材料成型及控制工程外文文献翻译
本科毕业论文
外文文献及译文
文献、资料题目：The effects of heat treatment on
the microstructure and mechani-
cal property of laser melting dep-
ositionγ-TiAl intermetallic alloys 文献、资料来源：Materials and Design
文献、资料发表（出版）日期：2009.10.25
院（部）：材料科学与工程学院
专业：材料成型及控制工程
班级：
姓名：
学号：
指导教师：
翻译日期：2011.4.3
中文译文：
热处理对激光沉积γ-TiAl金属间化合物合金的组织与性能的影响摘要：
Ti-47Al-2.5V-1Cr 和Ti-40Al-2Cr (at.%)金属间化合物合金通过激光沉积（LMD）成形技术制造。显微组织的特征通过光学显微镜（OM）、扫描电子显微镜（SEM）、投射电子显微镜（TEM）、和X射线衍射仪（XRD）检测。沿轴向评估热处理后的沉积试样室温下的抗拉
性能和维氏硬度。结果表明：由γ-TiAl 和α
2-Ti
3
Al构成的γ-TiAl基体试样具有全
密度柱状晶粒和细的层状显微组织。Ti-47Al-2.5V-1Cr基体合金和Ti-40Al-2Cr基体合金沿轴向的室温抗拉强度大约分别为650 MPa、600MPa，而最大延伸率大约为0.6% 。热处理后的Ti-47Al-2.5V-1Cr和Ti-40Al-2Cr合金可以得到不同的显微组织。应力应变曲线和次表面的拉伸断裂表明沉积和热处理后的试样的断裂方式是沿晶断裂。
1.简介
金属间化合物γ-TiAl合金由于其高熔点（﹥1450℃）、低密度（3g/cm3）、高弹性模量（160-180GPa）和高蠕变强度（直到900℃）成为很有前景的高温结构材料，一直受到广泛研究[1–4]。但是对于其结构应用来说，这种材料主要缺点之一是在室温下缺少延展性。此外，这种合金运用传统的制造工艺诸如锻压、轧制和焊接，加工起来比较困难[5]。
对于TiAl组份，传统的铸造技术不利条件是粗大的铸态组织导致室温下的机械性能变差。另一方面，在传统的缓慢冷却固结过程中诸如气孔和缩孔等金相缺陷是不可避免的。产品的形状和尺寸受热应力诱发结晶的制约，铸件的地延展性导致裂纹缺陷。虽然适当的组件可以通过传统的铸造工艺制造，但是这种方法相当昂贵、耗时。一些其他制造和加工方式如放电等离子烧结（SPS）[6,7]、混合粉末半固态成型[8]、烘托冶金反应[9]和激光工程粉末冶金零件近净成形(LENS) [10]一直受到广泛研究，以便制造出高质量的TiAl合金部件。然而，在此类金属的粉末冶金过程中不可避免的氮化和氧化的增强，进一步恶化了TiAl合金的延展性。
激光沉积（LMD）是一种利用电脑辅助设计（CAD）模型分层快速凝固材料添加剂为增效组分的制造技术。在LMD过程中，大功率激光束的运动有计算机数控（CNC）系统控制，而该系统由CAD模型发展而来。金属粉末注入激光聚焦带，然后从粉末输出喷嘴连续熔化。由于该方法冷却凝固速度高，连续层可堆积成全密度和极细小的快速凝固微观组织的近净成形零件。利用CAD文档的LMD添加剂分层制造的方式，可以得到任意复杂形状和尺寸的
近净成形零件。
在目前的研究中，激光沉积制造工艺成功制造出Ti–47Al–2.5V–1Cr和Ti–40Al–2Cr(at.%)金属间化合物合金零件。研究沉积试样热处理后的微观组织，并评估轴向维氏硬度和室温抗拉性能，表征拉伸断面和次表面的组织。
2.实验步骤
激光器（最大输出功率8000W）和BSF-2粉末输出装置熔化和传送GS-TFL-8000 CO
2
Ti–47Al–2.5V–1Cr 和 Ti–40Al–2Cr合金粉末，HNC-21M CNC数控装置控制工作台和激光束的运动。激光束和粉末喷嘴作为一个整体单元移动，以便合金粉末注入激光熔池。激光熔化沉积过程在一个特别设计的氩气清洗室中进行，恒压下，在氩气气氛中防止熔池氧化，清洗室中的氧含量小于万分之一。LMD加工过程中的参数：激光功率1500W，光束直径5mm，光束扫描速度5mm/s，单层沉积物厚度0.2-0.3mm，送粉速度4-5.5g/min。
在此研究中，Ti–47Al–2.5V–Cr和 Ti–40Al–2Cr合金粉末含氧量小于0.1(wt.%)，有真空熔化氩气等离子体雾化过程密封制造。Ti–6Al–2Zr–Mo–1V and Ti–47Al–2.5V–Cr铸态合金锭机械加工成直径10mm左右的细缆，然后通过特殊设计的喷嘴在等离子熔化炉中熔化。最后，喷嘴里的铸态合金在高速高纯度氩气流作用下形成球状粉，合金的粒度范围在70-75μm之间。另一方面，铸态Ti–6Al–2Zr–Mo–1V铸锭热滚到厚度为8–10 mm的薄墙型标本上作为基体材料（表1）。Ti–6Al–2Zr–1Mo–1V基体表面在激光熔化沉积之前预抛光，沉积试样密封在石英管中，然后在高温烘炉中热处理。
通过标准机械抛光法准备的金相试样用300 ml H2O、100 ml HNO3和100 ml HF混合溶液腐蚀。OLYMPUS BX51M光学显微镜、JEM-2100透射电镜和配备Lea-gue-2000 EDX 系统的KYKY-2800扫描电子显微镜表征微观组织、识别化学成分。使用HXZ-1000半自动硬度测试计测量梯度区的硬度，试验荷载200g，停留时间15s。拉伸试样（厚度1-1.5mm）
在MTS880测试系统上沿轴向测量试样的室温抗拉性能（图1）。
3.结果与讨论
3.1. 显微结构的分析
Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr合金薄板的几何尺寸都是40 m m×40 mm×6mm(图. 2a)。不同粒度组成的γ-TiAl和α2-Ti3Al相的沉积试样具有片状显微组织（FL）(图-2b 和c)，TiAl沉积试样中观察到细层的微观结构，可能是由于加工制造过程较高的凝固速率。γ-TiAl和α2-Ti3Al（图-3.b和c）有层状显微结构组成是固态相变的结果。含有46–49% (at.%)铝的TiAl合金在1125℃经历固态相变[12]：α→γ+α 2 。细化晶粒的尺寸是50–100 um ，超细层间距大约是0.2um。在激光熔化沉积过程中，沉积熔池下面的先前沉积层被扫描激光束连续不断的在加热至高温(>1500℃) [13]。熔池附近的热影响区必然发生前面提到的固态相变，最终导致片状显微组织的形成。该研究中，TiAl沉积试样中γ-TiAl (fcc)和α2-Ti3Al (hcp) 有一个方向关系(0 0 0 1) α2//(1 1 1)γ（图-3.e和f）。
图4显示了Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr沉积合金试样X射线衍射模型。沉积的Ti–47Al–2.5V–1Cr合金试样中可以清楚的观察Ti3Al-(2 0 0) 和Ti3Al-(2 0 1)峰值，但是，Ti–40Al–2Cr沉积合金试样的X射线衍射模型中却不显著。
不同加工方法得到的Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr合金试样热处理后的微观结构
不同（图5和图7）。同时，热处理后的TiAl 合金试样中γ-TiAl 和α2-Ti 3Al 片晶厚度见图
6。EDS 能谱仪分析结果显示试样的不同晶粒区（表2）的化学成分和腐蚀形态不同。这表明，经过1100℃和1125℃分别30分钟的热处理之后不能去掉材料的同质异性，而这可能是由于扩散速率低和热处理时间相对较短[14,15]。
3.2. 显微硬度
图8显示了热处理合金Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr沉积试样平均维氏硬度的变化。沉积Ti–47Al–2.5V–1Cr合金试样经1125℃退火30小时后水淬火，其维氏硬度从425HV 上升到455HV。另一方面沉积Ti–40Al–2Cr合金试样经1100℃退火30小时后空冷，其维氏硬度从400HV上升到450HV。这种变化可能是受长时间高温退火后不同肌理的细晶粒的形成引起微观组织变化的影响。
3.3. 室温抗拉性能
表3显示了沉积后热处理试样室温抗拉性能测试结果。十分明显，沉积试样Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr合金的极限抗拉强度（UTS）值与热加工试样相比低很多，这表明Ti–47Al–2.5V–1Cr和Ti–40Al–2Cr合金的室温抗拉性能受其微观结构的晶粒大小和层间隙的影响。图9所示的是热处理后Ti–47Al–2.5V–1Cr 和Ti–40Al–2C合金试样的室温拉伸应力—应变曲线，结果表明这种合金的延展性非常低。
热处理后的Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr合金试样的RT断裂表面和此表面沿纵向方向检测。沉积后热处理的Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr合金试样的断裂表面是平直且简单的。特别需要指出的是，韧性坑充分体现了层状显微结构的组织特征，这表明显微镜下可见的初始裂纹产生于单一晶粒，沿层界面生长，有时沿晶界处生长。
在本文中，激光沉积Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr合金成分沿纵向方向，有杰出的室温力学性能。沉积TiAl合金试样中观察到的细的层状显微结构可能是在LMD快速制造工艺中，由于凝固速率高产生的。与LMD加工工艺相
比，那些传统的铸造加工工艺，TiAl合金的凝固速率相对较低。相应的，那些缓慢冷却的加工工艺形成粗糙的等轴FL或者是复式（DP）显微组织。在这项研究中，在50-100um 范围的的显微结构沿纵向方向的室温拉伸强度能够达到550-650MPa。550-650MPa。然而，图6 b和c以及图7显示组织的层间隙几乎是在同一水平上，这说明相应的热处理时间不够长，还不足以使片层微观结构存
在明显的差异。与沉积合金试样相比较，热处理合金试样的极限抗拉强度的变化可以忽略不计。另一方面，与热处理试样0.6%的延展率相比，沉积Ti –47Al –2.5V –1Cr 和 Ti –40Al –2Cr 合金试样0.3%的延展率相对较低。图4是沉积后热处理的LMD 试样与传统加工TiAl 合金材料的室温抗拉特性的比较。许多研究表明，TiAl 合金的室温下的屈服强度和抗拉延性以及微观结构主要受晶粒大小和内部层间隙的影响[18–20]。通过各种固态热加工方法控制微观组织和细化晶粒可以改善激光熔覆沉积Ti –47Al –2.5V –1Cr 和 Ti –40Al –2Cr 合金的机械性能，这是因为机械性能对微观结构的敏感依赖性。
4. 结论
Ti–47Al–2.5V–1Cr 和Ti–40Al–2Cr (at.%) 金属间化合物合金通过激光沉积（LMD）制
造工艺制造。由γ- TiAl和α
2-Ti
3
Al构成的完全片状显微结构（FL）激光沉积形成γ-TiA l
样品。Ti–40Al–2Cr合金1100℃退火30分钟伴随无功电量可以获得晶粒度大小约为20um 的均匀的微观组织。Ti–47Al–2.5V–1Cr经过1125℃/30 min退火处理伴随无功电量，可获得晶粒大小约为100um微观组织。Ti–47Al–2.5V–1Cr合金伴随无功电量经1125℃/30min 退火处理后沿纵向方向，其室温抗拉强度高达650 MPa。Ti–40Al–2Cr合金经1100℃/30min 退火处理之后空冷，其室温抗拉强度沿纵向方向高达630 MPa。这种合金的延伸率至多为0.6%，这表明其延展性非常低。
鸣谢
本研究由国家基础研究项目(2006CB605206-2)和中国国家自然科学基金委员会(批准号No. 50625413)以及中国教育部长江学者创新研究小组资助研究。
参考文：
[1] Liu CT, Schneibel JH, Maziasz PJ, Wright JL, Easton DS. Tensile properties and fracture toughness of TiAl alloys with controlled microstructures. Intermetallics 1996;4:429–40.
[2] Liu CT, Maziasz PJ. Microstructural control and mechanical properties of dual-phase TiAl alloys. Intermetallics 1998;6:653–61.
[3] Kim YW, Karthikeyan S, Viswanathan GB, Gouma PI, Vasudevan VK, Mills MJ. Mechanisms and effect of microstructure on creep of TiAl-based alloys. Mater
Sci Eng A 2002;329:621–30.
[4] Novoselova T, Malinov S, Sha W. Experimental study of the effects of heat treatment on microstructure and grain size of a gamma TiAl alloy. Intermetallics 2003;11:491–9.
[5] Yamaguchi M, Kishida K, Inui H, Yao KF. Plastic deformation of V- and Zr-alloyed PST TiAl in tension and compression at room temperature. Acta Metall Mater 1995;43:1075–86. [6] Sun ZM, Hashimoto H. Fabrication of TiAl alloys by MA-PDS process and the mechanical properties. Intermetallics 2003;11:825–34.
[7] Sun ZM, Hashimoto H, Wang Q, Tada S, Toshihiko A. Synthesis and consolidation of TiAl by MA-PDS process from sponge-Ti and chip-Al. Intermetallics 2003;11:63–9.
[8] Wen CE, Yasue K, Yamada Y. Fabrication of TiAl by blended elemental powder semisolid forming. J Mater Sci 2001;36:1741–5.
[9] Jakob A, Speidel MO. Microstructure and tensile properties of TiAl compounds formed by reactive foil metallurgy. Mater Sci Eng A 1994;189:129–36.
[10] Zhang XD, Brice C, Mahaffey DW, Zhang H, Schwendner K, Evans DJ, et al. Direct laser deposition of alloys from elemental powder blends. Scripta Mater 2001;44:2419–24.
[11] Wan g HM, Zhang LY, Li A, Cai LX, Tang HB. Rapid solidi?cation laser processing and forming of advanced aeronautical metallic materials. J Beijing Univ Aeronaut Astronaut
2004;30:962–7.
[12] McCullough C, Valencia JJ, Levi CG, Mehrabian R. Solidi?cation micros tructure of supercooled Ti–Al alloys containing intermetallic phases. Acta Metall Mater 1989;37:1321–36. [13] Grif?th ML, Schlienger ME, Harwell LD, Oliver MS, Baldwin MD, Ensz MT, et al. Understanding thermal behavior in the LENS process. Mater Des 1999;20:107–13.
[14] Wang JN, Xie K. Re?ning of coarse lamellar microstructure of TiAl alloys by rapid heat treatment. Intermetallics 2000;5:545–8.
[15] Cao GX, Fu LF, Lin JG, Zhang YG, Chen CQ. The relationships of microstructure and properties of a fully lamellar TiAl alloy. Intermetallics 2000;5:647–53.
[16] Koeppe C, Bartels A, Clemens H, Schretter P, Glatz W. Optimizing the properties of TiAl sheet material for application in heat protection shields or propulsion systems. Mater Sci Eng A 1995;201:182–93.
[17] Gerling R, Bartels A, Clemens H, Kestler H, Schimansky FP. Structural characterization and tensile properties of a high niobium containing gamma TiAl sheet obtained by powder metallurgical processing. Intermetallics 2004;12:275–80.
[18] Kumpfert J, Kim YW, Dimiduk DM. Effect of microstructure on fatigue and tensile properties of the gamma TiAl alloy Ti–46.5Al–3.ONb–2.1Cr–0.2W. Mater Sci Eng A 1995;192:465–73.
[19] Gerling R, Schimansky FP, Stark A, Bartels A, Kestler H, Cha L, et al. Microstructure and mechanical properties of Ti–45Al–5Nb + (0–0.5C) sheets. Intermetallics 2008;16:689–97. [20] Liu CT, Wright JL, Deevi SC. Microstructures and properties of a hot-extruded TiAl containing no Cr. Mater Sci Eng A 2002;329:416–23.
建筑类外文文献及中文翻译
forced concrete structure reinforced with an overviewRein Since the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance. Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency. 1、steel mechanical link 1.1 radial squeeze link Will be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linked Characteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.
矫直机中英文对照外文翻译文献
中英文资料翻译 原文： AUTOMATING THE CONTROL OF MODERN EQUIPMENT FOR STRAIGHTENING FLAT-ROLLED PRODUCTS The company Severstal’ completed the successful introduction of new in-line plate-straightening machines (PSMs) on its 2800 and 5000 mills in August 2003 [1, 2, 3]. The main design features of the machines are as follows: ●each machine is equipped with hydraulic hold-down mechanisms (to improve the dynamics and accuracy of the machine adjustments and more reliably maintain a constant gap); ●the machines have mechanisms to individually adjust each work roller with the aid of hydraulic cylinders (this broadens the range of straightening regimes that can be realized by providing a measure of control over the change in the curvature of the plate); ●each work roller is provided with its own adjustable drive (to eliminate rigid kinematic constraints between the spindles); ●the system of rollers of the PSM is enclosed in cassettes (to facilitate repairs and reduce roller replacement costs); ●the PSM has a system that can be used to adjust the machine from a nine-roller straightening scheme to a five- ●roller scheme in which the distance between the rollers is doubled (this is done to widen the range of plate thick-nesses that the machine can accomodate). Thus, the new straightening machine is a sophisticated multi-function system of mechanisms that includes a wide range of hydraulically and electrically driven components controlled by digital and analog signals. The entire complex of PSM mechanisms can be divided into two functional groups: the main group, which includes the mechanisms that partici-pate directly in the straightening operation (the hold-down mechanisms, the mechanisms that individually adjust the rollers,the mechanisms that adjust the components for different straightening regimes, the mechanism that moves the top roller of the feeder, and the main drive); the auxiliary group (which includes the cassette replacement mechanism, the
土木工程外文文献及翻译
本科毕业设计 外文文献及译文 文献、资料题目：Designing Against Fire Of Building 文献、资料来源：国道数据库 文献、资料发表（出版）日期：2008.3.25 院（部）：土木工程学院 专业：土木工程 班级：土木辅修091 姓名：武建伟 学号：2008121008 指导教师：周学军、李相云 翻译日期： 20012.6.1
外文文献: Designing Against Fire Of Buliding John Lynch ABSTRACT: This paper considers the design of buildings for fire safety. It is found that fire and the associ- ated effects on buildings is significantly different to other forms of loading such as gravity live loads, wind and earthquakes and their respective effects on the building structure. Fire events are derived from the human activities within buildings or from the malfunction of mechanical and electrical equipment provided within buildings to achieve a serviceable environment. It is therefore possible to directly influence the rate of fire starts within buildings by changing human behaviour, improved maintenance and improved design of mechanical and electrical systems. Furthermore, should a fire develops, it is possible to directly influence the resulting fire severity by the incorporation of fire safety systems such as sprinklers and to provide measures within the building to enable safer egress from the building. The ability to influence the rate of fire starts and the resulting fire severity is unique to the consideration of fire within buildings since other loads such as wind and earthquakes are directly a function of nature. The possible approaches for designing a building for fire safety are presented using an example of a multi-storey building constructed over a railway line. The design of both the transfer structure supporting the building over the railway and the levels above the transfer structure are considered in the context of current regulatory requirements. The principles and assumptions associ- ated with various approaches are discussed. 1 INTRODUCTION Other papers presented in this series consider the design of buildings for gravity loads, wind and earthquakes.The design of buildings against such load effects is to a large extent covered by engineering based standards referenced by the building regulations. This is not the case, to nearly the same extent, in the
土木工程外文文献翻译
专业资料 学院： 专业：土木工程 姓名： 学号： 外文出处：Structural Systems to resist (用外文写) Lateral loads 附件：1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 抗侧向荷载的结构体系 常用的结构体系 若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。确实，较好的高层建筑普遍具有构思简单、表现明晰的特点。 这并不是说没有进行宏观构思的余地。实际上，正是因为有了这种宏观的构思，新奇的高层建筑体系才得以发展，可能更重要的是：几年以前才出现的一些新概念在今天的技术中已经变得平常了。 如果忽略一些与建筑材料密切相关的概念不谈，高层建筑里最为常用的结构体系便可分为如下几类： 1.抗弯矩框架。 2.支撑框架，包括偏心支撑框架。 3.剪力墙，包括钢板剪力墙。 4.筒中框架。 5.筒中筒结构。 6.核心交互结构。 7. 框格体系或束筒体系。 特别是由于最近趋向于更复杂的建筑形式，同时也需要增加刚度以抵抗几力和地震力，大多数高层建筑都具有由框架、支撑构架、剪力墙和相关体系相结合而构成的体系。而且，就较高的建筑物而言，大多数都是由交互式构件组成三维陈列。 将这些构件结合起来的方法正是高层建筑设计方法的本质。其结合方式需要在考虑环境、功能和费用后再发展，以便提供促使建筑发展达到新高度的有效结构。这并
不是说富于想象力的结构设计就能够创造出伟大建筑。正相反，有许多例优美的建筑仅得到结构工程师适当的支持就被创造出来了，然而，如果没有天赋甚厚的建筑师的创造力的指导，那么，得以发展的就只能是好的结构，并非是伟大的建筑。无论如何，要想创造出高层建筑真正非凡的设计，两者都需要最好的。 虽然在文献中通常可以见到有关这七种体系的全面性讨论，但是在这里还值得进一步讨论。设计方法的本质贯穿于整个讨论。设计方法的本质贯穿于整个讨论中。 抗弯矩框架 抗弯矩框架也许是低，中高度的建筑中常用的体系，它具有线性水平构件和垂直构件在接头处基本刚接之特点。这种框架用作独立的体系，或者和其他体系结合起来使用，以便提供所需要水平荷载抵抗力。对于较高的高层建筑，可能会发现该本系不宜作为独立体系，这是因为在侧向力的作用下难以调动足够的刚度。 我们可以利用STRESS，STRUDL 或者其他大量合适的计算机程序进行结构分析。所谓的门架法分析或悬臂法分析在当今的技术中无一席之地，由于柱梁节点固有柔性，并且由于初步设计应该力求突出体系的弱点，所以在初析中使用框架的中心距尺寸设计是司空惯的。当然，在设计的后期阶段，实际地评价结点的变形很有必要。 支撑框架 支撑框架实际上刚度比抗弯矩框架强，在高层建筑中也得到更广泛的应用。这种体系以其结点处铰接或则接的线性水平构件、垂直构件和斜撑构件而具特色，它通常与其他体系共同用于较高的建筑，并且作为一种独立的体系用在低、中高度的建筑中。
有关隧道方面外文文献与翻译
A convection-conduction model for analysis of the freeze-thaw conditions in the surrounding rock wall of a tunnel in permafrost regions HE Chunxiong( 何春雄 )， (State Key Laboratory of Frozen Soil Engineering, Lanzhou Institute of Glaciology and Geocryology, Chinese Academy of Sciences, Lanzhou 730000, China; Department of Applied Mathematics, South China University of Technology, Guangzhou 510640, China) WU Ziwang( 吴紫汪 )and ZHU Linnan( 朱林楠 ) (State key Laboratory of Frozen Soil Engineering, Lanzhou Institute of Glaciology and Geocryology Chinese Academy of Sciences, Lanzhou 730000, China) Received February 8, 1999 Abstract Based on the analyses of fundamental meteorological and hydrogeological conditions at the site of a tunnel in the cold regions, a combined convection-conduction model for air flow in the tunnel and temperature field in the surrounding has been constructed. Using the model, the air temperature distribution in the Xiluoqi No. 2 Tunnel has been simulated numerically. The simulated results are in agreement with the data observed. Then, based on the in situ conditions of sir temperature, atmospheric pressure, wind force, hydrogeology and engineering geology, the air-temperature relationship between the temperature on the surface of the tunnel wall and the air temperature at the entry and exit of the tunnel has been obtained, and the freeze-thaw conditions at the Dabanshan Tunnel which is now under construction is predicted. Keywords: tunnel in cold regions, convective heat exchange and conduction, freeze-thaw. A number of highway and railway tunnels have been constructed in the permafrost regions and their neighboring areas in China. Since the hydrological and thermal
土木工程专业外文文献及翻译
（ 二 〇 一 二 年 六 月 外文文献及翻译 题 目： About Buiding on the Structure Design 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程(建筑工程方向) 班 级：土木08-4班 指导教师：
英文原文： Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the
冲压模具成型外文翻译参考文献
冲压模具成型外文翻译参考文献 (文档含中英文对照即英文原文和中文翻译) 4 Sheet metal forming and blanking 4.1 Principles of die manufacture 4.1.1 Classification of dies In metalforming,the geometry of the workpiece is established entirely or partially by the geometry of the die.In contrast to machining processes,ignificantly greater forces are necessary in forming.Due to the complexity of the parts,forming is often not carried out in a single operation.Depending on the geometry of the part,production is carried out in several operational steps via one or several production processes such as forming or blanking.One operation can also include several processes simultaneously(cf.Sect.2.1.4). During the design phase,the necessary manufacturing methods as well as the sequence and number of production steps are established in a processing plan(Fig.4.1.1).In this plan,the
土木工程类专业英文文献及翻译
PA VEMENT PROBLEMS CAUSED BY COLLAPSIBLE SUBGRADES By Sandra L. Houston,1 Associate Member, ASCE (Reviewed by the Highway Division) ABSTRACT: Problem subgrade materials consisting of collapsible soils are com- mon in arid environments, which have climatic conditions and depositional and weathering processes favorable to their formation. Included herein is a discussion of predictive techniques that use commonly available laboratory equipment and testing methods for obtaining reliable estimates of the volume change for these problem soils. A method for predicting relevant stresses and corresponding collapse strains for typical pavement subgrades is presented. Relatively simple methods of evaluating potential volume change, based on results of familiar laboratory tests, are used. INTRODUCTION When a soil is given free access to water, it may decrease in volume, increase in volume, or do nothing. A soil that increases in volume is called a swelling or expansive soil, and a soil that decreases in volume is called a collapsible soil. The amount of volume change that occurs depends on the soil type and structure, the initial soil density, the imposed stress state, and the degree and extent of wetting. Subgrade materials comprised of soils that change volume upon wetting have caused distress to highways since the be- ginning of the professional practice and have cost many millions of dollars in roadway repairs. The prediction of the volume changes that may occur in the field is the first step in making an economic decision for dealing with these problem subgrade materials. Each project will have different design considerations, economic con- straints, and risk factors that will have to be taken into account. However, with a reliable method for making volume change predictions, the best design relative to the subgrade soils becomes a matter of economic comparison, and a much more rational design approach may be made. For example, typical techniques for dealing with expansive clays include: (1) In situ treatments with substances such as lime, cement, or fly-ash; (2) seepage barriers and/ or drainage systems; or (3) a computing of the serviceability loss and a mod- ification of the design to "accept" the anticipated expansion. In order to make the most economical decision, the amount of volume change (especially non- uniform volume change) must be accurately estimated, and the degree of road roughness evaluated from these data. Similarly, alternative design techniques are available for any roadway problem. The emphasis here will be placed on presenting economical and simple methods for: (1) Determining whether the subgrade materials are collapsible; and (2) estimating the amount of volume change that is likely to occur in the 'Asst. Prof., Ctr. for Advanced Res. in Transp., Arizona State Univ., Tempe, AZ 85287. Note. Discussion open until April 1, 1989. To extend the closing date one month,
土木工程外文文献及翻译
Original Article Impact of crack width on bond: confined and unconfine d rebar David https://www.wendangku.net/doc/9b2599588.html,w1, Denglei Tang2, Thoma s K. C.Molyneaux3 and Rebecca Gravina3 (1)School of the Built Environment, Heriot Watt University, Edinburgh, EH14 4AS, UK (2)VicRoads, Melbourne, VIC, Australia (3)School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne, VIC, 3000, Australia David W. Law Email: https://www.wendangku.net/doc/9b2599588.html,w@https://www.wendangku.net/doc/9b2599588.html, Received: 14January2010Accepted: 14Decemb er2010Published online: 23December2010 Abstract This paper reports the results of a research project comp aring the effect of surface crack width and degree of corrosi on on the bond strength of confined and unconfined deforme d 12 and 16mm mild steel reinforcing bars. The corrosion was induced by chloride contamination of the concrete and
材料英文文献翻译
The development of plastic mould China's industrial plastic moulds from the start to now, after more than half a century, there has been great development, mold levels have been greatly enhanced. Mould has been at large can produce 48-inch big-screen color TV Molded Case injection mold, 6.5 kg capacity washing machine full of plastic molds, as well as the overall car bumpers and dashboards, and other plastic mould precision plastic molds, the camera is capable of producing plastic mould , multi-cavity mold small modulus gear and molding mold. --Such as Tianjin and Yantai days Electrical Co., Ltd Polaris IK Co. manufactured multi-cavity mold VCD and DVD gear, the gear production of such size precision plastic parts, coaxial, beating requirements have reached a similar foreign the level of product, but also the application of the latest gear design software to correct contraction as a result of the molding profile error to the standard involute requirements. Production can only 0.08 mm thickness of a two-cavity mold and the air Cup difficulty of plastic doors and windows out of high modulus, and so on. Model cavity injection molding manufacturing accuracy of 0.02 to 0.05 mm, surface roughness Ra0.2 μ m, mold quality, and significantly increase life expectancy, non-hardening steel mould life up to 10~ 30 million, hardening steel form up to 50 ~ 10 million times, shorten the delivery time than before, but still higher than abroad,and the gap between a specific data table. Process, the multi-material plastic molding die, efficient multicolor injection mould, inserts exchange structure and core pulling Stripping the innovative design has also made great progress. Gas-assisted injection molding, the use of more mature technologies, such as Qingdao Hisense Co., Ltd., Tianjin factory communications and broadcasting companies, such as mold manufacturers succeeded in 29 ~ 34-inch TV thick-walled shell, as well as some parts on the use of gas-assisted mould technology Some manufacturers also use the C-MOLD gas-assisted software and achieved better results. Prescott, such as Shanghai, such as the new company will provide users with gas-assisted molding equipment and technology. Began promoting hot runner mold, and some plants use rate of more than 20 percent, the general heat-thermal hot runner, or device, a small number of units with the world's advanced level of rigorous hot runner-needle device, a small number of units with World advanced level of rigorous needle-hot runner mould. However, the use of hot runner overall rate of less than 10%, with overseas compared to 50 ~ 80%, the gap larger. In the manufacturing technology, CAD / CAM / CAE technology on the level of application of a new level to the enterprise for the production of household appliances representatives have introduced a considerable number of CAD / CAM systems, such as the United States EDS UG Ⅱ,
建筑外文文献及翻译
外文原文 Study on Human Resource Allocation in Multi-Project Based on the Priority and the Cost of Projects Lin Jingjing , Zhou Guohua SchoolofEconomics and management, Southwest Jiao tong University ,610031 ,China Abstract----This paper put forward the a ffecting factors of project’s priority. which is introduced into a multi-objective optimization model for human resource allocation in multi-project environment . The objectives of the model were the minimum cost loss due to the delay of the time limit of the projects and the minimum delay of the project with the highest priority .Then a Genetic Algorithm to solve the model was introduced. Finally, a numerical example was used to testify the feasibility of the model and the algorithm. Index Terms—Genetic Algorithm, Human Resource Allocation, Multi-project’s project’s priority . 1.INTRODUCTION More and more enterprises are facing the challenge of multi-project management, which has been the focus among researches on project management. In multi-project environment ,the share are competition of resources such as capital , time and human resources often occur .Therefore , it’s critical to schedule projects in order to satisfy the different resource demands and to shorten the projects’ duration time with resources constrained ,as in [1].For many enterprises ,the human resources are the most precious asset .So enterprises should reasonably and effectively allocate each resource , especially the human resource ,in order to shorten the time and cost of projects and to increase the benefits .Some literatures have