Fatigue fracture analysis and lifetime prediction of laser-cladded notched titanium alloy based on energy dissipation method

Abstract

The notched titanium alloys after laser cladding are often accompanied by anisotropic microstructural effects and metastable microstructures, and estimation of its remaining lifespan and fracture behavior becomes challenging. In this study, the effective fracture surface area of laser-cladded notched titanium alloy under different stress ratios is defined as an indicator of proposed dissipative energy damage model. The infrared thermographic cyclic tests are firstly conducted on repaired specimens of notched titanium alloy. Both fine granular area morphology and irregular nanoparticles are observed in crack initiation and early propagation zones from fatigue fracture surfaces. To better explain this phenomenon, the micro-strain field of the specimens under cyclic loading is measured using digital image correlation method. Then, the relationship between the effective fracture surface area and the stress amplitude is established, as well as an equivalent crack propagation rate. The predicted remaining lifespan of laser-cladded notched titanium alloy based on the dissipative energy damage model agrees well with the experimental data.