The Mechanical Behaviour of Metals
A- Comprehension
1- Complete these sentences, choosing the correct item from alternatives below each sentence
1- When two parallel, equal and opposite forces are exerted on a body along different lines of action, the body is said to be under:
a- tension b- compression c- shear d- elasticity
2- The ability of a material to return to its original shape when unloaded is called:
a- plasticity b- ductility c- elasticity d- strength
3- The ability of a body to be permanently deformed when the load is removed is called :
a - elasticity b- plasticity c- strength d- strain
4- The shearing stress that acts on a body does not affect its
a- length b. shape c- volume d- area.
5- The stress on an object is equal to
a- the relative change in the object dimension. b- the applied force per unit area, c- the elastic limit.
6- Many materials will return to their original form .
a- if their elastic limit is not exceeded, b- unless their elastic limit is exdeeded. c- provided that their elastic limit is exceeded.
7- A cable is usually under
a- compressive stress.b- shearing stress, c- tensile stress.
8- Fatigue happens in a material if the material is subjected to
a- constant stress and high temperatures, b- varying stesses. c- equal and opposite forces.
2- The following sentences have been divided into two parts. The first part of each sentences is in list A and the second part is in list B. Put the two parts together.
List A List B
1- material cannot be under stress a- when equal and opposite forces are applied along the same line of action
2- Modern building materials are deformed very slightly b- when the deforming force is removed
3- We cannot see the deformation in a concrete wall c- because it is subjected to high pressure and temperature
4- An elastic body returns to its original form d- although it is in compression
5- Tensile stress is set up in a body e- The magnitude of the force applied to it
6- Tensile stress is set up in a body f- without having strain
7- Elongation in a spring is directly proportional to g- unless two parallel forces act on it in opposite directions.
8- High temperature creep is developed in a boiler h- when a load is exerted upon them.
3 - Answer each of these questions in a complete sentence:
1 - What is elasticity?
2 - What does Hooke s law state?
3 - What relation is there between stress and strain?
4 - When is tension produced in a body?
5 - What is the difference between a tensile stress and a shearing one .
6 - How is a metal tested for hardness?
7 - Can you find any difference between elasticity and plasticity?
8 - What is the difference between creep and fatigue?
B - Language Practice
1- Give one word for each of the underlined words. Make any small changes you think necessary:
1- Copper has the property of being drawn into wires.
2- A change in the shape of a metal results when the metal is subjected to any load.
3- When a rope carries a load, it is in a stress caused by pulling forces.
4- Tension makes a material longer.
5- A chromium-steel ball has the ability to resist scratching by oik materials. r
6- When a material is subjected to forces which are coming from outside it is deformed.
7- When equal forces directed away from each other act on a body, elongate it.
8- We can easily cut a mark on some metals with something pointed.
2 - Complete these sentences with the correct adjective form of the words | parentheses. Some of them are already in the correct form.
1- In (tension) stress, equal and opposite forces act on a body.
2- Springs are always (elasticity).
3-(brittle) substances like glass do not bend at room temperature.
4- Drawing is important in (structure) design.
5- The amount of deformation produced in a body is directly (proportion) to the applied force.
6- Provided that the elastic limit is not exceeded, any (solid) material will return to its (origin) shape.
7- The constant K depends upon the (cross-section) area of the object under stress.
3- Complete these sentences, choosing the correct form from those in parentheses:
1- An easy method of comparing quantities (was,were, & are) by means of graphs.
2- Forces which (act, acts, acted) on a body (cause, causes, caused) deformation in that body.
3- When the deformation (do not, does not, did not) exceed the elastic limit , the body (return, returns , is returned) to its original shape when the stress (removes, is removed, removed).
4- When the deformation (does not charge, is not charged, do not charge) electrically.
5- Many years ago it (discovered, is discovered, was discovered) that a irrtuin kind of rock (had, have, has) the power of attracting small picccs of iron.
6- The nucleus (makes, made, is made, are made) up of protons and neutrons.
7- The wrong use of tools (causes, cause, caused) accidents.
8- Sound (do not travel, does not travel, did not travel) in a vacuum, (•finI ihese sentences
4- Read these sentences
a- Heat (generate) by friction. Heat is generated by friction.
b- Bodies can (stretch, compress, and bend). Bodies can be stretched, compressed, and bent.
c- A liquid (flow) when it (be) under pressure.
A liquid flows when it is under pressure.
Now complete these sentences with the correct tense and the correct voice of the verb in parentheses:
1- The elongation that (produce) in a body (be) directly proportional to the magnitude of the applied force.
2- Hooke s law (apply) to the deformation of all elastic bodies.
3- Springs, tyres, and footballs (be) common examples of elastic bodies.
4- The type of stress that (set up) by bending (know) as shear stress.
5- When a body (compress), it (become) shorter.
6- Most metals (stand) deformation beyond their elastic limit.
7- Provided that the applied force (be) not too great, a plastic body (not return) to its original shape after the stress (remove).
8- Liquids and gases cannot (support) any shear stress
5 - Use each group of words in a sentence of your own:
1- deformation, proportional
2- creep, high temperature
3- elastic limit, shape
4- tensile stress, elongation
5- stress, strain
6 - Supply the missing preposition . Where no preposition is needed, write N:
1- A body is deformed when it is.....stress.
2- Deformation is given.....N/m2.
3- Copper can be drawn .... wires.
4- ..... high temperature, metals are more ductile.
5- Boilers are subjected .....high temperatures.
6- Boilers are heated..... a high temperature.
7- Glass breaks..... its elastic limit.
8- Some metals resist ..... scratching more than others.
7- Make questions for which the following might be the answers:
1- No, there s no rigid body , in fact.
2- Yes, it causes failure in machines.
3- No, they are not N/m but N/m2 .
4- No, glass isn t elastic at room temperature.
5- You re quite right. They are N/m2 .
6- Yes, it does.
7- Yes, it is.
8- No, it isn t caused by varying stresses.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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