English For Mechanical Engineering

HO CHI MINH UNIVERSITY OF INDUSTRY\nMECHANICAL FACULTY\nNGUYEN THI MY DUNG\nEnglish for MECHANICAL ENGINEERING\nHO CHI MINH CITY - 2009\n(For Internal Use Only) HO CHI MINH UNIVERSITY OF INDUSTRY\nMECHANICAL FACULTY\nNGUYEN THI MY DUNG\nEnglish for MECHANICAL ENGINEERING\nHO CHI MINH CITY - 2009\n(For Internal Use Only) CONTENTS\n1. Unit one Engineering- What's it all about 05\n2. Unit two Engineering Materials and Plastics 11\n3. Unit three Metals 17\n4. Unit four Corrosion 23\n5. Unit five Materials Science and Technology 27\n6. Unit six Composite Materials 32\n7. Unit seven Mechanisms 36\n8. Unit eight Magnets, Magnetism and Magnetic Fields 39\n9. Unit nine Automation 43\n10. Unit ten Robots 49\n11. Unit Eleven Traditional Machine Tools 55\n12. Unit Twelve Welding 63\nReferences 72 UNIT ONE\nENGINEERING - WHAT'S IT ALL ABOUT\nWhat is engineering?\nEngineering is largely a practical activity. It is about putting ideas into action. Civil engineers are concerned with making bridges, roads, airports, etc. Mechanical engineers deal with the design, test, manufacture and operating tools and machinery of all types. Electrical engineering is about the generation and distribution of electricity and its many applications. Electronic engineering is concerned with developing components and equipments for communication, computing, and so on.\nMechanical engineering includes marine, automobile, aeronautical, heating, and ventilating, and others. Electrical engineering includes generating electricity, electrical installation, lighting, etc. Mining engineering and medical engineering belong partly to mechanical and partly to electrical.\nTransport: Cars, trains, ships, and planes are all products of mechanical engineering. Mechanical engineers are also involved in support services such as roads, rail track, harbors, and bridges.\nFood processing: Mechanical engineers design, develop, and make the machine and the processing equipment for harvesting, preparing and preserving the foods and drinks that fill the supermarkets.\nMedical engineering: body scanners, X- ray machines, life-support systems, and other high tech equipment result from mechanical and electrical engineers combining with medical experts to convert ideas into life-preserving products.\nBuilding services: Electrical engineers provide all the services we need in our homes and places of work, including lighting, heating, ventilation, air-conditioning, refrigeration, and lifts.\nEnergy and power: Electrical engineers are concerned with the production and distribution of electricity to homes, offices, industry, hospitals, colleges, and school, and the installation and the maintenance of the equipment involved in the processes.\nCareers in Engineering\nProfessional engineers may work as:\nDesign engineers: They work as part of a team to create new products and extend the life of old products by updating them and finding new applications for them. Their aim is to build quality and reliability into the design and to introduce new components and materials to make the product cheaper, lighter, or stronger.\nInstallation engineers: They work on the customer's premises to install equipment produced by their company.\nProduction engineers: They ensure that the production process is efficient, that materials are handled safely and correctly, and that faults which occur in production are corrected. The design and development departments consult with them to ensure that any innovations proposed are practicable and cost- effective.\nJust below the professional engineers are the technician engineers: they require a detailed knowledge of a particular technology: electrical, mechanical, electronic, and so on. They may lead teams of engineering technicians. Technician engineers and engineering technicians may work as:\nTest/ Laboratory technicians: They test samples of the materials and of the product to ensure quality is maintained.\nInstallation and service technicians: they ensure that equipment sold by the company is installed correctly and carry out preventative maintenance and essential repairs.\nProduction planning and control technicians: They produce the manufacturing instructions and organize the work of production so that it can be done as quickly, cheaply, and efficiently as possible.\nInspection technicians: They check and ensure that incoming and outgoing components and products meet specifications.\nDebug technicians: They fault find, repair, and test equipment and products down to component level. Draughts men / women and designers: they produce the drawings and design documents from which the product is manufactured.\nThe next grades are craftsmen/ women. Their work is highly skilled and practical. Craftsmen and women may work as:\nToolmakers: They make dies and moulding tools which are used to punch and form metal components and produce plastic components such as car bumpers.\nFitters: They assemble components into large products.\nMaintenance fitters: They repair machinery.\nWelders: They do specialized joining, fabricating, and repair work.\nElectricians: They wire and install electrical equipments.\nOperators require fewer skills. Many operator jobs consist mainly of minding a machine, especially now that more and more processes are automated. However, some operators may have to check components produced by their machines to ensure they are accurate. They may require training in the use of instruments such as micrometers, verniers, or simple gauges.\nA. Checking your comprehension\n1. Complete the blanks in the diagram using information from the text.\nEngineering\n |\n |\n Civil |\n |\n | Electrical\n |\n _____________________\n |\n Electricity |\n Electrical |\n |\n Installation |\n |\n |\n | Medical 2. Put T or F to indicate if the statements below are True or False:\n\na. Engineering is about putting ideas into action.\n\nb. Mechanical engineering is concerned with making bridges, roads, airports, etc.\n\nc. Electrical engineering is about developing components and equipment for communications, computing and so on.\n\nd. Cars, trains, ships and plane are products of civil engineering.\n\ne. Mechanical engineers deal with the design, making the machines and the processing equipment for harvesting, preparing and preserving the food that fill the supermarkets.\n\nf. Mechanical engineers are concerned with the production and distribution of electricity to home, offices, and industry.\n\n3. Complete the text using information from the diagram and language you have studied in this unit\nThe main branches of engineering are civil, (2)__________ and electronic. Mechanical engineering is (3)__________ (4)__________ machinery of all kinds. This branch of engineering includes marine, automobile, aeronautical, heating, and ventilating. The first three are concerned with (5)__________ ; (6)__________, cars and planes. The last (7)__________ with air-conditioning, refrigeration, etc.\nElectrical engineering deals with (8)__________ from generation to use. Electricity generating is concerned with (9)__________ stations. Electrical installation deals (10)__________ cables, switches, and connecting up (11)__________ equipment.\nTwo branches of engineering include both (12)__________ and (13)__________ engineers. These are mining and (14)__________ engineering. The former deals with mines and mining equipment, the latter with hospital (15)__________ of all kinds. 4. Answer the following questions:\nWho would be employed to:\n1. test completed motors from a production line?\n2. find out why a new electronics assembly does not work?\n3. produce a mould for a car body part?\n4. see that the correct test equipment is available on a production line?\n5. find a cheaper way of manufacturing a crankshaft?\n6. repair heating system installed by their company?\n7. see that a new product is safe to use?\n8. commission a turbine in a power station?\nB. Increase vocabulary\n1. Fill in each space with the correct form the word given:\nNoun\t\tAdjective\n\nMechanics\t\tMechanical\n\nElectricity\t\t__________\n\nPractice\t\t__________\n\n__________\t\tIndustrial C. Language Use\nWhat is the link between column A and column B?\nA\t\tB\nMechanical\tMachine\nElectrical\tElectricity\nColumn A lists a branch of engineering or a type of engineer. Column B lists things they are concerned with. We can show the link between them in a number of ways:\n1. Mechanical engineering deals with machines.\n2. Mechanical engineers deal with machines.\n3. Mechanical engineering is concerned with machines. Plastics were at first based on coal and wood. But today they are nearly all based on mineral oil, that is to say, oil which is found under the ground. Mineral oil, of course, is of no use to man until it has been cleaned and separated into its different commercial products- oil for ships and trains, petrol for cars and aero-planes, machine oil of all kinds. This cleaning and separating is known as “refining” and is done in big factories called \"refineries\".\n\nFor a long time scientists could find little use for the material which remained after the oil had been refined. Then one day scientists made the exciting discovery that it could be turned into plastics.\n\nThe manufacture of plastics demands an immense amount of heavy machinery as well as acknowledge of science. Today nearly all modern plastics are manufactured by the world’s great oil refineries and chemical works. The refineries and chemical works produce many different kinds of raw plastics. These are then sent to the tens of thousands of factories all over the world which make plastic goods.\n\nMachinery for making plastic goods is quite different from the machinery used for manufacturing articles of wood or metal or other natural materials. For raw plastics are first softened by heat and then pressed into moulds. It is the moulds which give plastic objects their shape. These moulds can be of any shape or size. And the same mould can be used over and over again. In fact, one mould can produce many thousands of articles before it wears out. It is this which makes plastic goods so cheap.\n\nAlthough there are so many different kinds of raw plastics, they can be divided into two main types.\n\nPlastics of the first type are hard. Once they have been taken from their moulds they will never melt or soften again under heat. Engineers have to know the best and most economical materials to use. Engineers must also understand the properties of these materials and how they can be worked. There are two kinds of materials used in engineering- metals and non-metals. We can divide metals into ferrous and nonferrous metals. The former contain iron and the latter do not contain iron. Cast iron and steel, which are alloys, or mixtures of iron and carbon, are the two most important ferrous metals. Steel contains a smaller proportion of carbon than cast iron contains. Certain elements can improve the properties of steel and are therefore added to it. For example, chromium may be included to resist corrosion and tungsten to increase hardness. Aluminum, copper, and the alloys, bronze and brass, are common non-ferrous metals.\n\nPlastics and ceramics are non- metals; however, plastics may be machined like metals. Ceramics are often employed by engineers when materials, which can withstand high temperature is needed.\n\nPlastics - Man's Most Useful Material\n\nThe word “plastic” comes from the Greek word “plastikos” and is used to describe something which can be easily shaped. You will see what a suitable name this is for “plastics”.\n\nNo other material in the history of the world has been used for so many different purposes. But what special qualities do plastics have?. The lightness of plastics is one of their most valuable qualities. Think how easy it is to lift plastic furniture! Think, too, how light plastic containers are! A delivery man can carry many more plastic containers made of wood or metal or glass.\n\nIt is quite extraordinary how many different kinds and qualities of plastics there are. They can be made so strong that they will last almost forever, or so thin and cheap that they can be thrown away after only being used once. They can be made as clear as glass or completely black. They can be made to look like wood or leather or rubber or stone. They are therefore very useful for radios and many different kinds of electrical articles. This type is termed thermosetting plastics.\n\nPlastics of the second type, thermoplastics, can be bent because they are softer. They are therefore perfect for pipes and containers of all kinds. They do not usually break if they are dropped and so they are very useful for everyday things like cups or plates. But if you put plastics of this kind too close to a fire they will melt. They often change their shape, too, if they are dropped into very hot liquids. Surprisingly, many of these softer plastics can be put into cold water, and can then be heated to a very great heat.\n\nA. Comprehension\n1. What are the two main kinds of materials used in engineering?\n2. Name the two subgroups of metals. Give some examples of each group.\n3. What is the property of Chromium?\n4. Mention the main property of tungsten.\n5. Is brass an alloy? Why?\n6. What are the two types of plastics?\n7. Can plastics be shaped and reshaped?\n8. What are the properties of plastics?\n9. What are the materials used to produce plastics?\n\nB. True or False\n1. Non- metals are used by engineers.\n2. Cast iron contains more carbon than steel.\n3. Chromium improves the property of steel.\n4. Copper is an alloy of iron.\n5. Plastics can be made from ceramics and wood.\n6. Thermosetting plastics can be machined like metals.\n7. Thermoplastics are formed into metals.\n8. Thermosetting plastics are softer than thermoplastics. Thermosets set on heating.\nThermosets will not re-melt.\n3. FROM/ TO\nPlastics are used to make a great variety of products.\nPlastics are used to make textiles.\nPlastics are used to make engineering components.\n4. SUCH AS\nPlastics are available in many forms.\nPlastics are available in the form of sheets, tubes, rods, moulding powers and resins.\n5. TO\nVarious methods are used.\nThey convert raw plastic into finished products.\n6. WITH/ WHICH\nThe equipment consists of a press.\nThe press has two heated platens.\nThe two platens carry an upper and a lower mould.\n7. THEN\nPower is placed in the lower mould.\nThis is moulding power.\nThe upper mould is pressed down on the lower mould.\n8. TO/ WHICH\nThe pressure and the heat change the power.\nThe power becomes liquid plastic.\nThe liquid plastic fills the space between the moulds. Exercise 2:\nDraw diagrams to classify the items in the following lists. Each diagram should have three levels.\n1. Alloys, copper, brass, pure metals, aluminium, metals.\n2. Brazing, electric- are welding, soldering, metals joining methods, welding, oxy-acetylene welding.\n3. Measuring instruments, non-precision instruments, micrometer, vernier gauge, meter sticks, precision instruments, slip blocks, foot-rule.\n4. Units of area, cubic meter, metric units, millimeter, square meter, linear units, kilometer, units of volume.\n5. Milling machine, copy miller, shaping machines, drilling machines, vertical shaper, radial arm drill, machine tools.\nE. Sentence Connectors\nSome common sentence connectors are however, because, and, whereas, such as, to, from/ to, with/ which, to/ which, then, by, etc.\nExamples:\nPlastics are used widely in engineering because they are cheap and have a resistance to atmospheric corrosion; however, they are not particularly strong.\nNow join the following groups of sentences using the connecting words printed at the beginning of each group. You may omit words and make whatever changes you think are necessary in the word order and punctuation of the sentences.\n1. AND\nThere are two types of plastics.\nThermoplastics are a kind of plastic.\nThe second one is thermosetting plastics.\n2. AND/ WHEREAS/ AND\nThermoplastics will soften when heated.\nThermoplastics will harden when cooled. Plastic goods can be made by machinery that is used to produce articles of wood or metal.\nCeramics can withstand high temperatures.\nC. Substitution\n1. Nickel steel is a mixture of iron, carbon and nickel.\n2. Chromium can be included in steel to provide a good cutting edge.\n3. There are many kinds of steel use in industry.\n4. Ceramics are used by engineers where heat-resistant materials are needed.\n5. Chromium steels resist corrosion.\n6. If you put thermoplastics near a fire, they will melt.\n7. Thermoplastics are ideal for pipes and containers.\nD. Completing\nExercise 1:\nComplete the diagram, using the information from the reading passage. UNIT THREE\nMETALS\n\nWhy does man use metals still so much today when there are other materials, especially plastics, which are available? A material is generally used because it offers the required strength, and other properties, at minimum cost. Appearance is also an important factor. The main advantage of metals is their strength and toughness. Concrete may be cheaper and is often used in building, but even concrete depends on its core of steel for strength.\n\nPlastics are lighter and more corrosion-resistant, but they are not usually as strong. Another problem with plastics is what to do with them after use. Metal objects can often be broken down and metals recycled; plastics can only be dumped or burned.\n\nNot all metals are strong, however. Copper and aluminum, for example, are both fairly weak but if they are mixed together, the result is an alloy called aluminum bronze, which is much stronger than either pure copper pure copper or pure aluminum. Alloying is an important method of obtaining whatever special properties are required: strength, toughness, resistance to wear, magnetic properties, high electrical resistance or corrosion resistance.\n\nThe properties of metals can be further improved by use of heat treatment. Heat treatment is the term given to a number of different procedures in which the properties of metals and alloys are changed. It usually consists of heating the metal or alloy to a selected temperature below its melting point and then cooling it at a certain rate to obtain those properties, which are required. For example, hardening is used to make metals harder. Tempering makes them softer and less brittle. Annealing is carried out to make a metal soft so that it can be machined more easily. In this way, metallic materials can be produced to meet every kind of engineering specifications and requirements.\n\nWhen Concorde was built, a material was developed which is tough and lightweight and is used in over 70% of Concorde's structure. Another 16% is made of high-strength steel, and titanium alloys are used in the engine surroundings to withstand temperatures of 4000 degrees centigrade. at least 45,000 flying hours. To achieve this, a special aluminum alloy was developed which is tough and lightweight and is used in over 70% of Concorde's structure. Another 16% is made of high-strength steel, and titanium alloys are used in the engine surroundings to withstand temperatures of 4000 degrees centigrade.\n\nMethods of extracting, producing and treating metals are being developed all the time to meet engineering requirements. This means that there is an enormous variety of metals and metallic materials available from which to choose.\n\nA. CHECKING READING COMPREHENSION\n\nPut True or False to indicate if the statements below are True or False according to the facts in the reading text\n1. Concrete isn't an inexpensive building material.\n2. Plastics are more easily recycled than metals.\n3. Aluminum bronze is an example of an alloy of copper.\n4. Pure copper is stronger than the alloys that are made by mixing copper with aluminum.\n5. Tempering is a kind of heat treatment used to make metals harder.\n6. Annealing is sometimes an advantage for a metal to be soft.\n7. Concorde is built mainly of steel. (B) SUBSTITUTION\n1. In paragraph 1, which noun does the underlined pronoun 'it' refer to?\n2. In paragraph 2, which noun does the pronoun 'them' substitute?\n3. In paragraph 3, what does the word 'which' substitute?\n4. In paragraph 4, what does the pronoun 'it' refer to?\n5. In paragraph 4, which noun does the word 'its' refer to?\n\nC. INCREASE YOUR VOCABULARY\n(A) Properties of materials\nThese words and phrases refer to properties of materials:\nStrength toughness corrosion resistant\nIn the passage, there are nine words or more which refer to properties of materials. List them below:\n1. __________\n2. __________\n3. __________\n4. __________\n5. __________\n6. __________\n7. __________\n8. __________\n9. __________\n\nNow you write the meaning of these words:\n1. loosen : __________\n2. tighten : __________\n3. stiffen : __________\n4. brighten : __________\n5. cool : __________\n(B) Nouns and Adjectives\nFill in each space with the correct form of the word given\nNOUN ADJECTIVE\n1. __________ strong\n2. __________ resistant\n3. metal __________ 4. weakness __________ 5. ___________ hot 6. importance ___________ D. SCAN THE TABLE WHICH FOLLOWS TO FIND A MATERIAL WHICH IS : 1. soft 2. ductile 3. malleable 4. tough 5. scratch - resistant 6. conductive and malleable 7. durable and hard 8. stiff and brittle 9. ductile and corrosion - resistant 10. heat - resistant and chemical - resistant Materials Properties Uses Metals Aluminum Light, soft, ductile, highly conductive, corrosion- resistant Aircraft , engine components, cooking utensils Copper Very malleable, tough, and ductile, highly conductive, corrosion - resistant. Electric wiring, tubing Brass Very corrosion - resistant. Casts well, easily machined. Can be work hardened. Good conductor. Valves, taps castings, ship fittings, electrical contacts Mild steel High strength, ductile, tough, fairly malleable. Can not be hardened and tempered. Low cost. Poor corrosion resistance. General purpose High carbon steel Hardest of carbon steels but less ductile and malleable. Can be hardened and tempered. Cutting tools such as drills, files, saws.. Thermoplastics ABS High impact strength and toughness, scratch - resistant, light and durable. Safety helmets, car components, telephones kitchenware Acrylic Stiff, hard, very durable, clear, can be polished easily. Can be formed easily. Aircraft canopies, baths, double glazing Nylon Hard, tough, wear- resistant, self-lubricating. Bearings, gears, castings for power tools Thermosetting plastics Epoxy High strength when reinforced, good chemical and wear - resistance. Adhesives, encapsulation of electronic components Polyester resin Stiff, hard, brittle. Good chemical and heat resistance. Moulding, boat and car bodies Urea formaldehyde Stiff, hard, strong, brittle, heat resistant, and a good electrical insulator Electrical fittings, adhesives E. LANGUAGE STUDY Making definitions Study these facts from the table about aluminum: 1. Aluminum is a light metal. 2. Aluminum is used to make aircraft. We can link these facts to make a definition of aluminum: \"Aluminum is a light metal which is used to make aircraft.\" Now you can use the table above to make definitions about some materials. FACULTY OF MECHANICAL ENGINEERING HO CHI MINH UNIVERSITY OF INDUSTRY\nUNIT FOUR\nCORROSION\nA major consideration in engineering design is maintenance. One of the commonest causes of failure in the long term is corrosion.\nCorrosion attacks all engineering material, especially metals. Corrosion is any chemical action which harms the properties of a material. It reduces the life of a material and increases the cost of a structure. For example, a steel bridge must be repainted regularly to protect it from rust. Various metals have therefore been developed to resist corrosion. Among them are the stainless steels. These metals contain from 12 to 35% chromium which forms a very thin layer or film of chromium oxide on the surface of the metal. This film protects the metal from corrosion. Alloys made from copper and nickel are also corrosion - resistant.\nWhen two different metals touch each other in the presence of moisture, corrosion occurs. This type of corrosion is known as galvanic or electrolytic corrosion because it has an electrical cause. The metals and the moisture act like a weak battery and the chemical action which results corrodes one of the metals. If, for example, aluminum sheets are riveted with copper rivets, the aluminum near the rivets will corrode in damp conditions.\nNo material can be completely corrosion - resistant. Even stainless steels will corrode. Engineers can, however, fight corrosion. For example, they can use high purity metals because these metals are more resistant than alloys. They can also make sure that two dissimilar metals are not allowed to touch each other. Finally, engineers can protect the surfaces of the metal in many different ways. One of the most common methods is to paint them. FACULTY OF MECHANICAL ENGINEERING HO CHI MINH UNIVERSITY OF INDUSTRY\nA. WORD FORMS\nAdjective Adverb\nA careful worker works carefully.\nA weak metal breaks easily.\nA good student studies hard.\nA bad student works lazily.\n\nChoose either the adjective or the adverb to complete each of the sentences below:\n1. Alloys are general / generally prepared by mixing molten metal.\n2. Pure iron is a softly / soft metal.\n3. Iron is easy / easily to extract from iron ores.\n4. Platinum has exceptional / exceptionally resistance to corrosion.\n5. Radium is an extremely rare / rarely metal.\n6. Rolled gold consists of a thin / thinly layer of good alloy.\n7. Magnesium is known as a metal which burns bright / brightly.\n8. It is also high / highly radioactive.\n\nB. ANSWER TRUE OR FALSE\n1. Corrosion attacks metals most.\n2. The life of a material can be shortened by corrosion.\n3. Chromium oxide increases corrosion.\n4. Nickel is an alloy.\n5. Electrolytic corrosion occurs in the presence of moisture.\n6. Stainless steels never corrode.\n7. Alloys are less resistant than high purity metals.\n8. If two dissimilar metals touch each other, they may cause corrosion. C. COMPLETING AND MATCHING\nStatements which contain higher - level items are more general than statements which contain lower- level items. Look at the following example:\nStatement (a) is the most general statement. When statement (a) is true, statements (b), (c) and (d) must also be true.\nNow study the following sentences. Column (a) contains statements with lower - level items. Column (b) contains more general statements with higher - level items. Match each lower-level statement with a general statement.\nIron rusts\n1. Iron rusts\n2. Bronze contains copper and tin\n3. A square meter is made by multiplying a meter by a meter.\n4. Chromium makes steel corrosion resistant.\n5. A load of five tons compresses a concrete column.\n6. Zirconia's heat shields withstand temperature over 2000° C.\n7. Vinyl can be shaped in a lathe.\n\nMetals corrode\n8. Railway lines extend in hot weather.\n\na. Metallic elements are added to steel to improve its properties.\nb. Compressive forces shorten bodies.\nc. Metals corrode.\nd. Derived units are products of basic units.\ne. Alloys are mixtures of metals.\nf. Ceramics can resist high temperatures.\ng. Plastics may be machined.\nh. Metals expand when heated. Language use:\nStudy these sentences:\n1. If a metal is flexible, it will bend easily.\n2. If a material is ductile, it can be stretched into another shape.\n3. Use a hoist to lift the cylinder head if it is heavy.\n4. A metal can be hammered or pressed if it is malleable. UNIT FIVE\nMATERIALS SCIENCE AND TECHNOLOGY\nMaterials Science is the study of materials, nonmetallic as well as metallic, and how they can be adapted and fabricated to meet the needs of modern technology. Using the laboratory techniques and research tools of physics, chemistry and metallurgy, scientists are finding new ways of using plastics, ceramics, and other nonmetals in applications formerly reserved for metals.\n\nRecent Development\nThe rapid development of semiconductors for the electronics industry, beginning in the early 1960s, gave materials science its first major impetus. Having discovered that nonmetallic materials such as silicon could be made to conduct electricity in ways that metals could not, scientists and engineers devised ways of fashioning thousands of tiny integrated circuits on a small chip of silicon. This then made it possible to miniaturize the components of electronic devices such as computers.\n\nIn the late 1980s, materials science research was given renewed emphasis with the discovery of ceramics that display superconductivity at higher temperatures than metals do. If the temperature at which these new materials become superconductive can be raised high enough, new applications, including levitating trains and super-fast computers are possible.\n\nAlthough the latest developments in materials science have tended to focus on electrical properties, mechanical properties are also of major, continuing importance. For the aircraft industry, for instance, scientists have been developing, and engineers testing, non-metallic composite materials that are lighter, stronger, and easier to fabricate than the aluminum and other metals currently used to form the outer skin of aircraft. Mechanical Properties of Materials\nEngineers must know how solid materials respond to external forces, such as tension, compression, torsion, bending, and shear. Solid materials respond to these forces by elastic deformation (that is, the material returns to its original size and form when the external force is lifted), permanent deformation, or fracture. Time-dependent effects of external forces are creep and fatigue, which are defined below.\n\nTension is a pulling force that acts: in one direction; an example is the force in a cable holding a weight. Under tension, a material usually stretches, returning to its original length if the force does not exceed the material's elastic limit. Under larger tensions, the material does not return completely to its original condition, and under even greater forces the material ruptures.\n\nCompression is the decrease in volume that results from the application of pressure. When a material is subjected to a bending, shearing, or torsional (twisting) force, both tensile and compressive forces are simultaneously at work. When a rod is bent, for example, one side of it is stretched and subjected to a tensional force, and the other side is compressed.\n\nCreep is a slowly progressing, permanent deformation that results from a steady force acting on a material. Materials subjected to high temperatures are especially susceptible to this deformation. The gradual loosening of bolts, the sagging of long-span cables, and the deformation of components of machines and engines are all noticeable examples of creep. In many cases the slow deformation stops because the force causing the creep is eliminated by the deformation itself. Creep extended over a long time eventually leads to the rupture of the material.\n\nFatigue can be defined as progressive fracture. It occurs when a mechanical part is subjected to a repeated or cyclic stress, such as vibration. When the maximum stress never exceeds the elastic limit, failure of the material can occur even after a short time. With some metals, such as titanium alloys, fatigue can be avoided by keeping the cyclic force below a certain level. No deformation is apparent during fatigue, but small localized cracks develop and propagate through the material until the remaining cross-sectional area cannot support the maximum stress of the cyclic force. Knowledge of tensile stress, elastic limits, resistance of materials to creep and fatigue is of basic importance in engineering. 1. True/False Decide if these statements are True or False. 1. Materials science began in the early 1960s. 2. Superconductivity can only be possible at very high temperatures. 3. Mechanical properties of materials are not as important as electrical properties. 4. Nonmetals have been used to replace metals in a number of applications. 5. Compression and tension never coexist. 6. Creep is the gradual deformation of a material due to constant stress. 7. Repeated vibration can cause cracks in a machine. 8. Fatigue does not cause damage to titanium alloys. 9. Engineers must have knowledge of properties of materials. II. Gap filling Fill in each gap with ONE suitable word from the box. property cycle semiconductors superconductivity force engineering electrical mechanical device 1. Sometimes __________ takes place at .100 degrees above absolute zero. 2. A generator is a machine for changing __________ energy into __________ energy. 3. A __________ is a phase in the working of an internal-combustion engine. 4. Electrical __________ is a branch of applied sciences. 5. Elasticity is a major __________ of rubber. 6. An integrated circuit is an extremely small complex electronic __________. 7. Germanium is a nonmetallic chemical element used in __________. 8. Torque is a __________ that causes rotation. III. Main idea Decide which of the following sentences gives the main idea of the reading passage. 1. Materials science has played a very important role in modern life. 2. Materials science has introduced valuable new applications of materials in many fields. 3. Materials science has discovered new properties of materials. V. Language use Study these sentences. 1. In the combustion chamber, the piston compresses the air/fuel mixture and captures the energy released by the ignition of the fuel. 2. Using the laboratory techniques and research tools of physics, chemistry, and metallurgy, scientists are finding new ways of using plastics, ceramics, and other nonmetals in applications formerly reserved for metals. 3. Creep is a slowly progressing, permanent deformation that results from a steady force acting on a material. 4. Seen from afar, this robot looks like a crane. 5. PMCS consist of fibers made of a ceramic material such as carbon or glass embedded in a plastic matrix. 6. Having discovered that nonmetallic materials could be made to conduct electricity in ways that metals could not, scientists and engineers devised ways of fashioning thousands of tiny integrated circuits on a small chip of silicon. 7. Having been warned about the serious problems, they decided to stop the research. * Underline the participles in the sentences given. * How many forms of participles can you recognize? * What is the purpose of using participles? * How is each of these forms used? * Write more sentences with participles. * Compare your sentences with your classmates'. UNIT SIX\n\nCOMPOSITE MATERIALS\n\nComposite material is made up of a combination of two or more different materials. A composite material can provide superior and unique mechanical and physical properties because it combines the most desirable properties of its constituents while suppressing their least desirable properties. For example a glass-fiber reinforced plastic combines the high strength of thin glass fibers with the ductility and chemical resistance of plastic; the brittleness that the glass fibers have when isolated is not a characteristic of the composite. The opportunity to develop superior products for aerospace, automotive, and recreational applications has sustained the interest in advanced composites. Currently composites are being considered on a broader basis-for applications that include civil engineering structures such as bridges and freeway pillar reinforcement-; and for biomedical products, such as prosthetic devices.\n\nComposite materials usually consist of synthetic fibers embedded within a matrix, a material that surrounds and is tightly bound to the fibers. The most widely used type of composite material is polymer matrix composites (PMCs). PMCS consist of fibers made of a ceramic material such as carbon or glass embedded in a plastic matrix. Typically, the fibers make up about 60 percent of a polymer matrix composite by volume. Metal matrices or ceramic matrices can be substituted for the plastic matrix to provide more specialized composite systems called metal matrix composites (MMCs) and ceramic matrix composites (CMCs), respectively.\n\nThe fibrous reinforcing constituent of composites may consist of thin continuous fibers or relatively short fiber segments. When using short fiber segments, however, fibers with a high aspect ratio (length-to-diameter ratio) are used. Continuous-fiber composites are generally required for high performance structural applications. The specific strength (strength-to-density ratio) and specific stiffness (elastic modulus-to- density ratio) of continuous carbon fiber PMCS, for example, can be vastly superior to conventional metal alloys. Composites can also have other attractive properties, such as high thermal or electrical conductivity, and a low coefficient of thermal expansion. Also, depending on how the fibers are oriented or interwoven within the matrix, composites can be fabricated to have structural properties specifically tailored for a particular structural use.\n\nAlthough composite materials have certain advantages over conventional materials, composites also have some disadvantages. For example, PMCS and other composite materials tend to be highly anisotropic-that is, their strength, stiffness, and other engineering properties are different depending on the orientation of the composite material. For example, if a PMC is fabricated so that all the fibers are lined up parallel to one another, then the PMC will be very stiff in the direction parallel to the fibers, but not stiff in the perpendicular direction. These anisotropic properties pose a significant challenge for the designer who uses composite materials in structures that place multidirectional forces on the structural members. Also, forming strong connections between separate composite material components is difficult.\n\nThe broader use of advanced composites is inhibited by high manufacturing costs. Currently, fabricating composite materials is a labor-intensive process. However, as improved manufacturing techniques are developed, it will become possible to produce composite materials at higher volumes and at a lower cost than is now possible, accelerating the wider exploitation of these materials. 1. Multiple choice\n\nCircle the letter of the answer that best matches the meaning of the underlined words.\n\n1. A composite material combines the most desirable properties of its constituents.\n a. valuable b. modern c. pleasing\n\n2. It suppresses the least desirable properties.\n a. presses b. adds c. removes\n\n3. People are interested in advanced composites.\n a. popular b. highly developed c. expensive\n\n4. A glass fiber reinforced plastic combines the high strength of thin glass fiber with the ductility chemical resistance of plastic.\n a. strengthened b. recycled c. compressed\n\n5. Composites have a low coefficient of thermal expansion.\n a. expand at high temperature. b. Do not expand much when heated. c. expand at low temperature.\n\n6. How the fiber are oriented within the matrix depends on particular structural uses.\n a. drawn b. arranged c. described.\n\n7. PMCS and other composites tend to be anisotropic.\n a. extremely strong b. stiff enough c. changing properties in different directions.\n\n8. These anisotropic properties pose a significant challenge for the designer who uses composite materials in structures that place multidirectional forces on the structure members.\n a. are interesting b. are good things c. are problems.\n\nII. Matching\n\nMatch each word in column A with its meaning in column B\n\nA B\n1. brittle a. for entertainment\n2. ductile b. cars and trucks\n3. tailored c. made for particular needs\n4. automotive d. manufactured 5. recreational\ne. direction\n6. orientation\nf able to be drawn into wire\n7. fabricated\ng. hard and breakable.\n\nIII. Gap filling\nFill in each gap with ONE suitable word from the passage (notice the form).\n1. Copper, silver and other metals are ___. They can be made into thin sheets or wires.\n2. High electrical resistance is the most important ___ of tungsten.\n3. ___ energy is energy produced by burning coal or gas.\n4. Some people are money ___. They are interested in things to do with making money.\n5. The ___ of a box of 1m x 1.5m x l m is 1.5m³.\n6. Concrete with metal rods in it is known as ___ concrete.\n\nIV. Main idea:\nWhat is the main idea of the text? 16\nFaculty of Mechanical Engineering Ho Chi Minh University of Industry\n\nUNIT SEVEN\nMECHANISMS\n\nMechanisms are an important part of everyday life. They allow us to do simple things like switch on lights, turn taps and open doors. They also make it possible to use escalators and lifts, travel in cars, and fly from continent to continent.\n\nMechanisms play a vital role in industry. While many industrial processes have electronic control systems, it is still mechanisms that deliver the power to do the work. They provide the forces to press steel sheets into car body panels, to lift large components from place to place, to force plastic through dies to make pipes.\n\nAll mechanisms involve some kinds of motion. The four basic kinds of motion are:\n\nRotary: Wheels, gears and rollers involve rotary movement.\nOscillating: The pendulum of the clock oscillates- it swings backwards and forwards.\nLinear: The linear movement of paper trimmer is used to cut the edge of the paper.\nReciprocating: The piston in a combustion engine reciprocates.\n\nMany mechanisms involve changing one kind of motion into another type. For example, the reciprocating motion of a piston is changed into a rotary motion by the crankshaft, while a cam converts the rotary motion of the engine into the reciprocating motion required to operate the valves.\n\nINCREASE YOUR VOCABULARY\n\nDealing with technical terms\nOne of the difficult things about English of engineering is that there are many technical terms to learn. Newer terms may be the same, or almost the same, in our language. But many terms