PSI - Issue 42

D. Kosov et al. / Procedia Structural Integrity 42 (2022) 545–552 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

547

3

2. Isotropic and damage material models 2.1. Isotropic hardening models To describe the process of deformation under static loading, it is necessary to use the model of isotropic hardening. In this study, the isotropic Voce hardening law (1) and the power law (2) were used:

0  = +  − −   inf 1 exp( R    pl

 

( ) R

)



(1)

y n

N

3     y y G   = +  

  



(2)

pl



0

0

0

2.2. Damage model In this study, the Lemaitre damage accumulation model was used. Damage accumulation in this model is based on thermodynamic theory and depends on the rate of plastic strain accumulation. In general, the model is described by the law:

1 s Y r    −     − 

  =

(3)

1

2 2 (1 ) eqv v R E    −

Y − =

(4)



eqv            p

( ) 2 1 3(1 2 ) 3  

R

= + + − 

(5)

v

 

It follows from equations (3) - (5) that the rate of energy release during deformation depends on the stress triaxiality parameter ( p / σ eqv ), which takes into account the effect of loading multiaxiality on the damage accumulation process. The Lemaitre damage model, which combines equations (1)-(5), was integrated into the ANSYS software package as a dynamic link library to determine the effect of damage on the stress-strain state of a material in a complex stress state. The numerical implementation of the Lemaitre model is described by Gates (2012). 3. Experimental study The purpose of the experimental studies was to determine the basic properties of the material under standard uniaxial tension and the characteristics of resistance to deformation and fracture under multiaxial loading. 3.1. Uniaxial Tensile Test At the first stage of the experimental study, a uniaxial tensile test was carried out on a smooth cylindrical specimen (Fig. 1b) to determine the main mechanical properties of the 2024 aluminum alloy. The result of the test is a uniaxial tensile diagram (Fig. 2), as well as the main mechanical properties of the material (Table 1).