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THE EFFECT OF CRACK LENGTH ON FATIGUE THRESHOLD
Author(s) -
Taylor D.
Publication year - 1984
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.1460-2695.1984.tb00195.x
Subject(s) - materials science , microstructure , aluminium , paris' law , structural engineering , alloy , fatigue testing , fracture (geology) , function (biology) , metallurgy , fracture mechanics , composite material , crack closure , engineering , evolutionary biology , biology
This paper puts forward a new method for analysing the behaviour of very short fatigue cracks. A probability function is introduced into the definition of the growth threshold, which rationalises the scatter in experimental data produced using an aluminium bronze alloy. This probability function can be visualised in terms of the microstructure of the material. It is shown that, in this material as in mild steels, fatigue crack initiation is not the critical stage. Initiation occurs relatively easily, but the cracks so formed may grow to only a few grain diameters in length before being arrested; thus it is the behaviour of cracks of this length which is critical in determining the fatigue strength of the material. These observations, when combined with the probability functions, allow estimation of the probability of failure of a component or structure in service with greater confidence than the methods used at present.