In this research, experiments and numerical simulations are employed to research the failure process of concrete. Fracture experiments on three-point bending (TPB) concrete beams with a prefabricated edge notch at the middle of the beam bottom are performed using a modified rigid testing instrument. The characteristics of the crack and section are analyzed, including the crack tensile opening displacement, crack length and width, and crack faces characteristics. Also, the full curves of the force-crack tensile opening displacement (CMOD) and force-deflection of the TPB beams with the prefabricated edge notch after breakage are obtained. The phase field (PF) damage model is applied to the mixed-mode and mode-I failure processes of concrete structures through the ABAQUS subroutine user defined element (UEL). The crack path and the full curves of force-CMOD and force-deflection obtained by numerical calculations are consistent with the experimental results and the calculated results of other researchers. The influences of the mesh sizes, initial lengths, and notched depths on the TPB beam of concrete are also analyzed.

在这项研究中，通过实验和数值模拟来研究混凝土的破坏过程。使用改良的刚性测试仪对三点弯曲（TPB）混凝土梁进行了断裂试验，该梁在梁底部的中间有一个预制的边缘槽口。分析了裂纹和断面的特性，包括裂纹的张开位移，裂纹的长度和宽度以及裂纹面的特性。此外，还获得了断裂后具有预制边缘缺口的TPB梁的力裂纹拉伸张开位移（CMOD）和力偏转的完整曲线。通过ABAQUS子程序用户定义元素（UEL）将相场（PF）损伤模型应用于混凝土结构的混合模式和模式I破坏过程。通过数值计算获得的裂纹路径和力-CMOD的全曲线和力-挠度与实验结果和其他研究人员的计算结果一致。还分析了网眼尺寸，初始长度和缺口深度对混凝土TPB梁的影响。