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Electromechanical responses and instability of electro-active polymer cylindrical shells
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作者 jiusheng ren Chengmin WANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2016年第8期1067-1076,共10页
Based on the theories of finite deformation elasticity, electromechanical responses and instability of an incompressible electro-active polymer (EAP) cylindrical shell, which is subjected to an internal pressure and... Based on the theories of finite deformation elasticity, electromechanical responses and instability of an incompressible electro-active polymer (EAP) cylindrical shell, which is subjected to an internal pressure and a static electric field, are studied. Deformation curves and distribution of stresses are obtained. It is found that an internal pressure together with an electric field may cause the unstable non-monotonic deforma- tion of the shell. It is also shown that a critical thickness for the shell exists, and the shell may undergo the unstable deformation if its thickness is less than this critical value. In addition, the effects of the electric field, axial stretch, thickness, and internal pressure on the instability of the shell are discussed. 展开更多
关键词 electro-active polymer (EAP) electromechanical instability finite deformation elastic theory non-monotonic critical thickness
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三江平原沼泽湿地4种优势植物空间格局对不同水位环境的响应 被引量:5
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作者 付裕 黄康祥 +7 位作者 蔡锦枫 陈慧敏 任久生 万松泽 张扬 任珩 毛瑢 石福习 《生物多样性》 CAS CSCD 北大核心 2022年第3期1-11,共11页
水文过程是沼泽湿地最基本的生态过程,理解物种空间格局形成机制及其种群特征随水位环境变化的规律对于科学指导沼泽湿地植被恢复具有重要意义。本研究分别选择三江平原季节性积水与常年积水沼泽,应用点格局方法中的完全空间随机模型、... 水文过程是沼泽湿地最基本的生态过程,理解物种空间格局形成机制及其种群特征随水位环境变化的规律对于科学指导沼泽湿地植被恢复具有重要意义。本研究分别选择三江平原季节性积水与常年积水沼泽,应用点格局方法中的完全空间随机模型、泊松聚块模型和嵌套双聚块模型分析了毛薹草(Carex lasiocarpa)、漂筏薹草(C.pseudocuraica)、狭叶甜茅(Glyceria spiculosa)、小叶章(Deyeuxia angustifolia)4个主要优势植物种群的空间格局,并测定了不同水位环境条件下的种群密度和个体大小特征。结果表明:在沼泽湿地中,4个优势种群在0-200 cm的尺度范围内都偏离了完全随机模型,表现为集体性聚集分布特征,且聚集距离主要集中在0-50 cm之间。随着水位的升高,毛薹草种群密度、个体生物量、株高和基径都呈显著增大趋势,但其聚集强度变弱;而小叶章种群密度和个体大小则显著降低,其聚集强度增大;漂筏薹草和狭叶甜茅种群密度、个体大小和聚集强度变化并不显著。在季节性积水区,4个物种在小尺度上均偏离了泊松聚块模型,符合嵌套双聚块模型,即在大聚块中分布较高密度的小聚块。但是,在常年积水区,仅毛薹草、漂筏薹草和狭叶甜茅3个物种符合嵌套双聚块模型,而小叶章种群则符合泊松聚块模型,说明在高水位胁迫下小叶章种群空间格局的大聚块中不存在较高密度的小聚块。综上所述,水位环境胁迫主要通过影响繁殖分配、种内竞争、易化作用以及个体大小变异等生物学过程共同决定着三江平原淡水沼泽湿地植物种群的斑块化分布特征,不同零模型可以帮助解释种群空间分布格局的形成机制。 展开更多
关键词 点格局 零模型 个体大小 沼泽湿地 三江平原
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FINITE DEFORMATION OF A CLASS OF RECTANGULAR RUBBER RINGS SUBJECTED TO END AXIAL LOADS 被引量:2
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作者 Wenzheng Zhang Xuegang Yuan +1 位作者 Hongwu Zhang jiusheng ren 《Acta Mechanica Solida Sinica》 SCIE EI 2012年第2期144-151,共8页
The problem of finite deformation of an incompressible rectangular rubber ring with an internal rigid body, where the ring is subjected to equal axial loads at its two ends, is examined. A reasonable mathematical mode... The problem of finite deformation of an incompressible rectangular rubber ring with an internal rigid body, where the ring is subjected to equal axial loads at its two ends, is examined. A reasonable mathematical model is formulated by using the nonlinear field theory and the implicit analytical solutions are derived. Then numerical simulations are implemented to further illustrate the results and obtain some meaningful conclusions. The deformation of the lateral surface of the ring becomes larger with the increasing axial loads, the decreasing ratio of the inner and outer radii and the increasing height of the ring. 展开更多
关键词 neo-Hookean material rectangular rubber ring axial load finite deformation implicit analytical solution
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DYNAMIC CHARACTERISTICS IN INCOMPRESSIBLE HYPERELASTIC CYLINDRICAL MEMBRANES 被引量:2
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作者 Datian Niu Xuegang Yuan +1 位作者 Changjun Cheng jiusheng ren 《Acta Mechanica Solida Sinica》 SCIE EI 2010年第5期420-427,共8页
In this paper, the dynamic characteristics are examined for a cylindrical membrane composed of a transversely isotropic incompressible hyperelastic material under an applied uniform radial constant pressure at its inn... In this paper, the dynamic characteristics are examined for a cylindrical membrane composed of a transversely isotropic incompressible hyperelastic material under an applied uniform radial constant pressure at its inner surface. A second-order nonlinear ordinary differential equation that approximately describes the radial oscillation of the inner surface of the membrane with respect to time is obtained. Some interesting conclusions are proposed for different materials, such as the neo-Hookean material, the Mooney-Rivlin material and the Rivlin-Saunders material. Firstly, the bifurcation conditions depending on the material parameters and the pressure loads are determined. Secondly, the conditions of periodic motion are presented in detail for membranes composed of different materials. Meanwhile, numerical simulations are also provided. 展开更多
关键词 incompressible hyperelastic material cylindrical membrane dynamical character- istic nonlinear periodic oscillation
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COUPLING EFFECTS OF VOID SHAPE AND VOID SIZE ON THE GROWTH OF AN ELLIPTIC VOID IN A FIBER-REINFORCED HYPER-ELASTIC THIN PLATE
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作者 jiusheng ren Hanhai Li +1 位作者 Changjun Cheng Xuegang Yuan 《Acta Mechanica Solida Sinica》 SCIE EI 2012年第3期312-320,共9页
The growth of a prolate or oblate elliptic micro-void in a fiber reinforced anisotropic incompressible hyper-elastic rectangular thin plate subjected to uniaxial extensions is studied within the framework of finite el... The growth of a prolate or oblate elliptic micro-void in a fiber reinforced anisotropic incompressible hyper-elastic rectangular thin plate subjected to uniaxial extensions is studied within the framework of finite elasticity. Coupling effects of void shape and void size on the growth of the void are paid special attention to. The deformation function of the plate with an isolated elliptic void is given, which is expressed by two parameters to solve the differential equation. The solution is approximately obtained from the minimum potential energy principle. Deformation curves for the void with a wide range of void aspect ratios and the stress distributions on the surface of the void have been obtained by numerical computation. The growth behavior of the void and the characteristics of stress distributions on the surface of the void are captured. The combined effects of void size and void shape on the growth of the void in the thin plate are discussed. The maximum stresses for the void with different sizes and different void aspect ratios are compared. 展开更多
关键词 fiber reinforced hyper-elastic material rectangular thin plate with void void shapeand void size potential energy principle growth of void
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