Faculty of Mechanical Engineering

SUBJECT : FINITE ELEMENT METHOD (SME3033) ASSIGNMENT : VALVE ANALYSIS BY USING FEMAP Ver 10.1.1 LECTURER : EN. AHMAD ZAFRI BIN ZAINUDDIN

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TABLE OF CONTENT

INTRODUCTION................................................................................................................................2

GEOMETRY, LOADING AND BOUNDARY CONDITIONS..........................................................9

MATERIAL.......................................................................................................................................14

RESULT AND DISCUSSION...........................................................................................................17

REFERENCES...................................................................................................................................20

TEAM MEMBERS

1. CHIN KOK WING

2. MOHD HAFIZ BIN MOHD RADZI

3. MOHD FARIDIS BIN MAT NAYAN

4. MOHD SYAH RULLACMAR BIN MOHAMED SHUIB

5. RIZLAN BIN ABDUL HAMID

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INTRODUCTION

An engine valve is a very important part of your engine running. It is in the head which is just

over the block and pistons. There are exhaust and intake valves. The camshaft triggers the valves

to go up at certain point to allow air and fuel in for intake and allow waste to get out through

exhaust. They return down with a spring and seal up the combustion chamber give you the

compression needed for the engine to run and the fuel to ignite and drive the pistons. Timing is

everything when it comes to valves or basically anything in an engine. Below is a picture showed

valve specifications and its component.

Figure 1: Intake and Exhaust Valves Functions and Arrangements

The valve arrangement in an engine controls the in and out movements of charge and

exhaust gases in the cylinders in relation to the piston positions in their bores. Now-a-days, this is

located in the cylinder head on all the engines. Among the commonly used sleeve, sliding, rotary,

and poppet type valves, the poppet-valve is most common because this offers reasonable weight,

good strength and good heat transfer characteristics.

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The most popular shape of the poppet-valve (Fig.2) for automobile application uses a

small cup at one end of the stem. The valve stem is placed in a guide hole made centrally in a

circular passage in the cylinder head. The valve disc head opens and closes the ported passage

leading to the cylinder during in and out movement of the stem.

Figure 2

Both inlet and exhaust ports are shaped to curve upwards and outwards emerging from one

or both sides of the cylinder head. It is normal to have one inlet and one exhaust valve and port

per cylinder. However, twin inlet and exhaust valve-and-port layouts are also adopted for some

high-performance or large capacity engines. Also, a few engines use twin inlets but only one

exhaust valve. Valves may be positioned vertically or slightly inclined relative to the cylinder

axis, matching the desired combustion chamber contour.

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Figure 3 : Valve arrangement

Problems

Valves are subject to both thermal and mechanical loads, the latter being applied by the springs

and actuating gear. All these loads are so severe as to justify an assertion that the valves are most

heavily loaded components in an engine. Modes of potential failure include Tensile Elongation or

fracture, either hot or cold corrosion, wear, burning, and flow of metal from the seating area, cold

corrosion being caused by condensation containing acid products of combustion. Nobody wants

engine problems such as oil consumption, a compression leak, valve train noise or an outright

valve failure. So every effort should be made to make sure everything that is worn or damaged is

replaced or reconditioned when rebuilding a cylinder head. But sometimes valve problems occur

anyway and lead to expensive comebacks.

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Weak springs or insufficient valve lash can also prevent good valve-to-seat contact and allow

excessive heat to build up in the valves. A loose seat or poorly fitting guide can also hinder heat

transfer to the head and contribute to burning.

Not paying attention to the installed valve height when doing a valve job can lead to burning.

When valves and seats are ground or cut, the valves sit deeper in the head than before. This

causes the stems to stick up higher which changes the rocker arm geometry and may lead to a

loss of valvelash when the engine gets hot. Two engines where this particular problem has been

turning up are the Ford 2300 OHC engine and the rear-wheel drive version of the Mitsubishi 2.6L

(which has hydraulic lash adjusters). If the proper geometry cannot be restored by grinding the

tips of the valve stems (no more than about .010 maximum or you run the risk of grinding

through the case hardened layer), the seats should be replaced to correct installed height (an

expensive fix but cheaper than a comeback). Another option is to install valves with slightly

oversized heads (.030 in.) that ride higher on the seat to compensate for seat machining.

Valve recession can cause the same kind of problem. As the seats wear away and the valves

recede into the head, valve lash is lost. Eventually there is little or no lash left and the valve

makes poor contact with the seat, overheats and burns. Valve recession tends to be more of a

problem on older engines that lack hard valve seats and are used in heavy-duty truck, marine,

agricultural or industrial applications. The cure here is to install hard seats. Stellite or hard faced

valves may also be necessary if the valves show evidence of erosion.

When the head of this valve fatigued and broke off, it stuck in the top of this forged piston. Had this been a cast piston, it would have shattered and probably the entire engine

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To avoid valve related problems down the road, do the following:

1. Analyze the amount of wear as well as wear patterns in the head and valve train components

when the head is disassembled. A careful inspection should reveal any abnormal conditions or

wear patterns that would indicate additional problems.

2. Inspect each and every component in the valve train and head so all worn or damaged parts can

be identified and replaced or reconditioned.

3. Keep a close watch over production quality so the parts that are being reconditioned are done

so correctly.

4. Pay attention to specs, critical dimensions and rocker arm geometry to assure proper

reassembly.

Figure 5 : Broken valve at stem end due to stress and tensile.

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Objectives of study case

A part from the problem mention above, we made a study case to tackle one of the problems and

to relate it in Finite Element Method. The problem that we want to prove is ‘what is the critical

point/stress at valve when applied some load in it.’ No hard and fast rules can be given to arrive

at a satisfactory valve life. Each case must be painstakingly investigated, the cause or causes

isolated and remedial action taken.

To comply what we have learn in subject Finite Element Method , we used a FEMAP software

when doing the analysis.

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GEOMETRY, LOADING AND BOUNDARY CONDITIONS

Figure 6 :Drawing & dimension

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Figure 7: Isometric View

Figure 8: Applied load at the head valve

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Technical Specification

ENGINE CODE : Campro S4PH

ENGINE CONFIGURATION : 1.6 liter 16V DOHC

Number of cyclinder : Inline – 4

DISPLACEMENT : 1597cc

BORE : 76 mm

STROKE : 88 mm

COMPRESSION RATIO : 10:1

VALVE TRAIN : Hydraulic Direct Acting

EMS Proton EMS700 Drive-By-Wire with detonation control

ANCILLARY DRIVE single Belt Auto Tensioner FEAD

CATALYTIC CONVERTER Single Close Couple Catalyst

PEAK PERFORMANCE POWER (Kw)

- TORQUE (Nm)

- 148@4000 rpm

Calculation :

FORCE

T = F x r

148 = F x (76x10 I ³ /2)

F = 3895 N

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Figure 9 : Applied constraint at the tip of valve.

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Figure 10 : Meshed geometry of the valve. The geometry used is solid geometry

Total Nodes : 15413Total Elements : 9336

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MATERIAL

CRITERIA OF EXHAUST VALVE • Resistance to high-temperature corrosion [ ~700°C ]

• Hot strength (endurance strength at high temperature ) [ ~500MPa ]

• Hot hardness [ strength at ~700°C ]

• Resistance to oxidation

• Resistance to seizing and galling

• Availability of material supplied

• Overall cost (material and manufacturing costs) [ moderate ]

Figure 11:

Copyright Granta Design Ltd, Cambridge, England. Reproduced with Permission.

Steel

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From the table shown above, the material that fulfill our criteria is only STEEL. Therefore we

eliminate nickel and so only left the steel group.

From the strength-temperature ashby chart, the suitable steel had been chosen is STAINLESS STEEL

Figure 12 : Copyright Granta Design Ltd, Cambridge, England. Reproduced with Permission. www.grantadesign.com

Stainless Steels are iron-base alloys containing Chromium. Stainless steels usually contain less

than 30% Cr and more than 50% Fe. They attain their stainless characteristics because of the

formation of an invisible and adherent chromium-rich oxide surface film. This oxide establishes

on the surface and heals itself in the presence of oxygen.

Steel NickelMelting Point( > 400°C ) √ √Tensile Strength (~500MPa)

√x

Cost of material (Moderate)

moderate relative to nickel

High relative to steel

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Stainless steels are commonly divided into five groups:

• Martensitic stainless steels

• Ferritic stainless steels

• Austenitic stainless steels

• Duplex (ferritic-austenitic) stainless steels

CRITERIA FOR MATERIAL SELECTION OF ENGINE VALVE SEAT INSERT

• Sufficiently wear resistant to avoid wear by the continuous pounding of the valve on it

• Strong enough to resist the hammering by the valve

• Sufficiently oxidation and corrosion resistance to prevent damage from impurities in the

fuel

• Hot Hardness and strength [ ~500MPa ] ( wear resistance at high temperature ) [ 700°C

(exhaust) ]

• High thermal conductivity ( to keep valve temperature within reasonable limits )

Since the engine valve and valve seat insert are operating at the same location in the automobile

engine block and experience the same condition ( high temperature cause by combustion of air-

fuel mixture ). So the group of the material that can be choose is similar with material of engine

valve that is Stainless Steel.

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RESULT AND DISCUSSION

Figure 13 : Deformed shape

Figure 14 : Higher stress at groove

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Result and Discussion

The Campro engine is the first automotive engine ever developed by the Malaysian automotive

corporation, Proton. The name Campro is short for Cam Profile. This engine powers the Proton

Gen-2, the Proton Satria Neo, the Proton Waja Campro as well as Proton's future models. The

Campro engine is aimed to show Proton's ability to make their own engines that produces good

power output and meets newer emission standards.

For our Project, we had using a real valve from Cam Pro engine. The technical specification as

provided shows that a maximum torque is 148 Nm at 6000 rpm. From this information we

calculated the maximum force that applied at the valve head when the engine was operate. The

value of maximum force is 3895 N.

To fulfill our objective of finding critical point/stress at valve when applied some load, this study

will make sure few assumption which includes:

a) No collision occurs between the valve and piston.

b) Power / force produced during the combustion process occur is fixed at all times.

c) There are no foreign objects in the combustion chamber during combustion process.

d) All of the components installed close to the engine valves operate properly.

Our group had used FEMAP software analysis for the components of the engine valve. The

results obtained showed that the groove faced maximum stress based on Von Mises Theory at

Element (ID 5221) is 106.044 KN/m² and the minimum stress at element (ID 2990) is 2518.523

N/m², while the stress on the other parts is at a safe level. This means failure might happen if

high force applied on the valve groove. The maximum deflection occurs at node (ID 34) is

1.51243E-6 m and the minimum deflection happen at node (ID 1) that the value is zero

(Constraint).

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 To cope with excessive stress occurs at the valve groove, we suggest that :-

1. Shrink the inner area of the groove, so that it can accommodate up to 1.3 MPa stress.

2. Shorten the groove height.

3. Changing the material used for the groove, using materials that have a higher yielding stress

that can withstand the stress 1.3 Mpa without fail.

Figure 15 : A typical tensile test curve for the steel

REFERENCES

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i. http://formula-first.org/html/tech_main.html

ii. http://what-when-how.com/automobile/intake-and-exhaust-valves-and-mechanisms-automobile/

iii. http://www.zerotohundred.com/newforums/proton/113915-campro-engine-informative.html