共查询到19条相似文献,搜索用时 149 毫秒
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为了提高求解断裂参数的效率和精度,将虚拟裂纹闭合法(Virtual Crack Closure Technique)与光滑节点域有限元方法(Node-Based Smoothed Finite Element Method)相结合,提出了SFEM-VCCT方法.基于三角形单元的光滑节点域有限元方法,对二维含中心斜裂纹受拉伸矩形板的断裂参数进行求解.通过不同的单元离散数量与FEM-VCCT做了比较.数值算例结果表明,SFEM-VCCT改善了FEM-VCCT刚度“过硬”的缺点,精度高于FEM-VCCT,并且对网格尺寸要求低、裂纹尖端单元不需要特殊处理、求解简单方便,具有广阔的应用前景. 相似文献
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三维势流场的比例边界有限元求解方法 总被引:3,自引:0,他引:3
比例边界有限元法(SBFEM)是线性偏微分方程的一种新的数值求解方法。该方法只对计算域边界利用Galerkin方法进行数值离散,相对于有限元方法(FEM)减少了一个空间坐标的维数,而在减少的空间坐标方向利用解析方法进行求解;相对于边界元法(BEM),比例边界有限元方法不需要基本解,避免了奇异积分的计算,所以它结合了有限元和边界元方法的优点。本文建立了利用比例边界有限元法求解三维Laplace方程的数值模型并用于计算三维物体周围的水流场,将计算结果与解析解和边界元方法进行了对比,结果表明此方法可以很好地模拟水流场,且具有较高的计算精度。 相似文献
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比例边界等几何分析方法Ⅰ:波导本征问题 总被引:2,自引:0,他引:2
提出比例边界等几何方法 (scaled boundary isogeometric analysis, SBIGA), 并用以求解波导本征值问题. 在比例边界等几何坐标变换的基础上, 利用加权余量法将控制偏微分方程进行离散处理, 半弱化为关于边界控制点变量的二阶常微分方程, 即 TE 波或 TM 波波导的比例边界等几何分析的频域方程以及波导动刚度方程, 同时利用连分式求解波导动刚度矩阵. 通过引入辅助变量进一步得出波导本征方程. 该方法只需在求解域的边界上进行等几何离散, 使问题降低一维, 计算工作量大为节约, 并且由于边界的等几何离散, 使得解的精度更高, 进一步节省求解自由度. 以矩形和 L 形波导的本征问题分析为例, 通过与解析解和其他数值方法比较, 结果表明该方法具有精度高、计算工作量小的优点. 相似文献
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不连续Reissner矩形板的自由振动 总被引:1,自引:0,他引:1
用分区加权残值法研究Ressner矩形板在几何形状,边界条件等有突变时的自由振动问题,将研究对象按照结构几何形状和边界条件的具体情况划分为若干子域,在每个子域内用不同的试函数代入该域的内的控制方程到内部残值,并代入板的边界条件和各子域的协调条件得到边界残值和连续性残值,然后用最小二乘法消除残值,得到特征方程,文中讨论了该方法的收敛性和计算精度,求解了开孔矩形板的固有频率,并与已有结果进行了比较,结果表明:?该方法收敛性好,精度较高,适用范围广。 相似文献
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以连续介质力学和弹性波动理论为基础,在Laplace积分变换域内推导了地震波激励下土与结构的多子域边界积分-边界单元方程,采用了一系列特殊的数值积分处理技术;根据随机过程原理以及基于基岩面运动的地震力理论建立了随机地震波数学模型;提出了一种新的Laplace数值反演变换方法,并引入了最小标准误差原理,实现了Laplace反演变换中各控制参数的最优化关联值,使计算精度与计算速度均有较大的改进和提高;编制了相应的计算机程序,并通过几个土-结构的地震响应算例分析,证实了方法和程序的可行性与有效性。 相似文献
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提出比例边界等几何分析SBIGA(Scaled Boundary IsoGeometric Analysis)方法来求解热传导问题。SBIGA兼具比例边界有限元和等几何分析的优势,特别适用于求解包含无限域和奇异物理场的问题。该方法造型十分方便,在径向具有半解析性质,仅需在计算域边界上用NURBS基函数自然离散,为实现CAD/CAE无缝融合提供了新的途径,大大节约前处理和计算耗时。此外,SBIGA无需进一步与CAD系统数据交换就可以保型细分。三个基准算例证明了其在热传导分析中的有效性。与传统比例边界有限元相比,SBIGA模型消除了几何模型误差,并显示出更高的计算精度和收敛速度。 相似文献
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A hybrid numerical scheme combining the Laplace transform and control-volume methods is presented to solve nonlinear two-dimensional
phase-change problems with the irregular geometry. The Laplace transform method is applied to deal with the time domain, and
then the control-volume method is used to discretize the transformed system in the space domain. Nonlinear terms induced by
the temperature-dependent thermal properties are linearized by using the Taylor series approximation. Control-volume meshes
in the solid and liquid regions during simulations are generated by using the discrete transfinite mapping method. The location
of the phase-change interface and the isothermal distributions are determined. Comparison of these results with previous results
shows that the present numerical scheme has good accuracy for two-dimensional phase-change problems.
Received on 17 October 1996 相似文献
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Based on the well-known Durbin method, an efficient numerical method was developed for the inversion of the two-sided Laplace transform. The accuracy of the method was verified using examples. As an application of the method, transient elastic waves propagating in a two-layered piezoelectric medium subjected to anti-plane concentrated loading and in-plane electric displacement loading were investigated. One-sided and two-sided Laplace transforms were applied to determine the shear stresses and electric displacements in the double Laplace transform domain. Subsequently, the Durbin method for one-sided Laplace transform inversion and the extended Durbin method for two-sided Laplace transform inversion were used to implement the numerical inversions. Additionally, the numerical results of the transient stresses and electric displacements were evaluated and discussed. It showed that the arrival time of transient waves satisfies physical phenomena, and the transient solution oscillates near the static solution and rapidly approximates the static solution. 相似文献
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插值型重构核粒子法的形函数具有离散点插值特性和不低于核函数的高阶光滑性,因而不仅可以直接施加本质边界条件,同时也保证了较高的计算精度.本文将弹性动力学方程作拉氏变换后,在变换域内用插值型重构核粒子法求解,最后再借助Durbin数值反演方法求得时间域的解.针对典型的弹性动力学问题,给出了插值型重构核粒子法的数值算例,并验证了本文方法的有效性. 相似文献
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A numerical method is presented in this paper for the solution of flow field in marine gas turbine air intake filtration channel.
The flow field was successfully calculated by this method, and aerodynamic characteristics were obtained for various types
of filtration channels. This work is expected to be of practical importance for the design of such filters. Upstream difference
was adopted to discretize the non-conservative type N-S equation for two-dimensional, time-dependnet, viscous and incompressible
flow, and the stability, convergence, accuracy and artificial viscosity of the resulting difference equation were examined.
This equation can be used to calculate viscous flows with Reynolds number up to tens of thousands. Also presented in this
paper is a calculation method for treating wall vortex at boundary inflection points. Careful studies show that calculation
based on the difference equational and wall vortex treatment proposed here are in good agreement with experimental results. 相似文献
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Y. MATSUDA C. SHAO K. MATSUMOTO H. FUJITA I. ICHIKAWA 《International Journal of Computational Fluid Dynamics》2013,27(3-4):323-330
In our previous research, the modified Galerkin method was proposed as one of the most efficient methods for the analyses of convection-diffusion problems and two-dimensional viscous fluid flow problems. In this modified Galerkin method, the inertia term is considered explicitly, so only the symmetrical matrixes appear. Then an artificial viscosity is introduced through an error analysis approach to improve its accuracy and stability. In this paper, we proposed a new finite element formulation for three-dimensional incompressible viscous fluid flow analysis. This formulation (‘MS’ algorithm and ‘MSR’ algorithm) is based on the modified Galerkin method coupled with the Semi-Implicit Method for Pressure-Linked Equations. The cubic cavity flow problems were investigated for the Reynolds number of 400, 1,000, 2,000 and 3,200 using non-uniform meshes. Finally, we confirmed the effectiveness of our proposed method through the comparison with other research works. 相似文献
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提出一种改进的灵敏度方法用于工程结构损伤检测中。通过在迭代算法中引入一个“加速”公式来迅速获得足够精确的识别结果,避免了多次迭代,可以大大减少计算花费。用文献[8]和文献[10]中的两个数值算例对所提方法进行了验证,并把结果和原文中的计算结果进行比较。结果表明:采用改进的方法一般只需经过一次计算即可获得精度更高的识别结果,避免了多次迭代,显著减少了计算花费,显示了改进方法突出的优越性。 相似文献
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本文提出一种用于含分层的双层梁线弹性断裂分析的有限元方法.将上下子梁均模拟为多个子层,采用只有平动位移自由度的新型梁单元,假设单元内的位移沿纵向和横向均线性变化,推导了该单元的单元刚度矩阵.将开裂部分和未开裂部分的子梁进行单元刚度矩阵组装,施加相应的等效结点力,得到整体平衡方程,并结合边界条件进行求解.为验证该方法的有效性和精度,开展非对称双悬臂梁(Asymmetric Double Cantilever Beam, ADCB)和单臂弯曲梁(Single Leg Bending, SLB)试样的断裂分析,利用虚拟裂纹闭合技术(Virtual Crack Closure Technique, VCCT)得到了试样的能量释放率及其分量,并将求得的结果与解析解和二维有限元解进行对比.计算结果表明,相对于传统双层模拟方法,该多层模拟方法能够精确、高效地计算各类梁试样的能量释放率及其分量,并且无需引入界面连续条件. 相似文献