Abstract
Numerical simulations of the fracture process are challenging, and the discrete element (DE) method is an effective means to model fracture problems. The DE model comprises the DE connective model and DE contact model, where the former is used for the representation of isotropic solids before cracks initiate, while the latter is employed to represent particulate materials after cracks propagate. In this paper, a DE particle-based cohesive crack model is developed to model the mixed-mode fracture process of brittle materials, aiming to simulate the material transition from a solid phase to a particulate phase. Because of the particle characteristics of the DE connective model, the cohesive crack model is constructed at inter-particle bonds in the connective stage of the model at a microscale. A potential formulation is adopted by the cohesive zone method, and a linear softening relation is employed by the traction–separation law upon fracture initiation. This particle-based cohesive crack model bridges the microscopic gap between the connective model and the contact model and, thus, is suitable to describe the material separation process from solids to particulates. The proposed model is validated by a number of standard fracture tests, and numerical results are found to be in good agreement with the analytical solutions. A notched concrete beam subjected to an impact loading is modeled, and the impact force obtained from the numerical modeling agrees better with the experimental result than that obtained from the finite element method.
Highlights
Fracture is a common failure mode for engineering structures and structural components.When structures are subjected to severe loading or large deformation, new fracture surfaces are created and cracks occur
A particle-based cohesive crack model was developed for the connective discrete element (DE) model to model the fracture process of brittle and quasi-brittle materials so as to formulate the material transition from a solid phase to a particulate phase
DE model, the cohesive crack model was constructed at inter-particle bonds in the connective stage of the model at microscale
Summary
Fracture is a common failure mode for engineering structures and structural components. The representation of continua by the connective model is based on the energy equivalence between the strain energy stored in solids and that stored in bonding springs Using this connective model, the macro-structural material response can be determined by the micromechanical interaction between particles at microscale, which is essentially different from the phenomenological material constitutive law often adopted by the FEM. The macro-structural material response can be determined by the micromechanical interaction between particles at microscale, which is essentially different from the phenomenological material constitutive law often adopted by the FEM This connective model is able to deal with fracture by means of the breakage of bonding springs. A particle-based cohesive crack model is proposed for modeling the mixed-mode fracture process of brittle and quasi-brittle materials.
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