基于XFEM的混凝土纯弯曲梁的裂缝扩展模拟研究

选取纯弯曲梁进行裂缝扩展研究，在理论上符合Ⅰ型断裂模式．因此，本文利用扩展有限元法(XFEM)模拟了混凝土纯弯曲梁裂缝发展的全过程，结合线性叠加渐进假定，得到了不同初始缝高比的P-δ曲线、P-CMOD曲线以及临界有效裂缝扩展长度(a_c-a₀)/h与裂缝发展路经．对比试验数据和模拟结果表明：随着初始缝高比的增大，起裂荷载P_ini、最大荷载P_max、离散弗雷歇距离δ_dF与δ_{d F}^′，以及临界有效裂缝长度(a_c-a₀)/h均逐渐减小；试验与模拟的裂纹发展路径存在一定偏差，可知试验数据与模拟结果存在规律性差异．

Simulation of Crack Propagation of Concrete Pure Bending Beam Based on XFEM

The pure bending beam is selected to study the crack propagation, which theoretically conforms to the mode I fracture mode. Therefore, in this paper we simulate the whole fracture process of the concrete pure bending beam using the extended finite element method, and obtain the P-δ curves and P-CMOD curves for different initial joint height ratios, as well as the critical effective crack propagation length (ac-a0)/h and the crack propagation path based on the the linear superposition progressive assumption. Comparing the experimental data with the simulation results, it shows that the initiation load Pini, the maximum load Pmax, and the discrete Fréchet distance δdF and δ'dF, as well as the critical effective crack length (ac-a0)/h all gradually decrease with the increase of the initial joint height ratio. There are some differences between the experimental data and the simulation results in terms of the crack propagation path. It indicates that there are regular differences between the experimental data and the simulation results.