The normal stress (axial stress or axial) is the internal stress or resulting from the tensions perpendicular (normal) to the cross section of a mechanical prism.

This type of stress formed by parallel stresses is directly associated with normal stress.

Given a section transverse to the longitudinal axis of a beam or pillar, the normal stress is the force resulting from the normal stresses that act on said surface.

If we consider a Cartesian coordinate system in which the

The sizing of mechanical parts with a constant section, usually beams, pillars, bars, axles and the like subjected to normal forces refers to the calculation of the minimum cross section to ensure that said element has adequate resistance against the normal forces acting on the part. The sizing is totally different if the piece is in tension or compression.

The sizing of parts subjected in all their sections to normal tensile stresses is very simple and is reduced to ensuring that the cross-sectional area is large enough so that the stresses are distributed over a sufficiently large area. In this case, the formula for the minimum area given by the Saint-Venant principle is usually used:

Where:.

In the case of pieces subjected to normal compression stresses, the minimum area is substantially larger since in that case the effects of buckling must be taken into account, which requires considering much larger sections:

Where:.