What type of stress is defined as force per unit area?

Normal stress is defined as force per unit area and is a key concept in mechanics of materials. It occurs when a force is applied perpendicular to the surface of a material. This type of stress can be tensile, resulting in stretching when the material is pulled, or compressive, leading to shortening when the material is pushed together.

The formula for normal stress is given by:

[

\sigma = \frac{F}{A}

]

where ( \sigma ) is the normal stress, ( F ) is the applied force, and ( A ) is the cross-sectional area over which the force is applied. This relation illustrates that normal stress is fundamentally linked to how forces distribute over areas in mechanical structures, influencing how materials deform under load.

Understanding normal stress is essential for analyzing material strength, designing safe structures, and predicting failure modes since engineers use it to ensure that components can withstand applied loads without yielding or breaking.