Обучение чтению литературы на английском языке по специальности «Прикладная механика» (120
..pdfМосковский государственный технический университет имени Н.Э. Баумана
И.И. Магидова
ОБУЧЕНИЕ ЧТЕНИЮ ЛИТЕРАТУРЫ НА АНГЛИЙСКОМ ЯЗЫКЕ ПО СПЕЦИАЛЬНОСТИ «ПРИКЛАДНАЯ МЕХАНИКА»
Методические указания
Москва Издательство МГТУ им. Н.Э. Баумана
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УДК 802.0 ББК 81.2 Англ-923
М12
Рецензент И.В. Стасенко
Магидова И.И.
М12 Обучение чтению литературы на английском языке по специальности «Прикладная механика» : метод. указания / И.И. Магидова. — М.: Изд-во МГТУ им. Н.Э. Баумана, 2011. — 30, [2] с.
Методические указания содержат оригинальные тексты? задания, направленные на закрепление лексико-грамматического материала, словарные блоки, включающие лексику, необходимую для понимания и перевода научно-технической литературы на английском языке.
Для студентов старший курсов, обучающихся по специальности «Прикладная механика» на факультете «Робототехника и комплексная автоматизация».
Рекомендовано Учебно-методической комиссией НУК ФН МГТУ им. Н.Э. Баумана.
УДК 802.0 ББК 81.2 Англ-923
© МГТУ им. Н.Э. Баумана, 2011
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ПРЕДИСЛОВИЕ
Методические указания содержат оригинальные тексты из английских научно-технических изданий для аудиторной и самостоятельной работы студентов, обучающихся по специальности «Робототехника и комплексная автоматизация» (VI–VII семестры).
В методические указания включены четыре блока, состоящие из нескольких текстов для изучающего, просмотрового и поискового чтения, активной лексики, упражнений, направленных на закрепление соответствующего лексико-грамматического материала, необходимого для перевода технических текстов по специальности «Робототехника и комплексная автоматизация». Предложены тексты для письменного перевода как с английского языка на русский, так и с русского на английский, требующие последующего обсуждения трудностей перевода.
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UNIT 1
New Words and Word Combinations
To be assumed to — предполагать, допускать Adjacent section — прилегающая секция
To express in terms of units — выразить (через, в терминах)
единиц силы
To designate — обозначить, назвать
Flexure — отклонение, сгибание, кривизна, искривление, изгибание
Hold in equilibrium — удерживать в равновесии
Intensity of stress — величина напряжения
To intend — намереваться, иметь в виду Per unit of stress — на единицу напряжения To use loosely — использовать свободно
To be valid for — иметь силу, соответствовать
1. Read and translate the text with a dictionary.
Text 1A. Unit Stress and Unit Strain
Mechanics of materials also called strength of materials or resistance of materials is that branch of engineering science which treats the relations between the external forces acting upon a body, the resulting forces and the changes in shape and size of the body. Mechanics of materials along with engineering mechanics is the basis for many branches of engineering design particularly machine design and structural design. The principles of mechanics of materials are employed to determine the proper dimensions of each member, so that it will be not only safe but also economical in proportion.
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An internal force set up within a body which resists or holds in equilibrium the externally applied forces is known as a stress. The stress may be expressed in terms of any suitable units of force such as pounds (lb), tons, kips (1000 lb), kilograms. The stress per unit of area is called the unit stress or intensity of stress and may be expressed in various units such as pounds per square inch (lb per sq. in.; lb/in.; or psi), tons per square foot.
The term stress is used rather loosely to indicate both total stress and unit stress. Unless absolutely necessary which meaning is intended the qualifying term “total” or “unit” should be used. The definition of unit stress is valid for any of the three types of stress: tension, compression or shear. The bar is said to be in simple tension when it is acted upon by two equal, collinear and oppositely directed forces. If the line of action of the forces is assumed to coincide with the axis of the bar the load is said to be axially applied.
If the forces acting on that bar are reversed in direction, the bar is said to be in compression and the internal force is called a compressive stress. External loads causing compressive stress also tend to produce a shortening of the bar. Stresses directed normal or perpendicular to the area upon which they act are called normal stress. Thus a normal stress may be either tension or compression.
A shearing stress is directed parallel to the area upon which the force acts and tends to cause a sliding action of the surface upon the adjacent section.
There are other terms in common use to designate various stresses or combinations of stresses. Flexural stress refers to the tensile and compressive stresses set up in the fibers of a beam by bending action or flexure. Torsion stress is a shearing stress developed as the result of torsion or twisting action applied to a bar.
A change of dimension or shape resulting from the external loading is known as strain or deformation. A strain that disappear when the load is removed is called an elastic strain, whereas a strain that remains after the load is removed is called a plastic strain.
2. Find the corresponding Russian equivalents to the following English word combinations with the word “stress”.
A. Allowable stress, safe stress, working stress, compressive stress, tensile stress, breaking stress, design stress, fatigue stress,
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impact stress, limit stress, repeated stress, bearing stress, normal stress, shearing stress, flexural stress, torsion stress, yield stress, buckling stress.
B. Расчетное напряжение, предельное напряжение, изгибающее усилие, сжимающее напряжение, усталостное напряжение, ударная нагрузка, переменное напряжение, рабочее напряжение, безопасное напряжение, прочность на продольный изгиб.
3. Look through Text 1B and answer the questions.
1. What is the difference between the allowable and the working stresses? 2. What material will the designer be governed while calculating the project if there are several materials at his disposal? 3. What is temperature stress? 4. What is the effect of stresses at elevated temperatures? 5. What is creep strength? 6. When does deformation produced in an elastic element remain unchanged? 7. When does the deformation increase infinitely? 8. What is the difference between compression and tensile stresses?
Text 2B. Allowable and Working Stress
The allowable stress for a material is the value of the unit stress which, as the result of tests and experience, is a safe value upon which to base the design of a member or structure composed of that material. The allowable stress is not necessarily a fixed value for the material but may depend on the conditions under which the material is used. The actual unit stress developed in the material under operating conditions may be termed the working stress. Stresses under actual working conditions are often less than allowable values but frequently, owing to influences unforeseen by the designer, may exceed the allowable values.
When two or more different materials are involved in a given member, the design will be governed by the material which reaches its allowable stress first under loading.
Most materials tend to expand when heated and to contract when cooled. Experiments have shown that within moderate changes of temperature, the change per unit of length per degree of temperature change is practically constant. It is called the coefficient of thermal expansion and will be represented by symbol α.
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A compression stress is developed if the temperature lowers and a tensile stress is developed if the temperature rises. Such stresses are called temperature stresses.
The deformation produced in an elastic material loaded at ordinary temperatures takes place immediately upon application of the load and appears to remain unchanged over an indefinite period, provided the load is maintained constant. At elevated temperatures (700o to 800o and above for steel) the deformation caused by a given load slowly increases indefinitely as long as the temperature is maintained. This slow but continuous deformation is called creep. It occurs at ordinary temperatures in some softer materials such as lead, but is of particular importance to take it into consideration in the design of machines such as turbines, boilers, engines, etc., which are subjected to high temperatures for long periods.
The creep strength (or creep limit) of a material is defined as the maximum unit stress that can be continuously applied during a specific length of time and at a specified temperature without causing the deformation to exceed some specified value.
4.Find the corresponding Russian words to the English ones with the suffix “able”.
A.Acceptable, achievable, advisable, allowable, applicable, available, amenable, considerable, desirable, durable, feasible, flexible, justifiable, maneuverable, preferable, reasonable, suitable, understandable, valuable, variable, viable, viewable, workable,
B.Видимый, рабочий, разнообразный, приемлемый, достижимый, рекомендуемый, приемлемый, допустимый, имеющийся, податливый, жизнеспособный, оправданный, необходимый, понятный, ценный, маневренный, выполнимый, прочный, гибкий, прочный, предпочтительный, пригодный, приемлемый.
5.Translate the following sentences into Russian paying attention to the understanding words..
1.New automatic loading methods became available. 2. For
reliability it is advisable to calculate the velocity, however the equation acceptable is rather complicated. 3.A reliable value of the ultimate strength can be obtained from model tests. 4. In the present study only stress problems are considered but the technique is equally applicable to
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strain deformation. 5. An approximate method of solution is presented here which is suitable for analyzing certain operations. 6. There are several reasons why the method given should be preferable. 7. These friction coefficient values may be high but are reasonable for local boundary interactions. 8. The performance of the mechanism may be unacceptable. 9. It is advisable that a more accurate representation of the effect is achievable. 10. The effect of vibration is small therefore an assumption (выбор) of its form is justifiable. 11. The feedback may be feasible through direct measurement in some applications.
6.Translate the following sentences paying attention to participles in different functions.
A.1. It was concluded that the concrete used was probably shrunk when cured (отвердеть) forming cracks. 2. A brittle material breaks when stressed to the ultimate strength whereas a ductile material continues stretching 3. The technical literature contains a number of reports on the fatigue strength of structures when subjected to excitation (возбуждение) by random vibration. 5. The shape of the compressive failure surface used is largely based on the experimental results.6. Though considered an important measurement tool the frequency analysis technique may be replaced by other forms of analysis. 8. Light electronic missile components will, while operating, be subjected to sinusoidal vibration.
B.1. The material was obtained from a steel roll supplied by the Steelworks, its properties being shown in the table presented. 2. The work has to be revised, the results being presented later. 3. The time history of the shock being known, it is possible to determine the corresponding Fourier spectrum.
7.Translate the following text in written form using a dictionary.
Text 1C. Crack Study
Three cases concerning the interaction between a surface breaking vertical (edge) crack and a subsurface horizontal crack have been studied. They are the following: 1) edge crack to the right of horizontal crack; 2) edge crack to the left of horizontal crack; 3) edge crack at various positions above horizontal crack.
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It was noted that the horizontal crack stress intensity factors (K) were extremely small when compared with those for the edge crack. Results of Ks are also found for the case when an edge crack is located above the horizontal crack. The results indicate that all Ks will increase with increasing edge crack length. However, the magnitude of K for the edge crack always is considerably larger than the corresponding Ks for the horizontal crack. If a surface breaking edge crack is present, then there may be a tendency for the crack to propagate in a direction opposite the direction of contact motion. The angle of crack extension will vary. The edge crack growth mechanism studied may explain why the surface breaking cracks that result in wear are inclined 20 deg. from the contact surface.
If a small surface breaking crack is formed above the horizontal crack, the vertical crack has a strong tendency to propagate downwards towards the horizontal crack. It may either break through or the horizontal crack may extend further; the tendency of the vertical crack to intersect with the horizontal crack is strong.
8. Translate the following text into English using RussianEnglish dictionary.
Text 1D. New Mathematical Model
В определенных условиях напряжения могут быть достаточно большими и вызывать внутренние или поверхностные трещины в стали. Чтобы лучше понять природу распределения напряжения и избежать образования трещин, разработана математическая модель на основе объединения температурного анализа и анализа напряжения деформации. Эта модель может помочь вычислить температурную последовательность (history) стали на конкретный (specified) период работы. На основе этой модели можно вычислить область напряженности, зная температурный градиент.
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UNIT 2
New Words and Word Combinations
Acquire v — приобретать
Breaking load — разрушающая нагрузка
Brittle material — хрупкий материал
Ductile material — пластичный материал
Increments of load — прирост нагрузки
Neck down v — образовать шейку
Precision — точность
Permanent set — остаточная деформация
Proportional limit — предел прочности
Rupture — излом, перелом, разрушение, разрыв
Stretch v — растягивать
Ultimate strength — предел прочности
Yield point — точка текучести
1. Read and translate the text with the dictionary.
Text 2A. Ultimate Strength. Elastic Limit
A material that experiences changes of shape and size when subjected to the action of external forces and then has the ability to regain its original shape and dimensions when the external forces are removed is said to be elastic. No material is perfectly elastic, that is, the property of elasticity is exhibited only within a limited range of applied forces. A material that undergoes deformation when subjected to the action of external forces but shows no tendency to recover its original dimensions when forces are removed is said to be plastic.
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