The equilibrium gap method : a two-scales approach

Optical full-field measurement methods are increasingly used in the field of experimental mechanics, and several techniques have been developped to make the most of the redundancy of the measured fields. However, the number of modelling parameters that can be retrieved is strongly connected to the noise level corrupting the measured fields. Focusing on the techniques based on the construction of a statically admissible field from the experimental data, a two-scales approach is proposed. It relies on the fact that, using a finite-element description of the struture, the larger the number of degrees of freedom to be measured, the more degraded by noise. It is therefore proposed to use displacement fields measured at two different scales. This paper describes the way the macro displacement fields basis is built.