Special virtual fields for the direct determination of material parameters with the virtual fields method. 1––Principle and definition

This paper deals with the direct and simultaneous estimation of parameters used in some constitutive laws. Wholefield data captured in mechanical configurations which give rise to heterogeneous stress fields are processed. Since no analytical relationship is available between measured data and unknown parameters, a specific procedure based on a relevant use of the principle of virtual work is proposed. The main advantage is to provide directly the unknown parameters. The main features of the method are described in the paper.