Issue 62

Yu. G. Matvienko et alii, Frattura ed Integrità Strutturale, 62 (2022) 541-560; DOI: 10.3221/IGF-ESIS.62.37

  k D S k for specimens of given geometrical dimensions is defined by mechanical properties material and

The coefficient

  k D i S R in each specific case follows from normalization of

parameters of loading program. The value of the coefficient

Eqn. (8) taking into account that the total sum in the right-hand side must be equal to one. This is attributed to the definition of limiting values of the damage accumulation function (6). The required procedure is based on the use of normalized distribution of each damage indicator    , m k N as a function of loading cycle number, which are constructed in the range from  0 m N to  Cr m F N N . These dependencies are presented in Fig. 10. A square lying under each normalized    1 curve, shown in Fig. 10, represents by itself initial experimental information essential for a calculation of the coefficient   k D S k . This square is denoted as    Σ k . Required coefficients are derived as an inverse proportional values:       1/ Σ k D S k k . (9) The developed procedure leads to an explicit form of the damage accumulation function (8). Data presented in Fig. 10 and Formula (9) provide normalizing coefficient values, which are listed in Tab. 6.

Normalizing coefficient   k D S k

Square under normalized curve    Σ k , conventional units

Damage indicator,    k

   1

0.967

1.03

   2

0.796

1.26

  k D S k .

Table 6: Values of normalizing coefficients

Graphical representation of Formula (8) implementation by using Tab. 5 data for obtaining an explicit form of the damage accumulation function are shown in Fig. 11.

     , m m D N k constructed proceeding from the evolution of different

Figure 11: The damage accumulation function

damage indicators.

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