Fig. 2. Sample output from a wax compression test. Strain is on the abscissa, calculated as the change in length divided by the original length of the sample, and has no units. Stress, in MPa, is on the ordinate and is calculated as the force applied to the sample divided by its cross-sectional area. The proportional limit is defined as the point where the curve leaves linearity and the sample moves from elastic to plastic deformation. The yield point is the point of local maximum stress that the sample can withstand. Resilience is defined by the area under the curve at the proportional limit and is a measure of the energy that the sample can absorb before deformation is permanent.