Mechanical properties of Solids

Mechanical Properties of Solids:

From engineering stand point, the most important properties of engineering materials are:
Elasticity, Plasticity, Ductility, Brittleness, Malleability, Toughness and Hardness.

Here we need to remember that, a particular material can't possess all of these simultaneously because of these are in opposition.


Now we learn about these engineering properties of materials in brief:

Elasticity:
The property by which a body returns to its original shape after the removal of external load is called Elasticity.
Note: 1. A material is said to be isotropic, if it is equally elastic in all directions.
         2. Steel, Copper, Aluminum, Stone etc., may be considered to be perfectly elastic, within certain limits
      

Plasticity:
The property by which no strain disappears when it is relieved from the stress.
Note: Plasticity is converse of elasticity.

(Meanings: con·verse - To engage in a spoken exchange of thoughts, ideas, or feelings, to be familiar; associate)
Ductility:
The property of a material by which it can be drawn out by tension to a small section. In a ductile material, therefore, large deformation is possible before the absolute failure or rupture takes place.
Note: During ductile extension, a material shows a certain degree of elasticity, together with a considerable degree of plasticity.

Brittleness:
A material is said to be brittle when it can't be drawn out by tension to smaller section.
Note: 1. Lack of ductility is brittleness
         2. In a brittle material, failure takes place with a relatively small deformation
         3. Brittleness is generally considered to be highly undesirable.

Malleability:
It is a property by which a material can be uniformly extended in a direction without rupture.
Note: 1. Malleable material possesses a high degree of plasticity.
         2. This property is utilised in many operations, such as forging, hot rolling, drop stamping etc.

Toughness:
This is a property of a material which enables it to absorb energy without fracture.
Note: This property is very desirable in components subject to cyclic or shock loading.

Hardness:
Ability of a  material to resist indentation or surface abrasion.