PSI - Issue 39

Viktor Morozov et al. / Procedia Structural Integrity 39 (2022) 432–440 Author name / Structural Integrity Procedia 00 (2019) 000–000

439

8

Table 1. Outcomes of experiments and their analysis. Group of experiments Vaporization time, µs

Crack length, mm

Pulse duration, µs

Amplitude off applied stress, MPa

Boundary fracture stress, MPa

Crack velocity, m/s

PMMA, cylinders, low voltage PMMA, cylinders, high voltage

18 18

17 25

3-5

1067 1650

485 750

940

1

1390

PMMA, lameles

–

– 5

20

80-120

70

130-700

fluoroplastic , low voltage

17

3,5

1058

1040

300

4. Conclusions Following conclusions may be made as an outcome of our tests and the analysis of their results. • Experiments with pulses duration from 1 µs up to 20 µs revealed a strong dependence between crack propagation velocity and pulse duration. For short pulses, such velocity may be equal to or exceed shear velocity. • Crack propagation velocity depends on the amplitude of applied pulse stress. Velocity increases with the growth of the amplitude of applied pulse stress. • Boundary (minimal) value of failure stress strongly depends on loading pulse duration and significantly increases with shortening of the pulse. • Tests on fluoroplastic cylinders revealed a completely different picture of fracture in comparison to PMMA samples. The grid of short cracks growing from the explosion cannel along its line initiated on the first step. And in the second step, these cracks grow to the outer surface of the cylinder. These cracks may merge and produce general cracks propagating along the generatrix of the cylinder and causing its failure. • To festimate time of relaxation to the stationary propagation mode for cracks of various range At the same time, crack propagation velocity in fluoroplastic is significantly low in comparison to PMMA, even under the action of relatively higher stresses due to its viscous nature. References Aleshin V. I., Aero E. L., Kuvshinskii E. B., Slavitskii I. A., 1981. Kinetics of cracks growth in the plates of acrylic glass. Izv. AN SSSR MTT [Mechanics of Solids] 2, 70–79 (in Russian). Atroshenko S. A., Krivosheev S. I., Petrov A. Yu., 2002. Crack propagation upon dynamic failure of polymethylmethacrylate. Technical Physics 47, 2, 194–199. Atroshenko S. A., Morozov V. А., Kats V. M., 2018. Destruction of plastics by exploding wire method, in “Physico -chemical aspects of extreme states and structural transformations in continuous media, materials and technical systems”, vol. 2. In Petrov Yu. V. (Ed.). Polytechnics, St Petersburg. 58–65 (in Russian). BratovV., Petrov Y., 2007. Application of incubation time approach to simulate dynamic crack propagation. International Journal of Fracture 146. 53–60. Cherepanov G. P., 1967. Crack propagation in continuous media. Journal of Applied Mathematics and Mechanics 31, 3, 503–512. Efimov V. P. Sher E. N., 2001. Dynamic crack resistance of acrylic plastic. Journal of Applied Mechanics and Technical Physics 42, 5, 918–924. Green A.K., Pratt P.L., 1974. Measurement of the dynamic fracture toughness of polymethylmethacrylate by high-speed photography. Engineering Fracture Mechanics 6, 1, 71–72, IN3– IN6, 73–80. Griffith A. A., 1920. The phenomenon of rupture and flow in solids. Philosophical Transactions of the Royal Society A 221, 687, 163–198. Imbert J., Rahmaan T., Worswick M., 2015. Interrupted pulse electromagnetic expanding ring test for sheet metal. EPJ Web of Conferences 94, 01048. Irwin G. R., 1957. Analysis of stresses and strains near the end of a crack traversing a plate. Journal of Applied Mechanics 24, 3, 361–364. Klepaczko J. R., Petrov Y. V., Atroshenko S. A., Chevrier P., Fedorovsky G. D., Krivosheev S. I., Utkin A. A., 2008. Behavior of particle-filled polymer composite under static and dynamic loading. Engineering Fracture Mechanics 75. 136–152. Lukin А. А., Моrozov V. А., 2010. Crack growth initialization under a short -duration pulse loading. Vestnik St.Petersburg University. Ser. 1 2., 134–139. Моrozov V. А., 2010. Сrack p ropagation under short-term impulse loading. Vestnik St.Petersburg University. Ser. 1 1, 105–111 (in Russian). Morozov V. A., Bogatko V. I., Atroshenko S. A., Kats V. M., Gazizullina A.R., 2020. Technical Physics 65, 2, 221–225. Morozov V. A., Lukin A. A., Atroshenko S. A., Gribanov D. A., Petrov Yu. V., 2016. Deformation and fracture of metal ring samples under the explosion of conductors. Procedia Structural Integrity 2, 1002–1006.