# Stress

Defined as the force per unit area of cross-section.

Where

σ = stress [Nm^{-2}]

F = force [N]

A = cross-sectional area [m^{2}]

As used with most mechanical tests, stress is based on original cross-sectional area without taking into account changes in area due to applied load. This sometimes is called conventional or engineering stress.

True stress is equal to the load divided by the instantaneous cross-sectional area through which it acts.

**See also: **Bending Stress, Breaking Stress, Compressive Stress, Creep, Critical Resolved Shear Stress, Elasticity, Elongation, Fatigue, Fibre Stress, Flow Stress, Hookes Law, Hoop Stress, Local Stress Relieving, Mean Stress, Neutral Plane, Nominal Stress, Normal Stress, Operating Stress, Overstressing, Peierls Stress, Proof Stress, Proportional Limit, Residual Stress, Rupture Strength, Shear Stress, Static Failure, Step Stressing, Strain, Stress Amplitude, Stress Concentration, Stress Concentration Factor, Stress Corrosion, Stress Intensity Factor, Stress Raisers, Stress Ratio, Stress Relaxation, Stress Resultant, Stress-Strain Diagram, Tensile Stress, Torsional Stress, True Stress, Viscous Force, Viscous Stresses, Working Stress, Young′s Modulus.

**Subjects: ** Durability Mechanical Engineering