FINITE ELEMENT ANALYSIS OF NOTCH-ROOT STRESS/STRAIN CONCENTRATION FACTOR APPLIED TO WELDED STRUCTURES

Antonio Miranda¹; Eduardo Fontes²; Jaime Tupiassu³

¹ UnB; ² IFP; ³ PUC/Rio

doi:10.20906/CPS/CILAMCE2015-0725

Resumo

Stress/strain concentration effects and residual stresses must be considered in mechanical analyses of welded structures. There is a vast literature on linear-elastic stress concentration factors Kt, which depend solely on the specimen/notch geometry and on the type of loading (Peterson, 1997). However, in the presence of plasticity at the notch root, the actual stress concentration factor Kσ becomes smaller than Kt, the stress gradient ahead of the notch root is affected by the stress redistribution at the yielding zone, and the strain concentration factor Kε, which strongly affects the fatigue life predicted by the εN method, can become much larger than Kt. Several approximated models have been proposed to estimate the elastic-plastic behavior at the notch root, which in many cases may provide rough but reasonable K and/or K values. However, the differences among the fatigue life predicted by such K/K estimation rules can be unacceptably large for practical purposes. In addition, they do not account for the geometrical changes at the notch root under large displacements, leading to further errors. In this work, 2D finite element analyses are carried out to evaluate elastic-plastic stress and strain distributions around notch roots. The proposed methodology can be applied to improve the analyses of welded structures.

Palavras-chave: stress/strain concentration factor; welded structures