Modélisation numérique de l´endommagement par fatigue d´une plaque composite carbone/époxy sollicitée en traction ondulée.

Depuis soixante ans, les matériaux dits composites suscitent un intérêt majeur, car des pièces de propriétés parfois comparables aux métaux peuvent être fabriquées à moindre poids. De nos jours, ils sont présents dans pratiquement tous les secteurs industriels. Malgré leurs qualités, ces matériaux hétérogènes et anisotropes sont sujets à différents types d’endommagements en service du fait de phénomènes de fatigue. L’aspect catastrophique des fractures par fatigue nécessite un examen approfondi et une connaissance parfaite du matériau utilisé. A fin de réduire le nombre des essais destructifs et coûteux, et éventuellement anticiper sur l’apparition des différents problèmes de tenue mécanique rencontré en service, il est important de développer des modèles numériques. Actuellement, il y a beaucoup de travaux qui s’intéressent au phénomène de fatigue, mais peu de travaux traitent de l’approche numérique de la propagation de l’endommagement et de la redistribution continue de l’effort pendant la durée de vie du matériau [1, 2]. L’objectif de cette étude est la modélisation par éléments finis de la cinétique de l’endommagement par fatigue d’un composite stratifié à fibres de carbone et à matrice époxyde, sollicité en fatigue (traction ondulée), utilisés dans la confection des structures dans le domaine aéronautique. L’évolution de l’endommagement par fatigue de nos matériaux est déterminée par la mesure de la chute de la rigidité lors d’essais cycliques à 65 % de la charge à rupture avec un rapport de contrainte R = 0.1. Le modèle analytique d'accumulation des endommagements en fatigue qui sera utilisé pour notre étude est celui de Mao et Mahadevan. Il traduit correctement les résultats expérimentaux obtenus, ceci sans prendre en compte la rupture finale du matériau. Ce modèle a été implémenté dans un code de calcul par éléments finis. Les résultats obtenus montrent une bonne corrélation avec les résultats expérimentaux

Aesthetic guidance and its Civilizational dimensions according To Malek ben Nabi

تهدف الدراسة إلى تبيان مفهوم الجميل عند مالك بن نبي الذي يتجاوز حدود الانفعالات الحسية والإدراكات الجمالية إلى أبعاد أخلاقية وتربوية، هذا ما تلخصه فكرة التوجيه الجمالي التي تعتبر بمثابة تربية اجتماعية يقر بن نبي بانحراف مفهوم الجميل نتيجة المصادرات الثقافية التي عرفها الفرد المسلم، حيث يتأكد له في مستويات الإثبات أن فكرة التوجيه تعمل على إعادة استرجاع كل المقومات الثقافية والأخلاقية والجمالية، ومنه يهدف مبدأ التوجيه الجمالي إلى بناء غاية محددة من الادراكات الجمالية وهي الغاية الأخلاقية التي ترتبط أساسا بالفكرة الدينية، الأمر الذي يجعل من الفرد المسلم فردا سائرا في طور الحضارة.The study aims to clarify the beautiful concept according to Malek Ben Nabi that exceeds the limits of sensory emotions and aesthetic perceptions to moral and educational dimensions, this is what summarized by the idea of ​​aesthetic guidance which is considered as social education. Ben Nabi acknowledges the deviation of the beautiful concept as a result of cultural confiscations known by the Muslim individual, as it is assured at the levels of proof that the idea of ​​guidance is recuperation all the cultural, ethical and aesthetic components. so, the principle of aesthetic guidance aims to build a specific purpose of the aesthetic perceptions, which is an ethical goal that is mainly related to the religious idea, the later makes the Muslim individual moving to the stage of civilization

Influence of fabric properties, hybridization, and thermal aging on properties of flax/jute fibres reinforced epoxy hybrid composites

426-435Mechanical properties (tensile and three-point flexural), physical properties (density and porosity rate), and thermal properties of flax, jute, and flax/jute fibres reinforced epoxy composites have been investigated. Laminate composites are fabricated by vacuum molding with a total fibre weight fraction maintained at 40%. Results show that the hybridization with jute fibres can significantly improve the mechanical properties of flax composites, while the thermal stability is decreased. The thermal aging at 250 °C during 400 h causes a decrease in tensile and flexural strength of the resulting composites, whereas their rigidity is increased. Morphological studies of fractured surfaces and the evaluation of porosity have been evaluated using scanning electron microscope and optical microscopy respectively

Influence of fabric properties, hybridization, and thermal aging on properties of flax/jute fibres reinforced epoxy hybrid composites

Mechanical properties (tensile and three-point flexural), physical properties (density and porosity rate), and thermal properties of flax, jute, and flax/jute fibres reinforced epoxy composites have been investigated. Laminate composites are fabricated by vacuum molding with a total fibre weight fraction maintained at 40%. Results show that the hybridization with jute fibres can significantly improve the mechanical properties of flax composites, while the thermal stability is decreased. The thermal aging at 250 °C during 400 h causes a decrease in tensile and flexural strength of the resulting composites, whereas their rigidity is increased. Morphological studies of fractured surfaces and the evaluation of porosity have been evaluated using scanning electron microscope and optical microscopy respectivel

A Novel Blind Image Source Separation Using Hybrid Firefly Particle Swarm Optimization Algorithm

Signal and image separation are extensively used in numerous imaging applications and communication systems. In this paper, a novel Blind Source Separation (BSS) approach, based on the Hybrid Firefly Particle Swarm Optimization (HFPSO), is proposed for separating mixed images. This approach processes the observed source without any prior knowledge about the model and the statistics of the source signal. The proposed method presents high robustness against local minima and converges quickly to the global minimum. Via numerical simulations, the proposed approach is tested and validated in comparison with standard Particle Swarm Optimization (PSO), Robust Independent Component Analysis (RobustICA), and Artificial Bee Colony (ABC) algorithms. The obtained results show that the presented technique outperforms the existing ones in terms of quality of image separation, the Signal-to-Noise Ratio (PSNR), and Structural Similarity Index Measure (SSIM). Moreover, the obtained results demonstrate that our approach provides also promising results in image separation from noisy mixtures

Study Biochemistry of <em>Mentha longifolia</em> (L.) Huds.: A Review

The Mentha longifolia were found to be a rich source of phytochemical compounds like piperitone, piperitone oxide, piperitenone, pulegone, d-limonene, menthone, carvone, menthol, β-caryophyllene, 1,8-cineole, 5,7,4-trihydroxy-6,2,3-trimethoxyflavone, carvone, limonene, tripal, and oxathiane. Mentha longifolia possess antioxidant effect that could be attributed to the presence of phytosterosls, unsaturated fatty acids, phenolic compounds, and specific volatile constituents and antimicrobial and interfere in the treatment of many diseases

Modelling VARTM process induced variations on bending performance of composite Omega beams

Finite element simulation with cohesive contact is presented, to correlate the vacuum assisted RTM process and the bending performance of Omega beams. The model considers the process induced variations, including part thickness, resin rich pockets and voids. The bending performance prediction relies on cohesive contact to model delamination initiation and propagation. Computing efficiency is achieved by mesh scaling. The modelling approach applies to three variations of Omega beams with the different mode-mixture ratios. The finite element predictions result in a high degree of agreement with the experimental measurements