PSI - Issue 36

G. Pysarenko et al. / Procedia Structural Integrity 36 (2022) 30–35 Pysarenko G., Voynalovich O., Maylo A. et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Table 1. Parameters of the descriptive statistics of damageability steel St 20. Cycles Number Max Sum

Mean Std. error Variance Std. dev 75 prcntil Skewness Kurtosis Coeff. var

10 5 10 6 10 7

256 256 256

128 169 405

4096 16

1.89

920.96 1320.83 4298.53

30.34 36.34 65.56

14.5

1.91 2.49 4.69

2.46 5.22

189.67 230.75 409.77

4096 15.75 2.27

4.5

4096 16

4.09

0

22.03

Fig. 4. Correlation characteristics of the intensity of the accumulation of deformation defects in steel specimens at the stages of high-cycle fatigue at symmetric tensile-compression cycles to failure: 1 - reference state; 2 - 10 5 , 3 - 10 6 , 4 - 10 7 cycles. It is suggested to determine the accumulated damage k D of metal structures by the ratio of the change in the current value of the deformation area defects to the base area of the specklogram defects. The coefficient k D defines a quantitative measure of the surface relative deformation. The calculated dependence for k D has the following form: k D = (I i – I 0 )/I i where the difference (I i - I 0 ) characterizes the damage by orthogonally directed displacement of surfaces of metal polycrystal faces within the matrix correlation zone; I 0 and Ii are the initial and current values of the deformation damage area parameter. The correlation characteristics of the kinetics of damage were obtained in the investigation, Pysarenko et al. (2013) presented by the graphs of damage factor influence on duration of amplitude cyclic stresses periodic loading at a symmetric loading cycle.