Eventos Anais de eventos
CONEM 2018
X Congresso Nacional de Engenharia Mecânica
Deviation in Fatigue Life Results due to Different Methods of Obtaining Constants
Submission Author:
Caio Ferreira Barros , RJ
Co-Authors:
Caio Ferreira Barros, Jorge Alberto Rodriguez Duran
Presenter: Caio Ferreira Barros
doi://10.26678/ABCM.CONEM2018.CON18-0210
Abstract
Fatigue life can be calculated from local strain amplitudes according to the well known Coffin-Manson relation. For notched bodies, neglecting transient, local strains should follow simultaneously the cyclic stress-strain curve and a stress concentration rule. Occasionally, the fitting constants for the cyclic stress-strain curve are not available and the so called compatible constants are used instead. The present paper evaluates the consequences that this decision have on the final life calculated by the strain approach to fatigue and how divergent results can be generated according to the material and analysis parameters applied. For steels, fatigue life results obtained with the compatible constants consistently represent the results obtained with the experimental constants, without divergence. However, for aluminum, when compared the experimental and compatible methods to obtain the constants, fatigue life results diverge in such a way that, according to the change in the values of the analysis parameters, such as stress amplitude, stress ratio and stress concentration factor, the results obtained using the constants from the compatible method can be either equivalent or slightly non-conservative, or even considerably conservative in relation to the results obtained with the constants from the experimental method.
Keywords
strain-based fatigue, aluminum fatigue, cyclic stress-strain constants, strain-life constants
