四边形地

The two extremities of this huge parallelogram were occupied, the one by the famous marble table, so long, so broad, and so thick that, say the old territorial records in a style that would whet the appetite of a Gargantua,"Never was such a slab of marble seen in the world"

这座呈平行四边形的宽阔无比的大厅，一端摆着那张名闻遐迩的大理石桌子，那么长，那么宽，那么厚，据古老地籍册所云，世上如此偌大的大理石，真是见所未见，这样一种说法可叫卡岗蒂亚②垂涎欲滴

To establish the constitutive equation of material, the metric tensor for stress , strain and their transformation equations between different configurations are derived, and basic theory of finite deformation as well as elasto-plastic deformation criterion are studied. By analyzing the applicability of different element models, four-node quadrilateral degenerated Mindlin isoparametric element is adopted because of its good versatility, and the element stiffness matrix is derived. The static implicit elasto-plastic finite element equation for complex skin stretch-forming is put forward based on Updated Langrange formulation.

本文首先系统地阐述了有限变形的相关基本理论，针对板料成形建立了应力应变度量张量及其相应的转换关系；介绍了材料的屈服准则、塑性变形强化规律、塑性流动规律以及加、卸载准则，并在此基础上建立了有限变形各向异性弹塑性本构方程；对板料成形的单元模型进行了分析，针对飞机蒙皮零件特点，采用通用性强的四节点四边形退化Mindlin等参壳单元进行成形模拟，并导出其单元刚度矩阵的具体形式；基于以上研究，以逐级更新Langrange描述的持续虚功率原理为基础，建立了率形式的复杂蒙皮拉形过程静态隐式弹塑性有限元方程。

A quadrilateral distortion metric was proposed, which considered both of element minimal angle and warpage. An mesh smoothing approach of combining Laplacian method and μGA for quadrilateral mesh was presented, which could improve the mesh quality significantly without effect the algorithm's performance.

提出一种综合考虑单元最小角和翘曲的四边形网格质量评价标准，以该标准为优化目标，提出了一种以面积为权值的Laplacian方法与小种群遗传算法相结合的网格光顺方法，在兼顾计算效率的同时，可有效地优化网格形态质量。

Slashing confidently through the hidden parallelogram of forces that were its destiny.

极有自信地划过主宰其命运那隐而不见的平行四边形。

The students can use the formula to calculate Parallelogram area and solve the related problems.

使学生能比较熟练地应用平行四边形面积的计算公式，解答有关实际问题。

The main results gained in this dissertation are as follows:1. The vector theory which originates from parallelogram rule of velocity and force is inspected in detail.

主要研究成果如下：一、较深入地考察了起源于力和速度的平行四边形法则的向量理论。

This will be the first and last image to demonstrate what I am basically doing throughout the initial modeling process; I started out with a simple rectangular plane with symmetry mode on and I keep on extruding its edges and placing them in their rightful coordinates repeatedly until the entire structure is complete.

这会是第一张，也是最后一张图说明我在整个的建模过程中使用的基本技巧。我从一个开启了对称模式的简单四边形开始制作，不断地将边挤出，然后把它们放置到合适的位置，直到完成整个结构。

It avoids the parallelogrammical output machine with a complicated planetary wheel system and the flexible wheel of resonance wave transmission, shortens the movement chain observably and reduces the loss of movement transfer.

偏心轮推杆行星传动属于活齿少齿差传动，它的推杆结构成功地解决了输入轴与输出轴同轴的问题，避免了复杂行星轮系的平行四边形输出机构和谐波传动的柔轮，显著缩短了运动链、减少了运动传递的损失。

The foundation of arch dam usually is layer rock base, and the depths of the layer are small, it is common that several layer rock base contact with one layer element grid. According to the geometry relation and the property of shape function, a new element kind that includes 24 nodes has been proposed to dissect the dam and foundation effectively, whose shape function are independent. In fact the element can be looked as a hexahedron divided into five small hexahedrons. It can be simulate all kind of the condition of the base and the dam.

拱坝的地基一般是层状岩石地基，有的层厚度很小，这样就有多个岩层和坝体某层单元接触，本文根据岩基与坝体接触的几何关系，利用形函数的性质，提出24节点六面体层单元，这种单元实际上是将一个厚的六面体单元分成5个更薄的六面体单元而形成的，其形函数采用可以拆分的形式表达，因此可以方便地解决坝体单元的一、二、三、四个面与错动带接触的情况，可以模拟一、二、三、四个棱边与错动带接触的情况，还可以退化为12节点的四边形面单元，以及五面体层单元。

By cooperating the two-model method with parallelogram frame in this paper, the curve of two crossed cylinders with their axises in a state of vertical can be easily and accurately realized, and the mechanism withdrawn from the method can be applied directly to the hole gas-cutting on high pressure capsules.

文摘：采用双靠模法与平行四边形机构的组合，可简易、准确地实现轴线垂直的两圆柱体相贯线轨迹的复现，其原理可直接用于压力容器上圆孔的气割。

But we don't care about Battlegrounds.

但我们并不在乎沙场中的显露。

Ah! don't mention it, the butcher's shop is a horror.

啊！不用提了。提到肉，真是糟透了。