PSI - Issue 13

N.S. Selyutina et al. / Procedia Structural Integrity 13 (2018) 700–704 Author name / StructuralIntegrity Procedia 00 (2018) 000 – 000

703

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0.001 s -1 (Fig.2a). Line 3 has a good correspondence with experimental data at strain rate 750 s -1 (Fig.2b). Thus, increase of strain rate from 0.001 s -1 to 750 s -1 affects on theoretical stress-strain dependences of material, plotted on the Johnson-Cook model (7). In the Fig.2 is shown, that the relaxation model of plasticity is effective for both cases of strain rate. Theoretical curve (line 1) plots for α = 1.22, τ =1.56 μ s, β =0.08 and material properties σ с =785 MPa; E = 230 GPa. These parameters are independent on strain rate unlike parameters of the Johnson-Cook model.

Fig. 2. Modeling of stress-strain dependences for MP800HY steel (Singh et al. 2011) by the relaxation model of plasticity (5) (line 1) and the Johnson-Cook formula (6) (lines 2 and 3) at strain rates of: (a) 0.001 s -1 ; (b) 750 s -1 .

4. Conclusions

The structural-temporal plasticity model is applied to describe MP800HY steel stress-strain dependences at quasi-static and high-rate loading. Invariance of parameters of relaxation plasticity model basing on structural temporal approach can give a good correspondence with experimental data in comparison with Johnson – Cook model. The presented relaxation model of plasticity has the most convenient numerical algorithm for stress-strain dependences of material subjected by dynamic loading, showing good agreement with experiment both in the strain rate range where the empirical Johnson – Cook model (6) is implemented and in a much wider rate range.

Acknowledgements

The work was supported by the Russian Science Foundation (grant 17-71-10061).

References

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