Stress
Stress is defined as the force per unit area of a material.
Stress = force / cross sectional area
σc = P/A
Unit: N/mm2
Strain
Strain is defined as extension per unit length.
Strain = extension / original length
ԑc = δL/L
Unit: No unit
Example problem
Question
A rectangular wooden column of length 3m and size 300mm x 200mm carries an axial load of 300kN. The column is found to be shortened by 1.5mm under the load. Find the stress and strain in the column.
Given data:
Original length of column (L) = 3m = 3000mm
Area of cross section (A) = 300 x 200 = 60000mm2
Axial Load (P) = 300kN = 300000N
Shortening of column (δL) = 1.5mm
Required:
Stress (σc) = ?
Strain (ԑc) = ?
Formula:
Compressive stress σc = P/A
Compressive strain ԑc = δL/L
Solution:
σc = P/A
= 300000/60000
= 5N/mm2
ԑc = δL/L
= 1.5/3000
= 0.0005
Result:
Stress σc = 5N/mm2
Strain ԑc = 0.0005
Click Here To See Brief Description About Stress And Strain Diagram
