基于XFEM的混凝土三点弯曲梁开裂数值模拟研究

扩展有限元法通过在相关节点的影响域上富集非连续位移模式,使对非连续位移场的表征独立于单元边界.采用扩展有限元法对单边切口混凝土三点弯曲梁进行数值模拟,混凝土采用最大主拉应力牵引损伤开裂准则和线性软化损伤模型,并将结果与试验进行对比,验证模型有效性.结果表明,扩展有限元法模拟值与试验值在起裂韧度、失稳韧度等方面存在差异,但总体相差不大.分析认为存在的差异主要是由于混凝土梁自重、支座摩擦力等原因造成,扩展有限元可有效模拟混凝土梁在含有初始裂缝情况下从加载到失稳破坏的全过程,获得裂纹萌生、扩展的过程及破坏形态.

Numerical Simulation of Concrete Three-point Bending Beam Cracking Based on XFEM

The extended finite element method（XFEM） can make the characterization of discontinuous displacement field independent on element boundaries through enriching discontinuous displacement mode in the related nodes. With XFEM technology,a single-notched concrete three-point bending beam is simulated. The maximum principal tensile stress damage and fracture criterion and linear softening damage model is used for concrete. The simulation results are compared with test results,and the model is verified. It shows that there is a little difference between results simulated by XFEM and test in initiation toughness and unstable fracture toughness,etc.,but arguably,they are in good agreement with each other. The difference is mainly due to reasons such as the self-gravity of concrete beams,the friction of abutments. XFEM can effectively simulate the whole process from the beginning of loading to the concrete failure,and the crack initiation,propagation process and the failure mode can be obtained.