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1.
Initial pre-stress finding procedure and structural performance research for Levy cable dome based on linear adjustment theory 总被引：1，自引：1，他引：1
ZHANG Li-mei CHEN Wu-jun DONG Shi-lin 《浙江大学学报(A卷英文版)》2007,8(9):1366-1372
The cable-strut structural system is statically and kinematically indeterminate. The initial pre-stress is a key factor for determining the shape and load carrying capacity. A new numerical algorithm is presented herein for the initial pre-stress finding procedure of complete cable-strut assembly. This method is based on the linear adjustment theory and does not take into account the material behavior. By using this method,the initial pre-stress of the multi self-stress modes can be found easily and the cal-culation process is simplified and efficient also. Finally,the initial pre-stress and structural performances of a particular Levy cable dome are analyzed comprehensively. The algorithm has proven to be efficient and correct,and the numerical results are valuable for practical design of Levy cable dome. 相似文献
2.
The determination of initial equilibrium shapes is a common problem in research work and engineering applications related to membrane structures. Using a general structural analysis framework of the finite particle method （FPM）, this paper presents the first application of the FPM and a recently-developed membrane model to the shape analysis of light weight mem- branes. The FPM is rooted in vector mechanics and physical viewpoints. It discretizes the analyzed domain into a group of parti- cles linked by elements, and the motion of the free particles is directly described by Newton＇s second law while the constrained ones follow the prescribed paths. An efficient physical modeling procedure of handling geometric nonlinearity has been developed to evaluate the particle interaction forces. To achieve the equilibrium shape as fast as possible, an integral-form, explicit time integration scheme has been proposed for solving the equation of motion. The equilibrium shape can be obtained naturally without nonlinear iterative correction and global stiffness matrix integration. Two classical curved surfaces of tension membranes pro- duced under the uniform-stress condition are presented to verify the accuracy and efficiency of the proposed method. 相似文献
3.
In this paper, a meshless method based on moving least squares (MLS) is presented to simulate free surface flows. It is a Lagrangian particle scheme wherein the fluid domain is discretized by a finite number of particles or pointset; therefore, this meshless technique is also called the finite pointset method (FPM). FPM is a numerical approach to solving the incompressible Navier-Stokes equations by applying the projection method. The spatial derivatives appearing in the governing equations of fluid flow are obtained using MLS approximants. The pressure Poisson equation with Neumann boundary condition is handled by an iterative scheme known as the stabilized bi-conjugate gradient method. Three types of benchmark numerical tests, namely, dam-breaking flows, solitary wave propagation, and liquid sloshing of tanks, are adopted to test the accuracy and performance of the proposed meshless approach. The results show that the FPM based on MLS is able to simulate complex free surface flows more efficiently and accurately. 相似文献
4.
TANG Qian ZHU Cai-chao LIAO Xiao-yun LU Bo 《重庆大学学报(英文版)》2005,4(3):125-128
Traditional variation analysis methods are not applicable to non-rigid assemblies due to possible part deformation during the assembly process. This paper presents the use of finite element methods to simulate assembly deformation. The relationship between the parts＇ variation and the variation of the key points in final assembly for quality control is set up by calculating the spring back deformation after assembly. Moreover, the optimization method for non-rigid assembly variations based on finite element analysis is presented. The optimal objective is to reduce the manufacturing cost. The approach is implemented by using ANSYS and MATLAB. The test example shows that the proposed method is effective and applicable. 相似文献
5.
INTRODUCTIONTensionedmembranestructuresaremostsuitableforuseasroofstructureforavarietyofbuildingtypes,astheyprovidealight,elegant,andefficientstructurespanningoveralargeclearspace (Otto,1 973 ) .Examplesincludegymnasi ums,exhibitioncenters ,concertpavilio… 相似文献
6.
研究目的：建立一种适用于理想膜结构可进行高精度褶皱形变模拟的稳定可靠的数值分析技术及方法。创新要点：根据薄壳理论,在向量式混合质点单元方法（VFPEM）薄膜计算理论的基础上,引入弯曲内力分析模型并与其进行组合,发展了一种能够描述膜材面外变形的新型非线性薄壳计算理论,同时给出了将其应用于褶皱形变模拟的关键求解技术。研究方法：1．针对薄壳计算模型中的弯曲内力,利用移动基础架构和逆向刚体运动的概念扣除刚体转动,在只含有节点独立转动自由度的单元变形坐标系下根据虚功原理和平衡条件进行计算;2．借助于薄壳非线性屈曲模拟方法,引入合理的初始扰动作为诱发理想平面膜材中形成褶皱的有效机制;3．采用拟动力显式数值积分技术求解质点运动方程,通过追踪质点平衡位置来获得稳态的褶皱构形。重要结论：采用本文模型和方法可以模拟薄膜结构在面内荷载作用下褶皱的分布模式、具体构形信息及应力状态,计算过程不存在收敛性困难,结果准确。 相似文献
7.
cable方程是神经元动力学中最重要的基本方程之一,而用于描述神经纤维活动的分数阶cable方程能够更好地模拟神经元的动力学行为.文章采用有限体积法离散得到数值逼近格式,求解一维和二维的分数阶cable方程.并用提出的数值方法求解一维和二维情况的两个数值例子,从而说明数值方法的有效性. 相似文献
8.
宋昌永 《浙江大学学报(A卷英文版)》2003,4(6):672-682
In routine design of tensioned membrane st ructures, the membrane is gen erally modeled using space membrane elements and the cables by space cable eleme nts, with no sliding allowed between the membrane and the cables. On the other h and, large deflections are expected and sliding between the membrane and the cab les is inevitable. In the present paper, the general finite element code ABAQUS was employed to investigate the influence of cable sliding on membrane surface o n the structural behavior. Three analysis models were devised to fulfill this pu rpose: (1) The membrane element shares nodes with the cable element; (2) The cab le can slide on the membrane surface freely (without friction) and (3) The cable can slide on the membrane surface, but with friction between the cable and the membrane. The sliding problem is modeled using a surface-based contact algorithm . The results from three analysis models are compared, showing that cable slidin g has only little influence on the structure shape and on the stress distributio ns in the membrane. The main influence of cable sliding may be its effect on the dynamic behavior of tensioned membrane structures. 相似文献
9.
郑达艺 《福建教育学院学报》2008,9(7):104-107
本文考虑空间分数阶对流一扩散方程（即在一个标准对流一扩散方程中,用分数阶导数代替空间二阶导数）混合问题的数值解,采用积分方法（有限体积方法）构造出它们的显式有限差分格式,并证明它们的稳定性和收敛性,最后给出数值例子。 相似文献
10.
INTRODUCTIONDuetothefinitewordlength (FWL)effect,acasualcontrollerimplementationmaydegradethedesignedclosed loopperformanceorevendestabilizethedesignedstableclosed loopsys tem ,ifthecontrollerimplementationstructureisnotcarefullychosen .Theeffectsoffinite… 相似文献
11.
宋雷 《兰州石化职业技术学院学报》2020,20(1):10-12
以李家湾大型滑坡治理为工程背景,采用“锚索+抗滑桩”的综合处治方案,利用有限元软件建立滑坡的数值模型并分析滑坡的塑性区、变形机理和特征,与支护后的坡体水平位移和塑性区云图对比,结果表明该方法是分析和治理大型滑坡的最有效途径之一。结果表明:(1)利用有限元软件建立大型滑坡的值模型,通过研究滑坡的塑性区和变形机理,数值模型结果与实际滑坡变形趋势及变形特征基本吻合;(2)未防护的边坡自坡顶至坡脚形成贯通的塑性区(潜在滑面),设置锚索-抗滑桩防护体系的坡体内未形成贯通塑性区,坡体位移趋于稳定,说明防护措施不但合理而且有效,同时为弥补工程经验不足而利用有限元软件模拟支护大型深部位移滑坡,为工程设计设计依据及经验参考;(3)适当的降低设计人员时间和工作量,该方法可为以后大型滑坡动态设计提供依据和经验。 相似文献
12.
本文采用三维杆系力学分析模型对钢结构框架进行分析,避免了传统的有限元方法要对构件大量划分网格进行计算而导致的计算自由度巨大,计算耗时的缺点。对于杆件单元,本文采用了一种变刚度的杆单元模型,建立了考虑塑性铰分布长度影响的构件单元刚度矩阵。在此基础上对经典的算例模型进行了静力全过程分析。 相似文献
13.
The closed-loop stability issue of finite-precision realizations was investigated for digital controllers implemented in block-floating-point format. The controller coefficient perturbation was analyzed resulting from using finite word length (FWL) block-floating-point representation scheme. A block-floating-point FWL closed-loop stability measure was derived which considers both the dynamic range and precision. To facilitate the design of optimal finite-precision controller realizations, a computationally tractable block-floating-point FWL closed-loop stability measure was then introduced and the method of computing the value of this measure for a given controller realization was developed. The optimal controller realization is defined as the solution that maximizes the corresponding measure, and a numerical optimization approach was adopted to solve the resulting optimal realization problem. A numerical example was used to illustrate the design procedure and to compare the optimal controller realization with the initial realization. 相似文献
14.
Wu-jun CHEN Jin-yu ZHOU Jun-zhao ZHAO 《浙江大学学报(A卷英文版)》2014,(10):813-828
研究目的：减小张力索网结构所求实际预应力与预期预应力之间的差异,并更完善地描述结构力学行为。创新要点：提出张力索网结构全过程分析概念,并用10个状态描述了其物理或分析的状态,以及15个过程揭示了状态间内在的逻辑关系和力学分析理论;在应力释放分析中,采用逆分析法提出了一种用于求解合理零应力状态的迭代计算方法;在预应力成形分析中,为获取预应力状态建立了另一种迭代计算方法。研究方法：应力释放分析主要包括四个步骤：构件无应力长度及伸长量计算,最小范数最小二乘法,数值迭代方法,和执行程序（图4）;预应力成形分析在能量方程的基础上提出了控制方程的显式表达式,并为避免初始刚度矩阵的奇异问题而采用了合理自应力模态（图5）。重要结论：比较本文提出的计算方法与动力松弛法得到的零应力态,发现结果吻合良好,证明计算过程收敛性良好且结果准确。在预应力成形分析中,采用本文迭代方法可以有效消除所求实际预应力与预期预应力之间的差异。此外,提出的所有计算方法都符合模块化流程,具有广泛适用性。 相似文献
15.
对二维热传导方程进行紧交替方向有限差分,该方法在空间方向上具有四阶精度,在时间方向上具有二阶精度。证明了当rx,ry≥1／6时该有限差分解收敛于连续解。数值例子验证了该有限差分法具有高阶精度。 相似文献
16.
以二维弹性力学问题为研究对象,采用常单元和线性非连续元离散边界积分方程,给出系数矩阵计算的精确表达式。数值实施证实此方法的准确性。和有限元相比,边界元的目的非常明确。它还使数值计算的维数降低一阶,所以计算效率也更高。 相似文献
17.
以二维弹性力学问题为研究对象，采用常单元和线性非连续元离散边界积分方程，给出系数矩阵计算的精确表达式。数值实施证实此方法的准确性。和有限元相比，边界元的目的非常明确。它还使数值计算的维数降低一阶，所以计算效率也更高。 相似文献
18.
颗粒材料力学性质的离散元数值模拟 总被引：2，自引：0，他引：2
基于颗粒离散元法对二维颗粒体进行了双轴压缩数值模拟.将离散系统中的变形与连续体中相应的变形联系起来,应用于颗粒离散元方法中平均应力的计算,比较了不同颗粒形状、颗粒间摩擦系数对颗粒体的微观-宏观力学性能的影响,并分别考虑了不同摩擦系数下,颗粒颗粒间接触力的法向分量和切向分量对剪切应力的贡献.本文的计算结果表明颗粒的形状和表面性质对颗粒体的力学性能有显著的影响. 相似文献
19.
本描述了对有需要看重分析的局部区域的电磁场进行有限元分析的复合网格法．这种方法基于通常的有限元方法，有总体分析，局部分析和修正后的总体分析3个基本步骤．在前2步中，利用较粗的网格进行总体分析，得到节点的电势，将其作为后续进一步分析的局部区域的人工边界条件．将这些有了边界条件的局部区域用更精细的网格进行分析，得到更为精确的电势与密度分布．在第3步中，进行修正后的总体分析，通过迭代不断改进结果，直到满足给定的求解精度，得到更好的电势与密度分布的结果．数值实验表明，与通常的有限元方法相比，复合网格法在得到同样求解精度的结果时所耗的计算时间要少得多． 相似文献
20.
The soil-pile-bridge interaction of super-large pile groups is a very complex issue for the design of deep pile group foundations. In this paper, the load distribution on the pile top of a super large bridge foundation and its influential factors are analyzed comprehensively using a three-dimensional elasto-plastic finite element method. The adopted model and its input parameters are firstly verified by comparing the numerical results with the measured data of static loading tests of a single pile. Numerical analysis is then performed to investigate the load distribution and the load-settlement characteristics of super-large pile groups, and the models are verified using centrifuge laboratory model testing data. The mechanism of the interaction between pile groups and soil under different conditions is explored. 相似文献