What is Elastic Material ?

 A material which regains its original size and shape on removal stress is said to be elastic stress.

What is Plastic material ?

A material which can undergo permanent deformation without rupture aid to be plastic material. This property of the material is known as plasticity. Plasticity is important when a material is to be mechanically formed by causing the material to flow.

 What is Ductile Material ?

A material which an undergo considerable deformation without rupture is said to be ductile material. The major portion of deformation is plastic.

 What is Brittle Material ?

A material which ruptures with little or no plastic deformation is said to brittle materials.

What is Elastic limit ?

The greatest stress that a material can take without permanent set on the removal of stress is known as elastic limit.

What is Endurance limit or Fatigue limit ?
The greatest stress, applied infinite number of times, that a material can take without causing failure is known as endurance limit or fatigue limit.

What is Modulus of Resilience ?

The energy stored per unit volume at the elastic limit is known as modulus of resilience.


What is Modulus of Toughness ?

The amount of work required per unit volume to cause failure, under static loading, is called modulus of toughness.

What is Modulus of Rupture ?

The ultimate strength in flexure or torsion is known as modulus of rupture.

 What is Strain hardening ?

The increase in strength after plastic zone due to rearrangement of molecules in the material.

 What is Proof stress ?

The stress which is just sufficient to cause a permanent set(elongation) equal to a specified percentage of the original gauge length.

What is Plastic Strain ?

It is a dimensional change that occurs in a material due to application of the loads and does not disappear after the removal of the loads.

What is Creep ?

The long term deflection due to sustained (constant) loads.

What is Factor of Safety ?

Factor of safety is defined as follows

For Ductile materials,

F.O.S = yield stress / working stress

For Brittle materials,

F.O.S = ultimate stress / working stress

What is Margin of Safety ?

Margin of safety = Factor of safety – 1

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