Banca de DEFESA: Paulo Roberto de Oliveira Junior

Calculation of 2D Stress Intensity Factor by Weight Function and Its Application in Fatigue of Welded Elements

Stress Gradient Factor; Welded Structures; High-Frequency Mechanical Impact Treatment; Fracture Mechanics; Weight Functions

The objective of this study is to develop the Stress Gradient Factor (K_gr) based on the Stress Intensity Factor (SIF) to estimate the useful life through Deformation-Based Fracture Mechanics (DBFM) in welded specimens treated with High-Frequency Mechanical Impact (HFMI). Using Weight Functions (WF), Stress Intensity Factors are computed for the cross-sectional geometries of welds employing an inverse contour algorithm utilizing the 2D point load weight function. The model described in this work can estimate the fatigue of welded components and cruciform joints treated with HFMI under varying loading conditions, considering an initial semi-elliptical crack growing in two directions using the K_gr equations. Modeling of K_gr was performed concerning the analysis intervals, resulting in defining equations to determine the values of K_gra and K_grc. The numerical analysis presented here to estimate welding fatigue life is compared with experimental data for 350W steel conducted at the University of Waterloo, Canada. Subsequently, a statistical analysis of data produced by the Monte Carlo method is conducted with found and simulated data to validate the model through S/N curves. The experimental curves demonstrate that treated samples exhibit longer fatigue lives compared to untreated ones, and the analyses performed manage to replicate this fatigue behavior. The modeling results compared with the data presented by Ghahremani (2015) and Ranjan (2019) show validation of the model.