Stress/Strain Curves

Stress/strain curves are often acquired under constant strain-rate conditions. The force required to produce this deformation behavior is measured with the Load Cell and normalized to yield the nominal or true stress.

Nominal stress/strain curves for Al₂ O₃ (a), a low carbon steel (b), a cross-linked natural rubber (c), and a the polymer, polymethyl-methacrylate, tested at 122 C are shown inthe figure opposite. Note that most of these materials fracture at a nominal stress less than 25%, and that the rubber extends by 800% before fracture. The aluminum oxide and the rubber behave elastically to their fracture point. The low carbon steel and the polymer show elastic and plastic behavior before fracturing.