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Vibration analysis of motorcycle handlebar for riding comfort using tuned

mass damper

Article in Journal of Measurements in Engineering · December 2020

DOI: 10.21595/jme.2020.21518

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Lecture Notes in Mechanical Engineering

Vilas R. Kalamkar
Katarina Monkova Editors

Advances in
Mechanical
Engineering
Select Proceedings of ICAME 2020
 S. S. Khune and A. R. Bhend

Design of Motorcycle Handlebar

for Reduction of Vibrations Using Tuned
Mass Damper

Sumit S. Khune and Amit R. Bhende

Abstract Vehicle comfort is related to vibrations induced due to surface irregulari-

ties and powertrain. It is a challenge to design a good suspension system and vibration
absorber which isolates the driver/rider from the induced vibrations. The principle
aim of a vehicle’s suspension system/vibration absorber is to isolate the occupant
from the induced disturbances, while still allowing the average driver to maintain
control over the vehicle and drive it safely. The purpose of the present study is to
investigate the vibrations in motorcycle handlebar and modify handlebar to reduce
the vibration for good ride comfort without affecting its handling. Motorcycle with
an under square engine is selected for the experimentation. The under square engine
has more stoke length than bore diameter, and hence, it is more susceptible to gener-
ate vibrations. A tuned mass damper system is designed and developed to attenuate
handlebar vibrations. The results of investigation show vibration attenuation from 23
to 66% at various cases. The effect of tuned mass damper is substantially visible at
higher engine RPM, and hence, proper modification of handlebar becomes essential
in case of high revving application.

· 5439-1&2 Tuned
Keywords Handlebar vibration ISO · mass damper (TMD) ·
Frequency response function (FRF) · Vibration attenuation

1 Introduction

Performance of vehicle not just depends upon good powertrain or fine aesthetics,
but on good levels of NVH (noise, vibration and harshness). Nowadays, vehicles are
expected to be reliable and comfortable. Comfort of the vehicle depends upon engine
noise, exhaust note and rattle noise between components, vibrations transferred to

S. S. Khune
VIT Vellore, ARAI Academy, Vellore, India
A. R. Bhende (B)
Mechanical Engineering Department, St. Vincent Pallotti College of Engineering & Technology,
Nagpur, Maharashtra 441108, India
e-mail: abhende@stvincentngp.edu.in

© Springer Nature Singapore Pte Ltd. 2021 329

V. R. Kalamkar and K. Monkova (eds.), Advances in Mechanical Engineering,
Lecture Notes in Mechanical Engineering,
https://doi.org/10.1007/978-981-15-3639-7_38
330 S. S. Khune and A. R. Bhende

human body, etc. In case of motorcycles, vibrations are transferred to human body
from three points, i.e. handlebar, foot pegs and seat. Long exposure of vibrations to
rider may lead to several body disorders in ligament, bones and joints, and some-
times, it may affect the nervous system. Occurrences of such disorders are categorised
under whole-body vibration syndrome (WVBS). The disorders caused due to han-
dlebar vibrations are categorised under hand-arm vibration syndrome (HAVS) [1].
Number of international organisations have provided standards and guidelines for
measurement and evaluation of vehicle vibration such as ISO 2631 or BS 6841 [2].
Standards and guidelines for the measurement and evaluation of hand transmitted
vibrations are provided in ISO 5349-1 and ISO 5349-2 [1].
The present study is carried out to investigate the vibrations in handlebar of a
motorcycle and incorporate the modification to reduce vibrations for good ride com-
fort without affecting its handling. Handlebar is modified using tuned mass damper
to attenuate vibration amplitudes. Vibration measurements are carried out for orig-
inal (stock) and modified handlebar. It has been observed that maximum amplitude
value is reduced by substantial margins using modified handlebar.

2 Literature Review

Vibration absorbers/dampers are used to minimise transfer of vibrations from one

component to other. Dampers are classified into passive dampers and active dampers.
Passive damping is further classified into two parts, i.e. material damping and tuned
mass damping. In case of material damping, a material is introduced to restrict the
transfer of vibration, and material properties are varied to get the desired vibra-
tion isolation. The most general vibration isolators are elastomers. The selection of
elastomeric material depends upon two factors, degree of vibration isolation and
durability of isolator. Synthetic elastomer can maintain the properties for wide range
of temperature making it better than natural rubber (NR) and ethylene propylene
diene monomer (EPDM) in thermal cyclic test [3].
In tuned mass damping, an additional degree of freedom is introduced to control
the frequency response function within the frequency range of interest [4]. Tuned
mass damper (TMD) can be implemented as an alternative engineering solution
to control steering wheel or handlebar vibrations in case of both four-wheeler and
two-wheeler. TMD is a suspended supplementary mass mounted on spring-damped
element, attached to primary/main system mass. TMD is also known as dynamic
neutraliser as it neutralises the main vibrations in main system by self-vibrations with
a phase difference. In addition, a single degree of freedom (SDOF) model is converted
to double degree of freedom (DDOF) model wherein two natural frequencies are
generated, either of which are not equal to natural frequency of SDOF model [5].
TMD is well-known concept, but it has its own share of limitation such as it
adds weight to the system, consumes space, and it cannot be tuned on the fly. To
overcome these drawbacks, active tuned absorber (ATA) is introduced. In ATA,
Design of Motorcycle Handlebar for Reduction of Vibrations … 331

spring and damper of TMD are replaced with actuation mass. Actuation mass is
of electromagnetic type which can be changed by merely changing coil current [6].
From the various studies carried out related to tuned mass damper system, natu-
ral frequency, amplitude and mass of the main system are the inputs for design of
TMD. TMD design is significantly dependent upon location of installation and the
production variability. If TMD is installed on a system without studying the natural
frequency of the system, then the modified design may fail due to resonance phe-
nomenon. Production variability is another crucial factor as no two components can
be manufactured exactly same with different natural frequencies.

3 Experimental Setup

In this study, vibration analysis on motorcycle handlebar is carried out on 2014

make Royal Enfield Thunderbird 350. Motorcycle is powered by 346 cc, air cooled
single cylinder under square engine. Motorcycle with under square engine, i.e. stroke
length greater than bore diameter, is selected for the study because the imbalance
and inertial forces are higher than that of over square engine, which further induces
more vibrations in various components and body panels. In addition, the imbalance
forces are not balanced at the crank by providing counterbalance. Since the engine is
mounted over the frame directly, more amount of vibrations are transferred to frame,
which otherwise could be dampened using elastomeric mounts. These vibrations are
further transferred to handlebar, tank, foot pegs and seat.
For TMD mass, MS bright bar with uniform diameter 15 mm, length 105 mm
and weight as 135 gm is selected on each side. Tuned mass is 13% that of handlebar
mass. Each bar is provided with two grooves of 2 mm diameter, at 20 mm from
each end to install elastomeric dampers with OD of 17 mm. The complete assembly
is pushed inside the hollow section of the handlebar. Figure 1 shows TMD used in
experimentation.
A piezotronics make single axis accelerometer is used as vibration transducer. The
accelerometer is integrated circuit piezoelectric (ICP) type with built-in amplifier,
sensitivity of 100 mV/g, frequency bandwidth 0–20 kHz, range ± 10 g. National
instruments make data acquisition system is used for the experimentation which
consists of 9234 DAQ card and 9171 chassis. The sampling frequency of the card is
51.2 kHz USB connected four input channels. This DAQ system is integrated with
LabVIEW 15.0 software to analyse vibration signal using various signal processing
techniques.
Motorcycle is parked on main stand; a rubber mat is placed below the stand to
avoid slippage over concrete flooring during experimentation. A 5.5 mm hole is
drilled, and 6.25 mm tap is used on handlebar to install stud mounted accelerometer.
Accelerometer is attached to handlebar by using stud as shown in Fig. 2. Experi-
mentations are carried out at different engine RPM by varying throttle valve position
of the carburettor. Engine RPM is displayed on integrated tachometer as shown in
332 S. S. Khune and A. R. Bhende

Fig. 1 Tuned mass damper

Fig. 2 Experimentation on motorcycle handlebar

Fig. 2. The engine is allowed to settle at particular RPM for approximately 90 s

before recording the readings.

4 Experimentation

Experimentation is carried out on stock handlebar for four different cases at various
RPMs. The four cases are as follows:
1. Plain handlebar (HB)
2. Bar ends attached to handlebar (HB + BE)
3. Lever, mirror and switches mounted on handlebar (HB + LSM)
4. Bar ends and other accessories installed on handlebar (HB + BE + LSM)
Design of Motorcycle Handlebar for Reduction of Vibrations … 333

Vibration signal is analysed in time domain and frequency domain plot to check
acceleration amplitude and its frequency. The acceleration and frequency readings are
recorded for each case as mentioned above. Stock handlebar is modified by inserting
designed TMD bars. The above procedure is repeated with modified handlebar.

5 Results and Discussion

The acceleration values are recorded and tabulated for the stock and modified han-
dlebar at various RPMs and at above mentioned four cases. Table 1 shows handlebar
(HB) reading for stock and modified handlebar. The tabulated data are graphically
represented: in Figs. 3 and 4.
For all the four cases mentioned above, vibration amplitudes are highest at 3750
engine RPM for stock handlebar. Natural frequency of stock handlebar is 392.5 rad/s
as per calculation, assuming stiffness of quad clamp as 394.384 kN/m and handlebar
bar mass as 2.56 kg. The external excitation engine frequency of a four-stroke engine
is 62.5 Hz or 392.5 rad/s. This indicates that external excitation frequency becomes
equal to natural frequency of handlebar, and system resonates with higher amplitudes
at 62.5 Hz.
TMD helps to minimise the vibration amplitude of the system but at the same time
adds weight to the system. However, to certain point, TMD becomes more effective
with increase in mass. Literature survey showed that 13.3% of handlebar mass can
be used as TMD mass which would attenuate the response and give optimum results.
Percentage attenuation achieved for above four mentioned cases is 23.5, 31.25, 65.9
and 56, respectively. The peaks have shifted in case of modified handlebar due to
shift in natural frequency.

Table 1 Handlebar (HB) readings for stock versus modified

RPM Stock handlebar Modified handlebar
Frequency (Hz) Amplitude (m/s2) Frequency (Hz) Amplitude (m/s2)
1000 70 0.006 66 0.008
1500 21 0.14 24 0.08
2000 33 0.31 63 7
2500 80 1.4 39 2
3000 50 4.9 47 9
3250 53 11 52 17
3500 58 20 56 65
3750 60 170 60 130
4000 66 101 64 90
334 S. S. Khune and A. R. Bhende

Fig. 3 Maximum amplitude at various frequencies for stock handlebar

Fig. 4 Maximum amplitude at various frequencies for modified handlebar

6 Conclusion

The study presents successful implementation of tuned mass damper (TMD) for
attenuation of handlebar vibration in all the mentioned cases. Best results are obtained
in case of HB +LSM in both stock and modified handlebar. It is inferred that
location of the additional weight plays crucial role in the vibrational behaviour of the
handlebar. Addition of weight at the ends of the handlebar would result in increase of
handlebar vibrations. It is observed that weight should be uniformly distributed over
the span of the handlebar for attenuation of handlebar vibrations. From the study,
it is also observed that the effect of TMD is substantially visible at higher engine
 Design of Motorcycle Handlebar for Reduction... 335
of Vibrations …
RPMs. Hence, proper modification of handlebar becomes imperial in case of high
revving application.

Conflict of Interest The authors declare that they have no conflict of interest.

Ethical Approval All procedures performed in studies involving human participants were in accor-
dance with the ethical standards of the institutional and/or national research committee and with
the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Ethical Approval This article does not contain any studies with human participants or animals
performed by any of the authors.

References

1. Fasana A, Giorcelli E (2010) A vibration absorber for motorcycle handles. Meccanica 45:79–88
2. ISO 2631-1, Second Edition, 1997, Mechanical vibrations and shock—evaluation of human
exposure to whole body vibrations
3. Sivakumar A, Tiwari A, Ragavendra G, Kolhe V (2009) Elastomer blend for vibration isolators
to meet vehicle key on—key off vibrations and durability. SAE Technical Paper
4. Tathawadekar P, Liu K-J, Rajan S, Johnson P, Application of tuned mass damper to address
discrete excitation away from primary resonance frequency of a structure
5. Barbetti M, Carvalho L, Calcada M (2017) Vibration absorber application, case study: mid-size
truck steering wheel vibration. SAE Technical Paper
6. Lee P, Rahbar A (2005) Active tuned absorber for displacement-on-demand vehicles. SAE
Technical Paper.

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