FINITE ELEMENT ANALYSIS OF UPPER CRANKSHAFT SIX STROKE ENGINE

USING CAE SOFTWARE

MUHAMMAD NASIRUDDIN BIN ANIDIN

A dissertation submitted in partial fulfillment of the requirements for the award of the degree of

Bachelor of Mechanical Engineering with Automotive Engineering

Faculty of Mechanical EngineeringUNIVERSITI MALAYSIA PAHANG

NOVEMBER 2009

ii

SUPERVISOR’S DECLARATION

I hereby declare that I have checked this thesis and in my opinion this thesis is

satisfactory in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering.

Signature:

Name of Supervisor: MR. MOHD RASHIDI BIN MAAROF

Position: LECTURER

Date: 24 NOVEMBER 2009

iii

STUDENT’S DECLARATION

I hereby declare that the work in this thesis is my own except for quotations and

summaries which have been duly acknowledged. The thesis has not been accepted for

any degree and is not concurrently submitted in candidate of any other degree.

Signature:

Name: MUHAMMAD NASIRUDDIN BIN ANIDIN

ID Number: MH06032

Date: 24 NOVEMBER 2009

iv

DEDICATION

This project is dedicated to both of my beloved parents,

Anidin bin Hj. Muhammad Nor & Zaitun Hj. Norsidek

for their priceless love and support.

v

ACKNOWLEDGEMENT

In the name of Allah, the Most Benevolet, the Most Merciful. Alhamdulillah, all

praise to the al mighty god, Allah swt for the countless goodness that are given to me

and all the required necessity to complete this project.

In particular, I wish to express my sincere appreciation to my main thesis

supervisor, Mr. Mohd Rashidi Bin Maarof, for all his endless supports, encouragement,

guidance, compromise and advise, without him I would not have been able to complete

this final year project successfully.

My sincere gratitude to Dr Mustafizur Rahman who willing to assist and guide

me to succeed in spite of his busy schedule. His compliments and critics had helped me

most in keeping me focused on my project and to finish in time. Also thanks for his

kindness to share his knowledge on the software.

I am also indebted to Universiti Malaysia Pahang (UMP) for providing internet

facility. Librarians at UMP also deserve special thanks for their assistance in supplying

the relevant literatures. Their views and tips are useful indeed.

Special thanks to my beloved parents for all their loves and encouragement to

excel in this project. Thanks for their continuous support through all the hard time and

for their trust in me.

Not to forget my appreciation to all of my lecturers and my fellow

undergraduates’ friends for their kindness to provide assistance and shared all the useful

knowledge they had with me to complete this project. Finally I would like to thanks all

person who had helped me learn the used software.

vi

ABSTRACT

This dissertation describes the stress distribution of the upper crankshaft for six

stroke engine by using finite element analysis. The finite element analysis is performed

by using computer aided engineering (CAE) software. The main objectives of this

project are to investigate and analyze the stress distribution of upper piston at the real

engine condition during combustion process. The dissertation describes the mesh

optimization with using finite element analysis technique to predict the higher stress and

critical region on the component. The upper crankshaft is implemented in the six stroke

engine of 110 cc Modenas motorcycle. Aluminum 356-T7 is selected as an upper

crankshaft material. Despite all the stresses experience by the upper crankshaft does not

damage the upper crankshaft due to high tensile strength but the upper crankshaft may

fail under fatigue loading. Thus, it is important to determine the critical area of

concentrated stress for appropriate modification. With using computer aided design

(CAD) which is SOLIDWORK, the structural model of an upper crankshaft is

developed. Furthermore, the finite element analysis performed with using MSC

PATRAN and MSC NASTRAN. The stress analysis results are significant to improve

the component design at the early developing stage. The result can also significantly

reduce the cost and time to manufactured the component and the most important to

satisfy customer needs.

vii

ABSTRAK

Disertasi ini menggambarkan serakan tekanan terhadap crankshaf atas dengan

menggunakan keadah analisis elemen terhingga. Kaedah analisis elemen terhingga

dilakukan dengan menggunakan perisian kejuruteraan bantuan computer (CAE).

Objektif utama projek ini adalah untuk mengkaji dan menganalisis serakan tekanan

terhadap crankshaf atas dalam keadaan sebenar enjin semasa proses pembakaran.

Disertasi menggambarkan pengoptimuman jala dengan menggunakan teknik analisis

elemen terhingga untuk menjangka tekanan yang lebih tinggi dan kawasan kritikal pada

komponen. Crankshaf atas digunakan pada enjin motorsikal Modenas enam lejang 110

cc. Aluminum 356-T7 dipilih sebagai bahan crankshaf atas. Meskipun semua tekanan

yang dialami oleh crankshaf atas tidak merosakkan crankshaf tetapi crankshaf atas

mungkin rosak apabila daya lesu dikenakan. Oleh demikian, sangat penting untuk

menentukan kawasan kritikal yang ditumpu oleh tekanan untuk pengubahsuaian yang

sesuai dapat dilakukan. Dengan menggunakan perisian lukisan bantuan komputer

(CAD) iaitu solidwork, model struktur crankshaf atas dapat dihasilkan. Seterusnya,

analisis elemen terhingga dilakukan dengan menggunakan PATRAN MSC dan MSC

NASTRAN. Keputusan analisis tekanan amat berguna untuk memperbaiki reka bentuk

komponen pada tahap awal penghasilan. Keputusannya juga dapat mengurangkan kos

dan masa untuk menghasilkan komponen dan yang paling penting bagi menjamin

kepuasan dan memenuhi kehendak pelanggan.

viii

TABLE OF CONTENTS

Page

PANEL DECLARATION ii

SUPERVISOR’S DECLARATION iii

STUDENT’S DECLARATION

TITLE PAGE iii

DEDICATION iv

ACKNOWLEDGEMENTS v

ABSTRACT vi

ABSTRAK vii

TABLE OF CONTENTS viii

LIST OF TABLES xii

LIST OF FIGURES xiii

LIST OF NOMENCLATURES xv

LIST OF ABBREVIATIONS xvi

CHAPTER 1 INTRODUCTION

1.1 Project Background 1

1.2 Project Title 3

1.3 Objectives 3

1.4 Scope of study 3

1.5 Problem Statement 3

ix

1.6 Flow Chart 4

CHAPTER 2 LITERATURE REVIEW

2.1 Six Stroke Engine 5

2.2 Aluminum 356- T7 6

2.3 Finite Element Analysis 8

2.4 Sofware

2.4.1 SolidWork 2008 (CAD)

2.6.2 MSC. Patran & MSC. Nastran (CAE)

9

9

10

CHAPTER 3 METHODOLOGY

3.1 Introduction 11

3.2 Methodology Flow Chart 12

3.3 Reverse Engineering 13

3.4 Design 13

3.5 Export Design to CAE Software 14

3.6 Mesh Convergence Analysis 14

3.7 Linear Static Stress Analysis 17

3.8 Analysis 18

x

3.9

3.8.1 Force Calculation

Different Orientation Analysis

19

20

CHAPTER 4 RESULTS AND DISCUSSION

4.1 Introduction 21

4.2 Structural Modeling 21

4.3 Mesh Convergence 23

4.4 Node and Element with Variable Mesh Length 24

4.5 Selection of Mesh Type 27

4.6 Different Orientation analysis results 28

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS

5.1 Overall Conclusion 33

5.2 Recommendation 34

REFERENCES 35

xi

APPENDICES

A Upper Crankshaft Right 37

B Upper Crankshaft Left 38

C Von Mises Stress on Crankshaft 39

D Tresca Stress on Crankshaft 40

E

F

G

Max Principal Stress on Crankshaft

Gantt chart / Project Schedule for Final Year Project 1

Gantt chart / Project Schedule for Final Year Project 2

41

42

43

xii

LIST OF TABLES

Table No. Page

2.2 Properties of Aluminum 356-T7 7

3.6 Parameter Analysis 18

4.4 Nodes and elements tables with variable global mesh length 24

4.6 Result of maximum stresses from different crankshaft angle 28

xiii

LIST OF FIGURES

Figure No. Page

1.6 Flow chart of project 4

3.2 The outline of this project methodology 12

3.6(a) Sample of TET 4 with 0.4 global mesh length 16

3.6(b) Sample of TET 10 with 0.4 global mesh length 16

3.8.1 Upper piston dimension in mm 19

3.9 Crankshaft from side view and angle position 20

4.2 3D model geometry of upper crankshaft with using CAD 22

4.3 Force and constraints on the 3D model geometry 23

4.4.1 Von misses stress result for TET 4 and TET10 25

4.4.2 Tresca stress result for TET 4 and TET 10 25

4.4.3 Max principal result for TET 4 and TET 10 26

4.6.1 Maximum stresses contour at 0º crankshaft angle 29

4.6.2 Maximum stresses contour at 30º crankshaft angle 30

xiv

4.6.3

4.6.4

Maximum stresses contour at 270º crankshaft angle

Maximum stresses contour at 315º crankshaft angle

31

32

xv

LIST OF NOMENCLATURES

ρ Density

k Thermal conductivity

T Temperature

E Modulus of elasticity

σUTS Ultimate Tensile strength

P Pressure

mm Millimetre

E Exponent

Pa Pascal

MPa Megapascal

GPa Gigapascal

xvi

LIST OF ABBREVIATIONS

Al Aluminium

CAD Computer-aided Design

CAE Computer-aided Engineering

FE Finite Element

FEM Finite Element Modeling

FEA Finite Element Analysis

FVM Finite Volume Method

FDM Finite Different Method

2D Two Dimension

3D Three Dimension

TET Tetrahedral

cc Centimetre Cubic

CPU Central Processing Unit

MPC Multi Point Constraints

xvii

SAE Society of Automotive Engineers

ASME American Society of Magazine Editors

Max Maximum

Min Minimum

1

CHAPTER 1

INTRODUCTION

1.1 Background

UMP has come to a challenge to create a first national motorcycle engine with

six stroke system by taking Modenas motorcycle four stroke engines as the main subject

for the modification. The concept of the engine was inspired from Ducati motorcycle

engine system which has been the pioneer of this type of engine. There are few slight

differences between a six stroke motorcycle engine and a conventional motorcycle

engine where the engine was designed with additional piston and crankshaft at the upper

part of the cylinder block. The engine was initially use four stroke system but the

additional upper part will operate in the same cylinder which will add 2 extra strokes

from the upper cylinder. The six stroke system will increase the pressure ratio of the

compression stage thus the efficiency of the engine will be increased.

The six stroke engine also has additional crankshaft which directly attached to

the upper piston. This project will be specifically analyze this upper crankshaft using

CAE software since this is the first study to be carry out using simulation on this engine.

The failure analysis will be carried out and this project is focused on determination of

computational maximum stresses resulting from combustion pressure on the crankshaft

during steady state condition. Stresses that are involved due to above load are analyzed

using CAE software.

2

The crankshaft is the principal member of the crank train or crank assembly,

which latter converts the reciprocating motion of the pistons into rotary motion or vice

versa. As a rule, crankshafts are forged in a single piece, but occasionally they are built

up. Built-up crankshafts are used in small single- and double-cylinder motorcycle

engines. The enclosed flywheels of these engines take the place of the crank arms, the

crankpin and crank journals being bolted to the flywheels, which latter are cast with

solid webs. The built-up construction also has advantages when it is desired to support

the crankshaft in three or more ball bearings, as with a one-piece shaft all intermediate

bearings would have to be stripped over the crank arms, and therefore would have to be

made extraordinarily large.

Advanced engineering analysis and design validation are increasingly needed by

major manufacturers and designers. This frequently leads to an increase in the

sophistication of the methods and technologies required. The distance between solid

modellers and analysis engineers has nowadays almost disappeared. The three types of

software that used in this project are SOLIDWORK (CAD), Msc.PATRAN (CAE) and

Msc.NASTRAN(CAE). The analysis types that are use with the CAE software are Static

Stress with Linear Material Model. From the simulation result of the upper crankshaft,

locations of weak-spots can be located and the maximum stress at each location can be

analyzed.

3

1.2 PROJECT TITLE

Finite Element Analysis of Upper Crankshaft Six Stroke Engine Using CAE Software

1.3 PROJECT OBJECTIVES

To develop a structural design of upper crankshaft of six stroke engine.

Identify the suitable mesh properties for the simulation.

To analyze the stress of the crankshaft using finite element analysis (FEA) in

different orientation

1.4 PROJECT SCOPES

Structural modeling using SOLIDWORK.

Mesh optimization for the accurate simulation.

Finite Element modeling and analysis using MSC. Patran and MSC. Nastran.

1.5 PROBLEM STATEMENTS

This project will focus on the study of maximum stresses on an upper crankshaft

of six stroke motorcycle engine at steady state condition resulting from engine

combustion pressure during starting the engine.

4

1.6 FLOW CHARTStart

Determination on the objective, scope, and the problem statements

Literature review of journal and references books on methodology

Is design of experiment/methodology

acceptable?

1st presentation

Design using the SOLIDWORK

Analysis using PATRAN & NASTRAN

Input data from previous studies

Is the result acceptable?

Conclusion

Report

2nd presentation

End

Figure 1.6: Flow chart of project

Final Year Project 1

Final Year Project 2

No

No

Yes

Yes

5

CHAPTER 2

LITERATURE STUDY

2.1 SIX-STROKE ENGINE

The six-stroke engine is a type of internal combustion engine based on the four-

stroke engine, but with additional complexity to make it more efficient and reduce

emissions. Two different types of six-stroke engine have been developed since the

1990s.

In the first approach, the engine captures the heat lost from the four-stroke Otto

cycle or Diesel cycle and uses it to power an additional power and exhaust stroke of the

piston in the same cylinder. Designs use either steam or air as the working fluid for the

additional power stroke. The pistons in this type of six-stroke engine go up and down

six times for each injection of fuel. There are two power strokes: one with fuel, the other

with steam or air. The currently notable designs in this class are the Crower six-stroke

engine, invented by Bruce Crower of the U.S. ; the Bajulaz engine by the Bajulaz S.A.

company of Switzerland; and the Velozeta Six-stroke engine built by the College of

Engineering, at Trivandrum in India.

The second approach to the six-stroke engine uses a second opposed piston in

each cylinder that moves at half the cyclical rate of the main piston, thus giving six

piston movements per cycle. Functionally, the second piston replaces the valve

mechanism of a conventional engine but also increases the compression ratio. The

6

currently notable designs in this class include two designs developed independently: the

Beare Head engine, invented by Australian Malcolm Beare, and the German Charge

pump, invented by Helmut Kottmann.

Blair (1990) studied about two-stroke engine which is the piston controlled the

intake opening and closing that combine the intake and compression stroke in 180˚

crank rotation. For four-stroke engine, the cycle is more fuel-efficient, clean burning and

higher engine power output compare to the two-stroke engine due to higher volumetric

efficiency, higher combustion efficiency and low sensitivity to pressure losses in

exhaust system. A single-cylinder two-stroke engine produces power every crankshaft

revolution, while a single-cylinder four-stroke engine produces power once every two

revolutions (Rajput, 2005). The two-stroke engine operational concept is applied to the

original existing four-stroke engine cylinder head. The combination of this two engine

operation is called six-stroke engine. There will have two pistons which are upper piston

and the original four-stroke piston at the bottom in one cylinder of engine head. The

ratio of stroke between upper piston and original four-stroke piston is 4:2 (Beare, 1998).

2.2 ALUMINUM 356-T7 (Al 356-T7)

Aluminum's appearance is dulled and its reactivity is passivated by a film of

aluminum oxide that naturally forms on the surface of the metal under normal

conditions. The oxide film results in a material that resists corrosion. A unique

combination of properties makes aluminum one of our most versatile engineering and

construction materials. A mere recital of its characteristics is impressive. In term of light

weight, aluminum 356-T7 has a density (ρ) of 2.68 Mg/m³, compared with 7.9 Mg/m³

for iron. Hence, for the same component, the aluminum will be about one-third of the

mass of the iron version and make aluminum crankshaft is more lightweight compare to

cast iron crankshaft.

7

Aluminum has a great affinity for oxygen and any fresh metal in air rapidly

oxidizes to give a thin layer of the oxide on the surface. This surface layer is not

penetrated by oxygen and so protects the metal from further attack. This self-protecting

characteristic gives aluminum its high resistance to corrosion. Unless exposed to some

substance or condition that destroys this protective oxide coating, the metal remains

fully protected against corrosion (Kalpakjian, 1995). Next, aluminum has high thermal

conductivity compare to cast iron. The high thermal conductivity enables heat to be

more rapidly conducted away and so result in the crankshaft running at a lower

temperature and increase the crankshaft lifespan (Philip & Bolton, 2002).

At temperature (T) up to about 300 ˚C in the engine, the material used must

retain its properties (Rajput, 2005). High thermal expansion is however a problem for

aluminum. Table 2.2 gives properties data for aluminum 356-T7.

Table 2.2: Properties of Aluminum 356-T7

Material Aluminum 356-T7

Density, ρ (Mg/m³) 2.7

Poisson Ratio 0.35

Modulus of Elasticity, E (Gpa) 72.4

Ultimate Tensile Strength, σUTS (MPa) 172

Source: Budynas & Nisbett (2008)