A new model of edge-to-edge contact for three dimensional discontinuous deformation analysis     

M. Mousakhani  A. Jafari 《Geomechanics and Geoengineering》2016,11(2):135-148

A robust contact theory can be regarded as key to three dimensional discontinuous deformation analyses (3D-DDA). Not only must this theory provide an efficient algorithm to judge the type and location of contacts but also it must be able to present comprehensive formulations for every kind of contact (open, sliding and locked contact). There are six types of contact in three dimensional discontinuous deformation analyses (vertex-to-vertex, vertex-to-edge, vertex-to-face, edge-to-edge, edge-to-face and face-to-face) that can be converted to vertex-to-face and edge-to-edge contacts. This paper presents a new model of edge-to-edge contact to three dimensional discontinuous deformation analyses (3D-DDA). This new model considers both kinds of edge-to-edge contact (cross-over and parallel edge-to-edge contact) and presents a criterion for inter-penetration. Sub matrices of normal and shear spring and friction force are derived by geometrical analysis and penalty method. This new model is implemented in a 3D-DDA computer programme, and the example results demonstrate the validity of the model.  相似文献   

漂浮植物修复技术净化城市河湖水体试验研究   总被引：7，自引：1，他引：6  

黄廷林  戴栋超  王震  解岳  钟建红 《地理科学进展》2006,25(6):62-67

阐述了漂浮栽培植物修复系统的技术原理、特点与系统组成, 研究了在该系统中种植美人 蕉和旱伞草2 种植物的生长状况以及这些植物对城市河湖水体中氮、磷等的净化效果。尝试了将 漂浮栽培植物与生物接触氧化技术结合起来, 并研究了植物与生物填料的组合系统对水质的改 善效果。结果表明, 美人蕉和风车草在漂浮植物修复系统对氨氮的去除率均在90%以上, 漂浮栽 培植物与软性填料的组合系统对水中COD_Mn 的去除率达46%以上。  相似文献   

基于ABAQUS的深水连接器连接性能分析     

曹博  蔡志杰  石中玉  张玉龙  段梦兰 《海洋工程》2020,38(3):132-139

为解决现有深水连接器连接性能研究中力学分析建模不准确,且缺乏抗弯抗扭能力分析的问题,基于ABAQUS有限元分析软件对深水连接器进行三维模型动态仿真分析,对连接器的受力、密封性能以及在实际工程需求中不同内压下的抗弯及抗扭性能进行深入研究。结果表明:在安装及生产两种工况下,深水连接器各部件除密封环外受力均满足其强度设计要求,密封环接触表面发生合理塑性变形,满足密封要求;随着内压的增加,深水连接器的抗弯能力逐渐下降,抗扭能力则呈现增加的趋势;极限弯矩分别在0 MPa与35 MPa内压下的判定依据为密封失效,在14 MPa与52 MPa内压下的判定依据为下毂座屈服,而极限扭矩在不同内压下的判定依据均为密封失效。  相似文献   

高速铁路对东北城市网络结构的空间影响   总被引：2，自引：0，他引：2  

刘书舟  韩增林  郭建科 《地理科学》2020,40(2):270-279

借鉴复杂网络理论,以铁路列车时刻表为基础数据,探讨高速铁路的开通对东北地区铁路网络结构和城市网络结构的空间影响。结果表明：① 高铁强化了东北地区铁路网络的小世界、无标度等网络特征,各网络节点在可达性和辐射能力方面受到4种不同形式的影响;② 高铁强化了沈阳和哈尔滨的主-副双核心铁路网络结构,使得拓扑网络的离散程度大幅降低,长春、大连等城市的网络联系中心性显著提升;③ 铁路交通重心向西北方向偏移,区域间不平衡性增强,吉林省成为东北铁路客运联系强度最高的地区;④ 大连市拥有特殊的门户城市特征,即对外联通能力强,但未形成足够吸引力。  相似文献   

Improving performances of ITO/GaP contact on AlGaInP light-emitting diodes     

李春伟  朱彦旭  沈光地  张勇辉  秦园  高伟  蒋文静  邹德恕 《海洋学报(英文版)》2010,29(9)

In this paper AlGaInP light emitting diodes with different types of electrodes: Au/Zn/Au-ITO Au/Ti-ITO Au/Ge/Ni-ITO and Au-ITO are fabricated. The photoelectricity properties of those LEDs are studied. The results show that the Au/Zn/Au electrode greatly improves the performance of LEDs compared with the other electrodes. Because the Au/Zn/Au electrode not only forms a good Ohmic contact with indium tin oxide (ITO), but also reduces the specific contact resistances between ITO and GaP, which are 1.273×10^-6 Ω · cm² and 1.743×10^-3 Ω ·cm² between Au/Zn/Au-ITO and ITO-GaP respectively. Furthermore, the textured Zn/Au-ITO/Zn electrode is designed to improve the performances of LEDs, reduce the forward-voltage of the LED from 1.93 to 1.88 V, and increase the luminous intensity of the LEDs from 126 to 134 mcd when driven at 20 mA.  相似文献   

GPS约束下陇西地区断裂带现今滑动速率的非连续接触模拟研究     

孟庆筱  景鹏旭  何申海  党学会 《大地测量与地球动力学》2018,38(12):1227-1231

以中国地壳运动观测网络1999、2001、2004和2007年4期GPS观测数据为边界条件,使用非连续接触有限元技术构建陇西块体二维有限元模型,在摩擦系数不确定性分析基础上,计算区内主要断裂带滑动速率。结果表明,现今地壳形变运动状态下陇西块体的北东向运动在海原断裂附近受到鄂尔多斯块体、阿拉善块体阻碍,陇西块体周缘的海原断裂带、老虎山断裂、西秦岭北缘断裂呈现左旋走滑特征,滑动速率为3.5 mm/a、2.2 mm/a和1.9 mm/a,说明在青藏高原推挤作用下以上关键部位正在进行快速的构造应变积累。  相似文献   

脐带缆螺旋滑移分析及力学性能研究   总被引：1，自引：0，他引：1  

李英  吴潘  冯雅萍  曹静萱 《海洋工程》2018,36(6):58-68

针对脐带缆内部螺旋层,应用Darboux标架建立螺旋结构空间坐标系,推导弯曲载荷下螺旋结构的局部变形和滑移。考虑螺旋构件间的接触和摩擦作用,建立螺旋结构的受力平衡偏微分方程,并研究螺旋角和摩擦系数对螺旋结构滑移的影响。基于同层螺旋结构本构关系相同假设,将所有螺旋结构力学性能线性叠加,拟合脐带缆整体弯曲刚度。运用建立的理论解析方法,对某双层铠装脐带缆的力学性能进行研究,并与数值模拟结果进行对比验证。对比结果表明,理论解析得到的螺旋滑移结果与数值模拟结果一致,理论解析得到的脐带缆弯曲刚度与数值模拟结果在全滑动阶段比较接近。  相似文献   

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李红  陈连旺  李玉江 《大地测量与地球动力学》2008,28(2):39-44

?????????????????????????????????????GPS????????????????????????????????????????4?????????????????????????????????????????????????????????????????????????壻??????????????????????????????????????????壻?齭???????????????????????????????????塣???????????????????????ζ?????????????????????????????????????????????κ??齭???????????????????????????????????????????????  相似文献   

Particle manifold method (PMM): A new continuum‐discontinuum numerical model for geomechanics     

L. Sun  G.F. Zhao  J. Zhao 《国际地质力学数值与分析法杂志》2013,37(12):1711-1736

Particle manifold method (PMM) is a new extension of the numerical manifold method (NMM). PMM uses a mathematical cover system to describe the motion and deformation of a particle‐based physical domain. By introducing the concept of particle into NMM, PMM takes the advantages of easy topological and contact operations with particles. In this article, the methodology, formulations and implementation of the method are presented, together with modelling examples for validation. It is found that good solutions for both continuous and discontinuous problems are obtained by the new developed PMM. Due to the underlying coupled continuum‐discontinuum property of PMM, it has great potential for modelling of geomechanical problems. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Re‐establishment of soil water repellency after destruction by intense burning in a Mediterranean heathland (SW Spain)     

Antonio Jordán  Félix A. González  Lorena M. Zavala 《水文研究》2010,24(6):736-748

Soil water repellency has been conventionally considered as a fire‐induced effect, but an increasing number of studies have suggested that natural background repellency occurs in many soil types, and many of them have suggested that water repellency can be re‐established over time after being destroyed. An experimental fire was conducted to study changes of the soil surface during the first 18 months following intense burning. The main objectives of this paper are as follows: (1) to investigate in situ water repellency changes at three soil depths (0, 2 and 4 cm) immediately after burning; (2) to evaluate the medium‐term evolution of water repellency under field conditions; and (3) to outline the main hydrological consequences of these changes. Also, different water repellency tests (water drop penetration time, ethanol percentage test (EPT) and contact angle (CA) between water drops and the soil surface) were carried out for comparison purposes. Field experiments showed that soil water repellency was partly destroyed after intense burning. Changes were relatively strong at the soil surface, but diminished progressively with depth. Levels of water repellency were practically re‐established 18 months after burning. This suggests that water repellency in the studied area is not necessarily a consequence of fire, but can instead be a natural attribute. Finally, although limited in time, destruction of soil water repellency has important consequences for runoff flow generation and soil loss rates, and, indirectly, for water quality. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献