1. Thesis Defence
Numerical and Experimental Impact Analysis
of Square Crash Box Structure with Holes
By:
Sahril Afandi Sitompul
23611004
Supervisors:
Dr. Tatacipta Dirgantara
Dr. Leonardo Gunawan
Prof. Dr. Ichsan S. Putra
Lightweight Structure Research Group
Faculty of Mechanical and Aerospace Engineering
Institut Teknologi Bandung
Jl. Ganesha 10 Bandung 40132, INDONESIA

2. Presentation Outline
Introduction
• Research Background
• Research Objectives
• Scope of works
• Methodology
Axial Crushing
• Theoretical Analysis
Finite Element Methods
• Computational Mechanics
•Explicit Finite Element Method
• Structural Model
• Modeling Procedure
Experimental Tests
• Tensile Testing
• Dynamic Axial Crushing Testing
Result and Analysis
• Numerical and Experimental Results
Conclusions and Future Works
Lightweight Structure Laboratory Structural Impact Engineering

3. Introduction
Research Background
Auto Motor und Sport spezial 1992, photo H.P. Seufert
Lightweight Structure Laboratory Structural Impact Engineering

4. Introduction
Research Background
T. Frank and K. Gruber. Numerical simulation of frontal impact and offset J. Marsolek and H. G. Reimerdes. Energy absorption of metallic cylindrical shells with induced non-
collisions.Cray Research Inc., CRAY Channels: 2–6, 1992. axisymmetric folding patterns. International Journal of Impact Engineering 30 (2004) 1209-1223.
Lightweight Structure Laboratory Structural Impact Engineering

5. Introduction
Research Background
Lightweight Structure Research Group
Concentrating
on one of Crashworthiness Safety
research areas:
STRUCTURAL
IMPACT PRESERVES SUFFICIENT SURVIVAL SPACE around the
ENGINEERING occupants to limit bodily injury during an accident.
CONTROLLING THE DECELERATION within an
acceptable safety level to prevent the injury to the
passenger.
Lightweight Structure Laboratory Structural Impact Engineering

6. Introduction
Research Objectives
To study the behavior of extruded aluminum thin-walled columns with square
cross-section and to examine the EFFECT OF INSERTING OF CIRCULAR HOLE(S)
as a crush initiator subjected to impact loading
Crashworthy Meet acceptable Light-weight vehicle
Peak Crushing safety level structure
Performance Load
Crushing Crushing Force Crash box
Parameters Efficiency design Reduce fuel
consumption
Mean Crushing
Reduce CO2
Force
emissions
Lightweight Structure Laboratory Structural Impact Engineering

7. Introduction
Scope of Works
• The numerical and experimental analysis are limited to a
square column with cross section 38 x 38 mm and thickness
1.15 mm subjected to axial impact load with initial velocity
below 4.5 m/s.
• In parametric study, the column width is varied from 40 to 80
mm with uniform thickness of 1.2 mm. The impact velocity is
4.5 m/s.
• The material used in this work was the aluminum extrusion
AA 6063-T1.
•The holes inserted on the column have the diameter to
column width ratios ranged from 0 – 0.8.
Lightweight Structure Laboratory Structural Impact Engineering

8. Introduction
Methodology
Axial Crushing of Square Crash Box
Experimental Numerical
Tensile Testing Parametric Study
Axial Crushing
Testing
Numerical and
Experimental Analysis
Conclusions and Future Works
Lightweight Structure Laboratory Structural Impact Engineering

9. Axial Crushing
Theoretical Analysis
Loading Thin-Walled Structures Material
Independent of Strain Rate
Axial Crushing Column Dependent of Strain Rate
Static Progressive Buckling
Low Velocity
(up to 10 m/s)
Dynamic Progressive Buckling
High Velocity Dynamic Plastic Buckling
Lightweight Structure Laboratory Structural Impact Engineering
N Jones. Structural Impact. 2003.
Ly Hung Anh. 2007.

10. Axial Crushing
Theoretical Analysis
Folding Mechanism of Square Column
Annisa Jusuf. 2012.
Super folding Element.
Inextensional mode plastic deformation.
Lightweight Structure Laboratory Structural Impact Engineering

11. Axial Crushing
Theoretical Analysis
60
Pmax Instantaneous Crushing Force Curve
MEAN CRUSHING FORCE
Instantaneous Crushing Force, P (kN)
Mean Crushing Force Curve
MAXIMUM
PEAK CRUSHING 40
FORCE
Pm CRUSHING FORCE EFFICIENCY
20
0
0 20 40 60 80 100
Crushing Length, (mm)
Lightweight Structure Laboratory Structural Impact Engineering

12. Finite Element Methods
Computational Mechanics
NANOMECHANICS & MICROMECHANICS SOLID MECHANICS
CONTINUUM MECHANICS FLUID MECHANICS (CFD)
SYSTEMS FLUID-STRUCTURE INTERACTION (FSI)
DISCRETIZATION
FINITE ELEMENT METHOD (FEM)
SPATIAL BOUNDARY ELEMENT METHOD (BEM)
FINITE DIFFERENCE METHOD (FDM)
FINITE VOLUME METHOD (FVM) EXPLICIT
SMOOTHED PARTICLE HYDRODYNAMICS FINITE ELEMENT
(SPH) METHODS
TIME EXPLICIT
IMPLICIT
Lightweight Structure Laboratory Structural Impact Engineering

13. Finite Element Methods
Explicit Finite Element Methods
Used in LS-DYNA commercial code Non-iterative
Formulations Small time step (conditional stability)
Finite Element Steps
Increment 1 Increment 2
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14. Finite Element Methods
Structural Model
Impact Impac
Number
b (mm) t (mm) D/b Velocity t Mass
of Holes
(m/s) (kg)
Set 1
(Experimental and Numerical )
0 4.3684
0.3 4.3751
38 1.15 1 45.5
0.5 4.4538
0.7 4.3824
Set 2
(Experimental and Numerical )
0.2 4.3812
45.5
38 1.15 0.3 2 4.3602
0.5 4.4024
Set 3
(Numerical )
40, 0,0.1,
Lightweight Structure Laboratory 50,…,80 …,0.8 Structural Impact4.5
1&2 Engineering 80

15. Finite Element Methods
Modeling Procedure
FINITE ELEMENT MODEL
OF THE COLUMN
IMPACTING mass 1
The impactor was modeled
as a rigid body using
hexahedral eight-node solid
rigid element HOLE location
VELOCITY 2 The hole was introduced in the column
model to achieve a stable deformation
Impact Velocity direction mode and reduce initial peak load during
loading
4
3
BOUNDARY condition
The column was fixed in all directions, the constraints
are located on every nodes from the lower end of the
5 columns to 12 mm above to simulate the lower jig in the
COLUMN wall
experiment
The column was fully modeled using
The impactor was constrained in all direction except
quadrilateral Belytscko-Tsay four-nodes shell
along the vertical axis which coincides with the direction
elements with size 1 mm x 1 mm
of the impact in order to ensure the impacting mass did
not rotate during impact
Lightweight Structure Laboratory Structural Impact Engineering

16. Experimental Tests
Tensile Testing High Speed Material Testing Machine for
INTERMEDIATE STRAIN RATE TENSILE TEST
(strain rate 1/s, 10/s, 100/s)
INSTRON 5585 for QUASI-STATIC TENSILE TEST
(strain rate 0.001/s, 0.1/s)
The behavior of AA 6063-T1
is
INDEPENDENT OF THE STRAIN
RATE
Engineering Stress – Strain Curve
Mechanical Properties of AA 6063 T1
160
AA 6063-T1
Young’s modulus, E (MPa) 7.32.104 Stress, σ (MPa)
120
Yield stress, y (MPa) 83.81 80
Tensile stress, u (MPa) 154
40
Poisson’s ratio,  0.3
Density,  (kg/mm3) 2.7×10–6 0
0 0.02 0.04 0.06 0.08 0.1 0.12
Lightweight Structure Laboratory Structural Impact Engineering
Strain, ε

17. Experimental Tests
Dynamic Axial Crushing Testing
Hoist
Clamp DROP WEIGHT IMPACT TESTING
Wheel
MACHINE SPECIFICATIONS :
Frame
Weightening mass
Max. Impact Mass 150 kg
Impactor head
Max. Impact Height 5m
Guide column Speed sensor Max. Impact Velocity 9.8 m/s
Specimen
Load cell
Steel plate
Concrete base
DAQ Data acquisition
Schematic drawing and picture of
equipment
dropped weight impact testing machine in the
Computer Lightweight Structure Laboratory,
Faculty of Mechanical and Aerospace Engineering
Institut Teknologi Bandung
Lightweight Structure Laboratory Structural Impact Engineering

18. Experimental Tests
Dynamic Axial Crushing Testing
Crushing Force History
Provide the output
Convert a physical Adjust the signal
signal representing DAQ NI USB-
property change into type and range of the
the measurement in 6211, Sampling Rate
an electrical signal output
a digital code 250 kHz
Wheatstone Bridge
Strain Gage
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19. Experimental Tests
Dynamic Axial Crushing Testing
Displacement History
Trapezoidal Integration rule applied
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20. Result and Analysis
Square Tubes with One Hole
COLLAPSE DEFORMATION MODES INSTANTANEOUS CRUSHING FORCE
25
Experimental
Crushing Force, P (kN)
20 Experimental (smoothing)
Numerical
15
10
5
0
0 10 20 30 40 50 60 70
square crash box with D/b = 0 (without hole) Crushing Length,  (mm)
25
Experimental
Crushing Force, P (kN)
20 Experimental (smoothing)
Numerical
15
Hole 10
location
5
0
square crash box with D/b = 0.3 0 10 20 30 40 50 60
Crushing Length,  (mm)
Lightweight Structure Laboratory Structural Impact Engineering

21. Result and Analysis
Square Tubes with One Hole
10 30
10 30
Mean Crushing Force, Pm (kN)
Peak Crushing Force, P Max
Mean Crushing Force, Pm (kN)
Peak Crushing Force, P Max
8 8 25
25
20
20
6 6
(kN)
15
15
(kN)
4 4 Experimental
Experimental 10
10 Experimental
Experimental
2 2 Numerical
Numerical 55 Numerical
Numerical
0 0 00
0 0 0.20.2 0.40.4 0.60.6 0.80.8 00 0.20.2 0.4 0.4 0.6 0.6 0.8 0.8
D/b
D/b D/b D/b
0.5
Crushing Force Efficiency, CFE
0.4 Experimental Numerical
0.3 D/b Pm Pmax CFE Pm Pmax CFE
(kN) (kN) (kN) (kN)
0.2
Experimental
Experimenta 0 8.09 24.45 0.33 6.78 18.62 0.36
0.1 l Numerical 0.3 8.24 22.60 0.36 6.62 17.76 0.37
0.5 7.63 21.55 0.35 6.76 16.39 0.41
0
0.7 7.84 22.88 0.34 6.19 14.67 0.42
0 0.2
0.2 0.4
0.4 0.6
0.6 0.8
0.8
D/b
D/b
Lightweight Structure Laboratory Structural Impact Engineering

22. Result and Analysis
Square Tubes with Two Holes
COLLAPSE DEFORMATION MODES INSTANTANEOUS CRUSHING FORCE
25
Experimental
20 Experimental (smoothing)
Crushing Force, P (kN)
Numerical
15
10
Hole
location 5
0
0 10 20 30 40 50 60 70
Crushing Length,  (mm)
square crash box with D/b = 0.2
Lightweight Structure Laboratory Structural Impact Engineering

23. Result and Analysis
Square Tubes with Two Holes
30
10
Peak Crushing Force, P Max (kN)
Mean Crushing Force, Pm (kN)
25
8
20
6
15
4 Experimental 10
Experimental
2 Numerical
5 Numerical
0 0
0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6
D/b D/b
0.5
Crushing Force Efficiency, CFE
Experimental Numerical
0.4
D/b Pm Pmax CFE Pm Pmax CFE
0.3
(kN) (kN) (kN) (kN)
0.2 Experimental
0 8.09 24.45 0.33 6.78 18.62 0.36
0.1 Numerical
0.2 7.71 22.63 0.34 6.29 17.79 0.35
0
0.3 7.72 21.43 0.36 6.34 17.21 0.37
0 0.1 0.2 0.3 0.4 0.5 0.6
D/b 0.5 7.59 19.55 0.39 6.40 15.29 0.42
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24. Result and Analysis
Parametric Study
Square Columns with One Hole
25
D/b = 0
Instantaneous Crushing Force, P (kN)
D/b = 0.2
20 D/b = 0.3
D/b = 0.4
D/b = 0.5
15 D/b = 0.6
D/b = 0.7
D/b = 0.8
10
5
0
0 20 40 60 80 100 120 140
Displacement, mm
Deformation modes of square crash box
with b = 40: (a) D/b = 0.3; (b) D/b = 0.4.
Lightweight Structure Laboratory Structural Impact Engineering

25. Result and Analysis
Parametric Study
Square Columns with One Hole
12 60 b = 40
Peak Crushing Force, P Max
Mean Crushing Force, Pm (kN)
b = 50
10 50 b = 60
8 40 b = 70
b = 80
6 30
(kN)
b = 40
4 b = 50 20
b = 60
2 b = 70 10
b = 80
0 0
0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1
D/b D/b
0.5
Crushing Force Efficiency, CFE
0.4
0.3
b = 40
0.2 b = 50
b = 60
0.1 b = 70
b = 80
0
0 0.2 0.4 0.6 0.8 1
D/b
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26. Result and Analysis
Parametric Study
Square Columns with Two Holes
25
D/b = 0
Instantaneous Crushing Force, P (kN)
D/b = 0.2
20 D/b = 0.3
D/b = 0.4
D/b = 0.5
15 D/b = 0.6
D/b = 0.7
D/b = 0.8
10
5
0
0 20 40 60 80 100 120 140
Displacement, mm
Deformation modes of square crash box
with b = 50: (a) D/b = 0.3; (b) D/b = 0.5.
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27. Result and Analysis
Parametric Study
Square Columns with Two Holes
60 b = 40
12
Peak Crushing Force, P Max (kN)
Mean Crushing Force, Pm (kN)
b = 50
10 50
b = 60
40 b = 70
8
b = 80
6 30
b = 40
4 b = 50 20
2 b = 60
b = 70 10
0 b = 80
0
0 0.2 0.4 0.6 0.8 1
0 0.2 0.4 0.6 0.8 1
D/b
D/b
0.5
Crushing Force Efficiency, CFE
0.4
0.3
0.2 b = 40
b = 50
0.1 b = 60
b = 70
0 b = 80
0 0.2 0.4 0.6 0.8 1
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28. Conclusions and Future Works
Conclusions
• The numerical simulation can predict the deformation mode
compared to the experiment results.
• It is found that inserting holes in a square box column will
decrease the peak crushing force and increase the CFE of the
column.
Lightweight Structure Laboratory Structural Impact Engineering

29. Conclusions and Future Works
Future Works
• Perform numerical and experimental analysis to obtain a
higher value of CFE with different geometrical
configurations and location of the discontinuities.
• Perform numerical and experimental analysis to study the
effect of discontinuities for different material properties.
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30. Thank You
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