用扩展有限元方法模拟混凝土的复合型开裂过程

用扩展有限元法对混凝土梁复合型开裂过程进行了数值模拟。裂纹面间的力学行为采用粘聚裂纹模型来描述,通过引入切向保留刚度考虑剪力分量的影响。开裂方向的计算采用了一种简化的最大切向应力准则。对Arrea和Ingraffea的混凝土梁复合开裂实验进行了数值模拟。计算给出了裂纹萌生、扩展的过程及破坏形态,并获得了与实验结果对比良好的荷载-裂纹开口滑移曲线。结果表明,扩展有限元法通过附加特定的位移模式,使裂纹两侧不连位移场的表达独立于网格划分,是一种能够模拟准脆性材料复合开裂问题的有效方法。

SIMULATION OF MIXED-MODE FRACTURE OF CONCRETE USING EXTENDED FINITE ELEMENT METHOD

The eXtended Finite Element Method (XFEM) is employed to simulate the fracture process of a concrete beam under mixed-mode loading. The cohesive crack model is used to describe the mechanical behavior between the crack surfaces. Tangential retention stiffness is introduced to consider the effects of the shear component. The cracking direction is determined by a simplified maximum tangential stress criterion. The experiments by Arrea and Ingraffea are simulated. The relationship between load and crack mouth sliding displacement (CMSD) predicted numerically agrees well with the experiment results. The results demonstrate that XFEM is an efficient method to simulate the mixed-mode fracture process of quasi-brittle materials because the expression of displacement discontinuities on both sides of cracks is independent of element meshes.