过程装备专业英语正文部分

######Manufacturing Engineering Processes1.Classification of Manufacturing ProcessesThe following table shows the classification of manufacturing engineering processes used in shaping materials. Note that only typical examples are mentioned in the table.2.Examples of Manufacturing ProcessesForging .Forging can be characterized as: mass conserving, solid state of work material (metal), mechanical primary basic process-plastic deformation. A wide variety of forging processes is used .The most common type of forging is drop forging .The metal is heated to a suitable working temperature and placed in the lower die cavity .The upper die is then lower so that the metal is forced to fill the cavity. Excess material is squeezed out between the die faces at the periphery as flash, which is removed in a later trimming process. When the term gorging is used, it usually means hot gorging. The material loss in forging processes is usually quite small. Normally, forged components require some subsequent machining, since thetolerances and surfaces obtainable are not usually satisfactory a finished product. Forging machines include drop hammers and forging presses with mechanical or hydraulic drives. Es involve simple .The machines involve simple translatory motions.Rolling Rolling can be characterized as: mass conserving, solid state of material, mechanical primary basic process-plastic deformation. Rolling is extensively used in the manufacturing of plates, sheets, structural beams, and so on. An ingot is produced in casting, and then, in several stages of rolling it is reduced in thickness, usually while hot. Since the width of the work material is kept constant, its length is increased according to the reduction. After the last hot-rolling stage, a final stage is carried out cold to improve surface quality and tolerances and to increase strength. In rolling, the profiles of the rolls designed to produce the desired geometry.Powder Compaction Powder compaction can be characterized as; mass conserving, granular state of material, mechanical primary basic process-flow and plastic deformation. In this context, only compaction of metal powder is mentioned, but generally compaction of molding sand, ceramic materials, and so on, also belong in this category.In the compaction of metal powders, the die cavity is filled with a measured volume of powder and compacted at pressures typically around 500N/mm2. During this pressing phase, the particles are packed together and plastically deformed. Typical densities after compaction are 80% of the density of the solid material. Because of the plastic deformation, the particles are”welded” together, giving sufficient strength to withstand handling. After compaction, the components are heat-treated—sintered—normally at 70%~80% of the melting temperature of the material. The atmosphere for sintering must be controlled to prevent oxidation. The duration of the sintering process varies between 30 min and 2h. The strength of the components after sintering can, depend on the material and the process parameters closely approach the strength of corresponding solid material.The die cavity, in the closed position, corresponds to the desired geometry. Compaction machinery includes both mechanical and hydraulic presses. The production rates vary between 6 and 100 components per minute.加工工艺过程1.加工工艺过程的分类2.锻造工艺过程分类锻造锻造过程的特性可表述如下，质量守恒，工作材料为固态，力学基本过程为塑性变形过程。

过程装备与控制工程英语1.过程装备(Process equipment)The process equipment in the factory is responsible for manufacturing products efficiently.2.控制工程(Control engineering)Control engineering plays a crucial role in ensuring the stability and reliability of industrial processes.3.设备(Equipment)The factory invested in state-of-the-art equipment to improve production efficiency.4.流程(Process)The production process includes multiple stages, each with its own specific requirements.5.控制(Control)The control system allows operators to monitor and adjust various parameters for optimal performance.6.自动化(Automation)Automation has greatly improved efficiency in manufacturing processes.7.传感器(Sensor)Sensors are used to collect real-time data and provide feedback for control purposes.8.测量(Measurement)Accurate measurement of process variables is crucial for maintaining quality standards.9.监控(Monitoring)Continuous monitoring of process parameters is essential for early detection of issues.10.仪表(Instrumentation)Instrumentation plays a vital role in collecting and displaying data from various sensors in a process.11.采样(Sampling)Regular sampling of raw materials ensures their quality meets the required standards.12.环境监测(Environmental monitoring)Efficient control engineering systems enable real-time environmental monitoring.13.压力(Pressure)The pressure in the system is carefully controlled to ensure stable operation.14.温度(Temperature)Temperature control is crucial for maintaining the desired chemical reaction rate.15.流量(Flow rate)Monitoring and controlling the flow rate of liquid or gas is important for process efficiency.16.液位(Liquid level)Accurate measurement of liquid level ensures proper functioning of the process.17.控制阀(Control valve)Control valves regulate the flow rate or pressure offluid in a process.18. PLC (Programmable Logic Controller)PLCs are widely used in control engineering to automate and monitor industrial processes.19.数据采集(Data acquisition)Data acquisition systems collect and record data from various sensors for analysis.20.仪器仪表校准(Instrument calibration)Regular instrument calibration ensures accurate measurement and control.21.故障诊断(Fault diagnosis)Advanced control engineering systems can detect and diagnose faults in real-time.22.实时控制(Real-time control)Real-time control engineering allows for immediate adjustments to process conditions.23.可靠性(Reliability)Reliability is a key factor in choosing process equipment and control systems.24.自适应控制(Adaptive control)Adaptive control algorithms constantly adjust process parameters to optimize performance.25.能源管理(Energy management)Efficient control engineering strategies can help optimize energy consumption in industrial processes.。

Reading material 14Evaporation1． IntroductionThe objective of evaporation is to concentrate a solution consisting of a nonvolatile solute and a volatile solvent. In the overwhelming majority of evaporations the solvent is water. Evaporation is conducted by vaporizing a portion of the solvent to produce a concentrated solution of thick liquor. Evaporation differs from drying in that the residue is a liquid-sometimes is highly viscous one-rather than a solid; it differs from distillation in that the vapor usually is a single component, and even when the vapor is a mixture, no attempt is made in the evaporation step to separate the vapor into fractions; it differs from crystallization in that emphasis is placed on concentrating a solution rather than forming and building crystals. In certain situations, e.g., in the evaporation of brine to produce common salt, the line between evaporation and crystallization is far from sharp. Evaporation sometimes produces a slurry of crystal in a saturated mother liquor.Normally, in evaporation the thick liquor is the valuable product and the vapor is condensed and discarded. In one specific situation, however, the reverse is true. Mineral-bearing water often is evaporated to give a solid-free product for boiler feed, for special process requirements, or for human consumption. This technique is often called water distillation, but technically it is evaporation. Large-scale evaporation processes have been developed and used for recovering potable water from seawater. Here the condensed water is the desired product. Only a fraction of the total water in the feed is recovered, and the remainder is returned to the sea.2. Liquid CharacteristicsThe practical solution of an evaporation problem is profoundly affected by the character of the liquor to be concentrated. It is the wide variation in liquor characteristics (which demands judgment and experience in designing and operating evaporators) that broadens this operation from simple heat transfer to a separate art. Some of the most important properties of evaporating liquids are as follows. Concentration Although the thin liquor fed to an evaporator may be sufficiently dilute to have many of the physical of water, as the concentration increases, the solution becomes more and more individualistic. The density and viscosity increase with solid content until either the solution becomes saturated or the liquor becomes too viscous for adequate heat transfer. Continued boiling of a saturated solution causes crystals to form; these must be removed or the tubes clog. The boiling point of the solution may also rise considerably as the solid content increases, so that the boiling temperature of a concentrated solution may be much higher than that of water at the same pressure.FoamingSome materials, especially organic substances, foam during vaporization. A stable foam accompanies the vapor out of the evaporator, causing heavy entertainment. In the extreme cases, the entire mass of liquid may boil over into the vapor outletand be lost.Temperature sensitivity Many fine chemicals pharmaceutical products, and foods are damaged when heated to moderate temperatures for relatively short times. In concentrating such materials special techniques are needed to reduce both the temperature of the liquid and the time of heating.Scale Some solutions deposit scale on the heating surface. The overall coefficient then steadily diminished, until the evaporator must be shut down and the tubes cleaned. When the scale is hard and insoluble, the cleaning is difficult and expensive.Materials of construction Whenever possible, evaporator are made of some kind of steel. Many solutions, however, attack ferrous metals or are contaminated by them. Special materials such as copper, nickel, stainless steel, aluminum, imperious graphite, and lead are then used. Since these materials are expensive, high heat transfer rates become especially desired to minimize the first cost of the equipment. Many other liquid characteristics must be considered by the designer of an evaporator. Some of these are specific heat, heat of concentration, freezing point, gas liberation on boiling, toxicity, explosion hazards, radioactivity, and necessity for sterile operation. Because of the variation in liquor properties, many different evaporator designers have been developed. The choice for any specific problem depends primarily on the characteristics of the liquid.3. Single and multiple-effect operationMost evaporators are heated by steam condensing on the metal tubes. Nearly always the material to be evaporated flows inside the tubes. Usually the steam is at low pressure, below 3 atm abs; often the boiling liquid is under moderate vacuum, at pressure down to about 0.05 atm abs. Reducing the boiling temperature of the liquid increase the temperature difference between the steam and the boiling liquid and thus increase the heat transfer rate in the evaporator.When a single evaporator is used, the vapor from the boiling liquid is condensed and discarded. This method is called single-effect evaporation, and although it is simple, it utilizes steam ineffectively. To evaporate 1 kg water from a solution call for from 1 to 1.3 kg of steam. If the vapor from one evaporator is fed into steam chest of a second evaporator and the vapor from second is then sent to a condenser, the operation becomes double-effect. The heat in the original steam is reused in the second effect, and the evaporation achieved by a unit mass of steam fed to the first effect is approximately doubled. Additional effects can be added in the same manner. The general method of increasing the evaporation per kilogram of steam by using a series of evaporator between the steam supply and the condenser is called multiple-effect evaporation.4. General types of evaporatorHorizontal-tube natural circulation evaporator the horizontal bundle of heating tubes is similar to the bundle of tubes in a heat exchanger. The steam enters into the tubes, where it condenses. The steam condensate leaves at the other end of the tubes. The boiling liquid solution covers the tubes. The vapor leaves the liquid surface, often goes through some deentraining device such as a baffle to preventcarryover of liquid droplets, and leaves out the top. This type is relatively cheap and is used for no viscous liquid having high heat transfer coefficients and liquids that do not deposit scale. Since liquid circulation is poor, they are unsuitable for viscous liquid. In almost all cases, this evaporator and the types discussed below are operating continuously, where the feed enters at a constant rate and the concentrate leaves at a concentrate rate.Vertical-type natural circulation evaporator in this type of evaporator, vertical rather than horizontal tubes are used, and the liquid is inside the tubes and the steam condenses outside the tubes. Because of boiling and decreases in density, the liquid rises in the tubes by natural circulation and flows downward through a large central open space or downcomer. This natural circulation increases the heat transfer coefficient. It is not used with viscous liquid. This type is often called the short-tube evaporator. A variation of this is the basket type. Where vertical tubes are used, but the heating element is held suspended in the body so there is an annular open space as the downcomer. The basket type differs from the vertical natural circulation evaporator, which has a central instead of annular open space as the downcomer, this type is widely used in the sugar, salt, and caustic soda industries.Long-tube vertical-type evaporator since the heat transfer coefficient on the steam side is very high compared to that on the evaporating liquid side, high liquid velocities are desirable. In a long-tube vertical-type evaporator the liquid is inside the tubes. The tubes are 3 to 10 m long and the formation of vapor bubbles inside the tubes causes a pumping action giving quite high liquid velocities. Generally, the liquid passes through the tubes only once and is not reticulated. Contact times can be quite low in this type. In some case,as when the ratio of the feed to evaporation rate is low.Natural recirculation of the product through the evaporators done by adding a large pipe connection between the outlet concentrate line and the feed line. This is widely used for producing condensed milk. Falling-film evaporator a variation of the long tube type is the falling-film evaporator, wherein the liquid is fed to the top of the tubes and flows down the walls as a thin film. Vapor-liquid separation usually takes place at the bottom. This type is widely used for concentrating heat-sensitive material such as orange juice and the other fruit juices, because the holdup time is very small (5 to 10 s or more).and the heat-transfer coefficients are high.Forced-circulation type evaporator this liquid film heat transfer coefficient can be increased by pumping to cause forced circulation of the liquid inside the tubes. This could be done in the long tube vertical type by adding a pipe concentrate with a pump between the outlet concentrate line and the feed line. However, usually in a forced-circulation type, the vertical tubes are shorter than in the long-tube type. Also, in other cases a separate and external horizontal heat exchanger is used. This type is very useful for viscous liquids.阅读材料14蒸发1、介绍蒸发的目的是浓缩不易挥发的溶质和易挥发的溶剂组成的溶液。

过程装备与控制工程专业英语本文为过程装备与控制工程专业英语的个人翻译尝试。

By LiyerPART 1 engineering mechanicUnit 1 introduction to mechanicof materials材料力学是应用力学的分支，用于解决固体遭受外部多种载荷产生的力学行为。

对这个课题领域的另外的称呼有材料强度与固体变形的力学。

本章节提及固体包括经受轴向载荷的杆、扭转的轴、弯曲的梁和被压缩的圆柱。

材料力学研究的主要目标是在外部载荷加载的时候确定结构的应力、压力和应变以及固体微元的具体变化。

如果能够得到物体从受载到失效的所有与载荷对应的这些物理量，我们就对物体的力学性能有了一个全面的了解。

对力学行为的理解对于各种类型结构的安全设计是十分必要的，不管是飞机和天线、建筑和桥梁、机器和发动机、或者是船和飞行器。

这就是材料力学在这么多工程领域里都属于基础学科的原因。

静力学和动力学也是基本的，但是这些学科主要解决与粒子和刚体相关的力和运动问题。

在材料力学中，我们可以通过检测一个在有限维度内受力变形的实物的应力和应变来进一步学习。

而为了确定应力和应变，我们一般使用材料的物理性质以及一些理论公式和概念。

理论分析和实验结果在材料力学中也扮演着重要的角色。

我们从理论中为预测力学状态导出了准则和公式，但这些表达方式不能被用于实际的设计中，除非材料的物性已知。

只有通过在实验室细心的实验测试，我们方能得到材料的物性。

而且，并不是所有实际问题都能通过理论分析来解决，在这种情况下，物性试验就是必要的了。

材料力学的发展是理论和实验的有趣的结合-理论有时候指明了可以得到重大进展的路，有时候实验也做到这一点。

一些著名的科学家，如Leonardo da Vinci和Galileo Galilei通过实验确定绳索、杆和梁等的强度，尽管从今天的观点，他们没有得出详尽的理论体系来解释他们的实验结果。

相反的，著名的数学家Leonhard Euler在1744年得出了圆柱体的数学理论并且计算了圆柱体的临界载荷，远早于任何能够证明他的结果重要性的实验证据出现。

过程装备与控制工程专业英语学院：化学化工学院1.Static Analysis of Beams⑴ A bar that is subjected to forces acting trasverse to its axis is called a beam. In this section weconsider only a few of the simplest types of beams, such as those shown in Flag.1.2. In every instance it is assumed that the beam has a plane of symmetry that is parallel to the plane of the figure itself. Thus ， the cross section of the beam has a vertical axis of symmetry .Also,it is assumed that the applied loads act in the plane of symmetry ,and hence bending of the beam occurs in that plane. Later we will consider a more general kind of bending in which the beam may have an unsymmetrical cross section.⑵ The beam in Fig.1.2, with a pin support at one end and a roller support at the other, is calleda simply support beam ,or a simple beam . The essential feature of a simple beam is that both ends of the beam may rotate freely during bending, but the cannot translate in lateral direction. Also ,one end of the beam can move freely in the axial direction (that is, horizontal). The supports of a simple beam may sustain vertical reactions acting either upward or downward .⑶ The beam in Flg.1.2(b) which is built-in or fixed at one end and free at the other end, iscalled a cantilever beam. At the fixed support the beam can neither rotate nor translate, while at the free end it may do both. The third example in the figure shows a beam with an overhang. This beam is simply supported at A and B and has a free at C.⑷ Loads on a beam may be concentrated forces, such as P1 and P2 in Fig.1.2(a) and (c), ordistributed loads loads, such as the the load q in Fig.1.2(b), the intesity. Distributed along the axis of the beam. For a uniformly distributed load, illustrated in Fig.1.2(b),the intensity is constant; a varying load, on the other hand, is one in which the intensity varies as a function of distance along the axis of the beam.⑸ The beams shown in Fig.1.2 are statically determinate because all their reactions can bedetermined from equations of static equilibrium. For instance ,in the case of the simple beam supporting the load P 1 [Fig.1.2(a)], both reactions are vertical, and tehir magnitudes can be found by summing moments about the ends; thus,we findL a L P R A )(1-= LL P R B 1= The reactions for the beam with an overhang [Fig.1.2 (c)]can be found the same manner.⑹ For the cantilever beam[Fig.1.2(b)], the action of the applied load q is equilibrated by avertical force RA and a couple MA acting at the fixed support, as shown in the figure. From a summation of forces in certical direction , we include thatqb R A =， And ,from a summation of moments about point A, we find)2(b a qb M A +=， The reactive moment MA acts counterclockwise as shown in the figure.⑺ The preceding examples illustrate how the reactions(forces and moments) of staticallydeterminate beams requires a considerition of the bending of the beams , and hence this subject will be postponed.⑻ The idealized support conditions shown in Fig.1.2 are encountered only occasionally inpractice. As an example ,long-span beams in bridges sometimes are constructionn with pin and roller supports at the ends. However, in beams of shorter span ,there is usually some restraint against horizonal movement of the supports. Under most conditions this restraint has little effect on the action of the beam and can be neglected. However, if the beam is very flexible, and if the horizonal restraints at the ends are very rigid , it may be necessary to consider their effects.⑼ Example Find the reactions at the supports for a simple beam loaded as shown infig.1.3(a ). Neglect the weight of the beam.⑽ Solution The loading of the beam is already given in diagrammatic form. The nature of thesupports is examined next and the unknow components of reactions are boldly indicated on the diagram. The beam , with the unknow reaction components and all the applied forces, is redrawn in Fig.1.3(b) to deliberately emphasiz this important step in constructing a free-body diagram. At A, two unknow reaction components may exist , since roller. The points of application of all forces are carefully noted. After a free-body diagram of the beam is made, the equations of statics are applied to abtain the sollution.∑=0x F ，R Ax =0∑+=0A M ，2000+100（10）+160（15）—R B =0，R B =+2700lb ↑∑+=0BM ,RAY(20)+2000—100（10）—160（5）=0，RAY=—10lb ↓ Check ：∑+↑=0FX ，—10—100—160+270=0 ⑾ Note that ∑=0x F uses up one of the three independent equations of statics, thus only twoadditional reaction compones may be determinated from statics. If more unknow reaction components or moment exist at the support, the problem becomes statically indeterminate. ⑿ Note that the concentrated moment applied at C enters only the expressions for summationmoments. The positive sign of RB indicates that the direction of RB has been correctly assumed in Fig.1.3(b). The inverse is the case of RAY ,and the vertical reaction at a is downward. Noted that a check on the arithmetical work is available if the caculations aremade as shown.横梁的静态分析⑴ 一条绕其轴水平放置的棒就是所谓的横梁，本章节我们将研究最简单的横梁模型形式，如图1.2所示。

Reading Material 16Pressure Vessel Codes①History of Pressure Vessel Codes in the United States Through the late 1800s and early 1900s, explosions in boilers and pressure vessels were frequent. A firetube boiler explosion on the Mississippi River steamboat Sultana on April 27, 1865, resulted in the boat's sinking within 20 minuted and the death of 1500 soldiers going home after the Civil War. This type of catastrophe continued unabated into the early 1900s. In 1905, a destructive explosion of a firetube boiler in a shoe factory in Brockton, Massachusetts, killed 58 people, injured 117 others, and did $400000 in property damage. In 1906, another explosion in a shoe factory in Lynn, Massachusetts, resulted in death, injury, and extensive property damage. After this accident, the Massachusetts governor directed the formation of a Board of Boiler Rules. The first set of rules for the design and construction of boilers was approved in Massachusetts on August 30, 1907. This code was three pages long.②In 1911, Colonel E. D. Meier, the president of the American Society of Mechanical Engineers, established a committee to write a set of rules for the design and construction of boilers and pressure vessels. On February 13, 1915, the first ASMEBoiler Code was issued. It was entitled "Boiler Construction Code, 1914 Edition". This was the beginning of the various sections of the ASME Boiler and Pressure Vessel Code, which ultimately became Section 1, Power Boilers.③The first ASME Code for pressure vessels was issued as "Rules for the Construction of Unfired Pressure V essels", Section Ⅷ, 1925 edition. The rules applied to vessels over 6 in. indiameter, volume over 1.5 3ft, and pressure over 30 psi. In December 1931, a Joint API-ASMECommittee was formed to develop an unfired pressure vessel code for the petroleum industry. The first edition was issued in 1934. For the nest 17 years, two separated unfired pressure vessel codes existed. In 1951, the last API-ASME Code was issued as a separated document. In 1952, the two codes were consolidated into one code----the ASME Unfired Pressure Vessel Code, Section Ⅷ. This continued until the 1968 edition. At that time, the original code became Section Ⅷ, Division 1, Pressure Vessels, and another new part was issued, which was Section Ⅷ, Division 2, Alternative Rules for Pressure Vessels.④The ANSI/ASME Boiler and Pressure Vessel Code is issued by the American Society of Mechanical Engineers with approval by the American National Standards Institute (ANSI) as an ANSI/ASME document. One or more sections of the ANSI/ASME Boiler and Pressure Vessel Code have been established as the legal requirements in 47 states in the United Stated and in all provinces of Canada. Also, in many other countries of the world, the ASME Boiler and Pressure Vessel Code is used to construct boilers and pressure vessels.⑤Organization of the ASME Boiler and Pressure Vessel Code The ASME Boiler and Pressure Vessel Code is divided into many sections, divisions, parts, and subparts. Some of these sections relate to a specific kind of equipment and application; others relate to specific materials and methods for application and control of equipment; and others relate to care and inspection of installed equipment. The following Sections specifically relate to boiler and pressure vessel design and construction.Section ⅠPower Boilers (1 volume)Section ⅢDivision 1 Nuclear Power Plant Components (7 volumes)Division 2 Concrete Reactor Vessels and Containment (1 volume)Code Case Case 1 Components in Elevated Temperature service (in Nuclear Code N-47Case book)Section ⅣHeating Boilers (1 volume)Section ⅧDivision 1Pressure Vessels (1 volume)Division 2 Alternative Rules for Pressure Vessels (1 volume)Section ⅩFiberglass-Reinforced Plastic Pressure Vessels (1 volume)⑥A new edition of the ASME Boiler and Pressure Vessel Code is issued on July 1 every three years and new addenda are issued every six months on January 1 and July 1. The new edition of the code becomes mandatory when it appears. The addenda are permissive at the date of issuance and become mandatory six months after that date.⑦Worldwide Pressure Vessel Codes In addition to the ASME Boiler and Pressure Vessel Code, which is used worldwide, many other pressure vessel codes have been legally adopted in various countries. Difficulty often occurs when vessels are designed in one country, built in another country, and installed in still a different country. With this worldwide construction this is often the case.⑧The following list is a partial summary of some of the various codes used in different countries:Australia Australian Code for Boilers and Pressure Vessels, SAA Boiler Code (Series AS 1200):AS 1210, Unfired Pressure Vessels and Class 1 H, Pressure Vessels of Advanced Design and Construction, Standards Association of Australia.France Construction Code Calculation Rules for Unfired Pressure Vessels, Syndicat National de la Chaudronnerie et de la Tuyauterie Industrielle (SNCT), Paris, France.United Kingdom British Code BS. 5500, British Standards Institution, London, England.Japan Japanese Pressure V essel Code, Ministry of Labour, published by Japan Boiler Association, Tokyo, Japan; Japanese Standard, Construction of Pressure Vessels, JIS B 8243, published by the Japan Standards Association, Tokyo, Japan; Japanese High Pressure Gas Control Law, Ministry of International Trade and Industry, published by The Institution for Safety of High Pressure Gas Engineering, Tokyo, Japan.Italy Italian Pressure Vessel Code, National Association for Combustion Control (ANNCC), Milan, Italy.Belgium Code for Good Practice for the Construction of Pressure Vessels, Belgian Standard Institute (IBN), Brussels, Belgium.Sweden Swedish Pressure Vessel Code, Tryckkarls kommissioner, the Swedish Pressure Vessel Commission, Stockholm, Sweden.压力容器准则①美国的压力容器规范历史在19世纪和20世纪初期，锅炉和压力容器频繁发生爆炸事件。

Reading Material 7Standard Mechanical TestsTo summarize the previous discussion, it is very important to know the strength of a material, both for its eventual use and also to determine the forces required to shape it. Since it is impracticable to test every article after it has been designed and made, several simple general tests are used to measure the mechanical properties of the stock material before, during and after manufacture of the final product.In sheet metal forming in particular it is important to recognize that the properties of rolled sheet may differ substantially in the rolling and transverse directions, as well as in the "through-thickness" direction. This feature can be measured in terms of the now well-known so-called γ-vaIue, which is the ratio of the transverse to the longitudina1 strain in a tensile test on wide, flat strip using techniques described by Hosford and Caddell. Volume is always approximately conserved in plastic deformation, so the thickness strain is also dependent upon the γ-value.(9) Plastic AnisotropyIn recent years much attention has been given to the fracture toughness of certain brittle materials, which is related to the ease with which a crack, once started, will propagate. A simple view of this process is that the opening of a crack releases elastic deformation energy but also requires the supply of surface energy to the two newly created areas of crack surface. If, in a brittle material, the released strain energy U is sufficient for this, the crack will propagate.8) Fracture ToughnessBecause of the length of time involved in creep testing, a shorter method is often used in which only approximate measurements of strain are made during the test, the main purpose of which is to determine the time to rupture at a given temperature and stress. These stress-rupture tests can be further speeded up by testing a string of specimens in series in a long furnace. The specimens are all subjected to the same end load but differing temperatures (which must be accurately measured, of course).An important feature of the hot tensile deformation of metals and alloys is that, at sufficiently high temperatures, extension will continue at a very slow rate under very low loads. This phenomenon, termed creep, is very important in gas turbines and many other high-temperature components. Creep tests are conducted over long periods, typically from 1000 to 10000 hours. (7) Creep TestsAt high temperature the plastic deformation of materials is dominated by diffusion processes which, for metals, become evident above about 2/3 of the absolute melting temperature T m, Tensile, compression or hardness tests may all be used at elevated temperatures.Another important subject is that of the behavior of relatively brittle materials such as cast iron, which may fail under even a single impact. Since it may be very important to avoid this type of fracture, impact tests have been devised in which a notched specimen is hit by a heavy pendulum. The energy absorbed is measured from the height of follow-through of the pendulum.(6) High-Temperature tests(5) Impact TestingAnother very important failure phenomenon is that of high--stress low-cycle fatigue which ispotentially dangerous in materials as disparate as animal bone and aerospace components.A very important phenomenon is called fatigue. It has been recognized for many years that static tensile or compressive testing is not adequate for predicting the strength of components subjected to vibration or repeated loading. These can fail at much lower stress levels, and there is a general relationship (due to Goodman) which shows the allowable oscillating stress level for a given mean stress. Fatigue testing needs considerable time, since each point on the final graph of applied stress S against the number N of cycles to failure requires a new specimen and N is usually between 106 and 108. For many non-ferrous alloys the S-N curve falls steadily, but for steels there is often a leveling-off after some 106 to 107 cycles. If the stress does not exceed this endurance limit, the specimen will last indefinitely.(4)Fatigue TestsIn the U. S. A., the Rockwell test is favored. In that test the depth of the indentation is measured whilst the load is still being applied (rather than the lateral dimensions). The Rockwell Hardness Number is designated as HR.The oldest and best known hardness tests in the U. K are the Brinell test in which a standard ball (usually 10 mm dia. ) is pressed into a metal under a prescribed load, typically 3000 kgf (= 29.42 kN or 66l5 lbf), and the Vickers test. The Brinell Hardness Number (BHN or HB) is defined as the load in kgf divided by the actual spherical surface area of the indentation in mm2. Likewise, the Vickers Hardness Number (VHN or HV) is the load in kgf divided by the pyramidal surface area (again in mm2) of the indentation.Tensile and compression tests are destructive of the sample, but it is often important to check the strength properties of stock material or finished components, without destruction. There are several types of hardness test for this purpose, which make only a small indentation in the surface.(3) Hardness TestingI t is important for metal forming calculations to know the yield stress at much higher strains than can be obtained in tension. Axial compression of a short cylinder may be used,with suitable correction for the frictional resistance on the flat ends, but a more accurate result is obtained by the transverse plane strain compression of a well-lubricated strip.(2) Compression TestsThe simplest and most widely accepted tensile test requires a cylindrical (or flat) bar with enlarged ends. This tensile specimen is subjected to a steadily increasing tensile force along its axis, and the extension of a gauge length is accurately measured as the load-extension curve, according to the appropriate standard. The results usually required are the maximum tensile stress, the yield stress, the percentage elongation to fracture and the reduction of cross-sectional area at fracture. In addition, the Young's Modulus of EIasticity, or Young Modulus may be measured. (1) Tensile Tests为了总结之前的讨论，了解材料的强度是非常重要的，包括它的最终使用还有决定使材料发生变形的力。

Reading Material 11Chemical Industry1. Definition of the Chemical IndustryAt the turn of the century there had been little difficulty in defining what constituted the chemical industry since only a very limited range of products was manufactured and these were clearly chemicals, e.g., alkali, sulfuric acid. At present, however, many thousands of chemicals are produced, from raw materials like crude oil through (in some cases) many intermediates to products which may be used directly as consumer goods, or readily converted into them. The difficulty comes in deciding at which point in this sequence the particular operation ceases to be part of the chemical industry’s sphere of activities. To consider a specific example to illustrate this dilemma, emulsion paints may contain poly (vuby1 chloride)/poly (viny1 acetate). Clearly, synthesis of viny1 chloride (or acetate) and its polymerization ate chemical activities. However, if formulation and mixing of the paint, including the polymer, is carried out by a branch of the multinational chemical companies which manufactured the ingredients, is this still part of the chemical industry or does it now belong in the decorating industry?It is therefore apparent that, because office diversity of operations and close links on many areas with other industries, there is no simple definition of the chemical industry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as “the chemical industry". It is important to bear these in mind when comparing statistical information which is derived from several sources.The major chemical companies are truly multinational and operate their sales and marketing activities in most of the countries of the world, and they also have manufacturing units in a number of countries. This international outlook for operations, or globalization, is a growing trend within chemical industry, with companies expanding their activities either by erecting manufacturing units in other countries or by taking over companies which are already operating there.Individual manufacturing plants have capacities ranging from just a few tons per year in the fine chemicals area to the real giants in the fertilizer and petrochemical sectors which range up to 500000 tonnes. The latter requires enormous capital investment, since a single plant of this size can now cost $250 million! This, coupled with the widespread use of automatic control equipment, helps to explain why the chemical industry is capital-rather than labor-intensive.The chemical industry is very high technology industry which takes full advantage of the latest advances in electronics and engineering. Computers are very widely used for all sorts of applications, from automatic control of chemical plants, to molecular modeling of structures of new compounds, to the control of analytical instruments in the laboratory.3. Research and Development (R&D) in Chemical IndustriesIn of the main reasons for the rapid growth of the chemical industry in the developed world has been its great commitment to, and investment in research and development (R&D). A typical figure is 5% of sales income, with this figure being almost doubled for the most research intensive sector, pharmaceuticals. It is important to emphasize that we are quoting percentages here not of profits but of sales income, etc, as well. In the past this tremendous investment has paid off well, leading to many useful and valuable products being introduced to the market. Examples includesynthetic polymers like nylons and polyesters, and drugs and pesticides. Although the number of new products introduced to the market has declined significantly in recent years and in times of recession the research department is usually one of the first to suffer cutbacks, the commitment to R&D remains at very high level.Likewise the chemical industry’s contribution to transport over the years has led to major improvements, Thus development of improved additives like anti-oxidants and viscosity index improves for engine oil has enabled routine servicing intervals to increase from 300 to 6000 to 12000 miles. Research and development work has also resulted in improved lubricating oils and greases, and better brake fluids. Yet again the contribution of automobile polymers and plastics has been very striking with the proportion of the total automobile derived from these materials---dashboard, steering wheel, seat padding and covering etc.--now exceeding 40%. (4)Shelter, leisure and transport.In terms of shelter the contribution of modern synthetic polymers has been substantial. Plastics are tending to replace traditional building materials like wood because they are lighter, maintenance-free (i.e. they are resistant to weathering and do not need painting). Other polymers, e.g. urea-formaldehyde and polyurethanes, are important insulating materials for reducing heat losses and hence reducing energy usage.Plastics and polymers have made a considerable impact on leisure activities with applications ranging from all-weather artificial surfaces for athletic tracks, football pitches and tennis courts to nylon strings for racquets and items like golf balls and footballs made entirely from synthetic materials.Other major advances in this sphere have been in color-fastness, i. e., resistance to the dye being washed out when the garment is cleaned.Parallel developments in the discovery of modern synthetic dyes and the technology to “bond” them to the fiber have resulted in a tremendous increase in the variety of colors available to the fashion designer. Indeed they now span almost every color and hue of the visible spectrum. Indeed if a suitable shade is not available, structural modification of an existing dye to achieve this can readily be carried out, provided there is a satisfactory market for the product.(3) Clothing. The improvement in properties of modern synthetic fibers over the traditional clothing materials (e.g. cotton and wool) has been quite remarkable. Thus shirts, dresses and suits made from polyesters liker Terylene and polyamides like Nylon are crease-resistant, machine-washable, and drip-dry or non-iron. They are also cheaper than natural materials.（2）Heath. We are all aware of the major contribution which the pharmaceutical sector of the industry has made to help keep us all healthy, e.g. by curing bacterial infections with antibiotics, and even extending life itself, e.g. blockers to lower blood pressure.(1)Food. The chemical industry makes a major contribution to food production in at leastthree ways. Firstly, by making available large quantities of artificial fertilizers which are used to replace the elements (mainly nitrogen, phosphorus and potassium) which are removed by the growing crops during modern intensive farming. Secondly,by manufacturing protection chemicals i.e. pesticides, which markedly reduce the proportion of the crops consumed by pests. Thirdly, by producing veterinary products which protect livestock from disease or cure their infections.It may seem strange in textbook like this one to pose the question "do we need a chemical industry?” However, trying to answer this question will provide (i) an indication of the range of the chemical industry’s activates. (ii) Its influence on our lives in everyday terms, and (iii) how great is society’s need for a chemical industry. Our approach in answering the question will be toconsider the industry’s contribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their turn are clothing and (briefly) shelter, leisure and transport.2. The Need for Chemical IndustryThe chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates, and then into a tremendous variety of other chemicals. These are then used to produce consumer products, which make our lives more comfortable or，in some case such as pharmaceutical products,help to maintain our well-being or even life itself. At each stage of these operations value is added to the product and provided this added value exceeds the raw material plus processing costs then a profit will be made on the operation. It is the aim of chemical industry to achieve this.It is therefore apparent that, because office diversity of operations and close links on many areas with other industries, there is no simple definition of the chemical industry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as “the chemical industry". It is important to bear these in mind when comparing statistical information which is derived from several sources.阅读材料11化学工业化学工业的定义上世纪初，定义化学工业的构成是没有什么困难的，因为只有非常有限的产品被生产，而且这些产品是无害的化学制品如强碱和硫酸。