Question Set 38

Question No.1

Define Ductility.


It is the property of the material enabling it to be drawn into wire, with the application of tensile force. It must be both strong and plastic. It is usually measured in terms of percentage elongation and reduction in area, (e.g.) Ni, Al, and Cu.

Question No.2

Define fatigue.


When a material is subjected to repeated stress, it fails at stresses below the yield point stress; such type of failure of the material is called fatigue.

Question No.3

Define: Factor of safety.


The ratio between maximum stresses to working stress is known as factor of safety.

Factor of safety = Maximum stress /Working stress

Question No.4

Define endurance limit.


Endurance limit is the maximum value of completely reversed stress that the standard specimen can sustain an infinite number (106) of cycles without failure.

Question No.5

What is impact load?


If the time of load application is less than one third of the lowest natural period of vibration of the part, it is called an impact load.

Question No.6

What are the various phases of design process?


The various phases of design process are:

1.     Recognition of need.

2.     Definition of problem

3.     Synthesis

4.     Analysis and optimization

5.     Evaluation

6.     Presentation

Question No.7

What are the different types of loads that can act on machine components?


Different loads on machine components are:

1.     Steady load.

2.     Variable load.

3.     Shock load

4.     Impact load.

Question No.8

What are the factors affecting endurance strength.


Factors affecting endurance strength are

1.     Load ii. Surface finish

2.     Size

3.     Temperature

4.     Impact

5.     Reliability

Question No.9

What are the types of variable stresses?


Types of variable stresses are:

1.     Completely reversed or cyclic stresses

2.     Fluctuating stresses

3.     Repeated stresses

Question No.10

Differentiate between repeated stress and reversed stress.


Repeated stress refers to a stress varying from zero to a maximum value of same nature.

Reversed stress of cyclic stress varies from one value of tension to the same value of compression.

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