Multi-parameter identification of the single edge notched tensile specimen using the virtual fields method

The elastic constants are significant indicators to evaluate the damage status during fatigue, whereas the stress intensity factors (SIFs) are essential parameters to study the fatigue crack growth rate. However, due to different configurations of the specimens, tests on these two types of parameters are typically performed independently. To simultaneously characterize the elastic constants and SIFs through a single experiment, the virtual fields method (VFM) for single edge notched tension (SENT) specimens was developed in this study. The proposed approach combines the full-field measurements and virtual fields generated by the finite element method (FEM), which can automatically satisfy the complex boundary conditions and effectively minimize the influence of the plastic zone near the crack tip. The feasibility of this approach was verified by simulation experiments and several key factors involving identification accuracy were investigated. In the application, the SENT testing of Ni-based superalloys was implemented by the digital image correlation (DIC) technique, and the identification results were compared with FEM, the least-squares method (LSM), and theoretical values. The results of the current study demonstrate the excellent accuracy and robustness of this approach, indicating its broad application in the engineering field.