EXPLOSION CAMERAS WITH PROTECTIVE FOAMY LINING: DEFORMATION MODES ARISING UPON EXPLOSIVE LOADING

EPNM-2012, Strasburg

A. G. Kazantsev 2, S. S. Smolyanin 2, L. B. Pervukhin 1, P. A. Nikolaenko 1, and R. D. Kapustin1

1 Institute of Structural Macrokinetics and Materials Science RAS, Chernogolovka, Moscow, 142432 Russia

2 Central Research Institute for Machinery Industry

(TsNIITMash), Moscow, Russia

kapustin-roman@mail.ru

As is known, from the published data, gas-liquid foams most effectively use for effective dissipation of shock energy. But gas-liquid foams exhibit a restricted service life. In this work, we explored the applicability of solid refractory foams for the above purpose.

Purpose of the work - to determine the effectiveness of the dissipation of explosive energy by solid porous materials (solid foams).

In the represented work is investigated the possibility of application for the dissipation of the shock waves of the solid aluminosilicate porous materials VBF of the production Privately held company NPKF “MaVR”.

Purpose of the work

Experimental model

finite-element model

Metall shellCellular material VBFexplosive charge (TNT);

air

Strains in metall shell

TNT m=600 gramm Model without solid aluminosilicate porous material VBF

TNT m=900 gramm Model with solid aluminosilicate porous material VBF

Pressure upon a container wall

TNT m=600 gramm Model without solid aluminosilicate porous material VBF

TNT m=900 gramm Model with solid aluminosilicate porous material VBF

Plastic deformations in metall shell

A) TNT m=600 gramm Model without solid aluminosilicate porous material VBF

В) TNT m=900 gramm Model with solid aluminosilicate porous material VBF

Experimental model

1 – Cellular material VBF;

2 – the strain gauge;

3 – explosive charge (TNT);

4 – the electric detonator;

5 – camera for the electric detonator and opening for wires or detonation cord;

6 – metall shell of the experimental model;

Dependence of the strains in metall shell of experimental models from the mass of explosive charge (TNT)

0

200

400

600

800

1000

1200

1400

1600

0 200 400 600 800 1000 1200

TNT mass, gramm

σ,М

Па

расчёт верх

расчёт бок

пустой верх

пустой бок

материал ВБФ-650 верх

материал ВБФ-650 бок

Strains in metall shell of experimental models, MPa

TNT mass,gramm

Model without solid aluminosilicate porous material VBF

Model with solid aluminosilicate porous material VBF

the upper surface The side the upper surface The side

200 72,2 88 31,8 42,6

400 244 304,7 24 31,8

600 352,3 397,2 137,8 194,1

900     341,9 423,4

The calculation of the efficiency of shock energy dissipation

QV = 1,4/0,14 = 10 MJ/m3 = 10 J/sm3

QV – volumetric energy-absorption of material VBF;

QП – the quantity of energy, absorbed by material VBF according to the results of the tests of experimental models;

V – the volume of material VBF in the experimental models

V

QQ ПV

Calculation of the stress-strain stateMaterial of metall shell – steel 9MnSi5; Diameter-1,2 m, Thickness of a wall-12 mmMass without VBF 700±20 kgCellular material VBF, thickness of a layer of 300 mm ρ = 0,7 gramm/sm3

1

1128,0 0

3

3

30

33

20

в

н

rR

QErr

R

При При R≤αrR≤αr00

TNT, kg r, m σн, МПа

0,25 0,033 110

0,5 0,042 168

0,75 0,048 220

1 0,053 271

1,25 0,057 321

1,5 0,06 371

1,75 0,064 420

2 0,066 469

2,25 0,069 518

2,5 0,072 567

2,75 0,074 616

3 0,076 665

3,25 0,078 713

3,5 0,08 762

где: σн – Strains in metall shell caused by influence on it of a shock wave, Rоб – radius of metall shell, δ – thickness of metall shell, r0 –TNT radius, α = 10 – the factor considering limiting expansion of products of a detonation, Q – specific energy allocation of TNT, Е – material,s elasticity module of shell, ρ0 – TNT density, ρв – air density, μ – Poisson's ratio

The results of the experiment

mTNT,kg Lsircle , mm of metall

shell before explosion

Lsircle , mm of metall shell

after explosion

relative lengthening

Notes

3,5 3852 3871 0,5 Plastic deformation is negligible or no

4,5 3852 3902 1,3 Plastic deformation

7,0 3832 4030 5,2 tensile strength exceeding

Main conclusions 1) Is developed the procedure of the experimental determination of

the energy-dissipate ability of the solid cellular materials by the method of their accomodation into closed metal shell from a change in the deformation of this of shell.

2) Used the method of calculation, based on the method of finite elements and the combined Lagrangian-Eulerian formulation of the equations of motion of a continuous medium. It allows to adequately describe the impact of a shock wave on the wall of the pilot sample, as with VBF, so without it. Experimental results were found to reasonably agree with calculated ones.

3) The foamy materials under investigation showed good results: the efficiency of shock energy dissipation was found to attain a value of about 10 J/cm3. Material VBF with the volume of 1 m3 absorbs the energy, isolated with explosion of the charge of TNT by the mass of 2,4 kg.

4) The scale factor in the case of a proportional increase in sample sizes and thickness of energy absorbing layer does not affect the ability of the VBF dissipation of shock energy

THANKTHANK YOU YOU FOR FOR ATTENTION!ATTENTION!