A friction energy-based damage model for discrete element simulation of fatigue damage evolution in concrete

The discrete results of concrete fatigue tests limit the research of concrete fatigue theory. Numerical simulation methods can model the damage of materials from multiple scales, which helps to reveal the fatigue damage mechanism and compensate for the inadequacy of physical tests. This study presents a novel damage model for simulating the fatigue damage evolution of cementitious materials within the framework of discrete element methods. The proposed friction energy-based fatigue damage model is underpinned by a clear fatigue damage mechanism and has only two independent parameters. The model underwent validation through a comparison between its predictions and the results of compression cycle tests performed on concrete specimens. The model reproduces the evolution characteristics of various fatigue damage indicators, including deformation, modulus, hysteretic energy, and number of cracks, and the fatigue damage accumulation rate presents sensitivity to the stress level. Furthermore, the model predicts a clear regularity in the fatigue damage thresholds, which is an important reference value for establishing fatigue failure criteria. The model can be used to predict fatigue life of fatigue tests with various maximum and minimum stress levels and the S-N curves obtained from the simulations fall within the range of test results.