Abstract
In order to solve the problem that the built-in parallel bond model in the discrete element software cannot adequately simulate the post-peak fracture behavior of quasi-brittle materials, a linear cohesive model was established. First, two particles are used to simulate the interface constitutive behavior in different modes. The results show that the new model can better simulate the behavior of Mode-I fracture, Mode-II fracture, and Mixed-mode fracture. Then, the influence of micro-parameters on the newly constructed constitutive model is analyzed, which provides a basis for the determination of micro-parameter values. Finally, the proposed softening model is applied to a three-point bending test of mortar, and the fracture behavior obtained is compared to the acoustic emission results. The simulation results also show that the constitutive model we built can be used to simulate the fracture behavior of quasi-brittle materials such as mortar and concrete.
Highlights
Quasi-brittle materials such as concrete, mortar, rock, or wood are widely used in various engineering fields [1]
Research on the properties of quasi-brittle materials should start with their mesostructure, focus on their heterogeneous composition, and appropriately investigate the damage and fracture mechanism of quasi-brittle materials according to their meso-mechanical properties
Two particles were used to check the load– displacement curves under the conditions of Mode-I fracture, Mode-II fracture, and Mixedmode fracture in order to evaluate the reliability of the constructed model
Summary
Quasi-brittle materials such as concrete, mortar, rock, or wood are widely used in various engineering fields [1]. The parallel bond model can no longer be used to simulate quasi-brittle materials with low tensile/compressive strength ratios, such as rock and concrete. Sinaie et al [21] successfully developed a cohesive force model to simulate the behavior of concrete under cyclic loading, where the microscopic parameters of the material were calibrated only by a monotonic stress–strain test. In this study, the limitation of the parallel bond model for simulating the three-point bending fracture behavior of notched mortar beams is verified first, and a linear cohesion model for the DEM to simulate the post-peak fracture behavior of mortar is developed. When the loading reaches the post-peak stage, the parallel bond model degenerates into a linear model and no longer bears tensile load This results in a rapidly descending curve, indicating a significant brittle fracture phenomenon.
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