Eventos Anais de eventos
MecSol 2017
6th International Symposium on Solid Mechanics
INVESTIGATIONS ON FRETTING FATIGUE CRACK NUCLEATION IN A CYLINDER ON FLAT CONTACT VIA MULTIAXIAL FATIGUE MODELS
Submission Author:
FERNANDO Salles da Silva Pires , RJ
Co-Authors:
Jaime T P Castro, Luiz Carlos Rolim Lopes
Presenter: FERNANDO Salles da Silva Pires
doi://10.26678/ABCM.MecSol2017.MSL17-0161
Abstract
This paper focuses on the prediction of crack nucleation under fretting fatigue loadings via multiaxial fatigue models for a couple of steel. In this work, numerical model of a two-dimensional cylinder on flat contact, which allows applying fretting and fatigue efforts was built using Abaqus application. Kujawaski’s critical-plane tensile-based model (SWTD) and Findley’s critical-plane shear-based model (F) were used to predict crack nucleation risk and were compared to the commonly models used in the literature for the same purpose such as Smith-Watson-Topper (SWT) critical-plane tensile based model and Crossland’s invariant-based model. Besides the crack nucleation risk analysis, finite life was estimated using Basquin`s law for each model. The numerical results have been compared among them and to the experimental results available in the literature. In case of elastic contact, the results predicted by SWTD and Findley’s models show good agreement with the experimental results. Nevertheless, the SWTD model does not reproduce the physics of fretting fatigue cracking which was better achieved by Findley’s model. For the experimental data set with the higher contact pressure, where plastic strain dominates (LCF), SWTD parameter shows good agreement with the experimental results when calculated at the contact bord. Furthermore, both SWTD and SWT parameters yields similar results as the local mean stress are moderately negative. The advantage on the use of these critical-plane parameters is that they do not require the definition of a critical length. Such issue is the great challenge of non-local strategies. However, finding the critical-plane is a task requiring an exhaustive search among all combinations of candidate planes. Non-local strategies combined with multiaxial models such as Crossland’s model have been considered by many authors to predict crack nucleation under fretting fatigue loadings. The calculation of Crossland’s damage parameter as an invariant stress-based model is straightforward and does not require the critical-plane search. On the other hand, identifying the critical length to calibrate this model can be a problem in case of lack of experimental results. For the couple of steel investigated in this work, the use of Crossland’s model combined with a critical length calculated via point method proposed by Taylor has produced non-conservative predictions. Nevertheless, considering half-critical length (LPM/2), the predictions correlated well with the experimental results.
Keywords
Fretting Fatigue, multiaxial fatigue, crack nucleation, Finite Element Model, steel
