共查询到20条相似文献,搜索用时 140 毫秒
1.
本文提出一种求解平面接触应力最大值的光弹性—数值计算组合方法,仅从光弹性等差线上采集实验数据,然后用牛顿—拉斐逊技术与最小二乘法相结合计算出结果。文中推导了控制方程,阐述了方法,研究了实验数据取值区域、取值个数以及接触长度测试误差等因素的影响。用两类平面接触问题作为应用实例,结果符合工程要求的精度。 相似文献
2.
3.
用数值计算方法对2MeV注入器上的外加螺线管线圈进行了设计和计算,最后提出在阳极杆部分另加外一反向线圈,得到了较佳结果,同时也给出了整个区域的磁场分布和在磁场作用下的电子束传输的束包络轨迹及束流参数等。 相似文献
4.
5.
对于已含初始裂纹平台管节点的寿命预测很大程度上依靠应力强度因子的精确值,而复杂载荷条件下的节点应力强度因子的计算尚无参数方程直接确定。本文提出了一种含表面裂纹的K节点的有限元网格产生方法,即把整个K节点划分为几个子区域,每个子区域的网格具有不同类型的单元和不同的密度。这种方法在控制网格密度,尤其是控制沿着裂纹边缘单元的边长比方面有其独特的优越性,当所有子区域的网格自动产生后,容易得到整个结构的有限元模型。同时用J积分和位移外推插值法分别计算了一个K型节点沿着裂纹前缘的应力强度因子值,发现:试验得到的应力强度因子值和提出的模型计算结果非常吻合,证明了所提有限元模型的准确性。 相似文献
6.
7.
对于已含初始裂纹平台管节点的寿命预测很大程度上依靠应力强度因子的精确值,而复杂载荷条件下的节点应力强度因子的计算尚无参数方程直接确定.本文提出了一种含表面裂纹的K节点的有限元网格产生方法,即把整个K节点划分为几个子区域,每个子区域的网格具有不同类型的单元和不同的密度.这种方法在控制网格密度,尤其是控制沿着裂纹边缘单元的边长比方面有其独特的优越性,当所有子区域的网格自动产生后,容易得到整个结构的有限元模型.同时用J积分和位移外推插值法分别计算了一个K型节点沿着裂纹前缘的应力强度因子值,发现:试验得到的应力强度因子值和提出的模型计算结果非常吻合,证明了所提有限元模型的准确性. 相似文献
8.
溅射MoS_2膜显微结构的生长可分为与膜厚有关的三个阶段:(1)成核时形成突起,(2)等轴转化区域和(3)针状结构。每个生长阶段是依据微晶的大小、形状和排列方向来表征的。有效润滑膜的厚度是依据滑动试验时显微结构生长阶段来确定的,此膜在柱状结构区域有破裂的倾向,实际润滑由保留下的0.18~0.22微米厚的膜来完成。为了评价溅射MoS_2膜的完整性还提出了一种直观的方法。润滑性能是用擦抹前后的光学性能变化来识别的,微晶的取向导致所观察到的光学上反射性的变化。 相似文献
9.
10.
弹性半空间中相邻两结构在SH波作用下的动力响应 总被引:3,自引:0,他引:3
1 问题的提出与求解考虑图1所示的圆筒地铁结构.设两个相邻圆筒沿oz 轴方向为无限长,其纵向轴线平行于地表,并具有相同的横截面,相同的埋置深度和由相同的材料构成.现论述在SH 波作用下如何采用边界元和波函数展开相结合的方法来求解其动力响应.设将半空间分成三个区域:R_1(包括R_1~Ⅰ和R_1~Ⅱ,分别表示左右圆筒),R_2和R_3.对区域R_3用波函数展开法求解,区域R_1和R_2则用边界元法求解,通过区域之间的位移、应力连续条件,求出各边界上的位移和应力,从而通过边界上的位移和应力值,求解各域内任意点的位移和应力. 相似文献
11.
对于考虑软土结构性的高度非线性弹塑性本构模型,在采用Newton-CPPM隐式算法对模型进行数值实现的过程中容易出现Jacobian矩阵奇异和不收敛问题。为此,本文提出了两种改进隐式算法。考虑到Newton-CPPM隐式算法是局部收敛性算法,因此引入大范围收敛的同伦延拓算法对Newton-CPPM算法的迭代初值进行改进,形成了同伦-Newton-CPPM算法。考虑到Newton-CPPM隐式算法单个迭代步的计算量过大,因此借鉴显式算法的思想提出一种两阶段迭代算法,第一阶段先求出一致性参数,第二阶段采用类似于显示算法的方法进行回代得出状态变量的值。然后,以考虑软土结构性的SANICLAY模型为例,从弹塑性本构模型的组成和算法的特点两个角度分析了引起Jacobian矩阵奇异和不收敛问题的原因,并且在单单元计算的基础上,对全显式算法、传统隐式算法和两种改进隐式算法在计算收敛性、计算精度和计算效率方面进行了对比。最后,将同伦-Newton-CPPM算法和传统隐式算法用于地基承载力多单元计算中,结果表明该算法能够有效地解决Jacobian矩阵奇异和不收敛问题。 相似文献
12.
K. Kanaka Durga 《International Journal of Non》2004,39(2):233-245
Full approximate storage (FAS) multigrid algorithm is the most commonly used multigrid algorithm for non-linear equations. The algorithm initially developed for steady-state equations was later extended to obtain steady-state solutions employing unsteady equations. In extending the FAS algorithm for the steady-state non-linear equations to unsteady non-linear equations, the FAS algorithm does not to take into account that the governing equations are typically linearized in time before they are solved. Thus, there is a scope to develop a new multigrid algorithm to apply the multigrid technique to the equations linearized in time. In the present work, such an algorithm is developed exploring this possibility and is implemented for two-dimensional incompressible and compressible flows coupled with explicit time marching procedures. The results of the new algorithm compare favourably with those of the FAS multigrid method and single grid. 相似文献
13.
回顾了有限元并行计算发展的历史,阐述了微机网络并行计算环境的意义,给出了基于微机网络并行环境的杆壳组合结构动力分析并行算法,该算法包括杆壳组合结构总刚度矩阵和总质量矩阵的并行计算以及求解广义特征值问题的并行子空间迭代法的并行计算,在多台微机上安装PVM.使用Linux操作系统.构成分布式微机网络并行计算环境,将上述算法用于某型号飞机机翼及某型号挂架动力特性的并行计算,在该并行环境下的教值试验表明所给算法是非常有效的。 相似文献
14.
15.
Recently a lot of methods have been presented for solving optimization problems. In this paper, we are trying to propose a new hybrid algorithm for solving these kinds of problem. The proposed algorithm is based on chaotic artificial bee colony and chaotic simulated annealing, CABC–CSA. The chaotic artificial bee colony finds new locations chaotically. Actually, the proposed algorithm provides a combination of local search accuracy of simulated annealing and the ability of global search of artificial bee colony. Furthermore, we used a different method for generating the initial population. The proposed algorithm is validated using 12 benchmark functions. The results are compared with those of the artificial bees’ algorithm, the hybrid algorithm of artificial bee colony and simulated annealing and particle swarm optimization. Simulation results show the efficiency of the proposed algorithm. 相似文献
16.
A new numerical algorithm for computation of phase response curves of stable limit cycle oscillators is proposed. The idea
of the algorithm originates from a direct method that is based on computation of the oscillator response to short finite pulses
delivered at different phases of oscillations. Here we adapt the direct method to the case of infinitesimal perturbations
and compare our algorithm with the standard algorithm based on the backward integration of the adjoint equations. In contrast
to the standard algorithm, our algorithm does not require any backward integration and it is easier to program since a necessity
of numerical interpolation for the Jacobian matrix is avoided. In addition, we demonstrate by examples that our algorithm
is faster than the standard algorithm and this advantage is especially notable for weakly stable limit cycle oscillators. 相似文献
17.
针对Hadoop MapReduce框架实现迭代算法效率不高的问题,提出了基于Spark RDDs(Resilient Distributed Datasets)的大规模线性有限元并行算法,探索在云平台上有效地实现迭代算法。在Hadoop+Spark实验室集群上,通过空间桁架进行算例验证,并与基于Hadoop MapReduce的线性有限元并行算法进行性能比较。结果表明,在本文搭建的集群上,基于RDDs的并行算法能求解15000000个自由度的空间桁架问题,远大于Hadoop平台上的3000000个自由度;对于小模型,Spark可获得200倍以上的加速比,对于大模型,获得7~8倍加速比。 相似文献
18.
2008年,本文作者和陶文铨等提出了一种用于速度和压力耦合求解的高效稳定压力修正全隐算法IDEAL,该算法通过在每个迭代层次上对压力方程进行两次内迭代计算,完全克服了SIMPLE算法的两个假设,充分满足了速度和压力之间的耦合,从而大大提高了计算的收敛性和健壮性.为了进一步实现IDEAL算法的推广应用,本文基于三维倾斜方腔顶盖驱动流动,研究了IDEAL算法在不同网格扭曲率下的求解特性.研究发现,在不同网格扭曲率下,IDEAL算法的健壮性和收敛性均优于SIMPLE算法,特别在高网格扭曲率情况下,IDEAL算法求解性能更加优于SIMPLE算法.在不同网格扭曲率下,IDEAL算法健壮性保持不变,几乎可以在任意速度亚松弛因子下获得收敛的解,同时IDEAL算法最短计算耗时较SIMPLE算法减少了56%~89%,验证了IDEAL算法的优越性. 相似文献
19.
An algorithm for the bench calibration of strapdown inertial navigation systems is studied. This algorithm was developed at
the Moscow Institute of Electromechanics and Automatics. A mathematical model for the calibration process is constructed.
A method for representing the original calibration problem in the form of a standard estimation problem is proposed with the
aid of a so-called “telescopic” system. On the basis of the original algorithm, a new calibration algorithm is constructed;
this new algorithm allows one to improve the estimation accuracy for the parameters of accelerometer and gyroscope units.
The maximum attainable estimation accuracy for these parameters is determined. 相似文献
20.
An algorithm for the inverse of a general tridiagonal matrix is presented. For a tridiagonal matrix having the Doolittle factorization, an inversion algorithm is established. The algorithm is then generalized to deal with a general tridiagonal matrix without any restriction. Comparison with other methods is provided, indicating low computational complexity of the proposed algorithm, and its applicability to general tridiagonal matrices. 相似文献