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PREDICTING FATIGUE CRACK INITIATION LIFE OF AN ALUMINIUM ALLOY AT LOW TEMPERATURES
Author(s) -
Baotong Lü,
Xiulin Zheng
Publication year - 1992
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1992.tb01258.x
Subject(s) - materials science , fatigue limit , aluminium , aluminium alloy , hardening (computing) , alloy , metallurgy , composite material , structural engineering , layer (electronics) , engineering
— A simple approach to predict the fatigue crack initiation (FCI) life of notches at low temperatures is developed. The stress cycle to initiate a 0.25 mm crack at a notch tip is presented as a function of an equivalent stress amplitude. The results of the study indicate that the FCI life of an aluminium alloy increases with decrease in temperature and the effect of temperature on the FCI resistance can be predict in the form of an FCI coefficient C and the FCI threshold. The coefficient C is the parameter controlling FCI resistance in the low cycle fatigue region and it can be calculated from the elasticity modulus and the strain hardening exponent. The threshold is the parameter governing FCI resistance in the high cycle fatigue region and its value depends mainly upon the endurance limit. The temperature‐ dependence of the endurance limit can be predicted by a thermal activation model. By means of this approach, the fatigue crack initiation life at low temperatures can be predicted from the material tensile properties without any additional low temperature fatigue tests and without any empirical modification so long as the endurance limit of the metal at room temperature is predetermined. The results suggest that this approach is applicable to other aluminium alloys.