05 mol/L), the results show that the crystalline phases of cement (CSH, CH, ettringite) seem unaffected in the interior of the sample where the sulphur is completely absent. On the other hand, the ammonium sulphate penetrates deeper (4mm) to a high concentration (0.25 mol/L). However in the case of attack by sulphuric acid, samples develop a dense surface gypsum deposit. The mechanical strength, including bending strength to be known very sensitive to surface, is important to study this durability

Buckling Analysis of Laminate Short Beams by High Order Theory

Le comportement  de cisaillement transversal des poutres composites peut être critique et doit donc être correctement représenté par les différents modèles des structures utilisées habituellement pour prévoir leur comportement ou pour identifier leurs propriétés. On propose dans ce travail, une analyse de gauchissement dans les poutres stratifiées courtes selon  une approche analytique simple basée sur des théories d’ordre élevé.The transverse shear behavior of the composite beams can be critical and must therefore be properly represented by the various models of structures normally used to predict their behavior or to identify their properties. We propose in this work, a warpage analysis in short laminated beams using a simple analytical approach based on the theories of higher order

Effet des fillers de laitier et marbre sur la durabilité des ciments Portland dans des environnements de sulfate

https://www.polytech.univ-savoie.fr/fileadmin/polytech_autres_sites/sites/augc2012/actes/Contribution1117.pdfNational audienceRÉSUMÉ. L'effet conjugué des fillers de marbre et de laitier de haut fourneau sur la durabilité des mortiers a été étudié. Des échantillons de mortier normal sont immergés et conservés durant 12 mois dans deux solutions de sulfate d'ammonium et d'acide sulfurique à deux concentrations (0,05M et 0,25M). L'évolution des phases cristallines est suivie par diffraction X et les minéraux sont observés au MEB. Pour une faible concentration, les résultats montrent que les phases cristallines du ciment (CSH, CH, ettringite) ne semblent pas affectées à l'intérieur de l'échantillon, le soufre est totalement absent. En revanche, pour une forte concentration (0,25M), l'ion sulfate pénètre plus profondément (4mm) et les échantillons exposés dans l'acide sulfurique développent un dépôt extérieur dense de gypse. La quantité optimale du filler de marbre est limitée à 5% et le taux du laitier de 25 à 30%. ABSTRACT. The effect of the combination of marble and blast-furnace slag fillers on mortar durability was studied. Samples of normal mortar were exposed for 12 months to two sulphate environments: ammonium sulphate and sulphuric acid at two concentrations (0.05 and 0.25 mol/L). The evolution of crystalline phases was analyzed by XRD and minerals were observed by SEM. For a low concentration of sulphate (0.05 mol/L), the results show that the crystalline phases of cement (CSH, CH, ettringite) seem unaffected in the interior of the sample where the sulphur is completely absent. On the other hand, the ammonium sulphate penetrates deeper (4mm) to a high concentration (0.25 mol/L). However in the case of attack by sulphuric acid, samples develop a dense surface gypsum deposit. The optimum quantity of marble filler is limited to 5% and BFS content 25 to 30%

Towards Language-Based Modulation of Assistive Robots through Multimodal Models

In the field of Geriatronics, enabling effective and transparent communication between humans and robots is crucial for enhancing the acceptance and performance of assistive robots. Our early-stage research project investigates the potential of language-based modulation as a means to improve human-robot interaction. We propose to explore real-time modulation during task execution, leveraging language cues, visual references, and multimodal inputs. By developing transparent and interpretable methods, we aim to enable robots to adapt and respond to language commands, enhancing their usability and flexibility. Through the exchange of insights and knowledge at the workshop, we seek to gather valuable feedback to advance our research and contribute to the development of interactive robotic systems for Geriatronics and beyond.Comment: GERIATRONICS SUMMIT 202

LoHoRavens: A Long-Horizon Language-Conditioned Benchmark for Robotic Tabletop Manipulation

The convergence of embodied agents and large language models (LLMs) has brought significant advancements to embodied instruction following. Particularly, the strong reasoning capabilities of LLMs make it possible for robots to perform long-horizon tasks without expensive annotated demonstrations. However, public benchmarks for testing the long-horizon reasoning capabilities of language-conditioned robots in various scenarios are still missing. To fill this gap, this work focuses on the tabletop manipulation task and releases a simulation benchmark, \textit{LoHoRavens}, which covers various long-horizon reasoning aspects spanning color, size, space, arithmetics and reference. Furthermore, there is a key modality bridging problem for long-horizon manipulation tasks with LLMs: how to incorporate the observation feedback during robot execution for the LLM's closed-loop planning, which is however less studied by prior work. We investigate two methods of bridging the modality gap: caption generation and learnable interface for incorporating explicit and implicit observation feedback to the LLM, respectively. These methods serve as the two baselines for our proposed benchmark. Experiments show that both methods struggle to solve some tasks, indicating long-horizon manipulation tasks are still challenging for current popular models. We expect the proposed public benchmark and baselines can help the community develop better models for long-horizon tabletop manipulation tasks.Comment: 6 pages, 4 figures. The video and code of LoHoRavens are available at https://cisnlp.github.io/lohoravens-webpage