Knowledge of material behaviour is necessary for any kind of analysis, and it is a mandatory input in order to obtain reliable simulation results.
Material characterisation consists of obtaining its constitutive equation, generally expressed by its stress-strain curve. Metallic materials are usually characterised by tensile tests, the plastic materials by tensile and flexion tests, the different kind of foams by compression tests.
Simulation of the material characterisation test is the best way to obtain the material characteristics to insert in a model. Tensile test conditions have to be reproduced, so the nodes of one of the test specimen ends remains fixed (null displacement) while a tensile force is applied in the free end nodes by boundary conditions imposition (displacement through time). From the measurement of the deformation produced in the strain gauge and the force measured in the dynamometric section then stress-strain curves of material behaviour are obtained from the simulation (the static one and dynamics curves obtained at different speeds), and also strain-rate values for each of these dynamic curves is evaluated.