油田用抽油杆镦锻成形过程数值仿真研究

介绍了抽油杆工艺特点及抽油杆镦锻成形工序过程.依据成形过程,基于三维刚-黏塑性有限元的理论,利用有限元软件对抽油杆镦锻成形各工步进行了数值仿真模拟.得到了抽油杆镦锻成形各工步的应力、应变、损伤场等的变化规律,为抽油杆镦锻成形提供了直观设计依据和经验.     

大型全纤维曲轴TR镦锻装置失效分析

对大型全纤维曲轴TR镦锻装置中的模座进行了断裂失效分析,该装置在修改曲轴大法兰成形方式为全封闭成型后的第一次使用中,上、下模座均断裂.采用DEFORM一3D软件对该全纤维钢曲轴镦锻成形进行数值模拟,计算获得锻件成形力和模具充填效果.采用I-Dears软件对曲轴TR镦锻装置进行结构强度计算,获得了镦锻装置的应力和变形状态,分析了模座发生断裂失效的原因.计算结果表明,模座实际的断裂部位和裂纹方向与强度分析结果吻合.     

利用圆环镦粗法测定工模具钢超塑成形条件下的摩擦系数

本文应用计算机绘制了圆环镦粗测定摩擦系数的理论校准曲线,首次研究了圆环镦粗法在工模具钢超塑成形条件下的应用,实测了在模具钢的超塑变形条件下几种常用润滑剂的摩擦系数,并分析了影响超塑条件下摩擦系数的因素。     

Ti-6Al-4V合金在快锻液压机上锻造工艺的计算分析

本文对Ti-6Al-4V合金在快锻液压机上锻造过程中的变形力及变形温度等工艺参数进行了计算;阐述了锻件在快锻液压机上镦粗及拔长过程中的温度变化及锻造回炉加热次数的计算方法,为锻造车间锻造工艺的确定和对锻造工艺更加深入的研究工作提供了参考。     

35CrMo曲轴热成形材料模型的研究

本文通过对大型曲轴用钢３５ＣｒＭｏ 的热力模拟试验和数据处理,探讨了曲轴弯曲镦锻的热成形机制,研究了变形温度、应变速率等参量对３５ＣｒＭｏ 钢应力应变关系和再结晶特征的影响。建立了该类钢热成形的材料模型、给有限元数值模拟曲轴弯曲镦锻热成形过程提供了基本数据,也为大型曲轴热成形力能参数和温度制度的合理确定提供了科学依据。材料模型的确定,对于研究热成形实质,预报与控制工艺质量和产品质量乃至新工艺开发都有重要意义。     

镦挤复合变形力的上限分析

本文运用上限法求解镦挤复合成形工艺过程中的消耗功率和单位变形力。首先采用塑胶泥和纯铅两种材料进行流动规律实验。在观察分析塑性流动模式的基础上,假设了对应于镦挤过程中两个不同阶段的运动学许可速度场,由之用上限法导出了求解镦挤成形消耗功率的两种模式的能量积分式。第Ⅰ模式适用于变形初始阶段,第Ⅱ模式适合于整个塑性变形阶段。第Ⅱ模式的能量式中有α_1、α_2及分流层半径R_n三个参数相互影响。通过三重迭代过程分别求出最佳α_1、α_2及R_n后回代求得最佳上限值。计算结果与纯铅试样的实测数据进行比较,吻合性良好。本文实验工作中还包括了用圆环镦粗法测定纯铅和10#钢相对于工具表面的不变摩擦因子m。     

锥形模镦锻规则探讨

本文根据金属在锥形模中的变形特点, 求出了模壁对弯曲毛坯第一个支撑点的位置和毛坯在锥形模中的最大弯曲;确定了锥形模膛的最小长度、模腔锥角与毛坯长度的关系;利用压杆塑性稳定条件,导出了锥腔的临界角;提出了不产生塑性失稳镦锻的综合条件.     

TC4钛合金热镦加热方法

通过对ＴＣ４钛合金加热方法的研究，提出了接触电加热快速升温的方法，有效避免了空气污染，针对加工中经常出现的热裂，用有限元法了加热过程中的温度场和应力场，结果表明加热效果良好，并且通过实验验证了其可行性，为钛合金棒料热镦工艺的确定提供了理论和实验基础。     

径向锻造终锻过程的流函数法解析

径向锻造的终锻变形过程,因锤宽与坯径比较大,几乎包围了整个圆周,故认为变形主要发生在轴向延伸,它与拉拔,镦粗等变形相似,但受方向及变形特点又不相同,为了解决与初锻过程出现同样“跳卡”和分析锻造质量问题,采用了流函数法对进料量、锤头尺寸,形状等因素的,影响进行了理论分析,为径向锻造选择合适的工艺参数提供了理论参考。     

管体摩擦焊顶锻变形阶段污物清除的估算

根据连续驱动摩擦焊顶锻变形的特点，提出了估算顶锻变形过程界面污物清除率模型，建立了污物清除率为一次焊接参数和二次参数的函数关系。以此为基础，分析了管结构摩擦焊变形过程中界面及近界面塑性区金属质点的运动规律，并结合石油钻杆摩擦焊的实际施焊情况，测定了顶锻终了接头的塑性变形区宽度，估算了顶锻变形过程界面污物清除率。     

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.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that