The document discusses the dynamic behavior of materials and structures, focusing on research regarding the high strain rate behavior of various materials, including tool steels and aluminum alloys. It highlights the need for more research on additive manufactured specimens, particularly in the context of tool steel materials in automotive applications. The proposed project aims to set up a split Hopkinson pressure bar for testing, characterize both additive and traditional materials, and validate findings through actual die industry applications.

1. 9/28/2015 1 1
151-0735: Dynamic behavior of materials and structures
1
Sheet Metal Dies

2. 9/28/2015 1 1
151-0735: Dynamic behavior of materials and structures
2
Review on Impact of Dies
Biswas and Ding [26] have studied numerical simulations to gain insights
on the observed material behaviour and a general understanding of the
dynamic responses of AM porous metals.
Sahu et al. [28] investigated the high strain rate behaviour of two
twinning induced plasticity steels, wherein the stability of austenite was
found to be high at higher strain rates than at lower strain rates.
Singh et al. [29-30] studied the dynamic compressive as well as tensile
properties of a structural steel using SPHB and determined the material
properties for the existing JC model.
Bobbili et al. [31] conducted compression SHPB tests on high strength
armor steel tempered at various temperatures in the range of 500-6500
C.
Pothnis et al. [32]studied the effect of strain rate on tensile properties of
IS 2062 mild steel and 7075 aluminium alloy using tensile SHPB apparatus

3. 9/28/2015 1 1
151-0735: Dynamic behavior of materials and structures
3
Comments on Review
However SHPB testing of additive manufactured specimens and efforts
on to characterize the dynamic behaviour of additive manufactured
parts have not been initiated in our country in a concerted manner
especially in dies materials.
As the use of AM parts in the mainstream applications of automotive
is on continuous. It is imperative carry out research, conducting of this
project is thoroughly justifiable.

4. 9/28/2015 1 1
151-0735: Dynamic behavior of materials and structures
4
The scientific importance of the
proposed project lies in four aspects
i. Setup of split hopkinson pressure bar for testing and
characterization of AM tool steel materials
ii. Characterization of AM and traditional manufactured tool
steel material and determination of strain rate of tool steel
materials (traditional and AM) using split hopkinson pressure
bar.
iii. Comparison between additives manufactured tool steel
material and traditional manufactured tool steel materials.
iv. For the validation of the proposed additive manufactured tool
steel material will be tested on actual die industries.

5. 9/28/2015 0
5 0
5
striker bar
specimen
strain
gage
input bar output bar
Launching
system
L L
High speed camera
 Stress can travel in a uni-axial direction.
 Incident bar creates a compressive stress wave.
 Both the compressive and tensile stress waves are
used to calculate the stress and strain in the test
specimen.
 Tensile wave for calculate strain and compressive
wave for calculate stress.
Fundamentals of the Split Hopkinson Pressure Bar

6. 9/28/2015 0
5 0
5
striker bar
specimen
strain
gage
input bar output bar
Launching
system
L L
High speed camera
Fundamentals of the Split Hopkinson Pressure Bar

7. 9/28/2015 0
5 0
5
striker bar
specimen
strain
gage
input bar output bar
Launching
system
L L
High speed camera
Fundamentals of the Split Hopkinson Pressure Bar

8. 9/28/2015 0
5 0
5
Mathematical Relations on Split Hopkinson
Pressure Bar
Relation between the stress and
strain by Kolsky
History of the specimen stress
E Output bar’s modulus of elasticity
Cross sectional area of the
transmitted bar
Cross sectional area of the specimen
A
Transmitted strain history
recorded at the transmitted bar
strain gage.

9. 9/28/2015 8 8
Fin (t)
L
Fout (t)
initial
Compression of a cylindrical specimen
Quasi-static equilibrium
Fin (t)  Fout (t)
Principle of Quasi-static Equilibrium
9

10. 9/28/2015 0
2 0
2
Hopkinson Bar Experiment
Typical system
characteristics:
•Striker bar length:
•Input bar length:
•Output bar length:
•Bar diameter:
20
Ls =1000 mm
Li= 3000 mm
Lo= 3000 mm
D= 20 mm
Specimen characteristics (for simplified theoretical
analysis):
•Ideal plastic, constant force

11. 9/28/2015 1
2 1
2
Hopkinson Bar Experiment
11

12. 9/28/2015 2
2 2
2
Hopkinson Bar Experiment
12

13. 9/28/2015 3
2 3
2
Hopkinson Bar Experiment
13

14. 9/28/2015 4
2 4
2
Hopkinson Bar Experiment
14

15. 9/28/2015 5
2 5
2
Hopkinson Bar Experiment
15

16. 9/28/2015 6
2 6
2
Hopkinson Bar Experiment
16

17. 9/28/2015 7
2 7
2
Hopkinson Bar Experiment
17

18. 9/28/2015 8
2 8
2
Hopkinson Bar Experiment
18

19. 9/28/2015 9
2 9
2
Hopkinson Bar Experiment
19

20. 9/28/2015 0
3 0
3
Hopkinson Bar Experiment
30

21. 9/28/2015 1
3 1
3
Hopkinson Bar Experiment
21

22. 9/28/2015 2
3 2
3
Hopkinson Bar Experiment
22

23. 9/28/2015 3
3 3
3
Hopkinson Bar Experiment
23

24. 9/28/2015 4
3 4
3
Time
 R ( x,
t)
HOPKINSON BAR TECHNIQUE
Measuring force with a slender bar
F (t)
xA
Time
 (t)
A
 L ( x,
t)
L
 R ( xA ,
t)
 L ( xA ,
t)
 A (t) 
 R ( xA , t)   L ( xA ,
t)
measured
applied
xA / c (2L  xA ) / c
2(L  x ) / c
24
A

25. 9/28/2015 7
3 7
3
HOPKINSON BAR TECHNIQUE
Split Hopkinson Pressure Bar (SHPB) experiment
Two force measurements
Time
 R (0, t)
Time
 (0,
t)
 (Lin ,
t)
 (Lin / 2,
t)
Time
 L (t)
 R (t)
 L (t)
 R (t)
 R
(t)
 L
(t)
2Lst / c
v0
striker input bar output bar
specimen
Lst
Lin
25

26. 9/28/2015 2
4 2
4
EXAMPLE EXPERIMENT
v0
striker output bar
input bar specimen
26

27. 9/28/2015 2
4 2
4
27
Thank You