PSI - Issue 32

O.B. Naimark et al. / Procedia Structural Integrity 32 (2021) 144–151 Author name / Structural Integrity Procedia 00 (2019) 000–000

148

5

was studied for a fused quartz cylindrical rod after its collision with a rigid target at the velocity 534 m/s. “In-situ” high-speed shadow framing revealed three shaded zones corresponding to collision surface (3), failure wave (2), and acoustic (shock) wave (1). The Failure Wave was explained by Naimark et al. (2003), as “resonance excitation” of blow-up fragmentation dynamics during the infinite gape of microshear density parameter in the metastability range c δ < δ .

150

3

100

4

5

50

v, m/s

0

12

8

4

0

t, µ s

a

b

Fig. 1. (a) Particle velocity profiles: 3 – 10 mm; 4 – 14 mm; 5 – 25 mm; (b) strain rate versus pulse amplitude.

30

25

y = 5,96x + 2,46

20

15

y = 1,57x + 4,66

10

y = 4,00x + 0,55

5

0

0

0,5

1

1,5

2

2,5

3

3,5

4

a

b

Fig. 2. High speed framing of Failure Wave dynamics: (a) shadow pictures of waves in shocked fused quartz (time 0.3 – 3.6 μs ); (b) distance Z versus time t diagrams for elastic front (1), Failure Wave front (2), collision surface (3). Travelling compressive elastic wave creates the spatial defects profile that is close to self-similar profile ( ) ζ f with the following triggering of blow-up kinetics of microshears over the length , K) L = kL (k = c H ... 1,2 with