FINITE ELEMENT ANALYSIS OF AUTOMOTIVE INTAKE MANIFOLD USING
CAE SOFTWARE
MUHAMMAD HAIKAL BIN HARON
A report submitted in partial fulfilment of the requirements
for the award of the degree of
Bachelor of Mechanical Engineering with Automotive Engineering
Faculty of Mechanical Engineering
UNIVERSITI MALAYSIA PAHANG
NOVEMBER 2008
ii
SUPERVISOR’S DECLARATION
We hereby declare that we have checked this project and in our opinion this project is
satisfactory in terms of scope and quality for the award of the degree of Bachelor of
Mechanical Engineering with Automotive/Manufacturing*
Signature
Name of Supervisor : Mohd Rashidi Maarof
Position : Lecturer
Date :
Signature
Name of Panel : Lee Giok Chui, SMP, KMN
Position : Lecturer
Date :
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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 concurently submitted for award of other degree.
Signature
Name : Muhammad Haikal bin Haron
ID Number : MH05066
Date :
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This project is dedicated to
both my beloved parents,
Haron Mohamed and Aishah Abd Rahman
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ACKNOWLEDGEMENTS
Alhamdulillah, all praises to the almighty god, Allah swt for the countless goodness
that are given to me and all the required necessity to complete this project.
I would also like to express my thanks and gratitude to Mr Mohd Rashidi bin Maarof,
supervisor of this project for all his endless supports, valuable ideas and guidance
throughout the project from the beginning until the end. I would also like to show my
sincere appreciation to Mr Ismail bin Ali, Jurutera Pelajar Faculty of Mechanical for his
kindness to permit me to use the equipments and apparatus in the Mechanical Laboratory
and all the valuable information he provided.
My sincere gratitude also to Mr Mohd Shahrir bin Mohd Sani who sacrificed his time
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 to my project and to finish in time.
Also thanks for his kindness to share his knowledge on the software.
Special thanks to my beloved parents and my loved ones for all their loves and
encouragement to excel in this project. Thanks for their continuous support through all
the hard time and for the dream they had for me.
I am grateful to express my sincere appreciation to all my lecturers and my fellow
undergraduates’ members 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 the person who had helped me learnt the required software.
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ABSTRACT
This project focused on simulation testing of automotive intake manifold design using
Computer Aided Engineering software. Finite element Random Vibration analysis is
conducted on Proton WAJA 1.6 intake manifolds designs for material cast aluminium
alloy AlSi12 and glass-fibred polyamide PA6 GF30. The purpose of this project is to
study the computational maximum stress on the model due to the effect of engine
vibrations and pressure pulsation loads. The input data of vibrations and pressure
pulsation loads are taken from previous studies. The softwares used are SOLIDWORK
2005 and ALGOR V16. Base on the simulation results obtained, the maximum stress of
both materials are compared to distinguish which is better in resisting the vibration loads
applied.
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ABSTRAK
Projek ini memfokuskan kepada ujian simulasi terhadap rekabentuk manifol pengambilan
automotif dengan menggunakan perisian kejuruteraan-bantuan-komputer. Analisis
Getaran Rawak finite elemen dijalankan terhadap rekabentuk manifol pengambilan untuk
kereta jenis Proton WAJA 1.6 yang diperbuat daripada bahan argentum aloi AlSi12 dan
poliamid gentian kaca PA6 GF30. Tujuan projek ini adalah untuk mengkaji regangan
maksimum pada model manifol akibat daripada getaran enjin dan denyutan tekanan yang
berada dalam manifol itu. Data input getaran dan denyutan tekanan itu diperolehi
daripada kajian-kajian lepas yang telah dijalankan oleh beberape penyelidik. Perisian
yang digunakan dalam projek ini ialah SolidWorks 2005 dan ALGOR V16. daripada
keputusan analisis yang diperolehi, regangan maksimum bagi kedua-dua bahan tersebut
dibandingkan untuk mengenal pasti bahan mana yang terbaik menahan getaran yang
dikenakan.
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TABLE OF CONTENTS
Page
SUPERVISOR’S DECLARATION ii
STUDENT’S DECLARATION iii
ACKNOWLEDGEMENTS v
ABSTRACT vi
ABSTRAK vii
TABLE OF CONTENTS viii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF NOMENCLATURES xiv
LIST OF ABBREVIATIONS xv
CHAPTER 1 INTRODUCTION
1.1 Background 1
1.3 Problem Statement 3
1.3 The Objectives 3
1.4 Project Scope 3
1.5 Flow Chart 4
1.6 Gantt Chart 5
CHAPTER 2 LITERATURE REVIEW
2.1 Intake Manifold – an overview 7
2.2 Air Intake System 8
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2.3 Materials 9
2.3.1 Cast Aluminium Alloy AlSi12 9 2.3.2 Polyamide Composite PA6 GF30 10
2.4 Engine Vibration 11
2.5 Pressure Pulsation 13
2.6 Power Spectrum Density 14
2.7 Couple Vibration and Pressure Loading Simulation 14
2.8 Software 15
2.8.1 SolidWorks 2005 15 2.8.2 ALGOR V16 16
CHAPTER 3 METHODOLOGY
3.1 Introduction 18
3.2 Methodology Flowchart 193.3 Reverse Engineering 203.4 Design 213.5 Export to CAE Software 23
3.5.1 Mesh Convergence analysis 23
3.6 Analysis 25
3.6.1 Natural Frequency (Modal) Analysis 25
3.6.2 Random Vibration analysis 26
3.7 Material Comparison 28
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Introduction 29
4.2 Mesh Convergence 304.3 Natural Frequency (Modal) Analysis 314.4 Random Vibration Analysis 32
4.4.1 Weak Spot Location 33 4.4.2 Results Validity 38
4.5 Material Comparison 40
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CHAPTER 5 CONCLUSION
5.1 Overall Conclusion 41
5.2 Recommendations 43
REFERENCES 44
APPENDICES
A Technical Drawing of Intake Manifold Design Model 46
B Comparison of Actual and cad design model 48
C Simplification of Intake Manifold Design Model 49
D Meshing Errors on The Intake Manifold Design Model 50
E Pressure Pulsation Load Data 51
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LIST OF TABLES
Table No. Page 2.1 Examples of automotive applications 10 2.2 An I4 Engine Duty Cycle Definition 12 4.1 Maximum Von-Mises stress of the intake manifold model with
respect to frequency and mode of vibrations 36
4.2 Comparison of maximum Von-mises stress for manifold model
material AlSi12 and PA6 GF30 at frequency 250Hz 38
4.3 Basic mechanical properties of PA6 GF30 and AlSi12 39
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LIST OF FIGURES
Figure No. Page 1.1 Flow chart of project 4 1.2 Gantt chart / Project Schedule for Final Year Project 1 5 1.3 Gantt chart / Project Schedule for Final Year Project 2 6 2.1 Typical intake manifold 7 2.2 Air induction system 8 2.3 A measured load contents of an engine 12 3.1 The outline of this project methodology 19 3.2 Design of Proton WAJA intake manifold model in CAD
environment 22
3.3 Boundary conditions of the model for Linear Model with Static
Stress Analysis 24
3.4 Free body diagram of the model 24 3.5 Sample of engine vibration load data 26 3.6 Application of engine vibration load data in the analysis parameter
option. 27
4.1 Mesh convergence results of intake manifold model. 30 4.2 Simulation result of Random Vibration analysis for the intake
manifold model. 32
4.3 Mode 1 weak spot location. 33 4.4 Mode 2 weak spot location. 34
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4.5 Mode 3 weak spot location. 34 4.6 Mode 4 weak spot location. 35 4.7 Stress PSD against frequency curve. 37
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LIST OF NOMENCLATURES
P Instantaneous power of vibration signal s(t) Vibration signal in time domain S(f) Vibration signal in frequency domain R(τ), Autocorrelation function f Frequency G(f) Power spectrum π Constant = 3.141592654
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LIST OF ABBREVIATIONS
AlSi12 Cast aluminium alloy with 12% Si PA6 GF30 Polyamide composite with 30% glass fibre CAD Computer-aided drafting CAE Computer-aided engineering FE Finite element PSD Power spectral density SAE Society of Automotive Engineers
CHAPTER 1
INTRODUCTION
1.1 Background
A properly designed intake manifold is essential for optimal functioning of an
internal combustion engine. Traditional intake manifold optimization has been based on
the direct testing of prototypes. This trial and error method can be effective, but
expensive and time consuming. Moreover this method cannot provide any information
about the actual structure properties of the intake manifold. One of the possible ways to
obtain this information within a reasonable amount of time and cost is to conduct
computational analysis.
Recently many studies have been carried out on flow through intake manifold in
the past using Computer Aided Engineering (CAE) software. However there are only few
studies of failure analysis for this automotive component using simulation. Hence this
project is focused on determination of computational maximum stresses resulting from
vibrations of operating engine and pressure pulsation load that occurs inside the intake
manifolds. Stresses that are involved due to above loads are analyzed using CAE
software.
Comparison of maximum stress on intake manifolds of different materials also is
done. The materials chosen for analysis are cast aluminium alloy AlSi12 and polyamide
PA6 GF30. The reason why these materials are chosen is because aluminium alloy is a
common material for intake manifolds while polyamide is a new trend in automotive
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industry to develop intake manifold by it. This comparison is done to determine which
material is better in term of maximum stress in withstanding the loads applied.
For the determination of the failure and wear causes, hands-on reverse
engineering approach is used. All the three type of intake manifolds are measured and the
parameters are transferred to CAD software. Later the CAD designs are analyzed using
CAE software. The two types of software that used in this project are SolidWorks (CAD)
and ALGOR V16 (CAE). The analysis types that are use with the CAE software are
Static Stress with Linear Material Model, Natural Frequency (Modal) analysis and
Random Vibration analysis.
From the simulation results of the intake manifold, locations of weak-spots are
located and the maximum stress at each location are analyzed and compared.
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1.2 Problem statement
This project will focus on the study of maximum stresses on an automotive intake
manifold design resulting from engine vibration and pressure pulsation loads.
1.3 Objectives
1. To carry out finite element stress analysis on an intake manifold design for
maximum stress using Computer Aided Engineering software.
2. To compare the maximum stress between two different materials for the intake
manifold.
1.4 Project Scope
The computational stress from finite element analysis will be carried out on a
Proton WAJA 1.6 intake manifolds design. It is decided that intake manifolds of a multi-
cylinder 1600cc internal combustion engine will be analyzed. The two different materials
that are chosen for analysis is cast aluminium alloy, AlSi12 which is common material
for intake manifold and polyamide PA6 GF30.
1.5 Flow Chart
Figure 1.1 Flow chart of project.
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1.6 Gantt Charts
WEEKS PROJECT ACTIVITIES
1 2 3 4 5 6 7 8 9 10 11 12 13 141 Discuss title and objectives 2 Discuss scope and problem statement 3 Chapter 1 4 Discuss the format of project 5 Literature - journals and ref. books 6 Discuss literature on the manifold 7 Discuss literature on CAD and CAE 8 Discuss literature on types of analysis 9 Chapter 2 - literature review 10 Discuss the analysis and methodology 11 Chapter 3 methodology 12 Preparation for presentation 1
Figure 1.2: Gantt chart / Project Schedule for Final Year Project 1
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WEEKS PROJECT ACTIVITIES
1 2 3 4 5 6 7 8 9 10 11 12 13 14
1 Literature review
2 Measure the dimension of intake manifolds
3 Design using SOLIDWORKS
4 Assemble the parts in SOLIDWORKS
5 Discuss on analysis, constraints and loads
6 Analyze manifold design using ALGOR
7 Analyze and discuss the simulation results
8 Conclude the project
9 Complete chapter 4 and 5
10 Prepare final report
11 Preparation for presentation 2
Figure 1.3: Gantt chart / Project Schedule for Final Year Project 2
CHAPTER 2
LITERATURE REVIEW
2.1 Intake Manifold – an overview
An intake manifold is one of the primary components regarding the performance of an internal combustion engine. An intake manifold is usually made up of a plenum, throttle body connected to the plenum and runners depending on the number of cylinders, which leads to the engine cylinder. A typical intake manifold is shown in Fig.1.4
.
Figure 2.1: Typical intake manifold
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2.2 Air Intake System
The main function of air intake system is to filter; meter and measure the air flow
into the engine cylinders. The air intake system consists of air filter and throttle body
assembly, which includes throttle valve, intake manifold and either fuel injectors or a
carburettor to inject fuel. The manifold consists of plenum chamber and manifold
runners. Cylinder head intake path and intake valves also form part of air intake system.
Figure 1.5 shows different parts of a general air intake system.
Figure 2.2: Air induction system [10]
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2.3 Materials
There are several types of material used to make intake manifolds. The materials
are cast aluminium alloy (AlSi12), magnesium alloy and polyamide composite (PA6
GF30) [14]. Locally, common intake manifolds are usually made of aluminium alloy.
The materials that used in this project for analysis are AlSi12 and PA6 GF30.
2.3.1 Cast Aluminium Alloy AlSi12
AlSi12 alloy is a common material widely used in automotive and general
engineering applications. It is also a material that most frequently encountered with in
automotive intake manifolds. It consist of about 87% Al, 12% Si, and the rest are Fe, Mn,
Zn, Mg, and Cu. [12]
The typical applications of this material are usually in casting intricate, thin-
walled components and pressure tight items which require very good corrosion
resistance, medium strength and high ductility. The mechanical properties are strongly
dependent on the casting method applied such as sand casting and gravity die casting.
Besides that, it also has excellent casting properties and can be produced by Hydro with a
low Fe-content. [11]
