机械设计中英文外文翻译文献

(文档含英文原文和中文翻译)

中英文资料外文翻译

Fundamentals Of Machinery Design

This introductory chapter is a general survey of machinery design．First it presents the definition and major role of machinery design，the relationship between machinery

and its components．Then it gives an overview of machinery design as a fundamental course and outlines a general procedure of machinery design followed by all the engineers．Finally, it lists the contents of the course and the primary goals to be achieved．

1．1 The role of machinery design

Machinery design is to formulate all engineering plan．Engineering in essence is to utilize the existing resources and natural law to benefit humanity．As a major segment of engineerin，machinery design involves a range of disciplines in materials，mechanics，heat，flow，control，electronics and production．Although many high

technologies are computerized and automated，and are rapidly merged into Our daily life，machines are indispensable for various special work that is difficult or impracticable to be carried out by human．Moreover，machinery can significantly improve efficiency and quality of production，which is crucial in current competitive global market．

In the modern industrialized world，the wealth and living standards of a nation are closely linked with their capabilities to design and manufacture engineering products．It can be claimed that the advancement of machinery design and manufacturing can remarkable promote the overall level of a country’s industrialization．Those nations，who do not perform well in design and manufacture fields，are not competitive in world markets．It is evident that several countries that used to be leaders in the design and manufacturing sectors until the l 960s and the

1 970s had，by the l990s，slipped back and lost their leadership．On the contrary, our Country is rapidly picking up her position in manufacturing industry since the l 9 80s and is playing a more and more vital role in the global market．To accelerate such an industrializing process of our country, highly skilled design engineers having extensive

knowledge and expertise are needed．That is why the course of machinery design is of great significance for students of engineering．

The course of machinery design is considerable different from those background subjects in science and mathematics．For many students，it is perhaps one of their basic professional engineering courses concerned with obtaining solutions to practical problem s．Definitely these solutions must clearly represent an understanding of the underlying science，usually such an understanding may not be sufficient，empirical knowledge or engineering judgement has to be also involved．Furthermore，due to be professional nature of this subject，most design problems may not have one right solution．Nevertheless it is achievable to determine a better design from all feasible solutions．

1．2 Machinery and components

A state-of-the-art machine may encompass all or part of mechanical，electrical，control，sensor，monitoring and lubricating sub—systems．In

terms

of the functions of those parts，the machine can also be viewed to be comprised of power，transmission，execution and control／manipulation parts．Regardless of the complexity, however，the major functional part may be still the mechanical system．For

convenience of analysis，the mechanical system can be decomposed int0．mechanisms that are designed to execute some specific tasks．And the mechanism can be further decomposed into mechanical components．In this sense，the mechanical components are the fundamental elements of machinery．

On the whole，mechanical components can be classified as universal and special components．Bolts，gear and chains are the typical examples of the universal components which can be used extensively in different machines across various industrial sectors．Turbine blades，crankshaft and aircraft propeller are the examples of

the special components，which Can be used extensively in different machines across various industrial sectors．turbine blades，crankshaft and aircraft propeller are

the examples of the special components，which are designed for some specific purposes．In addition to this，if a number of components are manufactured，assembled and even equipped as an individual system，e．g．leaf spring set

in a vehicle，it is also termed as a mechanical part．

A good machine definitely requires quality individual components．Thus，the design of components is very important．When designing a machine，on the other

hand，engineers invariably find that requirements and constraints of its components are

interrelated．As a local portion，the component is expected to play a certain role on the machine and therefore must be appropriately restrained by the whole system．The design of a gear drive in a speed—reducer，for instance，depends upon not only the strength and stiffness，but also the space available for the gears in the shaft and relation with other transmission drive．This means that the design of the mechanical components inevitably requires a whole view in the whole system．

Due to relationship between a machine and its components，the process of machinery design usually covers interconnected designs of machine，parts，and components．Any modification and adjustment in one component may considerably affect the designs of other components or parts．To present the best possible design solution，the iteration of evaluation，analysis and optimization across all the process seem indispensable．

1．3 Overview of machinery design

This course is primarily concerned with the design of specific components of machines or mechanical systems．Competence in this area is basic to the consideration and synthesis of complete machines and systems in subsequent courses and professional practice．It Can be seen that even the design of a single bolt or spring needs the designer’s thorough understanding of the principles and methods of

machinery design together with empirical information，good judgment and even a degre3e of ingenuity in order to produce the best product for the society today．

It is natural that designing engineers give first consideration to the functional and economic aspects of new products or devices．Machinery design needs to ensure safety

and reliability in a prescribed lifetime．To address such a problem conventionally，the technical consideration of the mechanical component design is largely centered around two main areas of concerns：(1) strength-stiffness-stability criteria involving the bulk of a solid member and (2) surface phenomena including friction，lubrication，weal7，and environmental deterioration．However，in comparison with such relatively straightforward computations as stress and deflection，the design determination of safety and reliability is likely to be an elusive and indefinite matter，complicated by psychological and sociological factors．It must be kept in mind that safety and reliability are inherently relative to each other，and the value judgments

must be made with regard to trade—offs between safety，reliability，cost，weight，and so

forth．

On the other hand，a practical design needs to reflect clearly manufacturability and economy to make sure of the lowest cost as well as the least consumption of energy and materials．Otherwise，the products or devices designed will be of no further engineering or commercial interests．Nowadays，the simultaneous considerations of manufacturing and assembly factors phases including design，manufacturing，inspection，as

assembly and other is considered in such a parallel fashion that the quality and cost are

best satisfied concurrently．

In addition to these traditionally technological and economic considerations fundamental to the design and development of mechanical components and systems，the modern engineers have become increasingly concerned with the broader considerations of sustainability，ecology，aesthetics，ergonomics，maintainability，and

overall quality of life．It is clear that a greater than ever engineering effort is being recently devoted to broader considerations relating to the influences of engineered products on people as well as on the environment．

The following is a list of general factors for engineers to consider in the design process，which from a different viewpoint shows us a panoramic picture with regard to the design-related activities and tasks．

(1) Cost of manufacturing．Will the selling price be competitive? Are there cheaper ways of manufacturing the machine? Could other materials be used? Are any special tools，dies, jigs，or fixtures needed? Can it easily be inspected? Can the workshop produce it? Is heat treatment necessary? Can parts be easily welded?

第4页

Cost of operation．Are power requirements too large? What type of fuel

will be used? Will operation cost be less expensive?

(3) Cost of maintenance．Are all parts easily accessible? Are access panels needed? Can common tools be used? Can replacement parts be available?

(4) Safety features．Is a suitable factor of safety used? Does the safety factor meet existing codes? Are fuses，guards，and／or safety valves used? Are shear pins needed? Is there any radiation hazard? Any overlooked ”stress raiser”? Are there any dangerous fumes?

(5) Packaging and transportation．Can the machine be readily packaged for shipping without breakage? Is its size suitable to parcel post regulations, freight car dimensions，or trailer truck size? Are shipping bolts necessary? Is its center of gravity in a desirable location?

(6) Lubrication．Does the system need periodic checking? Is it automatic? Is

it a sealed system?

(7) Materials．Are chemical，physical，and mechanical properties suitable to its use? Is corrosion a factor? Will the materials withstand impact? Is thermal or electrical conductivity important? Will high or low temperatures present any problem? Will design stress keep parts reasonable in size?

(8) Strength．Have dimensions of components been carefully calculated? Have all the load cases be taken into account? Have the stress concentrations been carefully considered? Has the fatigue effect be computed?

(9) Kinematics．Does it provide necessary motion for moving parts? Are rotational speeds reasonable? Could linkages replace cams? What will be the best choice，the belts，chains or gears? Is intermittent motion needed?

(10) Styling．Does the color have eye appeal? Is the sharp desirable? Is the machine well proportioned? Are the calibrations on dials easily read? Are the controls easy to operate?

(11) Drawings．Are standardized parts used? Are the tolerances realistic? Is the surface finish over-specified? Must the design conform to any standards?

(12) Ergonomics．Has the operator of the equipment been considered? Are the controls conveniently located to avoid operator fatigue? Are knobs，grab bars，hand wheels，levers，and dial calibrations of proper size to fit the average operator?

1．4 A general procedure of machinery design

Whatever design tasks the designers are expected to complete，they

always，consciously or unconsciously，follow the similar process which goes as follows：

(1)Studies of feasibility

After understanding the product functions，operational conditions，manufacturing constraints and key technologies，go on to uncover existing solutions to some similar problems so as to clarify the design tasks，understand the needs，present the major functional parameters and evaluate design tasks，proposal of design aims，and feasibility analysis．

(2) Conceptual design of configuration

According to the design of tasks and functional parameter，designs need to extensively search for various feasible configurations and alternatives．For

convenience，usually，the system can be analyzed comprehensively by decomposing it

into power sources，transmission and work mechanisms．

A great effort needs to be devoted to the analysis and synthesis of these different parts．For example，the power source may be selected from motor，engine and turbine．Each power source may have a range of power and kinematical parameters ．Similarly, power trains may have numerous options

available，e．g．belts，chains，gears，worm gears and many other drives．Obviously selecting an appropriate configuration would guarantee the Success of the whole design and the quality of the products．To make a best possible decision，an iterative process is normally required to select，analyze，compare and evaluate different configurations．At this stage，the goals involve sketching of configuration，determination of kinematical mechanisms，and evaluation of functional parameter(power and kinematics)．

(3)Detailed technical design

Based on the design of configuration and parameters，a number of

assembly and component drawings will be completed to reflect the detailed

design including kinematics，power，strength，stiffness，dynamics，stability，fatigue and SO on．Consideration should also be given to manufacturing

factors by presenting structural details，materials，and both geometric

and dimensional tolerances．This part of work will also be carried out in

a repeated process in drawings，calculation，evaluation and modification

until a best possible design is achieved．The goal at this stage is to

complete assembly and component drawings，structural details，design calculations and detailed technical documentations．

(4)Modification of design

After the design is completed，a prototype is usually made for a more realistic physical assessment of the design quality．This will help correct any drawback or fault that may be overlooked or neglected during the design process．At this stage，the goal is to correct the design imperfection，test the potential manufacturing or assembly flaws and refine /improve design．

1．5 Contents and tasks of the course

The course Machinery Design will cover the following contents：

(1)Preliminaries．the fundamental principles of machinery and

Components design，design theory，selection of materials，structure，friction

，wear and lubrication．

(2)Connection．sand．joints．thread．fasteners，keys，rivets，welds，bonds ．and adhesive and interference joints．

(3)Transmission．screws，chains，belts，gears，worms，bevel．gears

And helical gears．

(4)Shaft．system．rolling—contact．bearings，sliding

bearings，clutches，couplings，shafts，axles and spindles．

(5)Other part s．springs，housings and frame s．

The course centers on engineering design of mechanical components and

is in a category of fundamental methodology and procedure．It is not

feasible or realistic for the students to become involved in the detailed

design considerations associated with all machine components．Instead，the textbook has its main focus on some typical components and parts．However，

the methodologies and procedures to be developed in this course can be

extended to more design cases．For this reason，an emphasis will be laid

on the methods and procedure s over the course so that the student s will

gain a certain competence in applying these skills and knowledge to

designing more mechanical components．

As a professional fundamental course，it will help students to acquire

a sol id knowledge of mechanical design and engineering awareness．More specifically，the course will help to develop the students’ competence in

the following facets：

Competence of creative design and solving practical problem；

Competence of team work as well as professional presentation and communications：

Competence of apprehending the design principles and

regulations，synthesizing the knowledge to develop new designs：

Competence of engineering research as well as using design

code s，handbooks，standards and references：

Competence of doing experiments to solve problem in the design of

typical components：

Competence of understanding newly introduced technological as well as

economic codes to update the knowledge of machinery design．

It is worth noticing that the course will also integrate a number of

preceding relevant subjects at the university—level ，including mathematics ，physics，electronics，chemistry，solid mechanics，fluid mechanics，heat transfer，thermodynamics，computin9，and so forth．It will combine the knowledge about science and professional skills to solve some practical engineering problems，which will significantly advance students’ competence and enlarge their vision to the professional engineers．It should be pointed out that skills and experience could be

acquired only by a great deal of practice——hour after monotonous hour of

it．It is acknowledged universally that nothing worthwhile in life can

be achieved without hard work，often tedious，dull and monotonous，and engineering is no exception．

机械设计的基本原则

这个导言章节是对机械设计的一个纵览。第一它给出定义并且指出机械设计的重要角色，以及机械与其组成部分之间的关系．然后它给出了机械设计的概述作为一基础的课程和列出所有工程师都应该遵循的机械设计的一般程序．最后，它列出课程的目录和主要要达成的目标。

1.1个机械设计的角色

机械设计用来规划述所有的机械示意图。工程学本质上是利用现有的资源河自然法则为人类谋利。作为工程学的一个主要部分，机械设计在材料、力学、热、流量、控制、电子学和生产方面有一系列的原则。虽然许多高技术都采用计算机化和自动化，并且迅速的融入我们的日常生活，机器是各种不同的特殊工作不可缺少的，那些特殊工作对人类来说是非常难执行的或者是不可执行的。此外，机器可以明显的改良改良生产的效率和品质，效率和品质在现在竞争强烈的国际市场上起着决定性作用。

在现代的工业化的世界中，一个国家的财富和生活水平是与他们的设计和制造机械产品紧密相连的。可以断言，机械产品的设计和制造的提高能明显的促进一个国家的工业化总体水平。这些在设计和制造领域发展不好的国家，在国际市场中竞争力差。明显的，一些国家曾经是设计和制造业中的领头羊，直到七八十年代，到了九十年代他们后退并且失去了他们的领导地位。相反的，自从八十年代以后，国家正在快速地发展占据她在制造业中的位置并且在国际市场中担任一个越来越重要的角色。为了加速我国的工业化进程，有广泛知识和专长的高技术设计工程师是不可或缺的。那就是机械设计课程对学习机械的学生的重要的原因。机械设计的课程与科学和数学中背景科学有相当多的不同。对许多学生来说，它或许是他们用来解决相关实际问题的基本的专业工程课程。可以明确的是，这些解决办法一定可以明确的描绘对基础科学的一种理解，通常这样的理解可能不够充分，经验得来的知识或工程判断同样也被牵涉在内。此外，由于这么学科的专业性，大多数的设计问题可能没有一个正确的解决方式。然而，从所有可行的解决办法中确定一个更好的设计是可取的。

1.2机械和组成部分

一个技术发展水平机器可能包含所有的或部分机械、电力有关，控制、感应器，监听和加油子系统。就这些部分的功能来说，机器也可以看作是由动力、传动、实行和控制／处理零配件组成的。不管其复杂性，然而，其主要功能部分可以依然是机械系统。为了方便分析，机械系统能够分成运行一些特定任务的机械装置。机械装置可以进一步分成机械构件。在这种情况下，机械构件是机械的基础元素。总的来说，机械构件可以归类为普通构件和特殊构件。螺拴，传动机构和链条是能广泛地用于不同的机械构件横断面的不同的普通构件典型例子。轮机刀刃，曲柄桥和航空器螺旋浆是广泛地用于不同的机械构件横断面的不同的特殊构件典型例子轮机刀刃，曲柄桥和航空器航空器螺旋浆是为特殊目的制造的特殊构件的例子。除此之外，如果许多的构件制造出来，组装并且甚至是装备成一个独立的系统，比方说车辆中的板片弹簧组，它也叫做机械的一个部分。

一部好的机器一定需要优质的单独构件。因此，构件设计是非常重要的。当设计一部机器的时候，另一方面，工程师总是发现调整需要量和系统规定参数是相关的。作为局部的一部分，构件被用来在机器上起一个特定的作用，因此在整个系统中一定是被适当限制的。设计齿轮传动在一定的速度，比方说减压器，不仅仅取决于强度和刚性，同样取决于传动机构中的可用空间以及其与其他传动机构的关系。这就意味着机械机构的设计不可避免的需要对整个系统有个整体性了解。基于机器与起部件之间的关系，机构的设计工序通常涉及互相连接的机器设计，零件的设计以及部件的设计。对机器部件的任何修改和调整都有可能非常影响其它部件或部分的设计。为了达到最合适的设计方法，在整个工序中对数据的估算，分析和最优化似乎是必不可少的。

1.3 机械设计概述

这门课程主要的涉及机器或机械系统特殊部件的设计。在这方面的能力是学习后续课程中综合的和相关的成套机器与系统的基础。可以看出，甚至是一个单独的螺栓或弹簧都需要设计者对机械设计的原则和方法的彻底理解，以及以实验资料为依据，良好的判断力甚至是一定的心灵手巧，从而为现在的社会制造最好的产品。工程师第一当然要考虑到新产品或设备的实用性和经济方面因素。机器设计需要保证其在使用寿命内的安全性与可靠性。为解决这类问题，机械构架设计重要考虑的技术因素大部分都集中在两个主要的方面：（1）包括大部分实心的构件在内的强度-刚性-安全性的标准（ 2 ）表面的现象，包括摩擦，润滑，环境相比，这种相对简单的计算为应力和挠度，设计确定安全性和可靠性有可能是一个难以实现的和无限期的问题，复杂的心理和社会学.它必须牢记该安全性和可靠性具有内在的相对对方，和价值判断必须方面取得权衡安全性，可靠性，成本，重量和使用性。

另一方面，实际需要设计制造，并清楚地反映经济才能确保以最低的成本，以及最少的能源消耗和材料.否则，产品或设备的设计将不再工程或商业领域.现在同时考虑制造和组装阶段的因素包括设计，制造，检查，如大会和其他被认为是在这样的并行方式的质量和成本最满意的同时

除了这些传统的技术和经济方面的考虑基本的设计和开发的机械部件和系统，现代的工程师们越来越关注与更广泛的考虑可持续发展，生态，美学，人机工程学，可维护性，整体素质性能.它显然比以往任何时候都更大的工程正在努力最近专门讨论更广泛的考虑有关工程的影响产品的人，以及对环境的

（1）制造业.在成本的销售价格上具有竞争力？有更便宜的方法制造的机器？其他材料可以使用？任何特别工具，模具，夹具，或夹具需要？它可以很容易地进行检查？可以车间生产吗？热处理是必要的？可以很容易焊接的部分？

（2）业务费用.功率要求过大？什么类型的燃料将用于？将运营成本减少昂贵？（3）维修费. 所有地区都方便？是获得小组需要？可以共同使用的工具？可更换部件可？

（4）安全功能。仍是一个适当的安全系数使用？是否安全系数满足现有的守则？是引信，警卫和/或安全阀使用？正在剪脚需要？有没有辐射危害？任何忽视“强调养” ？是否有任何危险烟气？

（5）包装和运输。可以很容易的机器包装航运无破损？是它的尺寸适合邮寄包裹条例，货车尺寸，或拖车的卡车大小？出货螺栓有必要吗？是它的重心在一个理想的位置？

（6）润滑。该系统需要定期检查？它自动？是它的密封系统？

（7）材料。是化学，物理和力学性能适合它的使用？腐蚀是一个因素？将材料承受冲击？是热或电导率重要？将高或低的温度提出任何问题吗？将设计部分应力保持合理模磨具化？

（8）实力。有问题的部件经过精心计算的？有所有负载情况下予以考虑？具有应力集中经过仔细考虑？有疲劳作用计算？

（9）运动学。它提供必要的运动部件的动议？是旋转速度是否合理？可以联系更换凸轮？这将是最好的选择，皮带，链条或齿轮？间歇运动需要？

（10）造型。没有眼睛的颜色有吸引力？可取的是尖锐？是

机以及比例？是校准的转盘轻松阅读？是控制易于操作？

（11）图纸。标准化部件？是公差现实吗？是表面光洁度超过指定的？设计必须符合任何标准？

（12）工效。有运营商的设备被视为？是控制交通方便，以避免经营者的疲劳？是旋钮，扶手，手轮子，杠杆，和拨号校准的适当规模，以适应平均运营商？

1.4一般程序的机械设计

无论设计任务的设计，预计完成后，他们始终自觉或不自觉地遵循类似的过程顺利

如下:

（1）可行性研究

在了解产品的功能，运行条件，制造制约因素和关键技术，去发现现有的解决一些类似问题，以便澄清的设计任务，了解他们的需要，目前的主要功能参数和评价的设计任务，设计目标的建议，并可行性分析。

（2）概念设计的配置

根据设计任务和功能参数，设计需要广泛寻求各种可行的配置和替代品.为了方便起见，通常情况下，该系统可综合分析分解它到电源，传输和工作机制。伟

冲压模具技术外文翻译(含外文文献)

前言 在目前激烈的市场竞争中，产品投入市场的迟早往往是成败的关键。模具是高质量、高效率的产品生产工具，模具开发周期占整个产品开发周期的主要部分。因此客户对模具开发周期要求越来越短，不少客户把模具的交货期放在第一位置，然后才是质量和价格。因此，如何在保证质量、控制成本的前提下加工模具是值得认真考虑的问题。模具加工工艺是一项先进的制造工艺，已成为重要发展方向，在航空航天、汽车、机械等各行业得到越来越广泛的应用。模具加工技术，可以提高制造业的综合效益和竞争力。研究和建立模具工艺数据库，为生产企业提供迫切需要的高速切削加工数据，对推广高速切削加工技术具有非常重要的意义。本文的主要目标就是构建一个冲压模具工艺过程，将模具制造企业在实际生产中结合刀具、工件、机床与企业自身的实际情况积累得高速切削加工实例、工艺参数和经验等数据有选择地存储到高速切削数据库中，不但可以节省大量的人力、物力、财力，而且可以指导高速加工生产实践，达到提高加工效率，降低刀具费用，获得更高的经济效益。 1.冲压的概念、特点及应用 冲压是利用安装在冲压设备（主要是压力机）上的模具对材料施加压力，使其产生分离或塑性变形，从而获得所需零件（俗称冲压或冲压件）的一种压力加工方法。冲压通常是在常温下对材料进行冷变形加工，且主要采用板料来加工成所需零件，所以也叫冷冲压或板料冲压。冲压是材料压力加工或塑性加工的主要方法之一，隶属于材料成型工程术。 冲压所使用的模具称为冲压模具，简称冲模。冲模是将材料（金属或非金属）批量加工成所需冲件的专用工具。冲模在冲压中至关重要，没有符合要求的冲模，批量冲压生产就难以进行；没有先进的冲模，先进的冲压工艺就无法实现。冲压工艺与模具、冲压设备和冲压材料构成冲压加工的三要素，只有它们相互结合才能得出冲压件。 与机械加工及塑性加工的其它方法相比，冲压加工无论在技术方面还是经济方面都具有许多独特的优点，主要表现如下； (1) 冲压加工的生产效率高，且操作方便，易于实现机械化与自动化。这是

机械设计设计外文文献翻译、中英文翻译、外文翻译

机械设计 摘要：机器是由机械装置和其它组件组成的。它是一种用来转换或传递能量的装置，例如：发动机、涡轮机、车辆、起重机、印刷机、洗衣机、照相机和摄影机等。许多原则和设计方法不但适用于机器的设计，也适用于非机器的设计。术语中的“机械装置设计”的含义要比“机械设计”的含义更为广泛一些，机械装置设计包括机械设计。在分析运动及设计结构时，要把产品外型以及以后的保养也要考虑在机械设计中。在机械工程领域中，以及其它工程领域中，所有这些都需要机械设备，比如：开关、凸轮、阀门、船舶以及搅拌机等。 关键词：设计流程设计规则机械设计 设计流程 设计开始之前就要想到机器的实际性，现存的机器需要在耐用性、效率、重量、速度，或者成本上得到改善。新的机器必需具有以前机器所能执行的功能。 在设计的初始阶段，应该允许设计人员充分发挥创造性，不要受到任何约束。即使产生了许多不切实际的想法，也会在设计的早期，即在绘制图纸之前被改正掉。只有这样，才不致于阻断创新的思路。通常,还要提出几套设计方案，然后加以比较。很有可能在这个计划最后决定中,使用了某些不在计划之内的一些设想。 一般的当外型特点和组件部分的尺寸特点分析得透彻时，就可以全面的设计和分析。接着还要客观的分析机器性能的优越性，以及它的安全、重量、耐用性，并且竞争力的成本也要考虑在分析结果之内。每一个至关重要的部分要优化它的比例和尺寸，同时也要保持与其它组成部分相协调。 也要选择原材料和处理原材料的方法。通过力学原理来分析和实现这些重要的特性，如那些静态反应的能量和摩擦力的最佳利用，像动力惯性、加速动力和能量；包括弹性材料的强度、应力和刚度等材料的物理特性，以及流体润滑和驱动器的流体力学。设计的过程是重复和合作的过程，无论是正式或非正式的进行，对设计者来说每个阶段都很重要。 最后，以图样为设计的标准，并建立将来的模型。如果它的测试是符合事先要

外文翻译

Load and Ultimate Moment of Prestressed Concrete Action Under Overload-Cracking Load It has been shown that a variation in the external load acting on a prestressed beam results in a change in the location of the pressure line for beams in the elastic range.This is a fundamental principle of prestressed construction.In a normal prestressed beam,this shift in the location of the pressure line continues at a relatively uniform rate,as the external load is increased,to the point where cracks develop in the tension fiber.After the cracking load has been exceeded,the rate of movement in the pressure line decreases as additional load is applied,and a significant increase in the stress in the prestressing tendon and the resultant concrete force begins to take place.This change in the action of the internal moment continues until all movement of the pressure line ceases.The moment caused by loads that are applied thereafter is offset entirely by a corresponding and proportional change in the internal forces,just as in reinforced-concrete construction.This fact,that the load in the elastic range and the plastic range is carried by actions that are fundamentally different,is very significant and renders strength computations essential for all designs in order to ensure that adequate safety factors exist.This is true even though the stresses in the elastic range may conform to a recognized elastic design criterion. It should be noted that the load deflection curve is close to a straight line up to the cracking load and that the curve becomes progressively more curved as the load is increased above the cracking load.The curvature of the load-deflection curve for loads over the cracking load is due to the change in the basic internal resisting moment action that counteracts the applied loads,as described above,as well as to plastic strains that begin to take place in the steel and the concrete when stressed to high levels. In some structures it may be essential that the flexural members remain crack free even under significant overloads.This may be due to the structures’being exposed to exceptionally corrosive atmospheres during their useful life.In designing prestressed members to be used in special structures of this type,it may be necessary to compute the load that causes cracking of the tensile flange,in order to ensure that adequate safety against cracking is provided by the design.The computation of the moment that will cause cracking is also necessary to ensure compliance with some design criteria. Many tests have demonstrated that the load-deflection curves of prestressed beams are approximately linear up to and slightly in excess of the load that causes the first cracks in the tensile flange.(The linearity is a function of the rate at which the load is applied.)For this reason,normal elastic-design relationships can be used in computing the cracking load by simply determining the load that results in a net tensile stress in the tensile flange(prestress minus the effects of the applied loads)that is equal to the tensile strength of the concrete.It is customary to assume that the flexural tensile strength of the concrete is equal to the modulus of rupture of the

机械专业毕业论文外文翻译

附录一英文科技文献翻译 英文原文： Experimental investigation of laser surface textured parallel thrust bearings Performance enhancements by laser surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Test results are compared with a theoretical model and good correlation is found over the relevant operating conditions. A compari- son of the performance of unidirectional and bi-directional partial-LST bearings with that of a baseline, untextured bearing is presented showing the bene?ts of LST in terms of increased clearance and reduced friction. KEY WORDS: ?uid ?lm bearings, slider bearings, surface texturing 1. Introduction The classical theory of hydrodynamic lubrication yields linear (Couette) velocity distribution with zero pressure gradients between smooth parallel surfaces under steady-state sliding. This results in an unstable hydrodynamic ?lm that would collapse under any external force acting normal to the surfaces. However, experience shows that stable lubricating ?lms can develop between parallel sliding surfaces, generally because of some mechanism that relaxes one or more of the assumptions of the classical theory. A stable ?uid ?lm with su?cient load-carrying capacity in parallel sliding surfaces can be obtained, for example, with macro or micro surface structure of di?erent types. These include waviness [1] and protruding microasperities [2–4]. A good literature review on the subject can be found in Ref. [5]. More recently, laser surface texturing (LST) [6–8], as well as inlet roughening by longitudinal or transverse grooves [9] were suggested to provide load capacity in parallel sliding. The inlet roughness concept of Tonder [9] is based on ??e?ective clearance‘‘ reduction in the sliding direction and in this respect it is identical to the par- tial-LST concept described in ref. [10] for generating hydrostatic e?ect in high-pressure mechanical seals. Very recently Wang et al. [11] demonstrated experimentally a doubling of the load-carrying capacity for the surface- texture design by reactive ion etching of SiC

机械设计外文翻译(中英文)

机械设计理论 机械设计是一门通过设计新产品或者改进老产品来满足人类需求的应用技术科学。它涉及工程技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。 进行各种机械设计工作的人员通常被称为设计人员或者机械设计工程师。机械设计是一项创造性的工作。设计工程师不仅在工作上要有创造性，还必须在机械制图、运动学、工程材料、材料力学和机械制造工艺学等方面具有深厚的基础知识。如前所诉，机械设计的目的是生产能够满足人类需求的产品。发明、发现和科技知识本身并不一定能给人类带来好处，只有当它们被应用在产品上才能产生效益。因而，应该认识到在一个特定的产品进行设计之前，必须先确定人们是否需要这种产品。 应当把机械设计看成是机械设计人员运用创造性的才能进行产品设计、系统分析和制定产品的制造工艺学的一个良机。掌握工程基础知识要比熟记一些数据和公式更为重要。仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。另一方面，应该认真精确的进行所有运算。例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。 一个好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险，当新的方法不适用时，就使用原来的方法。因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。一个全新的设计，要求屏弃许多陈旧的，为人们所熟知的方法。由于许多人墨守成规，这样做并不是一件容易的事。一位机械设计师应该不断地探索改进现有的产品的方法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。 新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。 在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。即使产生了许多不切实际的想法，也会在设计的早期，即绘制图纸之前被改正掉。只有这样，才不致于堵塞创新的思路。通常，要提出几套设计方案，然后加以比较。很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。

机械设计中英文外文翻译文献

(文档含英文原文和中文翻译) 中英文资料外文翻译 Fundamentals Of Machinery Design This introductory chapter is a general survey of machinery design．First it presents the definition and major role of machinery design，the relationship between machinery

and its components．Then it gives an overview of machinery design as a fundamental course and outlines a general procedure of machinery design followed by all the engineers．Finally, it lists the contents of the course and the primary goals to be achieved． 1．1 The role of machinery design Machinery design is to formulate all engineering plan．Engineering in essence is to utilize the existing resources and natural law to benefit humanity．As a major segment of engineerin，machinery design involves a range of disciplines in materials，mechanics，heat，flow，control，electronics and production．Although many high technologies are computerized and automated，and are rapidly merged into Our daily life，machines are indispensable for various special work that is difficult or impracticable to be carried out by human．Moreover，machinery can significantly improve efficiency and quality of production，which is crucial in current competitive global market． In the modern industrialized world，the wealth and living standards of a nation are closely linked with their capabilities to design and manufacture engineering products．It can be claimed that the advancement of machinery design and manufacturing can remarkable promote the overall level of a country’s industrialization．Those nations，who do not perform well in design and manufacture fields，are not competitive in world markets．It is evident that several countries that used to be leaders in the design and manufacturing sectors until the l 960s and the 1 970s had，by the l990s，slipped back and lost their leadership．On the contrary, our Country is rapidly picking up her position in manufacturing industry since the l 9 80s and is playing a more and more vital role in the global market．To accelerate such an industrializing process of our country, highly skilled design engineers having extensive knowledge and expertise are needed．That is why the course of machinery design is of great significance for students of engineering． The course of machinery design is considerable different from those background subjects in science and mathematics．For many students，it is perhaps one of their basic professional engineering courses concerned with obtaining solutions to practical problem s．Definitely these solutions must clearly represent an understanding of the underlying science，usually such an understanding may not be sufficient，empirical knowledge or engineering judgement has to be also involved．Furthermore，due to be professional nature of this subject，most design problems may not have one right solution．Nevertheless it is achievable to determine a better design from all feasible solutions． 1．2 Machinery and components A state-of-the-art machine may encompass all or part of mechanical，electrical，control，sensor，monitoring and lubricating sub—systems．In

毕业设计外文翻译资料

外文出处： 《Exploiting Software How to Break Code》By Greg Hoglund, Gary McGraw Publisher : Addison Wesley Pub Date : February 17, 2004 ISBN : 0-201-78695-8 译文标题： JDBC接口技术 译文： JDBC是一种可用于执行SQL语句的JavaAPI（ApplicationProgrammingInterface应用程序设计接口）。它由一些Java语言编写的类和界面组成。JDBC为数据库应用开发人员、数据库前台工具开发人员提供了一种标准的应用程序设计接口，使开发人员可以用纯Java语言编写完整的数据库应用程序。 一、ODBC到JDBC的发展历程 说到JDBC，很容易让人联想到另一个十分熟悉的字眼“ODBC”。它们之间有没有联系呢？如果有，那么它们之间又是怎样的关系呢？ ODBC是OpenDatabaseConnectivity的英文简写。它是一种用来在相关或不相关的数据库管理系统（DBMS）中存取数据的，用C语言实现的，标准应用程序数据接口。通过ODBCAPI，应用程序可以存取保存在多种不同数据库管理系统（DBMS）中的数据，而不论每个DBMS使用了何种数据存储格式和编程接口。 1．ODBC的结构模型 ODBC的结构包括四个主要部分：应用程序接口、驱动器管理器、数据库驱动器和数据源。应用程序接口：屏蔽不同的ODBC数据库驱动器之间函数调用的差别，为用户提供统一的SQL编程接口。 驱动器管理器：为应用程序装载数据库驱动器。 数据库驱动器：实现ODBC的函数调用，提供对特定数据源的SQL请求。如果需要，数据库驱动器将修改应用程序的请求，使得请求符合相关的DBMS所支持的文法。 数据源：由用户想要存取的数据以及与它相关的操作系统、DBMS和用于访问DBMS的网络平台组成。 虽然ODBC驱动器管理器的主要目的是加载数据库驱动器，以便ODBC函数调用，但是数据库驱动器本身也执行ODBC函数调用，并与数据库相互配合。因此当应用系统发出调用与数据源进行连接时，数据库驱动器能管理通信协议。当建立起与数据源的连接时，数据库驱动器便能处理应用系统向DBMS发出的请求，对分析或发自数据源的设计进行必要的翻译，并将结果返回给应用系统。 2．JDBC的诞生 自从Java语言于1995年5月正式公布以来，Java风靡全球。出现大量的用java语言编写的程序，其中也包括数据库应用程序。由于没有一个Java语言的API，编程人员不得不在Java程序中加入C语言的ODBC函数调用。这就使很多Java的优秀特性无法充分发挥，比如平台无关性、面向对象特性等。随着越来越多的编程人员对Java语言的日益喜爱，越来越多的公司在Java程序开发上投入的精力日益增加，对java语言接口的访问数据库的API 的要求越来越强烈。也由于ODBC的有其不足之处，比如它并不容易使用，没有面向对象的特性等等，SUN公司决定开发一Java语言为接口的数据库应用程序开发接口。在JDK1．x 版本中，JDBC只是一个可选部件，到了JDK1．1公布时，SQL类包（也就是JDBCAPI）

机械类毕业设计外文翻译

本科毕业论文(设计) 外文翻译 学院：机电工程学院 专业：机械工程及自动化 姓名：高峰 指导教师：李延胜 2011年05 月10日 教育部办公厅 Failure Analysis，Dimensional Determination And

Analysis，Applications Of Cams INTRODUCTION It is absolutely essential that a design engineer know how and why parts fail so that reliable machines that require minimum maintenance can be designed．Sometimes a failure can be serious，such as when a tire blows out on an automobile traveling at high speed．On the other hand，a failure may be no more than a nuisance．An example is the loosening of the radiator hose in an automobile cooling system．The consequence of this latter failure is usually the loss of some radiator coolant，a condition that is readily detected and corrected．The type of load a part absorbs is just as significant as the magnitude．Generally speaking，dynamic loads with direction reversals cause greater difficulty than static loads，and therefore，fatigue strength must be considered．Another concern is whether the material is ductile or brittle．For example，brittle materials are considered to be unacceptable where fatigue is involved． Many people mistakingly interpret the word failure to mean the actual breakage of a part．However，a design engineer must consider a broader understanding of what appreciable deformation occurs．A ductile material，however will deform a large amount prior to rupture．Excessive deformation，without fracture，may cause a machine to fail because the deformed part interferes with a moving second part．Therefore，a part fails(even if it has not physically broken)whenever it no longer fulfills its required function．Sometimes failure may be due to abnormal friction or vibration between two mating parts．Failure also may be due to a phenomenon called creep，which is the plastic flow of a material under load at elevated temperatures．In addition，the actual shape of a part may be responsible for failure．For example，stress concentrations due to sudden changes in contour must be taken into account．Evaluation of stress considerations is especially important when there are dynamic loads with direction reversals and the material is not very ductile． In general，the design engineer must consider all possible modes of failure，which include the following． ——Stress ——Deformation ——Wear ——Corrosion ——Vibration ——Environmental damage ——Loosening of fastening devices

机械类外文翻译

机械类外文翻译 塑料注塑模具浇口优化 摘要:用单注塑模具浇口位置的优化方法，本文论述。该闸门优化设计的目的是最大限度地减少注塑件翘曲变形，翘曲，是因为对大多数注塑成型质量问题的关键，而这是受了很大的部分浇口位置。特征翘曲定义为最大位移的功能表面到表面的特征描述零件翘曲预测长度比。结合的优化与数值模拟技术，以找出最佳浇口位置，其中模拟armealing算法用于搜索最优。最后，通过实例讨论的文件，它可以得出结论，该方法是有效的。 注塑模具、浇口位臵、优化、特征翘曲变形关键词: 简介 塑料注射成型是一种广泛使用的，但非常复杂的生产的塑料产品，尤其是具有高生产的要求，严密性，以及大量的各种复杂形状的有效方法。质量ofinjection 成型零件是塑料材料，零件几何形状，模具结构和工艺条件的函数。注塑模具的一个最重要的部分主要是以下三个组件集:蛀牙，盖茨和亚军，和冷却系统。拉米夫定、Seow(2000)、金和拉米夫定(2002) 通过改变部分的尼斯达到平衡的腔壁厚度。在平衡型腔充填过程提供了一种均匀分布压力和透射电镜,可以极大地减少高温的翘曲变形的部分～但仅仅是腔平衡的一个重要影响因素的一部分。cially Espe,部分有其功能上的要求,其厚度通常不应该变化。 pointview注塑模具设计的重点是一门的大小和位臵,以及流道系统的大小和布局。大门的大小和转轮布局通常被认定为常量。相对而言,浇口位臵与水口大小布局也更加灵活,可以根据不同的零件的质量。 李和吉姆(姚开屏,1996a)称利用优化流道和尺寸来平衡多流道系统为multiple 注射系统。转轮平衡被形容为入口压力的差异为一多型腔模具用相同的蛀牙,也存

引进外资外文翻译资料

河南科技学院新科学院 2013届本科毕业生论文（设计） 英文文献及翻译 Foreign capital inflows and welfare in an economy with imperfect competition 学生姓名：王艳杰 所在院系：经济系 所学专业：国际经济与贸易 导师姓名：侯黎杰 完成时间：2013年4月15日

Foreign capital inflows and welfare in an economy with imperfect competition Abstract:This paper examines the resource allocational and welfare effects of exogenous inflows of foreign capital in a general-equilibrium model with oligopolistic competition and unemployment. Although the welfare impact for the short run is ambiguous and dependent upon the strength of excess profits and scale economies relative to unemployment in manufacturing, in the long run additional inflows of foreign capital always improve national welfare with capital mobility. Hence, attracting foreign capital remains a sound policy for economies characterized by imperfect competition, scale economies,and regional unemployment. Keywords: International capital mobility; Imperfect competition; Welfare 1.Introduction The welfare effects of exogenous inflows of foreign capital in the presence of trade restrictions have been extensively studied. Brecher and Diaz Alejandro (1977) show that when imports are subject to tariffs, an introduction of fo reign capital inflows accentuates the tariff distortion and hence reduces national welfare if the import-competing sector is relatively capital-intensive. In contrast, Dei (1985) shows that when imports are restricted by quotas,foreign capital inflows in the presence of foreign-owned capital always improve welfare by depressing the rental and so lowering the payments to existing foreign-owned capital. Recently, Neary (1981), using a common framework for both tariffs and quotas, obtains more general results of foreign capital inflows; the welfare effect of such inflows depends crucially on whether foreign-owned capital exists initially in the home country. In addition, Khan (1982) and Grinols (1991) have examined the effects of foreign capital inflows for a generalized Harris-Todaro economy under tariff protection. Khan finds that the result by Brecher and Diaz Alejandro is still valid even in the presence of unemployment, whereas Grinols argues that increased foreign capital need not be detrimental to welfare if the opportunity costs of labor are sufficiently low. Noteworthy is that the models used by these authors are all based upon the premise of perfect competition along with constant returns-to-scale technology. Although perfect competition serves as a useful assumption in crystallizing theoretical insights, it nevertheless fails to depict many of the real-world phenomena. The real-world economy is characterized, to a large extent, by imperfect competition and economies of scale. The policy implications of imperfect competition and economies

机械类毕业设计外文文献翻译

沈阳工业大学工程学院 毕业设计（论文）外文翻译 毕业设计（论文）题目：工具盒盖注塑模具设计 外文题目：Friction , Lubrication of Bearing 译文题目：轴承的摩擦与润滑 系（部）：机械系 专业班级：机械设计制造及其自动化0801 学生姓名：王宝帅 指导教师：魏晓波 2010年10 月15 日

外文文献原文： Friction , Lubrication of Bearing In many of the problem thus far , the student has been asked to disregard or neglect friction . Actually , friction is present to some degree whenever two parts are in contact and move on each other. The term friction refers to the resistance of two or more parts to movement. Friction is harmful or valuable depending upon where it occurs. friction is necessary for fastening devices such as screws and rivets which depend upon friction to hold the fastener and the parts together. Belt drivers, brakes, and tires are additional applications where friction is necessary. The friction of moving parts in a machine is harmful because it reduces the mechanical advantage of the device. The heat produced by friction is lost energy because no work takes place. Also , greater power is required to overcome the increased friction. Heat is destructive in that it causes expansion. Expansion may cause a bearing or sliding surface to fit tighter. If a great enough pressure builds up because made from low temperature materials may melt. There are three types of friction which must be overcome in moving parts: (1)starting, (2)sliding, and(3)rolling. Starting friction is the friction between two solids that tend to resist movement. When two parts are at a state of rest, the surface irregularities of both parts tend to interlock and form a wedging action. To produce motion in these parts, the wedge-shaped peaks and valleys of the stationary surfaces must be made to slide out and over each other. The rougher the two surfaces, the greater is starting friction resulting from their movement . Since there is usually no fixed pattern between the peaks and valleys of two mating parts, the irregularities do not interlock once the parts are in motion but slide over each other. The friction of the two surfaces is known as sliding friction. As shown in figure ,starting friction is always greater than sliding friction . Rolling friction occurs when roller devces are subjected to tremendous stress which cause the parts to change shape or deform. Under these conditions, the material in front of a roller tends to pile up and forces the object to roll slightly uphill. This changing of shape , known as deformation, causes a movement of molecules. As a result ,heat is produced from the added energy required to keep the parts turning and overcome friction. The friction caused by the wedging action of surface irregularities can be overcome