Comparison between dog-bone and Gaussian specimens for size effect evaluation in gigacycle fatigue

A. Tridello, D.S. Paolino, G. Chiandussi, M. Rossetto

Abstract


Gigacycle fatigue properties of materials are strongly affected by the specimen risk volume (volume
of material subjected to a stress amplitude larger than the 90% of the maximum stress). Gigacycle fatigue tests,
performed with ultrasonic fatigue testing machines, are commonly carried out by using hourglass shaped
specimens with a small risk volume. The adoption of traditional dog-bone specimens allows for increasing the
risk volume, even if the increment is quite limited. In order to obtain larger risk volumes, a new specimen shape
is proposed (Gaussian specimen). The dog-bone and the Gaussian specimens are compared through Finite
Element Analyses and the numerical results are validated experimentally by means of strain gages
measurements. The range of applicability of the two different specimens in terms of available risk volume and
stress concentration effects due to the cross section variation is determined.


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DOI: http://dx.doi.org/10.3221%2FIGF-ESIS.26.06