Identification de paramètres d'un modèle d'endommagement. Influence des conditions aux limites.

Calibration of damage models for cementitious materials using the Finite-Element Model Updating (FEMU) method often relies on simplifying assumptions regarding boundary conditions, which are difficult to measure with local sensors. This study proposes an experimental method to measure the actual boundary conditions applied during the test and incorporate them into a FEMU procedure with a reactive force-based cost function. The damage of an unnotched mortar prism, described by an adapted Mazars model, is investigated through a three-point bending test. Digital Image Correlation (DIC) is used to measure the two-dimensional displacement field on a finite element mesh. By exploiting the mechanical displacements of the prism at the supports and under the press bearing, parameter identification is significantly improved compared with simplified boundary conditions defined by the test bench design. This approach leads to a noticeable improvement in the calibrated parameters and provides a better description of the specimen’s mechanical response (deflection stiffness and crack opening). DIC thus offers a non-intrusive approach to identify model parameters from structural tests while accounting for realistic boundary conditions.