PSI - Issue 36

Valeriy Kharchenko et al. / Procedia Structural Integrity 36 (2022) 137–144 Valeriy Kharchenko, Eugene Kondryakov, Oleg Katok et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Fig. 2. Distribution of the equivalent strain at different time points under dynamic perforation by flat (a) and hemispherical (b) punches.

Figure 6 illustrates the shape of the plate fracture via a hemispherical punch from numerical simulation (Fig.6(a)) and experiment (Fig.6(b)). It implies that “petaling” fracture with the formation of “plug” is a common type at the striker velocities close to the ballistic limit. At the beginning of hemispherical punch loading, the plate exhibits biaxial tension conditions. Therefore, under static perforation tests, it is not simple to achieve this type of fracture due to insufficient loading unit stiffness of the experimental equipment. Fig.6(b) demonstrates “cap” fracture during static perforation tests by the hemispherical punch. The comparison of numerical and experimental loading diagrams in the coordinates force-displacement F (l) (Fig.6(c)) shows that fracture occurs earlier during calculations as compared with the experiment. It can be explained by the fact that the selected parameters of the Johnson-Cook model do not account for the material model sensitivity to the stress state. Thus, additional investigations are required to clarify these parameters.