A COUPLED CRITICAL PLANE MODELS - √area PARAMETER METHODOLOGY TO ESTIMATE FATIGUE LIFE IN THE PRESENCE OF SMALL ARTIFICIAL DEFECTS
MULTIAXIAL FATIGUE, LIFE ESTIMATION, MICRODEFECT, CRITICAL PLANES
In projects involving mechanical structures and components, the presence of notches, grooves, holes, cavities, inclusions, and scratches is common. In the presence of cyclic loads, these features can influence their fatigue strength and life. The objective of this thesis is to propose a methodology for estimating 'SN' curves for components with micro-defects and using them to calibrate critical-plane models for multiaxial fatigue life estimation. The approach of this work is formulated based on a calibration strategy for the Fatemi-Socie, Smith-Watson-Topper, and Susmel and Lazzarin models. The proposed methodology utilizes Murakami criteria, a Bandara et al. strategy, material static properties, and notch sensitivity factors to compute the micro-defect effect. The obtained results were compared and validated against experimental data and further corroborated with literature data for various steel and aluminum alloy materials, demonstrating its promising nature. Among the notable outcomes, the MWCM model stood out, with 92% of estimates falling within a 2-band range and 100% within a 3-standard deviation band. To extend and apply the proposed methodology more broadly, it is recommended to perform life prediction comparisons for different materials, loadings, and defect geometries