共查询到16条相似文献,搜索用时 8 毫秒
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接触-碰撞算法是影响动态接触问题数值分析精度的重要因素,发展健壮、精确的局部搜索算法对提高数值模拟精度具有重要意义。为解决点-面接触搜索算法存在的盲区问题,提出了一种基于面-面的局部搜索算法,并发展了相应的接触力计算方法。新的接触算法以面心坐标与特征长度表征接触片,进行预搜索快速排除不会发生接触的潜在接触对;利用主从接触片的投影与侵入深度关系确定接触片间的接触状态;利用等参逆变换解析给出接触点,避免了方程组的迭代求解。典型算例与工程实例计算表明,本文算法消除了接触搜索的盲区,具有很好的健壮性与计算精度。 相似文献
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接触搜索是接触-碰撞问题有限元模拟中最为耗时的部分,高效的接触搜索算法是提高数值分析效率的关键。以面心坐标和特征长度表征接触主片,并引入树包围盒和从节点包围盒的概念,基于八叉树算法发展了一种高效的全局接触搜索方法,计算复杂度为O(Nlog8M),其中N为从节点数,M为接触主片数。程序实现时,通过引入接触预搜索和相邻搜索方式加速搜索速度。本文算法基于PANDA-Impact软件实现,并进行了算例验证分析。结果表明,本文算法具有很好的接触搜索效率与适用性,与桶排序算法相比,当接触复杂且规模较大时,本文算法表现出较大的优势。 相似文献
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岩质圆形隧洞围岩应力场弹塑性新解 总被引:1,自引:0,他引:1
针对动态接触问题的有限元并行计算,提出了一种新的接触算法. 新算法引入局部拉氏
乘子技术来计算接触力. 由于同时考虑了无穿透的接触约束条件和相邻接触对的相互影响,
较之广泛使用的罚参数法,新算法使接触约束条件和系统平衡方程得到更充分的满足. 虽然
为提高接触计算精度而在局部采用了迭代技术,但算法仍然具有较高的效率,且与显式时间
积分方案完全相容. 此外,通过构造专门的区域分解方案,实现了将现有为串行程序开发的
搜索算法平滑移植到并行环境的目标. 数值算例表明,所提出的接触算法具有很好的并行性,
在保证了接触问题并行计算精度的同时,取得了满意的并行效率. 相似文献
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高速铁路的发展满足日益增长的运输需求,同时带来了轮轨型面磨损问题.通过磨耗预测模型对车轮踏面磨耗量进行预测,及时对磨损的车轮踏面进行镟修,对于列车安全运行具有重要意义.通过建立轮对-钢轨三维有限元模型进行接触计算,提出一种基于有限元算法的摩擦功计算方法,即接触节点的摩擦功等于接触摩擦力与节点相对位移的乘积,实现车轮踏面磨耗预测.通过接触计算,发现接触斑中心处的接触摩擦力较大,相对位移量较小,摩擦功较小;将接触斑摩擦功叠加得到车轮踏面摩擦功,数值曲线呈中部大边缘小,且随牵引力的增大而增大;通过动力学计算,发现列车在直线钢轨运行初期的车轮横移量近似呈正态分布;对列车在直线钢轨上运行不同里程的车轮踏面进行磨耗预测,发现预测型面与实测型面具有相同的磨耗趋势,即车轮名义滚动圆处磨耗最严重,且磨耗宽度随列车运行里程增加而逐渐增大;应用有限元法计算磨耗功并预测车轮踏面磨耗,具有一定的研究意义和实用价值. 相似文献
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一类针对高阶单元接触搜索算法:系统搜索算法 总被引:1,自引:1,他引:0
提出一类基于非线笥约束优化理论的高副搜索算法。通用的一些接触搜索算法一般针对低阶单元,它们具有较高的计算效率,但不适应于高阶单元。随着工整中对计算精度要求不断提高,高阶单元逐步被引入到接触问题计算程序中。因此,给出针对亢介单元而人有与现有的低阶算法相比扩计算效率的接触索算法具有现实意义,本文采用系统索方法和非线性约束优化理论,建立一种高阶单元接触点副搜索算法。计算表明,本算法具有较高的计算疚和良好 相似文献
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《International Journal of Solids and Structures》2005,42(23):6059-6070
A local basis algorithm for searching natural neighbours in Natural Element Method (NEM) is presented for solving the elasticity problems in this paper. Comparison with the global sweep algorithm used in natural element method or Natural Neighbour Method (NNM) for searching natural neighbours, the proposed algorithm is more expedient and convenient in the constructions and computation of natural neighbour interpolations. In the proposed NEM based on local search, the Laplace (non-sibson) interpolations are constructed with respect to the natural neighbour nodes of the given point which have been locally defined. The shape functions from the Laplace approximations have the delta function property and the Laplace interpolants are strictly linear between adjacent nodes, which facilitate imposition of essential boundary conditions and treatment of material discontinuity with ease as it is in the conventional finite element method. The Laplace interpolants derived from the local algorithm and the global algorithm in NEM are identical because of the uniqueness of the Voronoi diagram. Numerical results and convergence studies also show that the present NEM based on local search algorithm possesses the same accuracy and rate of convergence as they are in previous NEM. 相似文献
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A contact searching algorithm for contact-impact problems 总被引:5,自引:0,他引:5
A new contact searching algorithm for contact-impact systems is proposed in this paper. In terms of the cell structure and
the linked-list, this algorithm solves the problem of sorting and searching contacts in three dimensions by transforming it
to a retrieving process from two one-dimensional arrays, and binary searching is no longer required. Using this algorithm,
the cost of contact searching is reduced to the order ofO(N) instead ofO(Nlog2
N) for traditional ones, whereN is the node number in the system. Moreover, this algorithm can handle contact systems with arbitrary mesh layouts. Due to
the simplicity of this algorithm it can be easily implemented in a dynamic explicit finite element program. Our numerical
experimental result shows that this algorithm is reliable and efficient for contact searching of three dimensional systems.
The project supported by the National Natural Science Foundation of China (59875045), and the State Key Laboratory of Automobile
Safety and Energy Saving (K9705) 相似文献
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Ines Lopez Arteaga 《International Journal of Solids and Structures》2011,48(25-26):3462-3470
A new formulation to determine the unit impulse response (Green’s) functions of a loaded rotating tyre in the vehicle-fixed (Eulerian) reference frame for tyre/road noise predictions is presented. The proposed formulation makes use of the set of eigenfrequencies and eigenmodes for the statically loaded tyre obtained from a finite element (FE) model of the tyre. A closed-form expression for the Green’s functions of a rotating tyre in the Eulerian reference system as a function of the eigenfrequencies and eigenmodes of the statically loaded tyre is found. Non-linear effects during loading are accounted for in the FE model, while the frequency shift due to the rotational velocity is included in the calculation of the Green’s functions. In the literature on tyre/road noise these functions are generally used to determine the tyre response during tyre/road contact calculations. The presented formulation opens the possibility to solve the contact problem directly in the Eulerian reference frame and to include local tyre softening due to non-linear effects while keeping the computational advantage of describing the tyre dynamics as a set of impulse response functions. The advantage of obtaining the Green’s functions in the Eulerian reference system is that only the Green’s functions corresponding to the potential contact zone need to be determined, which significantly reduces the computational cost of solving the tyre/road contact and since the mesh is fixed in space, a finer mesh can be used for the potential contact zone, improving the accuracy of the contact force calculations. Although these effects might be less pronounced if a more accurate tyre model is used, it is found that using the Green’s functions of the loaded tyre in a contact force calculation leads to smaller forces than in the unloaded case, lower frequencies are present in the response and they decrease faster as the rotational velocity increases. 相似文献
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摩擦接触问题是计算力学领域最具挑战性的问题之一,接触系统的泛函具有非线性、非光滑的特点,导致接触算法的收敛性与精确性难以保证.因此将比例边界等几何分析(scaled boundary isogeometric analysis,SBIGA)与B可微方程组(B dierential equation,BDE)相结合,提出了求解二维摩擦接触问题的比例边界等几何B可微方程组方法.在比例边界等几何坐标变换的基础上,通过虚功原理推导了关于边界控制点变量的接触平衡方程,表示成B可微方程组形式的接触条件可被严格满足,求解B可微方程组的算法的收敛性有理论保证.此比例边界等几何B可微方程组方法(SBIGA-BDE)只需在接触体边界进行等几何离散,使问题降低一维,能精确描述接触边界,并可通过节点插入算法进行真实接触区域的识别.此外,由于几何建模和数值分析使用相同的基函数,节约了划分网格的时间.以赫兹接触问题和悬臂梁摩擦接触问题为例,通过与解析解及数值计算软件ANSYS计算结果进行对比,验证了该方法求解二维摩擦接触问题的有效性及高精度等特点. 相似文献
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针对于多目标在机载多普勒盲区测量数据丢失下的跟踪问题,提出了一种鲁棒无偏转换自适应门限的CPHD(Robust Unbiased Converted Measurements-Adaptive Gating-Cardinalized Probability Hypothesis Density,RUCM-AG-CPHD)算法。该算法首先对目标测量信息进行无偏转换,并将无偏转换得到的噪声协方差矩阵做解耦;然后设计增益调节矩阵提高滤波器在目标量测数据丢失下的鲁棒性;最后采用自适应门限去除不相关的量测信息,同时保证检测到新出现的目标,从而有效地降低了算法的计算复杂度。仿真结果表明该算法的有效性和可行性,可以更加准确的估计出目标在盲区内测量信息丢失下的目标个数和状态,且计算量相对于传统的CPHD算法减少了8.6%。 相似文献