Tese: Plastic stress concentration effects in fatigue strength
Aluno(a) : Mengen LiuOrientador(a): Marco A. Meggiolaro e Jaime Tupiassú
Área de Concentração: Mecânica Aplicada
Data: 27/03/2023
Link para tese/dissertação: https://doi.org/10.17771/PUCRio.acad.62552
Resumo: Elasto-plastic stress gradient factors ahead of notch tips are used to evaluate actual notch effects in fatigue strength, quantified by fatigue stress concentration factor . Usually, it is smaller than the linear elastic stress concentration factor of the notch, , due to material tolerance to non-propagating short cracks. Considering that local plasticity around notch tips plays a significant role in the growth behavior of short cracks within the notch plastic zone, a sound mechanical methodology is proposed to account for the effects of elasto-plastic stress and strain fields in the actual value. Two-dimensional finite element analyses are conducted to compute stress intensity factors of smooth and notched specimens. Ramberg-Osgood model and Neuber’s rule are used to achieve approximations for strain-based intensity factors. For methodology validation, numerical predictions are compared to experimental stress-life data of center, U, and V-notched plate specimens made of different materials and tested under uniaxial load ratios of 1, 0, and 0.1 collected from the literature. The comparisons show good agreement proving that the elasto-plastic solution provides more accuracy than the linear elastic one. The most discrepant results are obtained at load ratios of 0 and 0.1, and they can be significantly improved if non-zero mean stress effects are considered.