Complex quasi-brittle fracture modelling using lattice particle method coupled with a local isotropic damage model

In this paper, a local isotropic damage model is incorporated into the lattice particle method (LPM) to model complex quasi-brittle fracture problems. The issue of particle-size dependency is addressed using fracture energy in the damage model regularized with characteristic length that is particle-size dependent. The characteristic lengths are first estimated from mode-I fracture test by ensuring the prescribed and calculated fracture energies match well for both 2D and 3D cases. Extensive validation against experimental data in terms of crack path and structural response is then carried out to assess the accuracy of the proposed model in 2D and 3D settings. Positive outcomes, in line with the experimental findings, have been obtained for both 2D and 3D problems covering mode I and mixed-mode fractures. Furthermore, by employing a regular lattice network, the present model, when integrated with more sophisticated yield surfaces, can address intricate 3D fracture problems that entail the twisting of crack surfaces. Convergence of structural response and crack path is obtained when the particle spacing is refined.