首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 140 毫秒
1.
余天堂  姜弘道 《工程力学》1999,1(A01):108-116
基于网络和PVM的分布式并行环境的有限元并行计算是有限元并行分析的一个重要方向,此种并行计算方法具有投资少,灵活性强和得到的加速比高等优点,本文给出了基于网络和宾分布式并行环境的有限元分析的并行程序设计方法。  相似文献   

2.
姜新佩  王书报 《工程力学》1998,(A01):483-488
本文用矩阵位移法研究了弹性结点结构的内力计算问题,建立了弹性结点结构情况下的单元刚度矩阵,给出了此情况下等效荷载的确定方法,举例说明了矩阵位移法计算弹性结点结构内力的方法过程。  相似文献   

3.
给出了考虑剪力滞后及剪切变形效应条件下,复合材料薄壁层合箱梁静力行为控制微分方程组的初参数解。以此为基础,推导出了层合箱梁单元的刚度矩阵和等效结点荷载列阵,从而使薄壁层合箱梁的剪力滞、剪切变形效应分析方便地纳入了工程中广泛应用的矩阵位移法程序系统,为复合材料连续层合箱梁等复杂结构的强度及刚度分析提供了有效的计算手段。  相似文献   

4.
整体式反应位移法是目前常用的地下结构抗震实用分析方法,但在求解等效输入地震荷载的过程中,需对自由场土层模型中土-结构交界面所包围的所有土体单元施加自由场惯性力,处理过程相对复杂。该文基于有限元离散模型,从理论上证明了整体式反应位移法中由结构周边应力引起的等效地震荷载可通过仅由一层土体单元构成的子结构模型的一次静力分析获得,由此提出了一种基于土体内部子结构的地下结构整体式反应位移法,即改进方法一;进一步论证了改进方法一中内部土体子结构的惯性力对等效地震荷载的影响可以忽略,在此基础上提出地下结构整体式反应位移法的改进方法二,该方法避免了土层介质自由场惯性力的计算与施加,从而有效简化了整体式反应位移法的实施流程。通过与传统整体式反应位移法的对比分析,验证了该文改进方法具有良好的计算精度,可用于地铁车站、地下隧道等地下结构的地震反应分析与抗震性能研究。  相似文献   

5.
陈璞  肖梃松 《工程力学》1998,(A01):31-38
本文讨论了工程有限元分析中预条件共轭梯度法的实现,并分析了此方法的优缺点,为了提高整体的效率和改进LDL预优矩阵的稳定性,本文提出了双参数松弛方案和按元素的绝对值确定矩阵L的分解方案,双参数松弛方案基本上解决了LDL预优矩阵的稳定性问题,按元素的绝对值大确定矩阵L的分解方案可以改善LDL预优矩阵的稳定性,并提高预条件共轭梯度法在整体效率。  相似文献   

6.
基于局部静力测试的约束子结构修正法   总被引:1,自引:1,他引:0       下载免费PDF全文
针对局部子结构为修正对象的情况,提出只利用整体结构中局部子结构部分的静力位移即可精确修正子结构模型的约束子结构方法。首先利用静力测试获得局部子结构所对应的局部柔度矩阵,通过在子结构边界处施加虚拟固定支座,把子结构从整体结构中隔离出来成为约束子结构,同时构造出该约束子结构相应的柔度矩阵。然后利用柔度扰动新方法优化修正约束子结构,即等同于修正相应的子结构模型,从而可对该子结构的损伤状况作出评估。以一个平面桁架结构为例对所提方法进行了验证。结果表明,所提方法合理可靠,计算简单快捷且精度良好。  相似文献   

7.
针对共轭梯度法求解线性方程组Ax=b,提出一种预处理思想。基于次思想,首先给出预处理矩阵,然后求解预处理线性方程组,再使用共轭梯度法求解。最后通过几个数值试验,与直接使用共轭梯度法求解线性方程组相比较,本文的方法提高了收敛速度。  相似文献   

8.
余岭  陈震 《振动与冲击》2007,26(12):6-9,59
对桥梁移动荷载识别方程不适定问题进行研究,提出采用预处理共轭梯度法(PCGM)求解超定方程组,通过选择不同的预优矩阵,改善和解决超定方程组的欠秩和病态问题。为验证基于PCGM方法的现场实用性,设计制作了车桥试验模型,通过试验采集到的桥梁弯矩响应数据识别桥面移动荷载。比较桥梁模态数、预处理共轭梯度法迭代次数、桥面粗糙度、车辆重量以及测点选择对识别结果精度的影响后,研究结果表明:基于PCGM方法能够很好地识别车辆荷载,收敛较快且能较好改善荷载识别方程的不适定性。  相似文献   

9.
张力膜结构初始形态分析的曲面四边形单元   总被引:3,自引:0,他引:3  
纵智育  辛克贵  王珊 《工程力学》2006,23(3):32-36,26
张力膜结构的初始形状不能随意选择,它必须符合平衡条件和建筑使用要求。根据几何非线性有限元理论,提出张力膜结构初始形态分析的8结点曲面四边形等参单元。通过建立曲线坐标,在应变的线性部分引入法向位移及单元曲率和扭率的影响,推导了张力膜结构的单元刚度矩阵和结点力列阵。采用完全的Newton-Raphson迭代法求解非线性方程组。数值算例表明该单元是一种高效、稳定和可靠的单元。  相似文献   

10.
三维有限元并行EBE方法   总被引:6,自引:1,他引:6  
采用Jacobi预处理,推导了基于EBE方法的预处理共轭梯度算法,给出了有限元EBE方法在分布存储并行机上的计算过程,可以实现整个三维有限元计算过程的并行化。编制了三维有限元求解的PFEM(ParallelFiniteElementMethod)程序,并在网络机群系统上实现。采用矩形截面悬臂梁的算例,对PFEM程序进行了数值测试,对串行计算和并行计算的效率进行了分析,最后将PFEM程序应用于二滩拱坝-地基系统的三维有限元数值计算中。结果表明,三维有限元EBE算法在求解过程中不需要集成整体刚度矩阵,有效地减少了对内存的需求,具有很好的并行性,可以有效地进行三维复杂结构的大规模数值分析。  相似文献   

11.
This paper presents our new development of parallel finite element algorithms for elastic–plastic problems. The proposed method is based on dividing the original structure under consideration into a number of substructures which are treated as isolated finite element models via the interface conditions. Throughout the analysis, each processor stores only the information relevant to its substructure and generates the local stiffness matrix. A parallel substructure oriented preconditioned conjugate gradient method, which is combined with MR smoothing and diagonal storage scheme are employed to solve linear systems of equations. After having obtained the displacements of the problem under consideration, a substepping scheme is used to integrate elastic–plastic stress–strain relations. The procedure outlined controls the error of the computed stress by choosing each substep size automatically according to a prescribed tolerance. The combination of these algorithms shows a good speedup when increasing the number of processors and the effective solution of 3D elastic–plastic problems whose size is much too large for a single workstation becomes possible.  相似文献   

12.
 This work presents a novel iterative approach for mesh partitioning optimization to promote the efficiency of parallel nonlinear dynamic finite element analysis with the direct substructure method, which involves static condensation of substructures' internal degrees of freedom. The proposed approach includes four major phases – initial partitioning, substructure workload prediction, element weights tuning, and partitioning results adjustment. The final three phases are performed iteratively until the workloads among the substructures are balanced reasonably. A substructure workload predictor that considers the sparsity and ordering of the substructure matrix is used in the proposed approach. Several numerical experiments conducted herein reveal that the proposed iterative mesh partitioning optimization often results in a superior workload balance among substructures and reduces the total elapsed time of the corresponding parallel nonlinear dynamic finite element analysis. Received 22 August 2001 / Accepted 20 January 2002  相似文献   

13.
This paper discusses the implementation aspects and our experiences towards a data parallel explicit self-starting finite element transient methodology with emphasis on the Connection Machine (CM-5) for linear and non-linear computational structural dynamic applications involving structured and unstructured grids. The parallel implementation criteria that influence the efficiency of an algorithm include the amount of communication, communication routing, and load balancing. To provide simplicity, high level of accuracy, and to retain the generality of the finite element implementation for both linear and non-linear transient explicit problems on a data parallel computer which permit optimum amount of communications, we implemented the present self-starting dynamic formulations (in comparison to the traditional approaches) based on nodal displacements, nodal velocities, and elemental stresses on the CM-5. Data parallel language CMFortran is employed with virtual processor constructs and with:SERIAL and:PARALLEL layout directives for arrays. The communications via the present approach involve only one gather operation (extraction of element nodal displacements or velocities from global displacement vector) and one scatter operation (dispersion of element forces onto global force vector) for each time step. These gather and scatter operations are implemented using the Connection Machine Scientific Software Library communication primitives for both structured and unstructured finite element meshes. The implementation aspects of the present self-starting formulations for linear and elastoplastic applications on serial and data parallel machines are discussed. Numerical test models for linear and non-linear one-dimensional applications and a two-dimensional unstructured finite element mesh are then illustrated and their performance studies are discussed.  相似文献   

14.
Boundary element and finite element combination analysis on parallel schemes are improved in this paper. The conjugate gradient method (CG method) is introduced for renewal of unknowns on the combination boundary in place of the Schwarz method previously used, which makes it possible to determine a parameter required in the renewal iteration automatically. Further, the condense method is employed for higher efficiency of solution by reducing the number of degree of freedoms in both equations for the finite element and boundary element domains. Comparison of the present algorithm with the previous one in some numerical examples shows marked improvement in computational efficiency.  相似文献   

15.
胡宁 《工程力学》1992,9(1):65-71
本文提出了一种求解大型结构动力方程的新的并行直接积分方法。该方法在L.Brusa和L.Nigro提出的一步(one-step)直接积分方法的基础上,引进并行运算步骤。并行运算步骤是通过将动力积分方程子结构化,同时进行组集和凝聚实现的。该方法在西安交通大学ELXSI-6400并行机上程序实现,计算结果表明能有效地求解大型结构有限元动力方程的并行直接积分方法。  相似文献   

16.
部分观测下基于子结构的大型结构损伤诊断法   总被引:1,自引:0,他引:1  
雷鹰  毛亦可 《工程力学》2012,(7):180-185
该文提出一种适用于大型结构在激励与响应部分观测情况下进行结构损伤诊断的方法。基于有限元模型,大型结构被划分成若干个子结构。相邻子结构间的作用,视为对子结构的"附加未知激励"。依次采用扩展卡尔曼估计和最小二乘估计识别扩展状态向量和未知外部激励,在子结构界面响应未观测的情况下,对各子结构的单元动力参数分别进行识别,并以追踪子结构内单元结构参数的变化,例如单元刚度的退化,对大型结构的局部损伤进行诊断。通过一个较大型的平面桁架桥的损伤识别数值算例,证实了该方法的可行性。与其他方法相比,提出的方法减少了对结构响应观测的要求。  相似文献   

17.
The storage requirements and performance consequences of a few different data parallel implementations of the finite element method for domains discretized by three-dimensional brick elements are reviewed. Letting a processor represent a nodal point per unassembled finite element yields a concurrency that may be one to two orders of magnitude higher for common elements than if a processor represents an unassembled finite element. The former representation also allows for higher order elements with a limited amount of storage per processor. A totally parallel stiffness matrix generation algorithm is presented. The equilibrium equations are solved by a conjugate gradient method with diagonal scaling. The results from several simulations designed to show the dependence of the number of iterations to convergence upon the Poisson ratio, the finite element discretization and the element order are reported. The domain was discretized by three-dimensional Lagrange elements in all cases. The number of iterations to convergence increases with the Poisson ratio. Increasing the number of elements in one special dimension increases the number of iterations to convergence, linearly. Increasing the element order p in one spatial dimension increases the number of iterations to convergence as pα, where α is 1·4–1·5 for the model problems.  相似文献   

18.
A new procedure for implementing the stiffness derivative method for evaluating stress intensity factor is proposed. Unlike the original approach, the proposed method involves the nodal displacements and strain energies of the crack-tip elements only. The undesirable need to extract element stiffness matrices in the original approach is removed. The proposed approach can be easily implemented using commercial finite element packages.  相似文献   

19.
The paper presents an algorithm for the solution of problems that are discretized partly by the finite element method and partly by the boundary element method. The algorithm is based on the conjugate gradient method with preconditioning by an auxiliary conjugate projector that reduces the iterations to the interface. A numerical example is presented to illustrate the performance of the algorithm. The method may prove useful also in parallel environment.  相似文献   

20.
A high performance implementation is presented for three kernel routines commonly found in element-byelement preconditioned conjugate gradient finite element codes. These routines include forming the element stiffness matrices and loading vectors, or in the case of a non-linear problem, element residual vectors; and routines for applying element matrix–vector products. The present study considers tensor product elements of arbitrary mapping in 2-D, although the generalization to triangular elements and serendipity elements is straightforward. The implementation presented is most appropriate for high p type finite element methods, where the element matrices are relatively large and dense. This results in a set of high performance kernels for superscalar architectures, which otherwise may be memory bandwidth limited. Performance studies are presented for a representative superscalar microprocessor, the Intel i860. As these types of microprocessors are at the heart of modern workstations as well as several parallel supercomputing systems, this work is relevant across a variety of platforms. The resulting kernels yield both high performance on a variety of sequential architectures as well as a high degree of code portability through the basic linear algebra subprograms mechanism.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号