Hybrid phase-field modeling of mesoscopic failure in concrete combined with Fourier-Voronoi stochastic aggregate distribution modelling approach

Concrete crack propagation is significantly affected by its complex mesoscopic structure, tracking which is of great importance for revealing the fracture failure modes and crack propagation patterns of concrete. This study presents a stochastic aggregate distribution modeling approach combining the Fourier-Voronoi method and techniques with XCT images. it enables the generation of stochastic aggregate distribution models that mimic real concrete's morphological characteristics. Meanwhile, with the hybrid phase-field theory and finite element method, a multi-field coupling model is established to simulate the crack propagation. In contrast to the isotropic or anisotropic phase-field theory, with the hybrid phase-field theory the stiffness degradation of concrete material in all directions during crack propagation are taken into consideration. With the proposed methodology, the effects of volume fraction, shape, roughness and pre-notch depth on the fracture behavior and strength of concrete are investigated. Results show that both the tensile and shear strength of concrete grows with the increase of aggregate volume fraction. Benefited from the application of hybrid phase-field theory, two shear fracture failure modes of concrete with distinct shear strengths are revealed, influenced by aggregate interaction during the shear fracture process.