PSI - Issue 38

Benaouda Abdellaoui et al. / Procedia Structural Integrity 38 (2022) 116–131 Benaouda Abdellaoui et al / Structural Integrity Procedia 00 (2021) 000 – 000

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4.2.2. Manson-Coffin analysis On the diagram  /2-N (Fig. 6) were deferred the amplitudes of elastic, plastic or total deformation.  t /2 is expressed by the following relation, [9] and [14]: 2 = 2 + 2 = ′ (2. ) + ′ (2. ) (3) The elastic and plastic strain amplitudes were determined by the following formulas: 2 = 2 . (4) with E = 199085 MPa (average of modules E au 1 er cycle) 2 = 2 − 2 (5) The failure criterion selected to plot the Manson Coffin curve [9], was defined as the failure of the specimen. The parameters of the Basquin (  e /2 - N) and of Manson-Coffin (  p /2 - N) are given in Table 6. The identification of the parameters of the Manson-Coffin curve was made on the results of tests whose amplitude of deformation is between 0.450% and 0.248% for the plastic part and on all the valid results except unbroken specimen for the elastic part.

Table 6. Manson-Coffin curve parameters

b

C

 f '/ E

 f '

0.006860721

-0.0882

0.0032

-0.4938

Fig. 6. LCF fatigue test results, Manson-Coffin curve