Strain energy is the internal energy that is stored in any material which is loaded within elastic limit.

• SE is called as the work done by a loaded material.
• It is also called as ‘ Resilience’.
• Unit of SE is N-cm, N-cm, N-mm.
• For strain energy to be stored material must deform within the elastic limit.
• SE depends upon the applied load.
• When the load is removed the material will regain its original shape.

Application:- Used in springs.

The load applied on a material can be :-

• Gradually applied load.
• Suddenly applied load.
• Impact load [ load falling from height ]
##### Formula for strain energy:-

Strain energy (u) = ((σ)^2 × v)/2E (N-mm)

Where,

(σ) = stress in the material (N-mm^2)

E = young’s modulus

V = volume of material

##### Derivation of Strain Formulae:-

SE in an axially loaded member.

Stress , (σ) = P/a

Area = ½ × p × dl

= ½ × σA ×dl

= ½ × σA × (pl/AE)

= ½ × σA × (σAL/AE)

= σ^2V/2E

• The formula of SE is σ^2V/2E.
• The formula for a suddenly applied load is 2P/A
• The formula for impact loading

Authored by:- Cdt. Nikhil Choudhary, TMI

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