Stress–strain curve

A stress–strain curve is a graph derived from measuring load (compression.

Ductile materials

Steel generally exhibits a very linear stress–strain relationship up to a well defined fractures).

Most metals other than steel do not have a well-defined yield point (figure 2). For these materials the yield strength is typically determined by the "offset yield method", by which a line is drawn parallel to the linear elastic portion of the curve and intersecting the abscissa at some arbitrary value (most commonly .2%). The intersection of this line and the stress–strain curve is reported as the yield point.

Brittle materials

ceramics do not have a yield point. For these materials the rupture strength and the ultimate strength are the same, therefore the stress-strain curve would consist of only the elastic region, followed by a failure of the material.

Properties

The area underneath the stress–strain curve is the toughness of the material—the energy the material can absorb prior to rupture.

The resilience of the material is the triangular area underneath the elastic region of the curve.