共查询到17条相似文献,搜索用时 109 毫秒
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基于线变换方法与互补媒质理论提出了线变换下的椭圆柱外隐身斗篷,并得到了相应外隐身斗篷材料本构参数张量的表达式.根据导出的本构参数张量,利用电磁仿真软件分别对不同长度线段的外斗篷进行了仿真验证,仿真结果证实了所得到的本构参数张量的正确性.这种外斗篷的材料参数只在轴向变化,横向参数为常数,易于用超介质制备.考虑到损耗对隐身效果的影响,得到了引入损耗后的外斗篷磁场分布.最后给出了本构参数的分布.本文的研究为利用超介质制备外隐身斗篷提供了一种新的可行的方法. 相似文献
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建立了平面行星夹具薄膜淀积无量纲模型,通过对蒸发源位置L/H、行星主轴与副轴距离P/H、夹角倾角A以及蒸发源蒸汽发射特性N等因素的分析,得到了典型径向理论均匀的优化几何配置.并从优化几何配置的膜料效率、角向均匀性和膜厚分布对蒸发源蒸汽发射特性变化的敏感性方面评价优化结果,得到了最优化设计区域.结果表明,优化配置的L/H+P/H小,则角分布差异小;L/H+P/H和A小,则膜料效率高L<P,A=-15°时,优化配置对N变化最不敏感L>P时,由N变化引起的典型径向分布变化小于0.5%. 相似文献
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基于Y/G及G/B为常数的假设,构建了高导无氧铜的七种高压与高应变率本构模型.对于高导无氧铜进行了平面冲击波试验,采用纵向与横向锰铜应力计记录了试件中的纵向与横向应力,从而得到了屈服应力历史.用所构建的七种本构模型进行了数值模拟,并与高导无氧铜的平面冲击波试验结果进行比较.结果表明,平面冲击波载荷下高导无氧铜的屈服强度对于压力、密度、温度以及塑性应变的依赖性是本构描述的关键.而由Hopkinson试验取得的高导无氧铜高应变率本构模型,并不适合描述平面冲击波载荷下的本构特性.
关键词:
本构模型
高导无氧铜
平面冲击波试验
锰铜应力计 相似文献
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Based on transformation acoustics, an arbitrary-shaped acoustic cloak capable of functioning as an information exchange-enabling internal cloak and a movement-allowing external cloak is presented. The general expressions of material parameters for the acoustic cloaks with arbitrarily conformal or non-conformal boundaries are derived, and then the performances of developed cloaks are validated by full-wave simulations. Finally, the different characteristics of the linear and nonlinear transformations-based cloaks are compared and analyzed. The proposed cloak could lead to wider applications beyond that of normal cloaks, since it effectively compensates the insufficiencies of traditional internal and external cloaks. Besides, this work also provides a new method to design bifunctional device and suggests an alternative way to make a large object invisible. 相似文献
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Transformation optics offers remarkable control over electromagnetic fields and opens an exciting gateway to design 'invisible cloak devices' recently. We present an important class of two-dimensional (2D) cloaks with polygon geometries. Explicit expressions of transformed medium parameters are derived with their unique properties investigated. It is found that the elements of diagonalized permittivity tensors are always positive within an irregular polygon cloak besides one element diverges to plus infinity and the other two become zero at the inner boundary. At most positions, the principle axes of permittivity tensors do not align with position vectors. An irregular polygon cloak is designed and its invisibility to external electromagnetic waves is numerically verified. Since polygon cloaks can be tailored to resemble any objects, the transformation is finally generalized to the realization of 2D cloaks with arbitrary geometries. 相似文献
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基于麦克斯韦方程组在不同坐标系下具有形式不变性以及变换光学理论, 通过设计材料的本构参数(介电常数和磁导率)来引导电磁波的传播, 提出了具有电磁透明和电磁聚集两种功能的新型电磁器件-椭圆形透明聚集器的设计方法. 电磁波透明体不会阻挡电磁波的传播并且能够与斗篷内部进行交互; 电磁波聚集器是当电磁波入射到该装置上时, 电磁波能够被设计的装置按照要求集中到一个区域或者一个点, 实现电磁波能量的集中. 本文利用压缩变换和扩展变换推导出了这种电磁器件中各层的相对介电常数和相对磁导率的张量表达式, 并利用基于有限元算法的电磁仿真软件对该电磁器件进行了全波仿真验证, 得到了入射波从各个不同方向入射时磁场z 分量的分布图, 仿真结果证实了该设计方法和电磁参数的正确性. 最后还讨论了电磁器件存在损耗时的情况, 当损耗逐渐增大时, 器件的功能在一定程度上受到了削弱. 本文的设计方法为其他新型电磁器件的设计提供了一种新的思路. 相似文献
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基于变换光学理论设计了一种新型的多功能电磁器件—旋转集中器.它以特殊的方式引导电磁波使其传播方向在器件核心区发生指定角度的旋转,并同时实现电磁场能量向该核心区的集中.针对提出的三种等效的旋转集中器结构,分别推导了相应的本构参数表达式,并利用有限元软件对三种结构分别进行了全波仿真.仿真结果验证了本构参数表达式的正确性.这三种不同的结构中,前两种结构由三层介质构成,后一种简化为两层介质.对于给定的任意旋转角度和能量集中率,三种结构可以使电磁场发生等效的传播方向旋转和能量集中两种效果.这些结果有助于对旋转器和集中器机理的进一步理解,并为复合功能器件的设计奠定了更充分的理论基础.本文提出的旋转集中器在设计高效率接收天线和特殊电路封装互联器件等方面都有潜在的应用前景. 相似文献
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Two-dimensional(2D) elliptically cylindrical invisible cloaks with multiple regions are designed based on the transformation optics and the complementary media theory. Multiple invisible cloak regions can be obtained by properly using the compressed or folded transformation in each space layer. The constitutive parameter tensor expressions for each region have been obtained. The results of full wave simulations by using finite element software confirm the validity of the constitutive parameter tensor expressions. In addition, the parameters are relatively easier to realize. 相似文献
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Xinhua Wang Shaobo Qu Song Xia Binke Wang Zhuo Xu Hua Ma Jiafu Wang Chao Gu Xiang Wu Lei Lu Hang Zhou 《Photonics and Nanostructures》2010,8(3):205-208
In this paper, three-dimensional (3-D) open cloaks were designed based on the coordinate transformation method. When the transformation center point is close to the boundary of the cloaks, the material parameter tensors in the near-boundary areas of the cloaks approximate to those in the background, so the near-boundary areas can be designed to be open. Full wave simulations based on finite element method verified the open cloaks we designed. Open cloaks can exchange information and materials with background media. Using the design method proposed in this paper, the boundary of open cloaks can be arbitrarily shaped, which greatly enhances the applicability of open cloaks. 相似文献