光塑性力学分析法在冷挤压孔增寿机理研究中的应用

采用光塑性力学分析法,利用模型与原型的相似性来确定带衬套挤压和不带衬套冷挤压时孔边的载荷分布,并对这两种冷挤压方法所产生的差异进行了分析比较.结果表明:带衬套挤压和不带衬套冷挤压时孔边载荷的分布,模型材料与原型实际挤压结果相似;冷挤压孔在两个典型方向的应力、应变变化表现一定趋势,无衬套挤压中,孔边两个典型方向所产生的应力应变非常接近;而带衬套挤压中,衬套开口处产生的应力应变最大,与之相对的180°附近应力应变最小     

带衬套冷挤压孔在三维状态下的有限元分析

针对目前在研究冷挤压孔边残余应力时,大都采用基于厚壁圆筒的轴对称小变形、平面应力状态、孔边受力为均布载荷等假设所带来的不足,提出了在三维真实模型状态下,考虑衬套对孔边受力的影响、试件在厚度方向上的应力差异等因素．研究了带衬套挤压件在加载、卸载及疲劳拉伸载荷状态下的应力分布,并和无衬套挤压时的状态进行比较,从机理上揭示了带衬套挤压在改善试件抗疲劳性能方面的优势所在．     

内孔挤压强化板的弹塑性分析

基于塑性增量理论,用有限元方法,对内孔挤压增强的板条,在冷挤压过程中孔周的弹塑性应力场和挤压后孔周的残余应力场进行了计算分析,由有限元方法获得应力解与理论解完全符合。结果表明,有限元法是计算残余应力较精确方法.     

锥形件冷挤压变形过程的模拟和实验

通过刚塑性有限元分析和密栅云纹实验,揭示了锥形件冷挤压时的金属流动规律,应力场、应变场、工件接触面上的正压应力分布,挤压力的变化规律,以及挤压件的内部显微分布.实验结果表明,模拟过程和结果是可信的,与实验结果比较吻合.     

基于DEFORM-3D的管材开式冷挤压过程的数值模拟

开式冷挤压是一种高效、节能、节材的先进成形技术。利用刚塑性性有限元软件De—form-3D对管材在开式冷挤压成形过程进行了模拟,获得了挤压过程中的等效应力、等效应变以及速度场的分布云图,并对这些模拟结果进行了详细的分析,为优化开式冷挤压工艺提供了理论参考。     

构件预挤压孔的工艺弹塑性和残余应变分析方法

在对工艺应力进行理论分析的基础上,提出了一种构件预挤压孔的工艺弹塑性和残余应变分析方法,通过采用释放残余应变的方法和单光束激光散斑干涉术,分析了三种不同挤压量带孔铝板的预挤压孔对称面上的残余应力,验证了这种分析方法的可行性。     

孔挤压强化有限元分析及疲劳寿命估算

目前孔挤压强化过程仿真方面的文献主要是对于残余应力的分析,疲劳寿命主要由试验测量得到,对疲劳寿命的估算较少。通过三维非线性有限元方法,对7075铝合金芯棒和衬套挤压强化过程进行了仿真。分析了不同强化方法强化后的残余应力分布。在残余应力分析的基础上,估算了循环载荷下不强化、芯棒挤压和衬套挤压强化后元件的疲劳寿命;并与相应的试验数据进行了对比。结果表明,疲劳寿命估算结果与试验结果基本一致,估算方法可行。     

带孔无限大板的应力集中问题浅析

通过有限元方法探讨单向受载带孔无限大板件孔边应力集中的问题：逐步增大模型垂直于载荷方向的尺寸模拟无限大板;在此基础上探讨孔边应力集中系数与孔的几何特征的关系,即变圆孔为椭圆,垂直于受载方向孔半轴不变,载荷方向孔半轴变化,孔边应力集中系数随曲率半径增大而减小;减小圆孔半径,最大应力集中系数随之减小,并减小到弹性力学理论值3以下。上述结果说明连续介质力学理论有其自身的局限性,应力梯度在应力场变化很大的情况下对微元体平衡分析的影响不可忽视。     

三维光塑性法及其在挤压变形研究中的应用

本文对国产聚碳酸酯的力学光学性能进行了实验研究,建立了该光塑材料的应变光学定律。提出了用于三维轴对称变形的完整的光塑性方法,并对圆棒挤压变形分析进行了实际应用,获得了变形区内应力应变三维场分布。首次提出了塑性变形区内存在轴向压缩区的概念,揭示了挤压延伸变形的机制。     

正交各向异性板带有一般孔形时应力分析

采用复变函数方法研究面内均布荷载作用下带孔正交各向异性板的应力解析解.对含一个正六角形孔或不规则孔的无限平板进行分析,得到不同工况下(纤维角度、外荷载方向)孔边及部分孔外域的应力分布规律.结果表明,当单向荷载作用方向与孔边尖点指向垂直时,若正交各向异性板的纤维按0°和-90.0°布置,最大切向应力发生在孔边,并且位于尖点位置,但随着纤维角度的旋转,孔边的最大应力点逐渐偏离尖点,并且最大应力值也逐渐降低;因此,正交各向异性板的应力集中可以通过调整材料的纤维方向来改善.除此之外,当单向均布荷载σ的作用方向与坐标轴平行时,该坐标轴与孔边界交点的切向应力均为-σ.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to