8
I. A. Volkov et al.
1.3.1 Block-Type Asymmetric Soft Cyclic Loading
The first example presents the results of numerical modeling of deformation
processes in specimens of stainless steel SS304 (Guozheng et al. 2002) under
block-type asymmetric soft cyclic loading:
• in the first block, 50 cycles of asymmetric soft loading with the stress amplitude
of σ 11 = 248 MPa and average cycle stress of σ
aver
11 = 78 MPa are realized;
• the second block consists of 50 cycles of asymmetric soft loading with the
amplitude of σ 11 = 248 MPa and average stress of σ
aver
11 = 117 MPa;
• the third block includes 20 loading cycles with the stress amplitude of σ 11 =
248 MPa and average stress of σ
aver
11 = 78 MPa.
Tables 1.1, 1.2 and 1.3 present the main physical–mechanical characteristics
and material parameters of thermoplasticity model for SS304 steel, used in the
computations.
Figure 1.1 presents the results of comparing the calculated and experimental
curves of the average strain as a function of number of loading cycles, and Fig. 1.2
depicts the curves of cyclic deformation constructed on the basis of the numerical
results.
Table 1.1 Main physical–mechanical characteristics and material parameters of the model of plastic
deformation for SS304 steel
G, MPa
K, MPa
c o
p
g 1 , MPa
g 2
g 3 , MPa
g 4
k 1 , MPa
65,384
141,700
228–249
22,000
300
1000
10
0,68
k 2 , MPa
a 1
a 2
Q 2 , MPa
50
15
50
800
Table 1.2 Monotone isotropic hardening modulus q 1 as a function of plastic deformation path
length χ for SS304 steel (q 2 = 0)
q 1 , MPa
−13.462
−8508
−8738
−6027
−2690
−1173
−118
χ
0
0.001
0.002
0.003
0.005
0.007
0.01
q 1 , MPa
−489
0
0
χ
0.015
0.02
0.03
Table 1.3 Value of cyclic hardening modulus Q 1 as a function of maximum value of displacement
of the yield surface center ρ max for SS304 steel (Q 2 = 0)
Q 1 , MPa
228–241
220–241
220–241
ρ max , MPa
0
10
80