PSI - Issue 36

Valeriy Kharchenko et al. / Procedia Structural Integrity 36 (2022) 145–152 147 Valeriy Kharchenko, Eugene Kondryakov, Andriy Kravchuk et al. / Structural Integrity Procedia 00 (2021) 000 – 000 3

( ) t   =   = 

( )

V t L F t

(1)

( )

( ) t



  

2

sz A L t

( )



( ) t  =  

L

were A sz is the sectional area of the shear zone , F(t) is the force applied on the specimen, ΔL(t) is the relative displacement. To develop the shape of the specimens, as well as the structures of the support and the striker, numerical calculations are performed using the finite element (FE) method. A finite element model of dynamic shear testing is illustrated in Fig.2. The half part of the model is simulated with the corresponding boundary conditions of symmetry. The minimum size of elements in the shear zone is 50 microns. The Johnson-Cook material deformation model is used to simulate the behavior of the specimen under dynamic shear loading considering the strain rate and the corresponding fracture criterion. The model parameters for Armox 500T steel were taken from the literature data Iqbal et al. (2016).

Fig. 1. Geometric configuration of the double shear specimen. Fig. 2. FE model for the calculation of the dynamic shear loading. Figure 3 shows the distribution fields of equivalent plastic strains at different time points for the specimens with a shear zone length L = 1 and 2 mm. Fracture initiation in both cases occurs almost simultaneously at t = 350 μs in the concentrator within the lower part of the shear zone. It can be seen that in the specimen with L = 2 mm, fracture occurs along several trajectories, and at the end of the calculation at t = 600 μs, the complete fracture does not occur. And in a specimen with a shear zone length L = 1 mm, fracture occurs along one trajectory, the crack propagates at a sufficiently high speed, and at t = 576 μs, there is a complete fracture of the specimen.

Fig. 3. Distribution of te equivalent plastic strain at different time points for the specimens with a shear zone length L=1 mm (a) and L=2 mm (b).