Study on simulation of mixed-mode Ⅰ-Ⅱ fracture behavior of engineered cementitious composites with different notch-depth ratios

In order to explore the evolution law of mixed-mode Ⅰ-Ⅱ fracture properties of engineered cementitious composites （ECC） under the influence of notch-depth ratio， a numerical model of three-point bending ECC beams was established based on the ABAQUS analysis platform， combined with the concrete damage plasticity （CDP） model and element deletion technique. The validity of the simulation was verified by comparing the load-crack opening displacement curves and crack propagation paths obtained from both simulation and experimental results. Four specimens with different initial notch-depth ratios of 0.1， 0.2， 0.3， 0.4 were selected to establish the finite element analysis model. The influence of the notch-depth ratio on the mixed-mode Ⅰ-Ⅱ fracture properties was systematically analyzed from the aspects such as failure mode， load characteristics， and fracture toughness. The results showed that the specimen cracked from the pre-fabricated notch tip， then extended towards the upper surface of the specimen and finally formed a significantly deviated mixed-mode Ⅰ-Ⅱ through crack， but it did not reach the loading point. As the initial notch-depth ratio increased， the initial load， unstable load and toughness gradually decreased. The simulation process can reflect the three-stage propagation process of the mixed-mode Ⅰ-Ⅱ fracture.