The Stress strain curve has been commonly discussed in previous exams. It relates to the properties of materials and specifically metal. It is important to known how different materials behave in relation to each other such as Cement, Cobalt chrome and Titanium to name a few.
The stress- strain curve for metal is drawn with Stress on the Y-axis and Strain on the X-axis. Stress is force over area and therefore has units Newtons per metre squared(N/m2).
The Strain is the change in an object i.e. deformation. This can be length divided by original length and therefore can be expressed as a percentage or with no units.