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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
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!