切向气流作用下玻璃纤维复合材料的激光辐照效应

实验研究了样品表面有切向空气气流、切向氮气气流和无气流时,976 nm连续激光对玻璃纤维增强E-51环氧树脂复合材料的辐照效应。结果表明:无气流时,喷出的热分解产物会对入射激光产生屏蔽作用;有气流时,激光对玻璃纤维的破坏方式是其升温熔化后再被切向气流带走;当激光功率密度较低时,切向空气气流以加强样品表面的对流冷却作用为主,不利于激光对玻璃纤维复合材料的破坏;当激光功率密度较高时,切向空气气流以降低屏蔽作用和提供氧气助燃为主,有利于激光对玻璃纤维复合材料的破坏。三种气流状态下,质量损失随功率密度呈现单调增加趋势,当入射激光功率密度在100~600 W/cm2范围内,随着功率密度的增大,激光能量的利用效率逐渐增大并趋于稳定。     

Influences of complex multi-channel turbulator on hybrid nanoparticle transportation and thermal behavior

Journal of Thermal Analysis and Calorimetry - Turbulator with new shape is utilized in current research to improve thermal efficiency. Hybrid nanomaterial has been involved as carrier fluid and...     

Analysis of hybrid nanofluid behavior within a porous cavity including Lorentz forces and radiation impacts

Journal of Thermal Analysis and Calorimetry - We investigate the hybrid nanofluid convection transportation within a permeable medium in appearance of an externally applied magnetic force by...     

Nanomaterial between two plates which are squeezed with impose magnetic force

Journal of Thermal Analysis and Calorimetry - Current investigation is surveyed the role of altering Lorentz force on nanomaterial flowing within two discs and its thermal behavior. The basis...     

Impact of MHD on hybrid nanomaterial free convective flow within a permeable region

Journal of Thermal Analysis and Calorimetry - Computational modeling was employed to scrutinize the nanomaterial influence of flow patterns and thermal treatment within a porous region....     

Drapage géométrique des compositesGeometrical draping of composite fabrics

This paper presents a study devoted to the composite fabric shaping simulation in finite strain analysis. We introduce a new geometrical approach based on the fishnet method for which the deformation of a fabric mesh element consists in a pure trellis effect. Such a fabric mesh element is then defined by a curved quadrilateral whose edges are geodesic lines with the same length plotted onto the surface to drape. Given three vertices of the fabric mesh element on the surface, we propose an optimization algorithm to define the fourth vertex of the fabric mesh element. This algorithm allows us to drape the surface using an advancing front approach from the data of an initial impact point between the fabric and the surface and the initial fibre directions at this point. A numerical draping simulation example using this approach is given. To cite this article: H. Borouchaki, A. Cherouat, C. R. Mecanique 331 (2003).     

Remaillage adaptatif pour la mise en forme des tôles minces

Problems associated with finite element simulation of the forming processes are characterized by large elastoplastic deformations, evolutive contact with friction, geometrical nonlinearities inducing a severe distortion of the computational mesh of the domain. In this case, frequent remeshing of the deformed domain during computation are necessary to obtain an accurate solution and complete the computation until the termination of the numerical simulation process. This Note presents a new adaptive remeshing method of thin sheets for numerical simulation of metal forming processes. The proposed method is based on geometrical criteria and does not use the geometry of the forming tools. It is integrated in a computational environment using the ABAQUS solver. Numerical examples are given to show the efficiency of our approach. To cite this article: L. Moreau et al., C. R. Mecanique 333 (2005).     

Diagramme de Laguerre

This Note presents a generalization of a known fast and robust algorithm of incremental construction of the Delaunay triangulation to the case of the regular triangulation of points in ${\mathbb{R}}^d$. In particular, the transport formula of simplex circumball centers are naturally extended to the case of the regular triangulation. The associated Laguerre diagram can then be obtained by duality from the regular triangulation. Some numerical examples of Laguerre diagrams in three dimensions are given. To cite this article: H. Borouchaki et al., C. R. Mecanique 333 (2005).     

连续激光辐照下光学材料损伤阈值的光斑效应

实验发现，光学材料的激光损伤阈值对激光光斑大小有强烈的依赖关系。研究了连续激光和匀质材料相互作用的机制，针对小光斑情形的材料响应和大光斑情形的结构响应分别提出各自不同的物理模型来解释光斑效应。研究表明，材料响应中的光斑效应基于热传导引起的光斑区热弥散，边界条件不同，破坏阈值与光斑大小的依赖关系也不尽相同。     

Construction dʼun champ continu de métriques

Adaptive computation using adaptive meshes is now recognized as essential for solving complex PDE problems. This computation requires, at each step, the definition of a continuous metric field to govern the generation of the adapted meshes. In practice, via an appropriate a posteriori error estimation, metrics are calculated at the vertices of the computational domain mesh. In order to obtain a continuous metric field, the discrete field is interpolated in the whole domain mesh. In this Note, a new method for interpolating discrete metric fields, based on a so-called “natural decomposition” of metrics, is introduced. The proposed method is based on known matrix decompositions and is computationally robust and efficient. Some qualitative comparisons with classical methods are made to show the relevance of this methodology.