Experimental investigation and numerical modeling for elasto-plastic notch-root stress/strain analysis under monotonic loadings

Experimental investigation and numerical modeling on elasto-plastic notch-root stress/strain distributions under monotonic loadings of both the Ni-based directionally solidified (DS) superalloy and Titanium alloy were carried out simultaneously. For measuring inhomogeneous deformation fields at notch roots, an optical-numerical full-field surface deformation measurement system was developed based on the digital image correlation (DIC) method. The obtained strain distributions were then verified with reasonable accuracy by finite element simulation, where an anisotropic elastic-viscoplastic constitutive model was developed for DS superalloy and a simple isotropic stress-strain relationship was adopted for Titanium alloy. Meanwhile, factors affecting elasto-plastic notch-root stress/strain distributions were systematically investigated numerically, where the emphasis was placed on temperature, loading stress rate, sample shape, anisotropy and notch features. The results show that stress/strain behavior at notch root is significantly affected by the mentioned factors, which are concretely embodied in the distribution of tensile stress/strain, equivalent stress and accumulative equivalent plastic strain.