Strain rate dependency of materials can be described in 2 basic ways:
By means of analytical models: defining a function f (dependent on strain and strain rate) which acts as a dynamic amplification factor of the static stress - strain curve (being this curve a function σ0(ε) only dependent on strain). Represented expressions of Cowper-Symmonds and Johnson-Cook laws are two examples of this type of description. Dynamic material characterisation is based on the determination of a set of parameters in the analytical expressions of these laws (p, D), characteristics for each material.
By means of a set of stress - strain curves at different strain rates, in the same way that they are obtained in the material characterisation tests.