Impact Analysis of Ergonomic Bicycle Helmet Made from Polymeric
Foam Composite Strengthened by Coconut Fiber
Mahadi
1
, A. Syahrul
1
and K. Tugiman
1
1
Department of Mechanical Engineering, Faculty of Engineering, Universitas
Sumatera Utara Padang Bulan Medan 20155 Indonesia
Keywords: Bicycle, Helmet, Impact, Coconut Fiber.
Abstract: This research contains report result manufacture and impacts analysis of bicycle helmet made from polymeric
foam composite materials strengthened by coconut fiber. The ergonomic helmets are protective head gears
wear by bicycle riders for protection against injury in case of the accident. Helmet standards require helmets
to be tested with a simple drop test onto an anvil.The geometric helmet structure consists of shell and liner,
both layers have sandwich structure. The shell uses matrix unsaturated Polyester BQTN-157EX material,
chopped strand mat 300 glass fiber reinforce and methyl ethyl ketone peroxide (MEKPO) catalyst with the
weight composition of 100gr, 15gr, and 5gr. The liner uses matrix unsaturated Polyester BQTN-157 EX
material, coconut fiber reinforces , Polyurethane blowing agent, and MEKPO catalyst with the composition
of 33% wt (181,5gr), 10% wt (55gr), 52% wt (285 gr) and 5% wt (27.5 gr). Layers of the helmet made by
using hand lay-up method and gravity casting method. Mechanical properties of polymeric foam were the
tensile strength (ơ
t
) 0,09MPa, compressive strength (ơ
c
) 0.51 MPa, flexure strength (ơ
b
) 0,52MPa, elasticity
modulus (E) 2,76MPa, density (ρ) 140 (kg/m
3
). Sample model helmet is the most ergonomic with the
thickness 10 mm and the amount of air channel 5. Free fall impact test was done in 9 samples with the
thickness of 10 mm with the height of 1.5 m. The result of the impact test was maximum impact force (Fi)
381,13N, maximum Impact Stress (ơi) 5,71 MPa and maximum Impact Energy absorption (Ei) 493,41Joule.
1 INTRODUCTION
The appliance of laminated composites is improve in
all sorts of engineering applications especially in
bicycle sport. Function of helmets are protective head
by bicycle riders for protection against injury in case
of the accident (Peter A.Cripton 2014). Ergonomics
is the study of the interaction between humans and
system elements with the goal of increasing
efficiency and compatibility. Through an
understanding of the human form, muscle systems
and human limitations, ergonomic principles can be
applied to products used in business and personal
settings. Ergonomic products are any goods designed
to increase ease of use and reduce injuries.
The application of conservation of energy to a
falling object allows us to predict its impact velocity
and kinetic energy, but we cannot predict its impact
force without knowing how far it travels after impact.
The dynamic energy in a moving object can be
expressed as follows:


Potential Energy, PE = mgh
(2)
Kinetic Energy, KE = mv
2
(3)
The impact velocity, (4)
2 MATERIAL PROPERTIES
The material used is Polymer Unsaturated Polyester
BQTN-157 EX as the matrix, Coconut fiber as
reinforces and polyurethane as Blowing Agent (BA).
Unsaturated polyester resins are the condensation
products of unsaturated acids or anhydrides and diols
with/without diacids. The unsaturation present in this
type of polyesters provides a site for subsequent
cross-linking (Reinhold 1956). The properties of
matrix was Modulus Young (E) 2 s/d 4,5 GPa,
Density (ρ) 1,2 s/d 1,5 mg.mm
3
and Tensile Strength
(σ
T
) 90MPa.
ghv 2
Mahadi, ., Syahrul, A. and Tugiman, K.
Impact Analysis of Ergonomic Bicycle Helmet Made from Polymeric Foam Composite Strengthened by Coconut Fiber.
DOI: 10.5220/0010082802630266
In Proceedings of the International Conference of Science, Technology, Engineering, Environmental and Ramification Researches (ICOSTEERR 2018) - Research in Industry 4.0, pages
263-266
ISBN: 978-989-758-449-7
Copyright
c
 2020 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
263

Ket:
1. Framebase
2. Barrier
3. Pipe launcher
4. Height sensor
5. TestrigArm
6. Supporttable
7. Anvilsupport
8. Loadcell
9. Upper
10. Power DAQ
11. Com
p
ute
r
The research material is unsaturated polyester
BQTN-157 EX resin as the matrix, oil palm empty
fruit bunch fiber as reinforcement, polyurethane as
blowing agent and MEKPO as catalyst. Polymeric
foam helmet material is made using composition of
fiber 10% wt (55gr), unsaturated polyester 157
BQTN-EX 33% wt (181,5gr), polyurethane blowing
agent 52% wt (285 gr) and catalys methyl ethyl
ketone peroxide (MEKPO) 5% wt (27.5 gr).
Table 1: Material helmet mechanical properties
Tensile
Strength
(σ
t
) (MPa)
Compress
Strength
(σ
c
) (MPa)
Flexure
Strength
(σ
b
) (MPa)
Modulus
of
Elasticity
(E)
(MPa)
0,09 0,51 0,52 2,76
3 IMPACT TEST
The suitable utilization of protective helmets can
minimalize the danger of interminable harm. A free-
fall drop test construction as in Figure 1 was
employed to drop sample helmets onto a flat anvil
steel base which replicates a road surface. The drop
height based of the helmet was 1.5 to 2 m, which
coincides with the standard of Consumer Product
Safety Commission (CPSC) drop height.
Figure 1: Free fall drop test impact
The three institutions most frequently used helmet
testing standards are EN1078, CPSC, ASTM F1447
and Snell B-95. Table 2 demonstrates the correlations
among each standard for helmet strength. The
application of conservation of energy to a falling
object allows us to predict its impact velocity and
kinetic energy but cannot predict its impact force
without knowing how far it travels after impact.
Table 2: Helmet Test Criteria (CPSC 1998)
CPSC ASTM
F1447
Snell
B-95
EN
1078
Flat anvil (m) 2.0 2.0 2.2 1.5
Hemispherical
anvil (m)
1.2 1.2 1.5 N/A
Head form
weight (kg)
5 5 5 4
Failure
threshold (g)
300 300 300 250
4 RESULTS
The results of impact test on nine helmets thick 10
mm and drop height on flat anvil 1.5m and impact
area 119 mm
2
is shown in Figure 2 up to 4.
Figure 2: F vs. t Top
Figure 3: F vs. t Side
Figure 4: F vs. t Front
F
o
r
ce
vs
Tim
e
Force
(
N
)
Tim
e
(s)
Time
(
s
)
Force
(
N
)
Force vsTime
Time (s)
Force vsTime
(
s
)
Force
(
N
)
Time (s)
ICOSTEERR 2018 - International Conference of Science, Technology, Engineering, Environmental and Ramification Researches
264

Table 3: Result of Helmet Impact Test
Helm Impact
Point
Mass
(Helm+Rig)
(kg)
Impact
Force
(F
i
)(N)
Impact Time
(T
i
)(det)
Impact Stress
(σ
i
) (MPa)
Condition
1 Top 5,38
265,65 0,03 3,98
Fracture
2 Top 5,32
381,13 0,02 5,71
Fracture
3 Top 5,35
297,73 0,03 4,46
Fracture
4 Front
5,37 229,06 0,03 3,43
Fracture
5 Front
5,36 254,76 0,03 3,82
Fracture
6 Front
5,38 234,94 0,03 3,52
Fracture
7 Side
5,35 179,23 0,03 2,68
Fracture
8 Side
5,34 190,80 0,03 2,86
Fracture
9 Side
5,37 214,54 0,02 3,21
Fracture
Table 4: Impact Energy Absorption
Helmet
Weight
Helmet + Test Rig
(kg)
Theoretical
Impact Energy
Et = m.g.h
(Joule)
Impact
Force
(F
i
)(N)
Experimental Impact
energy
Ee =F
i
.h (Joule)
Impact Energy
Absorption
E
i
=Ee-Et (Joule)
1 5,38 79,16
265,65
398,47 319,31
2 5,32 78,28
381,13
571,69 493,41
3 5,35 78,72
297,73
446,60 367,88
4 5,37 79,02 220,92 331,38 252,36
5 5,36 78,87 185,61 278,40 199,53
6 5,38 79,16 106,04 159,06 79,90
7 5,35 78,72 159,12 238,68 159,96
8 5,34 78,57 167,85 251,77 173,20
9 5,37 79,01 260,48 390,72 311,71
Tabel 5: Force (F) and Impact Energy (Ei)
Average
Force (F) and Impact Energy (E
i
)
Top Front Side
Force
(N)
Impact
Energy
(
J
)
Force
(N)
Impact
Energy (J)
Force
(N)
Impact
Energy
(
J
)
314,83 393,53 170,85 177,26 195,81 214,95
Tabel 6: Result of free fall drop impact test
Parameter
Helmet Commercial CPSC
Impact Force (F
i
) (max) 381,13 N 441,84 N
-
Impact Energy (E
i
) (max) 493,41Joule 555,64 Joule 110 Joule
Impact stress (σ
i
) (max) 5,71 MPa 3,78 MPa
-
Mass (m) 357,7 g 300 g
300

Impact Analysis of Ergonomic Bicycle Helmet Made from Polymeric Foam Composite Strengthened by Coconut Fiber
265

5 CONCLUSIONS
Base on data of research can be concluded as the
impact energy of the helmet is greater than the
standard and technique of making helmet is shell
layer with hand lay up method, liner with cast method
and the both layers are sandwich structured. The shell
helmet uses matrix unsaturated Polyester BQTN-
157EX material, chopped strand mat 300 glass fiber
reinforced, and Methyl Ethyl Ketone Peroxide
(MEKPO) catalyst. The liner composition is matrix
unsaturated Polyester BQTN-157 EX material 33%
wt (181,5gr) , coconut fiber reinforces 10% wt (55gr),
Polyurethane blowing agent 52% wt (285 gr), and
catalyst MEKPO 5%wt (27.5 gr). The results of the
free fall impact test shows that there are different
parameters of the helmet with a sample, commercial
and CPSC standard.
ACKNOWLEDGEMENT
This research was supported by Universitas Sumatera
Utara
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