沥青混合料三点弯曲断裂的扩展有限元模拟

利用随机骨料生成和投放算法建立沥青混合料两相异质模型，借助ABAQUS软件开展了分别在跨中、偏中20mm和40mm不同位置包含预切口的沥青混合料三点弯曲试件断裂行为的扩展有限元模拟，分析了预切口位置对裂纹扩展路径、载荷位移曲线等的影响规律，并与实验结果进行了比较。结果表明，预切口偏离跨中越远，裂纹扩展方向偏离预切口延长线的角度越大，试件的峰值载荷越大，对试件承载能力的削弱越弱。实验和数值模拟结果在定性上的一致性表明，利用扩展有限元方法模拟沥青混合料断裂行为是可行的。

Numerical Simulation for Three-point Bending Fractures of Asphalt Mixture Based on Extended Finite Element Method

In this paper, regular octagon coarse aggregates with AC-16 gradation and sizes greater than 2.36 mm were generated by utilizing the random aggregate generation and packing algorithm, and fine aggregates were combined with asphalt in the matrix. As a result, some two-dimensional heterogeneous asphalt mixture beam models with two phases, namely coarse aggregates and matrix, were built. The enrichment functions were added into the standard finite element approximation in the extended finite element method so that fracture could step across the continuous finite elements. With the aid of ABAQUS software, the extended finite element simulations of three-point bending fracture were performed on the beam models with prenotches at the midspan, the 20 mm offset and the 40 mm offset, respectively. The bilinear damage evolution model and the maximum tensile stress criterion were employed to simulate micro-crack initiation and evolution as well as macro-fracture onset. Three groups of experiments were carried out, and some model parameters were obtained by the comparison between the simulations and the experimental results. The influences of prenotch location on the crack path and the load vs. displacement curve were analyzed. It was shown that the farther is the prenotch away from the midspan, the larger is the deflection angle between the crack propagation and the extension line of prenotch. It was also found that a specimen with a prenotch farther away from the midspan has a greater peak load, which means that a pernotch farther away from the midspan weakens the carrying capacity of asphalt mixture beam more gently. The qualitative consistency between experiments and simulations indicated that the extended finite element method is suitable for simulating the fracture behavior of asphalt mixture.