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)