1. S U M A N T H D O C H I B H A T L A
A L E C G U E N T H E R
J A I M I N P A T E L
Hybrid Members as Energy
Absorbers

2. Introduction
 Crashes are high-energy environments
 Need to protect occupants
 Must include paths for energy to be dissipated safely
 Hybrid members combine two dissimilar materials
 Three main groups
 Metal/Composite
 Organic
 Polymer

3. S U M A N T H D O C H I B H A T L A
Metal/Composite Hybrids

4. 1.0 Steel-GFRP metal hybrid (Hybrid 1)
 Mild steel tube of 200*60*1.4 mm was
externally reinforced by GFRP.
 The composite was E-glass fibers in polyester
resin.
 The influence of fiber orientation, and
composite layer thickness on energy
absorption and peak load are analyzed.
 The thickness of the fiber layers was 1.5, 2.25
and 3 mm for 4, 6 and 8 layers of composite
respectively. The samples were tested on
UTM under quasi-static compression.
 According to 1Reza Mehryari Lima, Z.N.
Ismarrubie, E.S. Zainudin, and S.H. Tang,
the high thickness composite layers
prevented the progressive folding of the inner
steel tube and resulted in global/Euler
buckling-catastrophic failure resulting in low
energy absorption of the composite.

6. 2.0 Steel-CFRP SHS (Hybrid 2)
 Steel Square Hollow Sections(SHS) of 300
mm were externally reinforced by CFRP .
 It was subjected to impact test by dropping a
mass of 574 Kg at 6 m/s.
 2M.R. Bambach, M. Elchalakani , and X.L.
Zhao, fabricated and tested, 50 SHS, 65 SHS,
75 SHS and 100 SHS samples with two
different layer setups- 1T1L and 2T2L.
 Influence of cross-sectional dimension on
energy absorption was studied. It was
observed that 2T2L specimens showed higher
delamination tendency than 1T1L specimens.

8. 3.0 Aluminum-CFRP (Hybrid 3)
 CFRP is bonded to Aluminum Z6-T5 II section
beam.
 Ref. 4 studies the influence of type of
composite, type of adhesive, and thickness of
composite on energy absorption- three kinds
of composite and adhesives were used for the
beam- T700, T800 and M40 composites, and
Urethane, high strength, and high elongation
adhesives.
 Thickness of the composite was varied from 1
to 3 mm
 4G. Ben, Yoshio Aoki, and Nao Sugimoto
fabricated 18 samples of metal hybrid
composites, and tested by dropping 100 kg
mass at 55 km/hr.
 beam with T800 CFRP, bonded by high
elongation adhesive absorbed 1827 J after
deforming 150 mm; failure in the composite
was due to fiber breakage.
 samples bonded using urethane absorbed low
energy because CFRP delaminated from metal
surface due to adhesive failure. Hence it is
important that adhesive sustains high
deformation.

10. 4.0 Plastic-Metal hybrid composite (Hybrid 4)
 Thin metal tubes are reinforced internally
with polymers and externally with
composites; the resultant structure is
known as plastic-metal hybrid composite.
 low density and high moldable properties
of plastic combines with stiffness
properties of metals, and high strength to
weight ratio of composite.
 ATB (Aluminum Tubular Beam) which is
internally reinforced with PA-6, a change in
the buckling mechanism of the beam is
noticed- The beam, buckles outward; by
changing buckling mechanism of the beam,
PA-6 enhances the load bearing capacity of
ATB.
 Adding external reinforcements further
enhances the load bearing capacity because
GFRP and CFRP resist outward wrinkling.
As a result, the metal tube undergoes a
more stable, plastic collapse- a mechanism
responsible for high energy absorption.

13. 5.0 Aluminum-C/GFRP (Hybrid 5.0)
 Aluminum 6063-T5 metal rings internally
reinforced by 5 layers of C/GFRP are
analyzed.
 Influence of D/t ratio on energy absorption is
studied. energy absorption in metals and
composites increases with D/t ratio; the
value being higher in composites.
 However, the energy absorption falls sharply
when the D/t ratio increases beyond a
threshold value due to Euler buckling in
metals, and delamination in composites.
 In Hybrid 5, the presence of outer metal tube
modifies the crushing mechanism of the
composite. The composite on the other hand,
prevents the inner buckling/wrinkling of the
outer metal tube. This way, both the
materials crush systematically, which
enhances the energy absorption properties of
the structure.

15. A L E C G U E N T H E R
Organic Hybrids

16. What are Organic Hybrids?
 Combines organic materials (natural fibers, rubber)
with inorganic materials (synthetic fibers, metals)
 Three main types considered
 Natural fibers
 Rubber
 Carbon Nanotubes
 Polymers will be discussed separately

17. Natural Fibers
 Advantages
 Less energy to manufacture
 Bio-degradable
 Meredith et al.6 conducted
dynamic crush tests
 Compared flax, jute, and
hemp to carbon fiber
 Jute: 32.6 J/g
 Flax: 45.3 J/g
 Hemp: 54.3 J/g
 Carbon Fiber: 55.7 J/g
 Fiber volume fraction
played large role
 Hemp had highest
 Jute had lowest

18. Natural Fiber Hybrids
 Khalid7 studied combining
jute fibers with glass-
epoxy composite
 Subjected them to quasi-
static lateral crushing
Lay-up CFE SEA (J/kg)
J6 0.75 360
G6 0.89 795
J2G2J2 0.82 460
G3J3 0.93 580
J3G3 0.93 596
JGJGJG 0.94 670
G2J2G2 0.96 705

19. Steel Lattice/Rubber Hybrid
 Gümrük et al.8 created a
steel lattice structure and
embedded rubber in the
open cells
 Resulting hybrid shows
several plateau regions
 Maintains stress over
large strain
 Demonstrates properties
of good energy absorbers
 Could prove useful in
sandwich panels for
ballistic protection

20. Carbon Nanotubes
 Light-weight, very stiff
nanostructures
 Zhang et al.9 constructed
hybrid using alternating
layers of clay and CNT film
 CNTs vertically aligned to
maximize energy absoprtion
 Achieved peak SEA of 149
kJ/kg at 25μm
 High degree of reversibility
 Within 20% original value after
20 cycles of 75% to 95% strain

21. CNTs and Laminated Glass
 Alhazov and Zussman10
tested embedding CNTs
in PVB layer of
laminated glass
 Much higher energy
absorbed
 Increase of almost 341% at
1.5% CNTs
 Impacts transmission of
light through glass
 Transmission reduced by
about 60% with 1.5%
CNTs

22. J A I M I N P A T E L
Polymer Hybrids

23. Outline
 Describe the different types of polymer hybrid
energy absorbers researched today
 Examine their effectiveness versus regular energy
absorbers used today
 Discuss how orientation, design and composition can
impact effectiveness

24. Types of Polymer Hybrids
 Polyethylene
terephthalate (PET)
foam core
 E-glass with epoxy
coating on aluminum
extrusion
 Carbon fiber reinforced
Hybrid Polymeric Matrix
(CHMC)
 Carbon fiber reinforced
epoxy-polyurea
Member Tested Specific Energy
Absorbed
(kJ/kg)
GFRP 5.48
PET foam 5.97
CHMC 8.79
Carbon Fiber w/
epoxy
2.74
Conical
Aluminum
2.36
Conical
Aluminum w/ E-
glass and epoxy
coating
2.44

25. Comparison to Other Hybrids
 GFRP and CFRP demonstrated
classic buckling
 PET foam shows progressive
crushing with similar SEA to
GFRP and CFRP
 Cork conglomerates lack the
necessary propertied desired
for crashworthiness

26. Crushing Mechanisms
 Empty extrusion and
GFRP filled extrusion
both display mixed
crushing methods
 PET foam filled
extrusion follows a ring
mode crushing method
 As discussed both cores
presented similar SEA
values

27. CHMC vs. Carbon Fiber Epoxy
 CHMC demonstrates a
progressive folding
method with desirable
SEA value
 Carbon fiber epoxy was
not a promising study as
the failure mechanism
led to a loss of contact to
the core

28. Conical Elements
 Aluminum vs. Glass
fiber/epoxy wrapped
hybrid conical frusta
(CWAC)
 Conical tests showed
promising results
especially with the polymer
element
 Changing the shape of the
energy absorber creates
many options in terms of
design and effectiveness

29. Conclusion
 Hybrid energy absorbers are proving to be
comparable, if not better, alternatives to current
energy absorbers
 Research with clay and CNTs is especially promising
with a SEA value of 149 kJ/kg
 Further research is required in the area to find the
optimal failure mode
 Optimal designs and cost effectiveness is still a major
of concern that needs to be investigated

30. Questions?

31. References
1Lima, R. Mehryari, Serdang, Ismarrubie, Z.N., Zainudin, E.S., and Tang, S.H.,
“Energy absorption capability of hybrid tube made by mild steel and GFRP under
Quasi-Static Loading”, Advanced Materials Research, Vol. 383-390, 2012, pp. 2741-
2746.
2M.R. Bambach, M.Elchalakani , and X.L. Zhao, “Composite Steel-CFRP SHS tubes
under axial impact”, Composite structures, Vol. 87, 14 February 2008, pp. 282-292.
3M.R. Bambach, “Fiber Composite strengthening of thin-walled steel vehicle crush
tubes for frontal collision energy absorption”, Thin-walled structures, Vol. 66, 2013,
pp. 15-22.
4G. Ben, Y. Aoki, and N. Sugimoto, “Impact properties of CFRP/AL beam for
absorbing impact energy in side collision of Automobiles”, 16th International
Conference on Composite Materials, ICCM-16 - "A Giant Step Towards
Environmental Awareness: From Green Composites to Aerospace, July 2007.
5Alia, R.A., Guan, Z.W., Umer, and R., Cantwell, W.J., ”The energy-absorbing
properties of internally reinforced composite-metal cylinder with various diameter-to-
thickness ratios”, Journal of reinforced composites and plastic, Vol. 34, No. 9, 4 May
2015, pp. 731-741.

32. References
6Meredith, J., Ebsworth, R., Coles, S.R., Wood, B.M., and Kirwan, K.,
“Natural Fiber Composite Energy Absorption Structures”, Composites Science
and Technology, Vol. 72, 2012, pp. 211-217.
7 Khalid, A.A., “Behavior of Hybrid Jute-Galss/Epoxy Composite Tubes
Subjected to Lateral Loading”, Materials Science and Engineering, Vol. 100,
2015, doi:10.1088/1757-899X/100/1/012068.
8Gümrük, R., Mazlum, U., Mines, R.A.W., “Compressive Mechanical
Behaviors of Hybrid Composite Materials Based on Micro Lattice Structure
and Rubberlike Materials”, Rubber Chemistry and Technology, Vol. 88, No.
1, 2015, pp. 147-162.
9 Zhang, Q., Zhao, M., Liu, Y., Cao, A., Qian, W., Lu, Y., and Wei, F.,
“Energy-Absorbing Hybrid Composites Based on Alternate Carbon-Nanotube
and Inorganic Layers”, Advanced Materials, Vol. 21, 2009, pp. 2876-2880.
10Alhazov, D., Zussman, E., “Study of the Energy Absorption Capabilities of
Laminated Glass using Carbon Nanotubes”, Composites Science and
Technology, Vol. 72, 2012, pp. 681-687.

33. References
 11Costas, M., Diaz, J., Romera, L. E., Hernandez, S., Tielas, A., “Static and
dynamic axial crushing analysis of car frontal impact hybrid absorbers,”
International Journal of Impact Engineering 62, June 2013, pp. 166-181.
 12Costas, M., Morin, D., Langseth, M., Romera, L., Diaz, J., “Axial crushing
of aluminum extrusions filled with PET foam and GFRP. An experimental
investigation,” Thin-Walled Structures 99, November 2015, pp. 45-57.
 13Zhou, H., Attard, T. L., Dhiradhamvit, K., Wang, Y., Erdman. D.,
“Crashworthiness characteristics of a carbon fiber reinforced dual-phase
epoxy-polyurea hybrid matrix composite,” Composites: Part B, October
2014, pp. 17-27.
 14Kathiresan, M., Manisekar, K., “Axial crush behaviours and energy
absorption characteristics of aluminum and E-glass/epoxy over-wrapped
aluminum conical frusta under low velocity impact loading,” Composite
Structures, October 2015, pp. 86-100.