共查询到19条相似文献,搜索用时 234 毫秒
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有限元分析的精度和效率与网格划分的质量有直接关系.目前尚缺乏一种普适性的自动网格划分方法,尤其是对于具有多种几何特征的复杂模型,现有的六面体网格自动划分算法存在不同几何特征间的网格兼容性较差以及孔状特征周围网格质量不高的问题.对此本文提出一种基于映射法的六面体网格自动生成方法,在映射法的基本框架下,将物理空间中的复杂几何体映射为计算空间中的规则几何体,引入边界顶点分类,将复杂几何体边界进行简化,将子域约束进行连接,寻找贯穿边界,以使映射网格在约束特征间兼容;对圆弧特征进行等效转化,降低曲率过大对于网格过渡的影响.实例验证表明,本方法稳定可靠,生成的六面体网格质量较高,能够解决多特征复杂几何体六面体网格自动划分问题. 相似文献
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在有限元分析中,高质量的结构网格可以有效地提高有限元分析的精度,但结构网格的几何适应性差,针对复杂边界的二维计算模型,现有的方法很难自动生成高质量的结构网格;而非结构网格几何适应性很好,但存在计算效率低和精度差等问题。提出了一种新的准结构网格生成方法,能够实现复杂区域的网格自动生成并且具有高网格质量。该方法首先对计算区域运用Delaunay三角剖分技术生成粗背景网格;然后利用背景网格,使用优化的Voronoi图生成过渡的蜂巢网格;最后,通过中心圆方法对蜂巢网格单元进行结构网格剖分。分析NACA0012翼型数值模拟结果表明,提出的新准结构网格生成方法能够对边界复杂的模型自动生成高质量的网格,并且通过三种不同拓扑类型网格计算结果相互对比及与实验结果对比,证明准结构网格具有高计算精度。 相似文献
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在有限元分析中,高质量的结构网格可以有效地提高有限元分析的精度,但结构网格的几何适应性差,针对复杂边界的二维计算模型,现有的方法很难自动生成高质量的结构网格;而非结构网格几何适应性很好,但存在计算效率低和精度差等问题。提出了一种新的准结构网格生成方法,能够实现复杂区域的网格自动生成并且具有高网格质量。该方法首先对计算区域运用Delaunay三角剖分技术生成粗背景网格;然后利用背景网格,使用优化的Voronoi图生成过渡的蜂巢网格;最后,通过中心圆方法对蜂巢网格单元进行结构网格剖分。分析NACA0012翼型数值模拟结果表明,提出的新准结构网格生成方法能够对边界复杂的模型自动生成高质量的网格,并且通过三种不同拓扑类型网格计算结果相互对比及与实验结果对比,证明准结构网格具有高计算精度。 相似文献
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分别运用扇形(Fan)、阶梯形(Ladder)、交界面形(Interface)网格对细长体小攻角对称、大攻角对称、大攻角非对称绕流流场进行了数值研究.通过涡核位置、涡簇显示、物面压力分布、轴向力分布等的计算结果比较了三种网格的计算精度.数值实验表明:细长体分离涡流场对边界层网格非常敏感,应严格控制边界层网格的正交性;随着攻角增大,流场对网格特性的敏感性有增高的趋势;阶梯形网格可能会对流场带入非物理性扰动,交界面网格对流场捕捉有不连续现象;将三种网格得到的物面压力、侧向力、流动分离位置与实验值进行对比,发现扇形网格误差最小、交界面网格误差最大;大攻角非对称流动时,扇形网格计算的侧向力有整体向细长体头部压缩的趋势,涡脱落位置靠前,第二个及第三个极值更大,说明非对称现象有向尾部发展的趋势. 相似文献
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The theory of an automated fringe-pattern analysis using temporal phase stepping method for moiré interferometry is presented.
The automated method provides a fast and accurate strain measurement for moiré interferometry. Measurements on a tapered composite
specimen with a dropped ply are shown to highlight the capability of this technique to obtain the strain distribution, particularly
around the region with a dropped ply. 相似文献
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In this paper an automated photoelastic method based on the phase stepping technique is described. It provides full-field
maps of the isoclinic parameter and the relative retardation. The technique is based on processing six images of a photoelastic
specimen acquired using plane and circularly polarized light. The number of acquisitions and the type of polariscope used
in this approach have been chosen with the aim at reducing the influence of quarter wave plate errors and obtaining raw photoelastic
data in a periodic form suitable for easy applications of automatic unwrapping routines. 相似文献
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一种快速稳健的并行多块结构动网格方法 总被引:2,自引:0,他引:2
为解决传统网格处理方法不能满足复杂外形在大设计空间内进行优化时对网格质量的要求的问题,提出了一种并行多块动网格方法,该方法基于初始外形的多块结构网格,根据优化过程中个体外形与初始外形拓扑结构相近的特性,利用体样条插值方法来拟合多块结构网格各块顶点的位移,得到几何外形变化后的拓扑结构,再利用无限插值方法并行地移动初始外形多块结构网格的边、面和块内的网格点,进行光顺处理后得到变形后几何外形的空间网格;该方法在保证网格质量的同时,可以极大地提高网格生成效率,本文以某翼身组合体为例结果表明,该方法在大设计空间的复杂外形设计问题中具有很强的实用性。 相似文献
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This paper describes a multiplied-moiré-fringe system, of in-plane displacement measurement, which is particularly suitable for high-sensitivity studies, both under laboratory conditions and for field studies. A replica technique is used for applying a relief grid to the specimen, and for recording the deformed grid. A fringe-multiplication method is used to give effective line densities in the range 400–2,000 lines/mm (10,000–50,000 lines/in.). Application of the method to fatigue studies is described. 相似文献
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An automated quasi three-dimensional finite element grid generation method is presented for particular three-dimensional complex connected domain, across which some are simply connected two-dimensional.regions and some are multiply connected two-dimensional regions. A subdivision algorithm based on the variational principle has been developed to ascertain the smoothness and orthogonality of the generated grid in any cross sections. Smooth transition between the simply and multiply connected regions is maintained. For illustration, the method is applied to generate a finite element three-dimensional grid for human above knee stump. 相似文献
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The objective of this paper is to explore both grid method and Digital Image Correlation (DIC) technique for microscale and
discontinuous displacement measurements, such as those associated with crack tips. First, the principle of the grid method
is revisited. The grid method and DIC technique are then applied to computer generated images to calculate the displacement
field around crack tips. Finally, the grid method is applied to actual experimental images of fracture tests which are conducted
inside a Scanning Electron Microscope (SEM) chamber. A new technique is developed to generate microscale pattern that is suitable
for both grid method and DIC technique. The displacement fields calculated from grid method are compared with those from DIC
technique to identify the strengths and weaknesses of each technique for the microscale and discontinuous displacement measurements.
It has been determined that grid method can obtain data closer to the discontinuity than DIC; however, DIC produces smoother
displacement fields at the far field. Using this new pattern generation technique, both grid method and DIC technique can
be applied to the fracture test at the microscale to complement with each other to achieve the best experiment results. 相似文献
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The visioplasticity method has been used to obtain the stress and strain distributions during planestrain bending in a standard Charpy V-notched specimen of low carbon steel. The specimen was slit longitudinally through the notch with a square grid inscribed on the interface. The instantaneous grid distortion was obtained during a three-point incremental bending test. A computer program was developed for the calculation of the instantaneous stress and strain distributions using the experimentally determined displacement field and the true stress-strain curve of the steel. 相似文献
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During recent years, the investigation of the strain-rate-dependent properties of materials has become more and more important.
The experimental techniques used to establish the specific dynamic behavior of materials all have in common that the acquisition
of information concerning the deformation of the specimen is cumbersone and often questionable. Mostly, only limited information
on the spatial distribution and time evolution of the deformation in specimen can be obtained. In this paper, a non-contact,
optical technique is presented, providing the time evolution and spatial distribution of the axial deformation in specimens
during a high strain rate test. The deformation of a line grid attached to the specimen is recorded during an experiment by
means of a rotating drum camera. The time history of the axial displacements is subsequently derived by an advanced technique
based on digital geometric moiré combined with a phase-shift method, specially developed to this purpose. The technique can
be applied to a wide range of materials and high strain rate tests, and is illustrated by means of a split Hopkinson tensile
bar experiment on a steel sheet specimen. 相似文献