Material parameter identification using finite elements

Inhomogeneous deformations in experimental tests of inelastic materials require the solution of the boundary-value problem by means of the finite element method. The application of the method of vertical lines in combination with least-square approaches yield clear concepts developed in Numerical Mathematics such as the simultaneous sensitivity analysis, internal and external numerical differentiation to obtain the sensitivities. Furthermore, the concept of identifiability has to be considered to find out whether the experiments are sufficient to address all material parameters.