Text B. Material Science and Technology



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Text B. Material Science and Technology



Ductilityis the ability of a material to deform without breaking. One of the great advantages of metals is their ability to be formed into the shape that is needed, such as car body parts. Materials that are not ductile are brittle. Ductile materials can absorb energy by deformation but brittle materials cannot.

Toughnessis the resistance of a material to breaking when there is a crack in it. For a material of given toughness, the stress at which it will fail is inversely proportional to the square root of the size of the largest defect present. Toughness is different from strength: the toughest steels, for example, are different from the ones with highest tensile strength. Brittle materials have low toughness: glass can be broken along a chosen line by first scratching it with a diamond. Composites can be designed to have considerably greater toughness than their constituent materials. The example of a very tough composite is fiberglass that is very flexible and strong.

Creep resistanceis the resistance to a gradual permanent change of shape, and it becomes especially important at higher temperatures. A successful research has been made in materials for machine parts that operate at high temperatures and under high tensile forces without gradually extending, for example the parts of plane engines.

Text D. Metals

Metals are materials most widely used in industry because of their properties. The study of the production and properties of metals is known as metallurgy.

The separation between the atoms in metals is small, the most metals are dense. The atoms are arranged regularly and can slide over each other. That is why metals are malleable (can be deformed and bent without fracture) and ductile (can be drawn into wire). Metals vary greatly m their properties. For example, lead is soft and can be bent by hand, while iron can only be worked by hammering at red heat.

The regular arrangement of atoms in metals gives them a crystalline structure. Irregular crystals are called grains.

The properties of the metals depend on the size, shape, orientation, and composition of these grains. In general, a metal with small grains will be harder and stronger than one with coarse grains.

5. Переведите на русский язык следующие слова:ability, application, brittle, density, rigid, to sink, toughness.

6. Переведите на английский язык следующие слова: деформация, плотность, материал, измерение, температура, повышение, ползучесть материалов.

7. Переведите на русский язык предложение, содержащее модальный глагол или его эквивалент. They will, in general, have to be content with the data available.

8. Выпишите из текста «C» предложение, содержащее глагол в страдательном залоге. Переведите предложение на русский язык.

9. Составьте резюме, используя образец в Приложении.

КОНТРОЛЬНАЯ РАБОТА № 1

Вариант № 6.

Выполните следующие задания:

1. Образуйте форму множественного числа следующих существительных: value, mean, density, item, frequency, level.

2. Напишите формы указательных местоимений, объясните правила их использования в предложении.

3. Образуйте степени сравнения следующих прилагательных и наречий: cold, old, short, bad, long, difficult, good, strong.

4. Прочтите и переведите тексты. Текст «А» переведите письменно и ответьте на вопросы после текста.

 

Text A. Composite materials

The combinations of two or more different materials are called composite materials. They usually have unique mechanical and physical properties because they combine the best properties of different materials. For example, a fibre-glass reinforced plastic combines the high strength of thin glass fibres with the ductility and chemical resistance of plastic. Nowadays composites are being used for structures such as bridges, boat-building etc.

Composite materials usually consist of synthetic fibres within a matrix, a material that surrounds and is tightly bound to the fibres. The most widely used type of composite material is polymer matrix composites (PMCs). PMCs consist of fibres made of a ceramic material such as carbon or glass embedded in a plastic matrix. Usually the fibres make up about 60 per cent by volume. Composites with metal matrices or ceramic matrices are called metal matrix composites (MMCs) and ceramic matrix composites (CMCs), respectively.

Continuous-fibre composites are generally required for structural applications. The specific strength (strength-to-density ratio) and specific stiffness (elastic modulus-to-density ratio) of continuous carbon fibre PMCs, for example, can be better than metal alloys have. Composites can also have other attractive properties, such as high thermal or electrical conductivity and a low coefficient of thermal expansion.

Questions:

What is called “composite materials”? What do composite materials usually consist of?

Text B. Composite materials

Although 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 fibres are lined up parallel to one another, then the pMC will be very stiff in the direction parallel to the fibres, but not stiff in the perpendicular direction. The designer who uses composite materials in structures subjected to multidirectional forces, must take these anisotropic properties into account. Also, forming strong connections between separate composite material components is difficult.

The advanced composites have high manufacturing costs. Fabricating composite materials is a complex process. However, new 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.

 

Text C. What is engineering?

In general, engineering is a science that deals with design, construction and operation of structures, machines, engines and other devices. Engineer is a person who has received technical education and has a basic knowledge of other engineering fields, because most engineering problems are complex and interrelated. The term engineering is difficult to translate into Russian because it has a lot of meanings. Most often it is translated as: инженерное дело, техника, машиностроение, строительство. There exist the following main branches of engineering.

5. Переведите на русский язык следующие слова:грубый, форма (для отливки), ковать, расширение, матрица, керамический.

6. Переведите на английский язык следующие слова и словосочетания: композитные материалы, эксплуатация, упрочненный, удельная прочность.

7. Переведите на русский язык предложение, содержащее модальный глагол или его эквивалент. This latter case is considerably more difficult to represent, since all subcomponents of a program will need to be activated.

8. Выпишите из текста «C» предложение, содержащее сказуемое в страдательном зaлоге. Переведите предложение на русский язык.

9. Составьте резюме, используя образец в Приложении.

 

КОНТРОЛЬНАЯ РАБОТА № 1

Вариант № 7.

Выполните следующие задания:

1. Образуйте форму множественного числа следующих существительных: element, nature, liquid, director, time, man, textbook.

2. Напишите формы возвратных местоимений, объясните правила их использования в предложении.

3. Образуйте степени сравнения следующих прилагательных и наречий: important, wild, interesting, little, bad, first, last, wonderful.

4. Прочтите и переведите тексты. Текст «А» переведите письменно и ответьте на вопросы после текста.

 

Text А. Steel

The most important metal in industry is iron and its alloy steel. Steel is an alloy of iron and carbon. It is strong but corrodes easily through rusting, although stainless and other special steels resist corrosion. The amount of carbon in steel influences its properties considerably. Steels of low carbon content (mild steels) are quite ductile and are used in the manufacture of sheet iron, wire and pipes. Medium-carbon steels containing from 0.2 to 0.4 per cent carbon are tougher and stronger are used as structural steels. Both mild and medium-carbon steels are suitable for forging and welding. High-carbon steels contain from 0.4 to 1.5 per cent carbon, are hard and brittle and are used in cutting tools, surgical instruments, razor blades and springs. Tool steel, also called silver steel, contains about 1 per cent carbon and is strengthened and toughened by quenching and tempering.

The inclusion of other elements affects the properties of the steel. Manganese gives extra strength and toughness. Steel containing 4 per cent silicon is used for transformer cores or electromagnets because it has large grains acting like small magnets. The addition of chromium gives extra strength and corrosion resistance, so we can get rust-proof steels. Heating in the presence of carbon or nitrogen-rich materials is used to form a hard surface on steel (case-hardening). High-speed steels, which are extremely important in machine-tools, contain chromium and tungsten plus smaller amounts of vanadium, molybdenum and other metals.

Questions:

What kinds of steel do you know? Where are they used?

Text B. Arabic Numerals

The Arabic system of numerical notation is used in most parts of the world today. This system was firstdeveloped in India in the 3rd century ВС. At that time the numerals 1, 4, and 6 were written in the same form as today.

The important innovation in the Arabic system was the use of positional notation, in which individual number symbols assume different values according to their position in the written numeral. Positional notation is made possible by the use of a symbol for zero. The symbol 0 makes it possible to differentiate between 11, 101, and 1,001 without the use of additional symbols, and all numbers can be expressed in terns of ten symbols, thenumerals from 1 to 9 plus 0. Positional notation also greatly simplifies all forms of written numerical calculation.



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