Glossary | Stress Strain Curve
A stress strain curve relates the forces on a member to the deflections imposed by the forces. An XY graph of force versus deflection is one way to depict this relationship. When the size of the member is changed, however, a new graph will need to be drawn. Expressing the relationship in the form of a stress strain curve eliminates the need to redraw the graph each time member dimensions are changed. Stress is obtained by dividing the applied force by the original cross sectional area of the member. Strain is obtained by dividing the change in length of the member by its original length. Stress strain curves are frequently generated by universal testing machines equipped with an extensometer. The testing machine is used to load the member to failure and record the stress versus strain relationship.