A bridging-domain approach for multiscale modeling of anisotropic fracture in large-scale heterogeneous structures

The prediction of the mechanical response of strongly heterogeneous structures containing defects critically depends on accurately capturing crack nucleation at micro scale. Fully resolved (high-fidelity) models are costly, whereas homogenized approaches may fail to represent initiation near heterogeneities. An efficient multiscale method is proposed in this work to simulate crack nucleation and propagation by bridging a high-fidelity micro-subdomain, dedicated to initiation, with a homogenized macro-subdomain used for propagation. The two subdomains overlap, may be discretized with nonconforming meshes, and are coupled through an energy-based formulation. The main contribution lies in the use, at the macro scale, of a surrogate anisotropic damage model constructed offline within the DDHAD (Data-Driven Harmonic Analysis of Damage) framework. This model reproduces direction-dependent crack propagation, while nucleation is resolved at the micro scale by the high-fidelity model. Significant computational speed-ups are achieved as compared to high-resolution simulations of the entire structure, and by accurately capturing initiation of the cracks in the microstructure. Examples on heterogeneous media exhibiting strong preferred crack orientations are presented to illustrate the potential of the approach.