An innovative quasi-bond approach to bridge continuity, anisotropic damage and macroscopic fracture of solids and structures

Spontaneous formation and evolution of discontinuities in solid media still poses one of the significant challenges in solid mechanics and computational mechanics. To facilitate numerical modeling, a new model called herein 'quasi-bond' model is proposed, which redefines the form of local interaction between material particles. Unlike traditional discrete methods that require direct connections between material particles, in this quasi-bond method, only one end of each bond is actually connected to a material particle, rendering great flexibility in describing bond distribution and anisotropic damage by bond breakage. Homogenization of solid body can be performed by an integral over quasi-bonds, while the process of crack nucleation, propagation and coalescence to form fracture is simulated through bond breakage. Especially, the relationship between material elastic constants and bond stiffness parameter is established in both two-and three-dimensional contexts. Furthermore, a smoothed strain-based fracture description is proposed with the ability of eliminating particle density/distribution dependence problems. Finally, several benchmark tests are conducted to demonstrate the efficiency and accuracy of the proposed approach in solving elasticity and fracture problems.