Stress-Strain Diagram

Consider a cylindrical specimen placed in a system to measure its tensile strength.

Two gauge marks are inscribed on the central portion of the specimen. The length between the marks is known as the gauge length.

Then, a tensile load is applied on both ends of the specimen.

As the load increases, the gauge length increases, and the elongation is recorded for each load value.

The change in the diameter of the specimen is also recorded simultaneously.

Stress is computed by dividing the load by the original cross-sectional area of the specimen. Strain is calculated by dividing the elongation by the original gauge length.

A stress-strain diagram is then obtained by plotting strain as an abscissa and stress as an ordinate.

It is observed that stress varies linearly with strain during the initial loading. However, as the load increases, small changes in the stress lead to significant changes in the strain values for most materials.

Depending on their temperature and loading speed, the results vary for some materials.