MAGNETORHEOLOGICAL ELASTOMER ENGINE MOUNT SYSTEM

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DYNAMIC ANALYSIS OF

MAGNETORHEOLOGICAL ELASTOMER ENGINE MOUNT SYSTEM

BY

ISMAIL LADELE LADIPO

A thesis submitted in fulfilment of the requirement for the degree of Doctor of Philosophy (Engineering)

Kulliyah of Engineering

International Islamic University Malaysia

DECEMBER 2016

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ABSTRACT

Passive, semi-active and active mounts have been used to isolate vibration in engines.

However, due to changes in materials used for engine construction, there is a need to improve the performance of engine mounts. These improvements require sophisticated computation software, experimentation difficulties and cost. On the other hand, smart materials applications in engineering is growing but with lesser research on the analysis of models used for simulating behaviors of these smart materials. With proper analysis of mathematical models, isolation of engine vibrations can be improved in modern vehicles using smart materials. One of such smart materials is Magnetorheological Elastomer (MRE). Usually, dynamic responses of visco-elastic materials are observed using phenomenological experiments which include creep, stress relaxation and rheological models. The simulations of these dynamic responses and characterization of engine mounts using Magnetorheological Elastomers (MREs) are limited in literature. These have contributed largely to the absence of commercial MRE mounts albeit their characteristics and performance in theory. The aim is to develop characteristics equation for MREs and simulate its behavior as MRE mount. In this research, the comparison between the Standard Linear Solid (SLS) model and the MRE model reveals the mechanical properties of MREs. These mechanical properties are utilized in the simulation of dynamic behaviors of MRE mount. Sensitivity Analysis (SA) is then used to determine the importance of the parameters which contribute to the performance of MRE mount. The SA reveals that that magnetic field input is more important than characteristic constituents’ stiffness of MREs. With this knowledge, MRE mount is controlled to reduce low frequency and high frequency vibration in half car model. It is shown by using different vibration measurement criteria, that there is significant reduction of vibration by using MRE mount. The results obtained when the Passive rubber mount was replaced with MRE mount shows 27% reduction in vibration in low frequency and 25% reduction in vibration in high frequency. The performance of the MRE in nonlinear model is however less promising as shown in the simulation results and further studies are needed. The values identified in this study can be useful in the subsequent design of MRE mounts in engine mount systems.

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ثحبلا ةصلاخ

داوملا يف تاريغتلل ةجيتن ،لاح يأ ىلع .تاكرحملا يف زازتهلاا لزعل ةطشنلا هبشو ةطشنلا تاتبثملا مدختست تايجمرب ىلإ جاتحت تانيسحتلا هذه .كرحملا تاتبثم ءادأ نيسحتل ةجاح كانه نإف ،كرحملا ءانب يف ةمدختسملا فاضلإاب ةيرابتخا تابوعص هجاوتو ،ةدقعم باسح داوملا تاقيبطت نإف ،ىرخأ ةيحان نمو .ةيداملا فيلاكتلا ىلإ ة

يف ةمدختسملا جذامنلا ليلحت لاجم يف ثاحبلأا نم ليلق ددع كانه نكلو ،رمتسم روطت يف يه ةسدنهلا يف ةيكذلا كمي كرحملا تازازتها لزع نإف ،ةيضايرلا جذامنلل بسانم ليلحتبو .ةيكذلا داوملا هذهل ةاكاحملا تايكولس اهنيسحت ن

)ةطنغملل ساسحلا طاطملا( ةيكذلا داوملا هذه نمو .ةيكذ داوم مادختساب ةثيدحلا تارايسلا يف ( Magnetorheological Elastomer (MRE) نم ظحلات جزللا طاطملا داومل ةيكيمانيدلا تاباجتسلاا ،ةداع .)

لا جذامنلاو داهجلإا ءاخرإو فحزلا نمضتت يتلا رهاوظلا تارابتخا للاخ ةيكيمانيدلا جذامنلا هذه ةاكاحم .ةيجولوير

( مادختساب كرحملا تاتبثم فصوو ريبك لكشب مهاس اذهو .ةقباسلا تاساردلا يف دودحم لكشب هلوانت مت )MRE

( تاتبثم بايغ يف ريوطت وه فدهلا .يرظنلا لاجملا يف اهئادأو اهتازيمم مغرب ،يراجتلا قاطنلا يف )MRE

( ـل تازيمملا ةلداعم )MRE

( تاتبثمك اهكولس ةاكاحمو يجذومن نيب ةنراقملا رهظت ،ثحبلا اذه يف .)MRE

( Standard Linear Solid (SLS) ( و )

( ـل ةيكيناكيملا صئاصخلا )MRE صئاصخلا هذه .)MREs

( تاتبثمل ةيكيمانيدلا تايكولسلا ةاكاحم يف تمدختسا ةيكيناكيملا ديدحتل ةيساسحلا ليلحت مادختسا مت اهدعب .)MRE

( تاتبثم ءادأ يف مهاست يتلا تلاماعملا ةيمهأ مهأ لخدُمك يسيطانغملا لقحلا نأ رهظي ةيساسحلا ليلحت .)MRE

( تانوكم ةبلاص نم ( تبثم نإف ةمولعملا هذه نم .)MREs

ددرتلا لاجم يف زازتها ليلقتل هب مكحتلا نكمي )MRE

تسا نم رهظي .ةرايسلا فصن جذومن يف يلاعلا ددرتلاو ضفخنملا كانه نأ زازتهلاا سايقل ةفلتخم ريياعم مادخ

( تبثم مادختساب زازتهلال ًاريبك ًاضيفخت طاطملا لادبتسا مت امدنع اهيلع لوصحلا مت يتلا جئاتنلا ترهظأ .)MRE

( ـب يداعلا ةبسنب زازتهلاا ضيفخت نأ )MRE

و ضفخنملا ددرتلا لاجم يف %27 .يلاعلا ددرتلا لاجم يف %25

تنلا ترهظأ امك جئا

( ءادأ نأ ةيفاضإ تاسارد ىلإ ةجاح كانهو ًاريثك ًادعاو سيل ةيطخلا ريغ جذامنلا يف )MRE

كرحملا تيبثت ةمظنلأ قحلالا ميمصتلا يف ةديفم نوكت نأ نكمي ةساردلا هذه يف ةف ّرعملا ميقلا .لاجملا اذه يف ( .)MRE

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APPROVAL PAGE

The thesis of Ismail Ladele Ladipo has been approved by the following:

….…………..………

Fadly Jashi Darsivan Supervisor

….…………..………

Waleed Feekry Faris Co-Supervisor

….…………..………

Sany Izan Ihsan Internal Examiner

….…………..………

Jawaid Iqbal Inayat Hussain External Examiner

….…………..………

Ahmad Kamal Ariffin External Examiner

….…………..………

Mohd Feham Md Ghalib Chairman

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DECLARATION

I hereby declare that this thesis is the result of my own investigations, except where otherwise stated. I also declare that it has not been previously or concurrently submitted as a whole for any other degrees at IIUM or other institution.

Ismail Ladele Ladipo

Signature………. Date ……….

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INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA DECLARATION OF COPYRIGHT AND AFFIRMATION OF

FAIR USE OF UNPUBLISHED RESEARCH

DYNAMIC ANALYSIS OF MAGNETORHEOLOGICAL ELASTOMER ENGINE MOUNT SYSTEM

I declare that the copyright holder of this thesis are jointly owned by the student and IIUM

No part of this unpublished research may be reproduced, stored in a retrieval system or transmitted, in any form or by means, electronic, mechanical, photocopying, recording or otherwise without prior written permission of the copyright holder except as provided below

1. Any material contained in or derived from this unpublished research may only be used by others in their writing with due acknowledgement.

2. IIUM or its library will have the right to make and transmit copies (print or electronic) for institutional and academic purpose.

3. The IIUM library will have the right to make, store in a retrieval system and supply copies of this unpublished research if requested by other universities and research libraries.

By signing this form, I acknowledged that I have read and understand the IIUM Intellectual Property Right and Commercialization policy.

Affirmed by: Ismail Ladele Ladipo

……….. ………

Signature Date

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Dedicated to Allah (SWT)

“And [remember, O Muhammad], when those who disbelieved plotted against you to restrain you or kill you or evict you [from Makkah]. But they plan, and Allah plans. And Allah is the best of planners”

- Quran (8:30)

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ACKNOWLEDGEMENTS

Praise be to Allah (SWT), the Most Beneficent the Most Merciful, for giving me the opportunity to meet my mentor, Sheikh Dr. Abdul Hakeem Abayomi (RLT). His guidance and spiritual dossier has enabled me to complete this journey.

I am highly indebted to all the researchers whose references I have used in this treatise. The difficult part of this research is finding the appropriate course to take within the scope of research area which this study presented. It is their work that forms my understanding of the subjects being discussed and their work always give the required focus that is needed for this academic piece. Above all, without their outstanding contributions, this work would have rather been shallow.

I would like to appreciate Dr. Jashi Fadly Darsivan and Prof. Waleed Fekry Faris for their contributions to this research.

I am also grateful to all the academic and non-academic staff members of both the Department of Mechanical Engineering and Mechatronics Engineering for giving me the facilities necessary to complete this arduous task.

Unquantifiable thanks goes to the light of my life, soulmate, a pure sincere friend: Kafayat Oluwatomi Ladipo. Not only did you give the advice to travel to Malaysia for my postgraduate studies, but also unconditional support and love. A guide and a companion, without whom I would have been lost. Also to my progenies;

Ramadan, Yassin, Abdullah and Firdaus for your perseverance on our struggles. My dad who knew the importance of a good education and sacrificed to give one. My mum whose prayers were always on time and my siblings who had to adjust to my absence and stood by me even when distance is a factor; while leaving them to achieve this feat.

I hope to make up for my absence.

I am indeed indebted to Allah; Despite my shortcomings, He lifted me.

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LIST OF TABLES

Table No. Page No.

2.1 Engine mount design requirements 15

2.2 Engine mount systems summary 16

2.3 Meta-analysis 34

4.1 Mathematical derivations for MRE and Elastomeric model mechanical properties

73

5.1 Quarter car model parameters 96

5.2 Low frequency MRE mount parameters for quarter car model 100 5.3 High frequency MRE mount parameters for quarter car model 102 5.4 Merits and demerits of Sensitivity Analysis methods 104

6.1 Half car model parameters 119

6.2 Low frequency MRE mount parameters for half car model 121 6.3 Peak reductions in displacement of chassis and engine at low

frequency

124

6.4 Relative displacements at low frequency 127

6.5 High frequency MRE mount parameters for half car model 128

6.6 Force transmissibility at high frequency 129

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LIST OF FIGURES

Figure No. Page No.

1.1 Research methodology chart 9

2.1 Commercial engine mount 14

2.2 6-DOF engine modes 15

2.3 Passive rubber mount 17

2.4 Passive rubber mount model 18

2.5(a) Hydraulic engine mount 18

2.5(b) Hydraulic engine mount cut away view 18

2.6 Passive hydraulic mount model 19

2.7 Different passive engine mount attachment types 22

2.8(a) MRF mount 24

2.8(b) MR fluid mount cut-away view 24

2.9 ERF engine mount 24

2.10 Semi-active engine mount model 25

2.11 Active engine mount 27

2.12 Active mount model 28

3.1 Maxwell model 41

3.2 Stress and strain relationship for Maxwell model 42

3.3 Maxwell model creep recovery response 43

3.4 Kelvin-Voigt model 44

3.5 Kelvin-Voigt model creep recovery response 45

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3.6 Maxwell form of SLS model 46

3.7 Generalized Maxwell model 46

3.8 Generalized Kelvin model 46

3.9 Three-parameter KSLS model 48

3.10 MRE model 50

4.1 Dynamic stiffness frequency dependence for MRE and Elastomeric model

62

4.2 Damping modulus frequency dependence for MRE and Elastomeric model

66

4.3 Shear stress and strain hysteresis loop for MRE and Elastomeric model at 15Hz

71

4.4 Shear stress and strain hysteresis loop for MRE and Elastomeric model at 100Hz

71

4.5(a) Mounting system showing displacement transmissibility 75

4.5(b) Mounting system showing force transmissibility 75

4.6 Engine mount system 79

4.7 Transmissibility of mountings of natural rubber when filled with particles of different materials

82

4.8 Transmissibility (MRE and Elastomeric model) 90

5.1(a) Quarter car model with Passive rubber mount. 93

5.1(b) Quarter car model with MRE mount 93

5.2 Three dimensional plots of storage modulus for MRE mount at magnetic field input of 1T

98

5.3 Three dimensional plot of loss factor for MRE mount at magnetic field input of 1T

98

5.4 Displacement transmissibility of MRE mount 99

5.5 Relative displacements (MRE and Passive rubber mount) 101

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5.6 Force transmissibility (Passive rubber and MRE mount) 102 5.7 Relative displacement against compositional stiffness 106

5.8 Relative displacement against magnetic field 107

6.1 Six degrees of freedom (6-DOF) of passenger vehicle 110

6.2 Half car model 112

6.3 Engine displacement (Passive rubber and MRE mount) 121 6.4 Chassis displacement (Passive rubber and MRE mount) 122 6.5 Engine rotational displacement (Passive rubber and MRE mount) 122 6.6 Chassis rotational displacement (Passive rubber and MRE mount) 123 6.7 Acceleration of engine (Passive rubber and MRE mount) 125 6.8 Acceleration of chassis (Passive rubber and MRE mount) 125 6.9 Relative displacement (Passive rubber and MRE mount) 126 6.10 Engine oscillation at 15Hz (Passive rubber and MRE mount) 127 6.11 Force transmissibility (Passive rubber and MRE mount at 25-250Hz) 129 6.12 Chassis time response (Passive rubber and MRE mount at 25-250Hz) 130

7.1 Nonlinear half car model 133

7.2 Linear and nonlinear spring forces 134

7.3 Linear and nonlinear damping forces 134

7.4 Engine displacement in nonlinear half car (k_ns=10%;c_ns= 41%) 136 7.5 Engine displacement in nonlinear half car (k_ns 5%;c_ns 21%) 137 7.6 Engine displacement in nonlinear half car (k_ns 60%;c_ns 81%) 138 7.7 Sensitivity of MRE compositional stiffness in nonlinear half car model 139 7.8 Sensitivity of MRE magnetic field in nonlinear half car model 140

7.9 Tuned MRE mount in nonlinear half car model 141

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LIST OF ABBREVIATIONS

6-DOF 6-Degree of freedom

dB decibel

CS Characteristic stiffness

ER Electrorheology

ERF Electrorheological Fluids

FRF Frequency Response Function

GSLS General Standard Linear Solid

KSLS Kelvin Standard Linear Solid

MR Magnetorheology

MF Magnetic field

MS Magneto Sensitive

MRE Magnetorheological Elastomer

MREs Magnetorheological Elastomers

MRF Magnetorheological Fluid

MRFs Magnetorheological Fluids

MRFE Magnetorheological Fluid Elastomer

MRVE Magnetorheological Visco Elastomer

NVH Noise, Vibration and Harshness

Rd Relative displacement

RPM Revolution per minute

SA Sensitivity Analysis

SI Sensitivity Index

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LIST OF SYMBOLS

𝜃̈_𝑏 Chassis angular acceleration 𝜃_𝑏 Chassis angular displacement

𝑚_𝑐 Chassis mass

𝑥_𝑐 Chassis displacement η Coefficient of viscosity

K Constant for the dimensions of length for mount Ɩ Connecting rod length

𝜔_𝑐 Crankshaft angular velocity J Creep compliance function

ζ Damping ratio

𝑇_𝑑 Displacement transmissibility 𝐺_𝑜 Dynamic stiffness at resonance

α Dynamic stiffness ratio at low and high frequency 𝐺_{(𝜀,𝜔)𝐸} Elastomer model storage modulus

𝛼_𝐸 Elastomer model storage modulus ratio at low and high frequency 𝜂_𝐸 Elastomer model coefficient of viscosity

𝜔_𝑡(𝐸) Elastomer model transition frequency 𝛿_{𝐺(𝜀,𝜔)𝐸} Elastomer model loss factor

𝜃̈_𝐸 Engine angular acceleration 𝜃_𝐸 Engine angular displacement

𝐹_𝑇 Engine force

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𝑚_𝑒 Engine mass

𝑐_𝐸 Engine mount damping coefficient

𝜔 Frequency (rad/s)

Ω Frequency ratio

𝑇_𝑓 Force transmissibility

𝐹_𝑜 Force transmitted by engine to chassis 𝐶_𝑠𝑓 Front suspension damping

𝑘_𝑠𝑓 Front suspension stiffness

Hz Hertz

𝜎_𝑜 Initial stress 𝜀_𝑜 Initial strain

𝐵_𝑙 Input matrix at low frequency 𝐵_ℎ Input matrix at high frequency β Magnetic field intensity

𝑚 Mass

𝛼_𝑀 MRE model storage modulus ratio at low and high frequency 𝐺_{(𝜀,𝜔)𝑀} MRE model storage modulus

𝜂_𝑀 MRE model coefficient of viscosity 𝛿_{(𝐺(ԑ,𝜔)𝑀)} MRE model loss factor

(𝜔_𝑡)_𝑀 MRE model transition frequency 𝜔_𝑜 Natural frequency

(1..2)

Fs Nonlinear front and rear suspension spring force

(1..2)

Fd Nonlinear front and rear suspension damper force

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𝐺_{(𝜀,𝜔)𝑃}^∗ Passive rubber mounts complex shear modulus 𝐺_{(ԑ,𝜔)𝑃} Passive rubber mounts storage modulus

𝛿_{(𝐺(ԑ,𝜔)𝑃)} Passive rubber mounts loss factor

φ Phase angle

𝑟 Ratio of harmonic force frequency over undamped natural frequency 𝑘_𝑠𝑟 Rear suspension stiffness

𝑅_𝑑 Relative displacement

𝜔_𝑜 Resonance frequency

𝑋_𝑜 Road profile initial displacement 𝑟_𝑐 Rotational radius of crank arm

σ Stress

𝜎_𝑠 Stress in spring element 𝜎_𝑑 Stress in damping element 𝜎_𝑀 Stress in Maxwell model 𝜎_𝐸 Stress in spring element

𝜀 Strain

𝜀_𝑠 Strain in spring element 𝜀_𝑑 Strain in damper element 𝑘_𝑠 Suspension total stiffness

𝑐_𝑠 Suspension damping

𝑇 Tesla

θ Temperature

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CHAPTER ONE INTRODUCTION

1.1 OVERVIEW

Rubber is the conventional material for mounts used in passive isolation of engine vibration. Semi–active and active methods have also been suggested and used in different research. Hydraulic, Electrorheological (ER) and Magnetorheological (MR) fluids are used in semi-active and active mounts.

Different research on fluids with nonlinear characteristics in adaptive hydraulic engine mount systems have been reported (Geisberger, Khajepour, & Golnaraghi, 2002;

Gołdasz & Sapiński, 2011; Kim, Choi, Hong, & Han, 2004). While active mounts have been used as a replacement for semi-active mounts. Active mounts are however complex, less reliable and expensive (Kim et al., 2004).

Recently in the automobile industry, efforts have been directed towards using lighter materials for construction of engines. However, the power requirement of new vehicle engines is on the increase. The construction materials and power requirements of engines affects the selection of appropriate engine mounts in modern vehicles.

It is evident that conventional mounts have for the past three decades reached their performance limits due to evolving vehicle designs and can no longer meet the requirements by current practices in automotive engineering (Harrison, 2004). The associated noise, vibration and harshness (NVH) issues with modern automobiles vehicles are cause for concern.

Apart from the trends in automobile industry, operation behaviors of engine mounts require that mounts have variable loss factor and storage modulus properties.

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Thus, the need to find alternative materials that are suited for the requirements. The identification of engineering materials which have variable dynamic stiffness and damping modulus represents immense potentials in reducing engine vibration.

MR or Magneto-sensitive (MS) materials to which Magnetorheological Elastomers (MREs) belongs, are a class of smart materials whose dynamic stiffness and damping modulus can be varied by applying magnetic field (Li, Zhang, & Du, 2013).

MR materials in liquid and foam forms are called Magnetorheological Fluids (MRFs).

MREs are solid analogue of MRFs (Li, Li, Li, & Du, 2014). Unlike MRFs, MREs are non-contaminable. The research into the engineering applications of MREs is relatively new when compared to MRFs.

The composition of MREs is a complex polymeric system which consists of elastomeric medium (highly viscoelastic medium) serving as the dispersed medium for different solids and liquids. The particle chains in MREs are intended to always operate in pre-yield regions while in MRFs, the particle operate in post yield continuous shear or flow regimes. With continuously variable rheological properties, MREs could be used for numerous applications.

Various magneto-mechanical properties have been reported to be exhibited by MREs (Ginder, Clark, Schlotter, & Nichols, 2002; Guan, Dong, & Ou, 2008). Some of the important differences between MREs and MRFs are that, MRFs have field dependent yield stress but MREs have controllable shear modulus that is dependent on magnetic field. Also, MREs do not require containers to hold the MR materials and the solid matrix particles do not coagulate with time. Unfortunately, little is known in publication on the commercial uses of MREs (Brigadnov & Dorfmann, 2003).

The engine mount system comprises of vehicle chassis (the foundation), the engine and the road (source of vibration) and engine mounts (isolator). The application

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of MREs as engine mount is relatively new. Almost all commercially available semi- active mounts are made of rubber, hydraulic fluid, Electrorheological Fluids (ERFs) or MRFs.

The ability to manipulate the storage modulus and loss factor of MREs in engine mount systems is of interest in this research. Of the two properties, that is most difficult to model but easier to control is damping modulus (Kallio, 2005). The needs for solid state mechatronics device such as MREs are a growing field. Like other smart materials, hysteresis behavior of magnetorheological composites is nonlinear and thus mathematical models that can be used to study MREs behaviors must also be able to predict the phenomenological behaviors of MREs.

This research aims to study an alternative rubberlike material whose variable dynamic properties can be used in solving the problems in engine mount systems. The mechanical properties of MREs is investigated from the mathematical equations developed from the MRE model. The simulation behaviors of MREs is then compared to existing model. Magnetorheological Elastomer (MRE) model is used to replace MRE mount and used in simulation studies for comparison of the performance of Passive rubber mounts and MREs mounts in engine mount systems.

One of the motivations of this work is the unavailability of dynamic analysis developed from the mechanical model which can be used to simulate the magnetorheological response of MREs.

The results of this research can thus be adapted to simulate MREs in other applications where semi-active vibration isolation using MREs are required.

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1.2 PROBLEM STATEMENT AND ITS SIGNIFICANCE

The connection of more powerful engines to lighter vehicle frames has indeed resulted in vibration problems that passive elastomeric and hydraulic mounts cannot adequately address (Marzbani, Jazar, & Fard, 2013). The following are some problems in existing engine mount systems:

(a) Passive rubber mounts are designed with a trade-off when selecting frequencies of vibration which the mount will isolate. It is either low frequency or high frequency vibration that is reduced. The vibrations in both frequencies are difficult to be isolated due to the static properties of rubber mount. Passive rubber mount therefore perform poorly for transient response of shock excitations (Adiguna, Tiwari, Singh, Tseng, & Hrovat, 2003).

(b) Semi-active and active mounts are expensive, complex and their performance is nonlinear (Shangguan, 2009). Semi-active mounts with fluids causes contamination to the environment due to spilling (Elahinia, Ciocanel, Nguyen, & Wang, 2013). Thus, existing engine mount systems needs modifications in their design or improvement in properties of materials that are currently used as mounts (Yu, Naganathan, & Dukkipati, 2001).

(c) MREs applications to solve engineering problems still need to be understood properly before it is implemented in real applications (Li, Zhou,

& Tian, 2010). Despite the success of using smart material such as Magnetorheological Fluid (MRF) in engineering applications like structural vibration isolation, engine mounts and suspension system, it has constraints

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namely being a liquid are non-environmentally friendly unlike MRE (Kciuk

& Turczyn, 2006).

(d) The application of MREs to engineering problems is also limited due to the unavailability of analytical models to describe the rheological and phenomenological behavior of MREs. The lack of a standard for the constituents’ components of MREs during fabrication also hindered the development of a mathematical model which can be used to simulate the behaviors of MREs (Hu et al., 2005).

The implementation of MRE as an engine mount is influenced by simulation results with parameters to predict accurately the behavior of MRE mount. Due to the limited research on the use of MREs, such simulation parameters are unavailable in literature.

The MRE has the potentials to replace existing passive engine mounts in vehicles Therefore, there is need to develop a mathematical model which can be used for MRE and simulate behaviors of engine mount systems that uses MREs isolators.

1.3 RESEARCH PHILOSOPHY

The powertrain of automobiles is the largest concentration of mass in a vehicle. This implies that the engine design and its components vibration is a factor to be considered in the design of automobiles (Darsivan, Martono, & Faris, 2009). The situation is critical now that lighter engine designs are emerging. The traditional passive isolators are becoming deficient in performance and there is the need to improve their capabilities.

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Based on the engineering applications of MREs which is a rapidly growing field of knowledge, it is proposed that further studies on the mechanical properties of this smart material will increase the understanding and potentials of MREs.

The ability to describe the behavior of MRE using analytical model in simulation before implementation in real vehicles is important (Dorfmann & Ogden, 2003). The development of models which can be used in the design studies of the prototype MRE mount enables the characterization of MREs in general and its behavior as engine mounts in particular. These mathematical models are used to simulate the mechanical behaviors of MREs when used in different engineering applications. The mechanical behaviors include shear stress and strain properties (which determines the damping modulus), hysteresis (energy lost during working cycles), temperature and magnetic field input effect.

MREs have dynamic characteristics which can be utilized in the design of engine mounts to reduce the vibration of engine mount system in all frequency. The performance evaluation of MRE (which have promising performance) to rubber (that are currently been used) as passive engine mount is thus important.

The use of MRE mounts could lead to increase attenuation of vibrations in engines and other applications where mounts are required. Thus, further investigation of existing mathematical models for rubberlike materials is necessary. This is partly due to the peculiar nature of MREs which is different from other visco-elastic materials.

This could lead to the establishment of the advantages of using MRE as mounts in engine mount systems.