If an imposition from outside the bar having a working parallel to the axis of the bar, then inside the bar will arise opponent forces generated by the force between molecules themselves.
The forces arising in this bar in general is:
a. Normal force, the force perpendicular to the direction of bar cross section.
b. Tangential force, with the parallel / cross-section located on the bar.
Assuming that the forces that arise are divided evenly on the entire cross-sectional area. So the forces working on a cross-sectional area is called ‘Stress’.
Stress = Force/ Sectional area (N/mm2)
From the forces that arise, it is generally stress divided into:
a. Normal stress (s )
If the sectional area A = mm2 , accordingly stress is:
Normal stress = F/A (N/mm2)
b. Tangential stress ( t )
If the sectional area A = mm2 , accordingly stress is :
Tangential stress = F/A (N/mm2)