Issue 38

C. Xianmin et alii, Frattura ed Integrità Strutturale, 38 (2016) 319-330; DOI: 10.3221/IGF-ESIS.38.42 330 [16] Rasool, I., Zhang, X., Cui, D., Fatigue life prediction of 3-d problems by damage mechanics with spectrum loading, In: ICAS 2002, (2002). [17] Jobn, H., Effects of loading sequence for notched specimens under high-low two-step fatigue loading, NASA TN D- 6558, (1971). [18] Hélder, F. S., Pereira, G., et al, Influence of loading sequence and stress ratio on fatigue damage accumulation of a structural component, Ciência e Tecnologia dos Materiais, 20 (2008) 60-67. [19] Morrow, J. D., The effect of selected subcycle sequences in fatigue loading histories, In Random Fatigue Life Predictions, ASME Publication PVP, 72 (1986) 43-60. [20] Nijssen, R.P.L., Van Delft, D.R.V., Van Wingerde, A.M., Alternative fatigue lifetime prediction formulations for variable-amplitude loading, J Sol Energy Eng, 124(4396) (2002) 396-403. [21] Ling, J., Pan, J., A maximum likelihood method for estimating P-S-N curves, Int. J. Fatigue, 19(5) (1997) 415-419. N OMENCLATURE b = self-consistent exponent dependent on the fatigue life distribution b j = the self-consistent exponent dependent on the fatigue life distribution under j th load level Δ = a random variable with mean value equal to zero d = Morrow’s plastic work interaction exponent D = damage value D B = damage caused by one loading block D Bj = damage caused by the j th level of stress Dc = critical damage value E = mathematical expectation m = number of stress levels in a spectrum loading n = cycle number in one loading block n i = cycle number under the i th stress level n j = cycle number under the j th stress level n f = cycle number to failure N = fatigue life N 95/95 = fatigue life with 95% reliability and 95% confidence level N i = fatigue life under the i th stress level N j = a random number obeying the distribution of fatigue life under j th stress level N k = the number of stress peak to cause failure under the constant stress amplitude of S k N f = the predicted fatigue life under block loading N p = the fatigue life of the test sample with reliability of p R E = the ratios of mathematical expectation between model and test data R σ = the ratios of standard deviation between model and test data R N 95 = the ratios of N 95/95 between model and test data S = the stress level of the constant amplitude loading S j = stress peak of the j th stress level S k = stress peak of the k th stress level S max = the maximum stress in the stress history 1 max  j S = the maximum stress among the stress levels from S 1 to S j-1 v = a constant depending on the material itself and the assumption of fatigue life distribution α = shape parameter α of Weibull distribution  ˆ = the estimation of shape parameter β = scale parameter of Weibull distribution β c = the estimation of characteristic life with confidence level of c  ˆ = the estimation of characteristic life μ = mean value of Weibull distribution σ = standard deviation of Weibull distribution