Calibration of a higher-order continuum model using global and local data

Part of the reliability of numerical models for the description of localized failure in quasi-brittle materials strongly depends on the correct identification of the model parameters. Particularly, the solution of an inverse problem is required for those model parameters for which a clear physical meaning is not established and, as a consequence, direct measurements in laboratory tests are not possible. This is the case for the continuum gradient damage model, regularized by the introduction of a length scale parameter. For this model, an inverse strategy for the identification of parameters is proposed. Local experimental data related to the width of the fractured area of the specimen are used, in addition to global force–deformation curves, so that the inverse problem results to be well posed. Two series of experimental data, concerning different specimen sizes and loading conditions, are considered in order to investigate the limits and potential of the calibrated model in terms of predictive capabilities.