-
22 15-17 2551
Striker Split Hopkinson Pressure Bar
Compressed-Air Striker Launching System for Split Hopkinson
Pressure Bar
*,
51 . 10530 086-298-8510* e-mail: [email protected]*
Split Hopkinson Pressure Bar (SHPB) (102-104 s-1) Striker
Pressure Bar Striker Striker Electro-Pneumatics 15 bar Striker 26
mm 0.50 m 2.17 kg 0.25 m 1.11 kg 14 bar Striker 0.50 m 28.05 m/s
Striker 0.25 m 45.95 m/s Striker 0.50 0.25 m 1.18 m/s 3.67 m/s
St.A30 Copper Strain rate 102 s-1 Aluminum Strain rate 102 103 s-1
Striker SHPB
Abstract Split Hopkinson Pressure Bar (SHPB) is a
well-recognized technique for measuring dynamic properties of metal
at high strain rate (102-104 s-1). This technique was developed on
theory of longitudinal wave propagation in rod in which a
compressive stress wave is generated by an impact velocity of
striker. This paper represents a compressed-air Striker Launching
System which is capable of controlling the impact velocity of
striker at a setup value by means of an electro-pneumatics system
within a range of 15 bar of working pressure. Two 26 mm in
diameter
strikers (0.50 m in length weighted 2.17 kg and 0.25 m weighted
1.11 kg) were used to conduct the tests. It was found that, at the
14 bar working pressure, the maximum impact velocity generated by
both 0.50 m and 0.25 m strikers are 28.05 m/s and 45.95 m/s
respectively. Throughout the experiment, both average maximum of
the measured velocities are lower than the theoretical values: 1.18
m/s for the 0.50 m striker and 3.67 m/s for the 0.25 m striker.
Within a range of available impact velocities from this system, it
can be stated that St.A30 and Copper can be conducted at range of
102 s-1 while Aluminum is in a conducting range of 102-103 s-1.
Therefore it can be concluded that the SHPB test can be conducted
by a use of this Compressed-Air Striker Launching System. 1.
10 s-1 UTM 1 s-1
1 Split Hopkinson Pressure Bars for French-German
Research Institute of Saint-Louis
-
10 s-1 Taylor[1] Split Hopkinson Pressure Bar (SHPB)[2] SHPB
stress wave SHPB (Specimen) SHPB Specimen, Striker, Incident Bar
Transmitted Bar, Momentum Trap Striker Striker Striker Striker SHPB
Electro-Pneumatics 15 bar Striker 26 mm 0.50 m 2.17 kg 0.25 m 1.11
kg 2. Split Hopkinson Pressure Bar (SHPB)
- SHPB 1 (One-Dimensional Elastic Wave) Kolsky [2,5] Elastic Bar
Elastic Wave Pressure Bar (Incident Bar Transmitted Bar) Pressure
Bar
Incident Strain Wave, Reflected Strain Wave Transmitted Strain
Wave ,i r , t Incident Bar 1u Transmitted Bar 2u 2
2u1u
sl
ir t
2 Incident Bar, Transmission Bar
(Specimen) [2]
Cauchy [3] 1
2 2
2 2 20
1u ux c t = , 0
Ec = (1) 0c Longitudinal Wave Pressure Bar E Pressure Bar
Pressure Bar Pressure Bar DAlembert [3] 2
( ) ( ) ( )1 1 0 1 0,u x t f x c t g x c t= + + ( ) ( )2 2 0,u x
t f x c t= (2)
1f , 1g 2f Function Incident Wave Reflected Wave Transmitted
wave Pressure Bar
SHPB Pressure Bar Pressure Bar 3 4
( )1 i rF AE = + (3) 2 tF AE= (4)
A Pressure Bar E Pressure Bar SHPB Pressure Bar Force
Equilibrium Deforming Uniformly ( )1 2F F= 3 4 5
i r t = + (5) ( ) 6
02 rs
cl =
(6)
Longitudinal impact of two rod
2 0v =1v
x1l 2
l2 2 2v E1 1 1v E
3 [3]
3 1 2 1 2 1 2, ,E E A A = = =
-
2l = 3 ( )0t = DAlembert [3]
1V 2 0V = 2 7
( ) ( ) ( )1 1 1 1,v x t c f x c t c g x c t = + + ( ) ( ) ( ){
}1 1,x t E f x c t g x c t = + + (7)
Pressure Bar 8
1 1 1
2cV = (8)
Transmission into another rod (Reflect wave) (transmitted wave)
Pressure Bar
2 2c1 1c r
it
4 Incident wave, Reflect wave Transmit wave
[4] 4 Pressure Bar 9
( )1 2i r tA A + = (9) Reflected wave
2 2 2 1 1 11 1 1 2 2 2
r i
A c A cA c A c
= +
2 2 2 1 1 1
1 1 1 2 2 2
A c A cA c A c
= +
Reflected wave 10
r i = (10)
3. Striker ( ) 6 SHPB Striker 102-104 s-1 Striker
3.1 Striker SHPB Striker ( ) 6 Striker
02 rs
cl E =
8 10 6 0 1c c=
21 1 1
s
c Vl E
= Striker Strain rate
1 21 1
sl EVc=
Striker Strain rate 102-104 s-1 Striker Copper, Aluminum St.A30
1
1 [5,6]
Materials Density: ( 3/kg m )
Youngs modulus: E (Gpa )
Copper 8,740 101 Aluminum 2,790 73.1
St.A30 7,850 200 St.4340 7,850 205
2
(m/s) Strain rate L/D = 1.5 L/D = 2
Mater
ials
102 103 104 102 103 104 copper 7.11 71.05 710.50 9.47 94.73
947.34
Aluminum 4.39 43.90 439.04 5.85 58.54 585.39 St.A30 10.24 102.47
1024.71 13.66 136.62 1366.28
Pressure Bar St.4340 1 26 mm 2.5 m SHPB L/D 1.5-2 Pressure Bar
0.75 25% SHPB Striker Strain rate 2(Air Gun)
-
3.2 (Air Gun)
Striker FN
-
5.46 m/s Striker
Striker
20
30
40
50
60
(m
/s)
7
Striker 2 0.50 m 2.17 kg 0.25 m 1.11 kg 6.
Striker 2 Striker 0.5 m 0.25 m 2 bar 10.25 m/s 16.77 m/s 14 bar
28.67 m/s 47.72 m/s Striker s ( 5) Striker Striker Striker 0.5 m
0.25 m 1.18 m/s 3.67 m/s St.A30 Copper Strain rate 102 s-1 aluminum
Strain rate 102 103 s-1 Striker SHPB
1 Gordon R. Johnson, William H. Cook, A Constitutive
model And Data for Metals Subjected to Large Strains, High
Strain Rates And High Temperatures Proc. 7th Int. Symp. on
Ballistics 1983, 541-547
2 Michael Adam Kaiser, Advancements in the Split Hopkinson Bar
Test, Blacksburg Virginia ,1998
3 Karl F. Graff, Wave Motion in Elastic Solid, by Oxford
University, 1975
4 Wang Li-li, Foundations of Stress Waves First Edition 2007,
Elsevier BV. All rights reserved, 2007
5 Michael R. Staker, Army Materials & Mechanic Research
Center ASM Handbook Volume 8 Mechanical Testing, metals Handbook,
1945-1973
6 R.C. Hibber Mechanics of Materials Fifth Editiomn,2003
thv Striker 0.25 m
thv Striker 0.50 m
expv Striker 0.25 m
expv Striker 0.50 m
