STRENGTH OF MATERIAL VIVA PART-2
11. What is Malleability?
Malleability is a special case of ductility which permits materials to be rolled or hammered into thin sheets. A malleable material should be plastic but it is not essential to be so strong. The malleable materials commonly used in engineering practice (in order of diminishing malleability) are lead, soft steel, wrought iron, copper and aluminium.
12. What is Toughness?
It is the property of a material to resist fracture due to high impact loads like hammer blows. The toughness of the material decreases when it is heated. It is measured by the amount of energy that a unit volume of the material has absorbed after being stressed upto the point of fracture. This property is desirable in parts subjected to shock and impact loads.
13. What is Machinability?
It is the property of a material that refers to a relative case with which a material can be cut. The machinability of a material can be measured in a number of ways such as comparing the tool life for cutting different materials or thrust required to remove the material at some given rate or the energy required to remove a unit volume of the material. It may be noted that brass can be easily machined than steel.
14. What is Resilience?
It is the property of a material to absorb energy and to resist shock and impact loads. It is measured by the amount of energy absorbed per unit volume within the elastic limit. This property is essential for
spring materials.
15. What is Creep?
When a part is subjected to constant stress at high temperature for a long period of time, it will undergo a slow and permanent deformation called creep. This property is considered in designing internal combustion engines, boilers and turbines.
16. What is Fatigue?
When a material is subjected to repeated stresses, it fails at stresses below the yield point stresses. Such type of failure of a material is fatigue.
17. What is Hardness?
It is property of material which resistant to wear, scratching, deformation and
machinability etc. It also means the ability of a metal to cut another metal.
18. What is factor of safety?
It is ratio of yield stress to the maximum applied stress.
19. What is moment?
Moment is the product of force and distance between the perpendicular force vector to the moment center. Moment gives you the tendency to bend a beam.
20. What is difference between torque and moment?
Torque is the couple acting about the longitudinal axis of an object.
The moment is the couple acting about the transverse axis of an object.
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