PSI - Issue 42

D.I. Fedorenkov et al. / Procedia Structural Integrity 42 (2022) 537–544 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

540

4

( ) 2 1 3(1 2 ) 3      = + + −         . e p 

(5)

R

v

The ratio / e p  is a parameter of stress triaxiality. It takes into account the multiaxial loading effect on the damage accumulation process. The scalar damage parameter varies in the range of 0 1    , and in case of 0  = the material has no damage, and in case of 1  = the material considered destroyed. All the model representations (1)-(5) listed in this work were reduced to a common resolving equations structure and incorporated into the ANSYS user material subroutine. 3. Experimental studies In this article, 25Cr1Mo1V steel was used to verify the proposed method. The experimental study was given to determine the mechanical material properties at room temperature. Uniaxial tension tests were carried out on a universal testing equipment at a strain rate of 1 mm/min. The strains of test specimen were measured with a hinged deformation meter TC 703-3549-025M-050-ST. As a result of the tests, a uniaxial tension diagram and the mechanical material properties (Table 1) was obtained.

Table 1. Mechanical properties of 25Cr1Mo1V steel. E , MPa σ 0 , MPa σ u , MPa

σ R , MPa

δ , %

ψ , %

211000

353

618

433

25

62

Fig. 1. Fatigue curve of 25Cr1Mo1V steel.

Low-cycle fatigue tests at room temperature and stress controlled with an asymmetry factor of minus one and a frequency of ten hertz were performed on a Zwick/Roell HA100 test equipment. Hysteresis loops were recorded using a hinged strain meter TC 703-3549-010-050-ST. As a result, a fatigue curve of 25Cr1Mo1V steel was obtained (Fig. 1). 4. Method for determining constants 4.1. Isotropic hardening The exponential isotropic hardening law (1) includes two constants inf R and  . inf R is the asymptotic limit of