基于DIC技术和无网格法的裂尖应变场分析方法

针对数字图像相关(DIC)技术难以获得精准的裂纹尖端应变场问题,提出一种基于DIC技术和伽辽金无网格法(EFG)的混合方法来分析裂尖应变场.该方法基于DIC技术导出场节点建立无网格模型,采用EFG法结合衍射法表示裂纹不连续性,进而计算全场应变值.以Q235qE钢材制成的紧凑拉伸(CT)试样为例开展了准静态循环拉伸试验,...

An analysis method for strain field of crack tip based on DIC technology and meshless method

Because it is difficult to obtain accurate crack tip strain fields by digital image correlation (DIC) technology, a hybrid method was proposed based on the DIC technology and element-free Galerkin (EFG) method. The meshless model was established by field nodes based on DIC technology. The diffraction method was used to consider the crack discontinuity and full-field stress and strain was calculated by the EFG method. The quasi-static cyclic tensile test was carried out on the compact tensile (CT) specimens made of Q235qE steel. The validity and stability of the method were verified by the analytical solution of crack tip strain and test results. Then, applications of DIC-EFG method in the plastic zone and stress intensity factor (SIF) calculation of crack tip were studied. Results show that, the DIC-EFG hybrid method is simple in modeling and can obtain the full-field strain including crack tip accurately without knowing loads and constraint conditions of the structure. Compared with the traditional DIC technology, the hybrid method may solve the problem of missing results near the crack, and it shall be more accurate in the calculation results of SIF when being in conjunction with J-integral method. The proposed method can be applied to the study of fracture properties such as the plastic zone and SIF calculation of fatigue crack.