Finite element methods for structural hot spot stress determination—a comparison of procedures

Three methods for determining the structural hot spot stress for fatigue analysis of welded structures are presented. These include linear surface extrapolation (LSE), through thickness at the weld toe (TTWT), and the Dong method. The methods were applied to evaluate finite element analysis results obtained for a simple 2D structure and 3D structural detail. The limits and accuracy of the methods were investigated. LSE and TTWT are based on normal stresses while the Dong method also requires that shear stresses are correct. For 2D models, TTWT and the Dong methods gave uniform results for virtually all mesh variations used in this study. For 3D structures, the Dong method requires more care during meshing and is numerically more demanding during post-processing than other methods. When TTWT is used for 3D structures, the computed structural stress is virtually identical to that found using Dong method, but the meshing requirements are somewhat easier and the post-processing requires only that nodal averaging be considered.