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DESIGN & ANALYSIS OF DAMPER SPRING

AND DRIVE PLATE FOR CLUTCH ASSEMBLYFinal Year Project

Guided ByMr. K.E.Kumaraguru. M.E.

(Senior Lecturer)

Done By

J. Dilip Kumar - 11508102008

V. Kishore - 11508102020

R. Praveen Kumar - 11508102032

D. Vignesh Kumar11508102045

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Abstract Our Project deals with the failure analysis of clutch arising from

the daily operation of the vehicle and to provide an economicalsolution for the problem.

Most common failures occurring in the clutch system are

Damper Spring Failure, Drive plate fracture.

We aim to rectify this type of failure by re-designing and

analysing the Damper Spring for a specific type of clutch and

also by re-designing (updating) & analysing Drive plate for theproposed design of the spring.

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Scope Of The Project The Scope of our Project involves the Classical Design

Calculations for Damper Spring by considering appropriate

conditions. The 3D modeling of the parts such as the Damper

Spring and the Drive plate are to be done in Catia V5 R20

software. Also note that the Damper Spring Analysis is carriedout in Catia V5 R20 (Generative Structural Analysis Module).

The Pre-Processing works of Drive plate such as Meshing,

Material Definition, Load Definition, boundary definition areto be done in Hyper mesh 9.0 and Solution, Post Processing

such as stress and strain contour plot of various sections is to

be done using Abaqus 6.10 software.

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Introduction

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Types Of Friction Clutches

There are many types of friction clutches, yet the following are

the most important types:

1. Disc or plate clutches.

a) Single Plate Dry Clutch.

b) Wet Multi-Plate Clutch.

2. Cone clutches.

3. Centrifugal clutches

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Roles Of Clutch

To transmit the torque fully in engaged position role of the

facings (coefficient of friction and mean radius)

To restore the engine torque with progressivity role of the

cushion disc (Axial stiffness)

To filter the Torsional vibrations on the driveline in all

configurations role of the damper spring. (circumferential

stiffness and hysteresis)

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Clutch Working Procedure

Disengaging:

The clutch is disengaged by pushing the clutch pedal down

moving the pressure plate away from the friction disc.

Engaging :

Releasing the clutch pedal engages the clutch. Spring force

clamps the friction disc between the pressure plate and the

flywheel.

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Purpose Of Clutch

Torque Transmission:

Allow energy dissipation

Avoid SlippingAvoid high wearing

Withstand maximum Torque in Drive and Coast.

Torque Interruption:

Shift ability, Ergonomic, Noise

Avoid noise during gear-shifting

Avoid judder during re-engagement

Allow gear shifting without excessive pedal load

Filter Vibrations:

NVH Comfort

Filtering idle rattle-noise

Filtering "clack" rattle-noise

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Torque Flow

Flywheel

Clutch facing

Cushion plate

Retainer plate

Damper spring

Drive plate

Hub

Input shaft of Gearbox

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Role of Damper

It reduces vibrations while transmission of power from

engine to gear box. It absorbs the cyclic vibrations from the rotation of crankshaft-

flywheel-clutch.

These cyclic vibrations depend upon the inertia while

rotation of crankshaft-flywheel-clutch. These cyclic vibrations give rise to a rough clutch operation to

the driver.

Hence the presence of damper will eliminate these unnecessary

rough operating conditions.

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Damper Springs:

These springs are placed radially in the clutch disc assembly.

Absorbs the Vibrations produced during the engine operation.

These Springs will be compressed while transmitting torque and

absorbing torsional vibrations.

Cushion Disc:

It is placed between the two friction facings.

These cushion discs are slightly bent to an angle so that it takes up

crushing load or impact loading.

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Hysteresis curve

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PROBLEM DESCRIPTION

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We were assigned with the task of identifying, rectifying the problem

of particular type of clutch. Based on Customer Complaints & failure

reports, we listed out all causes of failures that occurred in the

clutches:

Damper Spring Failure.

Drive Plate Fracture.

Uneven Finger height.

Clutch Judder.

Scoring of pressure plate.

Face Wear. Clutch Drag.

Clutch Slip.

Spline Wear.

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Customer complaint report

CUSTOMER COMPLIANTS- April 07 to April 08

20

261

185 225

1028

52

145

180

100

0

200

400

600

800

1000

1200

Clutch not

working

Clutch hard Gear Shift

hard

Juddering Spring

Failure

Slip / Poor

pickup

Clutch

Jerking

Burnt /

Damage

Visually ok Other

Complaints

Models

No

ofPieces

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Result of graph

From the above we can see that the main type of failureand the cause for the clutch to fail or stop working is Damper

Spring Failure. This Graph reveals that the failure of Damper

Spring has occurred at least 1028 times since the start of

production in 2007.

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Root cause analysis:

We carried out further root cause analysis to find the reasonwhy the failure of clutch is occurring due to Damper spring

failure.

In our root cause analysis study we used 5W+2H and Fish

Bone Diagrams to single out our problem.

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5 W + 2H Analysis

What Happen?Clutch Failure (Hard gear

shifting)

Why is it a Problem? The car cannot be moved

When it happened? 2007- Present

Who detected? Customer end

Where detected Customer dealer endHow detected? During Vehicle running.

How Many? Refer graph.

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Our viewWhat symptom do we see on

the part?

i. Spring came out from Disc

assembly.

ii. Spring shear failure.Was part reworked by

company?

No

When was it manufactured at

company?

2007 (Start Of Production )

Who manufactured? Company Disc assembly line

operator

Is the product used in any other

application?

No

Does defect occur when part is

delivered to Customer?

No

Did a similar problem happenbefore?

No

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Fish Bone Diagram

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Man:

Based on the Service Report the Following was determined:

Clutch riding : It is not the cause of thisfailure

Frequent Clutch change : It is not the cause of this

failure

Improper Pedal Adjustment : Vehicles were checked forthis and this is not the

cause of failure

Clutch Design : To be reviewed.

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Spring Material Report

Sl.

No Test Parameters Specification

Company Material Report Supplier Material report

JudgmentCase 1 Case 2 Case 1 Case 2

1 Visual

Free from seams, pits,

die marks, uniform end

chamfer

OK OK OK OK OK

2 Chemistry

C : 0.50.6%

Mn : 0.50.8%

Si : 1.21.6%

S : 0.025%Max

P : 0.025%Max

Cr : 0.5 - 0.8%

0.53

0.68

1.29

0.02

0.015

0.7

0.55

0.70

1.35

0.021

0.015

0.65

Not Given Not Given OK

3 Hardness ~ 55 HRc 56 HRc 55 HRc 53 54 OK

4 MicrostructureFine Tempered

MartensiteConfirms Confirms Confirms Confirms OK

5 Decarb layer < 10 micronsNo decarb

noticed

No decarb

noticedNot Given Not Given OK

6 Shot peening coverage Min 90% Confirms Confirms Confirms Confirms OK

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Fish bone diagram

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Based on the spring material report, the spring meets the

chemical, Hardness & Microstructure Threshold References.

From the above condition material was eliminated.

All the factors show that the main problem is spring coming out of

the assembly.

This problem ofspring failure originates from Disc Assembly.

The only problem is found to be in the spring design under the

section Man fromsub division ofClutch Design, meaning the

clutch plate design had to be updated.

Conclusion of Root Cause Analysis

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DAMPER SPRING DESIGN

CALCULATION

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The Springs Physical Requirements:

Mean Coil Diameter DM (mm).

Wire Diameter D (mm).

Free Length (mm).

Solid Length (mm).

Stiffness (N/mm).

Deflection (mm).

Spring Index.

Number of coils.

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Assuming that the outer diameter of the spring to be 19.5mm.

To calculate the Mean Diameter (DM):DM = (D1D)

= (19.53.5)

DM = 16mm

To calculate the Coil ratio (C):

C = DM

/ D

= 16/ 3.5

C = 4.5 (Criteria: Should be more than 3.0)

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To calculate the Wahls factor (K):K = (4 x C)1 + 0.615

(4 x C)4 C

= (4 x 4.5)1 + 0.615(4 x4.5)4 4.5

K = 1.352

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To calculate the Stress ():= 8 W DM x K

D3= 8 x 670 x 16

x 1.352

x 3.53

= 860 N/mm2

Criteria: Should be less than 1100 N/mm2

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Factor of Safety (FOS):FOS = Ultimate Shear Stress

Working Shear StressFOS = 1100

860FOS = 1.3

To calculate the Deflection ():

= 8 W DM3 Nu

G D4

= 8 x 670 x 163 x Nu

83000 x 3.54

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Here both deflection and active no. of coils are unknown. So, by

assuming Active Coils the Deflection is obtained.

Assuming Nu = 4.5, we get

= 8 mm.

To calculate the Total Coils (n):

n = NU +1.5 (for squared and ground ends)

= 4.5 + 1.5

n = 6

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To calculate the Solid Length (LB):

LB = N x D

= 6 x 3.5

LB = 21mm

To calculate the Free Length (LF):

LF = Solid length + deflection + Clashing Allowance

LF = 21 + 8 + 1 mm

LF = 30 mm.

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To calculate Spring Rate (Stiffness) R:

R = G x D4

8 x DM3

x Nu

R = 83000 x 3.54

8 x 163 x 4.5

R = 84.4 N/mm.

The Specifications of this resultant design is acceptable according

to the Torque Application, Stress condition and Space considered.

It can be seen that all the parameters have been calculated and are

found to satisfy the design criteria. So, spring design is found to

be SAFE.

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3D MODELING OF THE DAMPER

SPRING

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THE LOGIC IN DESIGN

Stage I

(proto-

typing)

Stage II

(pilot

production)

Stage III

(Mass

Production)

If reviewneeded

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The modeling of spring was done in CATIA V5 R20 it is

obtained by using various techniques such as:

Surface Sweep. (with pulling direction)

Extract Boundary.

Rib Definition.

Pocket Definition. (for squared and ground ends)

Close surface.

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Modeled Spring From CATIA V5

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Finite Elemental Analysis Of Spring Using Catia

Generative Structural Analysis:Generative Structural Analysis:

The spring model was Meshed with a Tetrahedron structure with

the following definition:

Element Size: 1mmSag Size: 0.2mm

Mesh:

Entity Size

Nodes 44026

Elements 25165

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Element type:

Materials:

Connectivity StatisticsTE10 25165 ( 100.00% )

Material SteelYoung's modulus 3e+007N/m2

Poisson's ratio 0.3Density 7860kg/m3

Yield strength 2.5e+008N_m2

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Boundary Conditions:

One end of the spring and its washer (spring seat) has been fixed.

On the other face a Linear Distributed load of 1541 N has been

applied.

This load of 1541 N corresponds to Over torque condition (2.3 x

Max torque) of Engine.

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Meshed Spring:

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Static Case Solution - Deformed Mesh:

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Static Case Solution - Von Mises Stress

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Cut Sectional View:

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Static Case Solution - 1Principal Stress

Component:

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Conclusion (spring design)

As it can be seen from pictures and stress levels, critical stress is

not induced in the spring even at over torque conditions; hence

we conclude the design of the spring to be SAFE.

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Analysis Procedure For Drive Plate

Finite Elemental Analysis method is used to analyze the drive

plate (Pre-processing in hypermesh, solution and post-

processing in Abaqus).

Checked for over-torque and self load arising due to rotation.

Drive plate is made from DD11 steel with yield point at 300N/mm^2

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Continued

The load constraints are:

The teeth of the drive plate that mates with hub is provided

zero Degree of Freedom [no motion].

The Calculated spring load is applied on the face of the drive

plate window [1541 N].

Rotational load(centrifugal) constraint is provided for the drive

plate @[3500rpm].

Only static analysis is carried out.

The real time validation is done with the assembled unit withinthe customer premises and only the result date is flourished.

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Drafted Image Of Existing Drive Plate

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Modeled Drive Plate In Catia V5

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Meshed Drive Plate

Tetramesh with 2D set to tria and 3D to tetra element and feature angle is

set to 45

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Von Mises Stress Contour Of Drive Plate

The image shows the max. Von-Mises (in N/m2) stress plot on the

drive plate where the before mentioned load constraints are

provided and post-processed. The Max stress region is observed

in a region between the red and the orange domain on the plot.

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Von Mises Stress Plot On The Critical Region

Red and Orange domains are observed at the contact region of the

spring and the drive plate window.

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Von Mises Stress at Teeth Contact Point

Max stress region found at the teeth contact point of the drive

plate and the drive hub. These have been reduced in order to save

teeth damage.

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Strain Contour Plot Of The Existing Plate

It is evident from the above contour that the critically strained

region are those which have the direct contact with the

transmitting elements (spring, stop pin, drive hub).

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Strain at Teeth Contact Point

The critically strained region at the teeth contact point. This can be minimized

by increasing the thickness of the plate.

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Strain at Stop pin contact point

Critically strained region at the stop pin contact point. This can be diminishedby increasing the thickness of plate.

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Reason For The Re-design

With respect to the early design, the window size is more to

accommodate the new spring. So it has to be reduced, keeping

in mind that the damping characteristics of spring is under the

limit.

In order to reduce the max stress and the strain level in the

critical points the thickness is increased. The increased value is

chosen to be 3.5mm from various iteration on the design.

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Drafted Image Of New Design

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Modeled New Drive Plate In Catia V5

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Meshed Image Of New Plate

Tetramesh with 2D set to tria and 3D to tetra element and feature angle is

set to 45.

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Von Mises Stress Contour Of Drive Plate

The relieved stress contour plot upon increasing the thickness and under similar

load condition.

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Von Mises Stress Plot On The Critical Region

Relieved stress plot at the spring contact points on the drive plate window. The

image highlights the corner points where the stresses are diminished in

magnitude.

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Von Mises Stress at Stop Pin Contact Region

Relieved stress plot at the stop pin contact region.

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Strain Contour Plot Of The New Plate

Relieved strain contour plot on the drive plate.

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Strain at Hub Teeth Contact Regions

Relieved max. strain region on the hub teeth contact regions. Proves a saferdesign.

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Strain at Spring Contact Face & Stop Pin Region

Relieved max. Strain region at the Spring contact face and the stop pin

regions.

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Conclusion Based On Virtual Simulations

It is seen from the various stress contour of different section of

the drive plate, that the newer design has provided thesatisfactory result.

Due to the increase in the thickness increases the area of

contact with the stop pin and the spring, thereby reducing themaximum pressure that is imposed due the forces on the

elements.

The design is proposed for proto-typing at the Stage I of thedesign loop and the results are purely based on the assembled

testing. The components arent tested on individual bases.

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Real Time Validation

Spring Fatigue Test:

Test Condition:

The spring is subjected to axial dynamic testing from Free Length

to LMU for at least 6 x 106

cycles at ambient temperature (guidefrequency: 5 to 50 Hz, recommended value 33 Hz).

Test Result:

Spring has passed the 6 million cycle test.

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We planned to simulate Durability Test For Disc Assembly:

the existing failure in test lab. We made the new disc assembly

with existing design. After the disc assembly, we started the Over

Torque durability test until failure.

Test Condition:

Torque : 2.3 times of Engine TorqueNo. of Cycle : Till Failure.

Temperature : Room Temperature (28C)

Test Result:

Disc assembly has failed during the 1,56,875 cycles. Spring

failure is similar to field failure. So, confirmed that Drive Plate

center & Drive Plate profile design.

Conclusion:

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Conclusion:

In this project, we have considered all the relevant factors of

the types of failures, the different modes of failures of the

clutch and then identified the most common type of failure(damper spring failure).

The damper spring was modeled and analyzed in

Catia V5 R20. The Driveplate has been modeled in Catia V5R20 and the analysis were done with softwares such as

Hypermesh v9.0 and Abaqus 6.10.

The Company has validated our design by creating prototypesand then putting them through a series of bench tests, it is

found that the parts have substantially passed all the tests.