Effect of Specimen Thickness on Probability Distribution of Grown Crack Size in Magnesium Alloys

Authors: Seon Soon Choi

Abstract:

The fatigue crack growth is stochastic because of the fatigue behavior having an uncertainty and a randomness. Therefore, it is necessary to determine the probability distribution of a grown crack size at a specific fatigue crack propagation life for maintenance of structure as well as reliability estimation. The essential purpose of this study is to present the good probability distribution fit for the grown crack size at a specified fatigue life in a rolled magnesium alloy under different specimen thickness conditions. Fatigue crack propagation experiments are carried out in laboratory air under three conditions of specimen thickness using AZ31 to investigate a stochastic crack growth behavior. The goodness-of-fit test for probability distribution of a grown crack size under different specimen thickness conditions is performed by Anderson-Darling test. The effect of a specimen thickness on variability of a grown crack size is also investigated.

Keywords: Crack size, Fatigue crack propagation, Magnesium alloys, Probability distribution, Specimen thickness.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1093195

References:

[1] K., Tokaji, M., Nakajima, and Y., Uematsu, "Fatigue crack propagation and fracture mechanisms of wrought magnesium alloys in different environments,” International Journal of Fatigue, Vol. 31, Issue 7, pp. 1137~1143, 2009.
[2] P., Venkateswaran, S., Ganesh Sundara Raman, S. D., Pathak, Y., Miyashita, Y., Mutoh, "Fatigue crack growth behaviour of a die-cast magnesium alloy AZ91D,” Materials Letters, Vol. 58, pp. 2525~2529, 2004.
[3] D. X., Xu, L., Liu, Y. B., Xu, E. H., Han, "The fatigue crack propagation behavior of the forged Mg-Zn-Y-Zr alloy,”Journal of Alloys and Compounds, Vol. 431, pp. 107~111, 2007.
[4] S. S. Choi, "Estimation of probability distribution fit for fatigue propagation life of AZ31 Magnesium alloy,” Transactions of the KSME(A), Vol. 33, No. 8, pp. 707-719, 2009.
[5] M. Sivapragash, P.R. Lakshminarayanan, R. Karthikeyan, "Fatigue life prediction of ZE41A magnesium alloy using Weibull distribution,” Materials and Design, Vol.29, pp. 1549-1553, 2008.
[6] ASTM E647-00, Standard Test Method of Fatigue Crack Growth Rates. Pennsylvania: ASTM International, 2000.
[7] B. Dodson, The Weibull Analysis Handbook. Wisconsin : ASQ Quality Press, pp. 115-117.