Dynamics

Powertrain induced NVH

Stephanos Theodossiades

email: [email protected]

Wolfson School of Mechanical and Manufacturing Engineering

Loughborough University, Loughborough

United Kingdom

- Overview

- Investigation Strategy

- Transmission Rattle

- Axle Whine

Powertrain

All the components in a vehicle that contribute to the generation, transmission,

and distribution of drive torque to the wheels

Drivertrain

All the components required to deliver engine power to the road surface

Driveline

Assembly of the parts that transmit torque from the transmission to the wheels

How NVH issues initiate?

The continuous trend for increased engine power,

reduced vehicle weight and lower costs have driven developments towards lighter,

thinner components -> increased vibration levels in powertrains

The significant advances in the reduction of engine/aerodynamic/tyre noises have

brought to the forefront other powertrain noise sources, previously masked

Powertrain induced NVH Phenomena

Vehicle

shunt, boom

Clutch

whoop, judder

Axle Drive

whine

Drivetrain/Transmission

Clutch

whoop (200-500Hz) – knocking effect on clutch pedal during engagement/disengagement

and radiated noise in the driver foot area

judder (7-20Hz) – torsional rigid body mode of powertrain at low engine speeds due to

stick-slip motion between flywheel/friction disk and friction disk/pressure plate

Gearbox

rattle (below 2000Hz) – result of impacts between meshing gear teeth under various

loaded or unloaded conditions

whine (400-4000Hz) – tonal noise excited by meshing gears in the gear meshing

frequency or/and its multiples

Differential

whine (200-800Hz) – same mechanism as in gearbox

Drivetrain

shuffle/shunt (2-7Hz) – coupled rigid body torsional and axial low frequency oscillations of

the drivetrain system,

clonk-thud (500-5000Hz) – short duration transient response of metallic nature, usually

the result of a load reversal in the presence of backlash

Vehicle Cabin

boom (20-160Hz) – drumming noise, excited by engine orders due to coincidence

between structural modes of vehicle body and its acoustic cavity modes

The Plethora of NVH Concerns

Investigation Strategy

Experimentation (Down-cascading)

Vehicle test in the semi-anechoic chamber

Engine-transmission test bed

Electrically driven transmission-based rig

Single gear pair rig

Any public or commercial use requires the agreement of the author.

Gear teeth impact-induced oscillations in manual

transmissions promoting Gear Rattle

Problem definition - what is gear rattle?



Noise generated due to impacts between manual transmissions’ meshing gear

teeth in the presence of backlash and induced engine order vibrations

Mechanism of rattle

Types of rattle

- Idle rattle (clutch engaged, transmission in neutral, engine at idle rpm).

- Drive/Creep rattle (clutch engaged, any gear, 1200 - 2000 rpm).

Experimentation:

High and low rattle measurements

Spectral content:

Low rattle condition

Regime of Lubrication

Ra

h





Stribeck Curve

Boundary lubrication (λ < 1)

Mixed (1 ≤ λ ≤ 3)

Elastohydrodynamic (3 ≤ λ < 5)

Hydrodynamic (5 ≤ λ < 100)

N – normal applied load [N]

F

_f

– friction force [N]

h

– film thickness

Ra

– RMS

surface roughness

N

F

_f





1

3 5 10

100





Mathematical Formulation of Conjunctions:

(a)- Loose gear pairs

 

0 0 3 2 , 0 2 2 , 0 eq eq eq Lη r _{π h h} W u h h t t r Lη r _h W u          _  _              b p p w w

h



C



r φ



r φ

0 1 os

πη v l r

F

C



0

2

s eq f

πη L u

r

F

h



Pinion

Loose Wheel

W

F

h

cp

r

cw

r

os

r

W

Shaft

Lubricant

Lubricant between

gear teeth surfaces

Pinion

Loose Wheel

W

F

h

cp

r

cw

r

os

r

W

Shaft

Lubricant

Lubricant between

gear teeth surfaces

• Forcing elements for loose gears (analytical solution)

Petrov friction:

Flank friction:

Hydrodynamic impact load:

Lubricant film thickness:

Mathematical Formulation of Conjunctions:

(b)- Engaged gear pair

• Forcing elements for engaged gear (analytical solution)

Grubin’s relationship for load (W)

and lubricant film thickness (h

o

):

1₂ 2 2 1 2 ln 2 * * 2 1 2 ln 2 p l mv b δ πLE πlE W δ l b    _     _ _                     _{ }   _   _{  }       





8 ₁ 11

_*

11

2.076

x o x x

E lr

αηu

h

r

r

W











_

_

_

_









Since there is no relative

speed between shaft and

gear, no Petrov friction

Visous friction

Adhesive fricion

f v a v a

F

F

F

F

F









Pinion

Loose Wheel

W

F

h

cp

r

cw

r

os

r

W

Shaft

Lubricant

Lubricant between

gear teeth surfaces

Pinion

Loose Wheel

W

F

h

cp

r

cw

r

os

r

W

Shaft

Lubricant

Lubricant between

gear teeth surfaces

Mathematical Formulation of Conjunctions:

(c)- Reynolds’ solution

Converged shape

from Reynolds' 1-D solution

h



No Petrov friction for engaged

gear and analytical solution

for loose wheels

Visous friction

Adhesive fricion

f v a v a

F

F

F

F

F









Loose Wheel

W

F

h

cp

r

cw

r

os

r

W

Shaft

Lubricant

Lubricant between

gear teeth surfaces

Loose Wheel

W

F

h

cp

r

cw

r

os

r

W

Shaft

Lubricant

Lubricant between

gear teeth surfaces

3 3

6

2

h

p

h

p

h

h

h

u

v

x

x

y

y

x

y

t

















_





_



_



_

















_





_



_





_

_







_

Mathematical Formulation of Conjunctions:

(d)- Energy equation

2 ₂

2

compressive heating viscous heating convection cooling _{conduction cooling}

x e x x p c

v

p

θ

θ

v v θ

η

ρv C

k

x

z

x

z





















_

_





_











_



_



_



_













_

_

2

8

s p

ηu b

θ

h ρC

 

2 *

2

entr s

kπηu

R

θ

c Q

 

2 max max

2

'

'

i o o o o

bηu

uθ α h p

h

θ

bk

_{uα h p}

h



_











_



_







 





_











_

_







EHL conjunction

• In elastohydrodynamic films, the heat

is generated by compressive and

viscous heating

• Due to thin film thickness and a low

Peclet number, convective cooling can

be neglected

Hydrodynamic conjunctions

• In flank conjunctions, because of low

generated pressures, the effect of

compressive heating is neglected

• Due to relatively high film thicknesses

and a high Peclet number, conduction is

assumed to be insignificant

• Lubricant temperature rise in Petrov

bearings’ can be estimated as in

journal bearings

Mathematical Formulation of Conjunctions:

(e)- Effective viscosity

273 , 273

bulk bulk contact contact contact bulk contact

θ θ

      

    

EHL conjunction

• The effective temperature in the

contact is given by:

Hydrodynamic conjunctions

• Low generated pressures in

hydrodynamic contacts (flank and

Petrov bearing) do not cause a change

in viscosity, hence:

• The mean Hertizan pressure is:

1 2 *

'

4

m x

P E

p

r





 











• The effective viscosity in the contact is

a function of pressure and temperature,

as proposed by Houpert:

 

So m Z o o p α η p  _{   } _{ }         _{ }  __  _ _  _    _{ }   * 8 1 _{ln 9.67} 138 _{1 1} 138 1.98 10 α p

η η e



* 1050.6 129

0.0001

θ

η

e

   _   



Shaft and Bearing Dynamics – Coupled to Gear Dynamics

CAE Numerical Model



All the numerical models were created following Newton-Euler’s formulation



The gear bodies are assumed to be rigid (except for local contact deformation)



The transmission casing is a deformable body

Input shaft 1st_{Output shaft} 2nd_{Output shaft} D iff eren tia l 1st 2nd 5th 3rd 4th 6th Rev. 1

F

2

F

3 F 4

F

6

F

5

F

rev

F

1 fd

F

2 fd F Input shaft 1st_{Output shaft} 2nd_{Output shaft} D iff eren tia l 1st 2nd 5th 3rd 4th 6th Rev. 1

F

2

F

3 F 4

F

6

F

5

F

rev

F

1 fd

F

2 fd F

Natural Frequencies of the Torsional Linear System

Lubricant Stiffness

 

_



















1 0

cos

sin

p i i sp i i cp i i

K

K

pn

K

pn

K











0

6 1 0









 i i wi in pi pi i in in

K

r

r

r

I



















0

)

(

I

₁



I

_prev







_1,prev



K

₀₁

r

_w1

r

_w1



_1,prev



r

_p1



_in



K

_0(rev)

r

_prev

r

_prev



_1,prev



r

_wrev



_wrev





_{2 2 2}



0

2 02 2 2



K

r

w

r

w



r

p in



I













_{3 3 3}



0

3 03 3 3



K

r

w

r

w



r

p in



I













_{4 4 4}



0

4 04 4 4



K

r

w

r

w



r

p in



I













_{5 5 5}



0

5 05 5 5



K

r

w

r

w



r

p in



I













_{6 6 6}



0

6 06 6 6



K

r

w

r

w



r

p in



I













_1,



0

0







_{rev wrev wrev wrev prev prev}

wrev

wrev

K

r

r

r

I











Linearised Equations of Motion

 

1

₂

~

h

h

W

K

i i i

_







0

1 1 1 1 1 4 1 1 1 1 1 1

















y

K

x

K

K

K

K

x

M

_{x x y} i in in x rev rev x i i x











0

1 1 1 1 1 4 1 1 1 1 1 1

















y

K

x

K

K

K

K

y

M

_{y x y} i in in y rev rev y i i y











0

1 1 2 1 1 2 6 5 2 2 2 1 21 2 2



















y

K

x

K

K

K

K

K

x

M

_{x x x y} i in in x rev rev x i i x x













0

1 1 2 1 1 2 6 5 2 2 2 1 21 2 2



















y

K

x

K

K

K

K

K

y

M

_{y x y y} i in in y rev rev y i i y y













Natural Frequencies and Mode Shapes of the Linearised System (1)

2 3 4 5 6 7 -40 -30 -20 -10 2 3 4 5 6 7 -35 -30 -25 -20 -15 -10 -5 2 3 4 5 6 7 -30 -20 -10 10 ωn = 138Hz 1st Gear Reverse Gear 2nd Gear ωn = 193Hz ωn = 225Hz 1st Gear 4th

Gear Reverse Gear

2 3 4 5 6 7 -50 -40 -30 -20 -10 2 3 4 5 6 7 -40 -30 -20 -10 2 3 4 5 6 7 -80 -60 -40 -20 4th Gear ωn = 258Hz 3rd Gear ωn = 359Hz 6th Gear ωn = 438Hz

Natural Frequencies and Mode Shapes of the Linearised System (2)

2 3 4 5 6 7 -80 -60 -40 -20 5th Gear ωn = 1080Hz 1 X Hz n 1775



1 X Hz n 1775



1 Y Hz n 1800



1 Y Hz n 1800



2

X

Hz

n



1989



2

X

Hz

n



1989



2

Y

5th_Gear

Hz

n



2146



2

Y

5th_Gear

Hz

n



2146



RMS Values of the Idle Gears’ Rotational Accelerations with respect to Temperature:

(a) 1st, (b) 2nd and (c) 6th gear

20 30 40 50 60 20 30 40 50 Rad/s2 C (a) 20 30 40 50 60 30 60 90 Rad/s2 C (b) 20 30 40 50 60 15 25 35 Rad/s2 C (c)

Model predictions – creep rattle conditions

Engaged gear wheel:

Loose gear wheel:

• Meshing frequency dominates

• Improper meshing

• Input energy converted to rattling at engine

order harmonics

Transient at 60C Transient at 50C Grubin at 60C Grubin at 50C Analytical (Grubin) Numerical transient

Comparison of load per EHL conjunction under

transient and analytical quasi-static conditions (60

o

_C)

Transient history of central oil film thickness

of typical loaded gear teeth pair

EHL of an engaged gear

Temperature variation for one meshing cycle (EHL - Hydrodynamic conditions)

EHL (inlet temperature of 20



C)

Hydrodynamic (inlet

temperature of 60



C)

Shaft/Gear Wheel conjunction

(inlet temperature of 60



C)

Impulsion ratio



Impulsion ratio ( )



If < 1  Decelerative motion of loose gears



If = 1  Uniform motion



If > 1  Accelerative motion



Three aspects may be controlled



Clearance between loose wheel and retaining shaft



Viscosity ratio (in the flank and Petrov bearing conjunctions)



Inertia is a controllable parameter (however it should not affect

torque transmission when engaged)

pet f drive m drag pet

C

T

I

T

h









m

I

Measured response with medium rattle input (DMF)

• Wavelet response of accelerometer output from

transmission casing (lower shaft bearing cap)

• Low-medium spectral content agrees with

numerical predictions

• High spectral content is due to modal behaviour

of casing

• Wavelet response of microphone output

positioned 1 metre from bearing cap

•Structure-borne noise identified, commensurate

with wave propagation through solid and air

• Noise response at point (B) in microphone signal

corresponds to structural vibration at point (A)

Literature

- M. De la Cruz, W.W.F. Chong, M. Teodorescu, S. Theodossiades and H. Rahnejat. Transient mixed thermo-elastohydrodynamic lubrication in multi-speed transmissions. Tribology International, 2012, 49, 17-29.

- M. De la Cruz, S. Theodossiades, P. King and H. Rahnejat. Transmission drive rattle with thermo-elastohydrodynamic impacts: Numerical and experimental investigations. International Journal of Powertrains, 2011, 1(2), 137-161.

- De la Cruz, M., Theodossiades, S. and Rahnejat, H. An investigation of manual transmission drive rattle. Proceedings of the Institution of Mechanical Engineers Part K: Journal of Multibody Dynamics, 2010, 224(2), 167-181.

- Tangasawi, O., Theodossiades, S., Rahnejat, H. and Kelly, P. Non-linear vibro-impact phenomenon belying transmission idle rattle. Proceedings of the Institution of Mechanical Engineers, Part C, Journal of Mechanical Engineering Science, 2008, 222(10), 1909-1923.

- Tangasawi, O., Theodossiades, S. and Rahnejat, H. Lightly loaded lubricated impacts: idle gear rattle. Journal of Sound and Vibration, 2007, 308(3-5), 418-430.

- Theodossiades, S., Tangasawi, O. and Rahnejat, H. Gear teeth impacts in hydrodynamic conjunctions promoting idle gear rattle. Journal of Sound and Vibration, 2007, 303(3-5), 632-658.

- Grubin, A. N. Contact stresses in toothed gears and worm gears. Book 30 CSRI for Technology and Mechanical Engineering, Moscow DSRI Trans. 1949;337

- Snidle, R.W. and Evans, H.P. Elastohydrodynamics of gears. Trib. Series (Elsevier Sci.). 1997;32:271-280

- Evans, C. R. and Johnson, K. L. Regimes of traction in EHD lubrication. Proc. IMechE, Part C: J. Mech. Engng. Sci. 1986;200:313-324 - Gohar, R. and Rahnejat, H. Fundamentals of tribology, Imperial College Press, London. 2008

- Greenwood, J. A. and Tripp, J. The contact of two nominally flat rough surfaces. Proc. IMechE, J. Mech. Engng. Sci. 1970-71;185:625-633 - Li, S and Kahraman, A. A transient mixed elastohydrodynamic lubrication model for spur gear pairs. Trans. ASME, J. Trib. 2010;132

- Wang, K. L. and Cheng, H. S. A numerical solution to the dynamic load, film thickness and surface temperatures in spur gears, Part I – Analysis and Part II – Results. ASME Journal of Mechanical Design. 1981a;103:177-187, 1981b;103:188-194

- Hua, D. Y. and Khonsari, M. Application of transient elastohydrodynamic lubrication analysis for gear transmissions. STLE Trib. Trans. 1995;38:905-913

- Brancati, R., Rocca, E. and Russo, R. A gear rattle model accounting for oil squeeze between the meshing gear teeth. Proc. IMechE , Part D: J. Automobile Engng. 2005;219:1075-1083

- Houpert, L. New results of traction force calculations in elastohydrodynamic contacts. Tran. ASME, J. Trib. 1985;185:241-248 - Stribeck, R. Die Wesentliechen Eigenschaften der Gleit und Rollenlager. Z. Ver. Dt. Ing. 1902;46;38:1341-1348,1432-1438 and 1902;46;39:1463-1470.

- Rahnejat, H. Computational modelling of problems in contact dynamics. Engineering analysis. 1985;2:192-197

- Rahnejat, H. Multi-body Dynamics: Vehicles, Machines and Mechanisms, Professional Engng. Publ. (IMechE) and SAE (Joint publishers), London, UK and Warrendale, PA, USA. 1998.

- Gohar, R. Elastohydrodynamics. Imperial College Press, London. 2001

Gear vibrations in automotive differentials promoting

Axle Whine

Vehicle tests

front of Vehicle Wheels Z Nose Acceleration Y Nose Acceleration

Mic1: Driver’s ear Mic2: Back of the cabin Mic3: Underbody of vehicle

Y X Z Mic 2 Mic 3 Mic 1

Measurements

Wavelet of signal from the rear cabin microphone

Wavelet of microphone data from differential nose

Vibration Intensity Znose - Temperature

0 0.5 1 1.5 2 2.5 3 3.5 0 200 400 600 800 Frequency (Hz) In te g ra te d P o w e r Test 14 - 49C Test 16 - 51C Test 20 - 61C Test 26 - 68C

Methods of investigation

MDOF rear axle multibody model

(ADAMS) - Large Scale

Contact ellipse at mesh point of

gear pair - Micro Scale

S-bend of leaf springs with twist

of the rear axle (at 356 Hz)

RWD Driveline Model

Butterfly mode with multiple

leaf spring bending (at 772 Hz)

Gear pair model

Free body diagram

Equations of motion

)

(

)

(

)

(

)

(

)

(

)

(

0 0

t

e

dt

t

R

dt

t

R

t

x

t t g p g t t p p p



















































b

x

b

x

b

x

b

b

x

b

x

x

f

_g

,

,

0

,

)

(

…or 1 DOF!

 

p m g

   

p m p g

 

g g g g

R

c

x

R

k

f

x

T

I























 

p m p

   

p m p g

 

p p p p

R

c

x

R

k

f

x

T

I





















p



g



   

k

f

(x

)

R

_p



_{p m}



_{p g}

 

p m p

c

R



x

 

p m g

c

R



x

pinion

gear

p

T

g

T

   

k

f

(x

)

R

_g



_{p m}



_{p g}

Contact Properties

Geometrical

Data

Numerical

Simulation of Gear

Mesh – Tooth

Contact Analysis

(TCA)

_{Load distribution}

Contact area

Rigid body

deflection

Meshing properties (1)

Mesh Stiffness k

_m

Pinion Contact Radius

Meshing properties (2)

Gear Contact Radius

Gear pair dynamics

0 0.2 0.4 0.6 0.8 1 1.2 80 90 100 110 120 130 140  mesh/n m a xi m u m d isp la ce m e n t (  m )

single DOF - reduced order system double dof system

Effect of sliding – frictional properties

Friction coefficient and corresponding Torque

Pinion speed 1800 RPM

(continuous contact)

Pinion speed 3600 RPM

(loss of contact)

Thermal effects

Lubricant Temperature and viscosity variation

Pinion speed 1800 RPM

(continuous contact)

Pinion speed 3600 RPM

(loss of contact)

Tooth Contact Analysis

(TCA)

Elastohydrodynamic Lubrication (EHL)

Tribo-dynamic

behaviour of

engaged gears

Flank data,

Machine setting

and assembly

parameters

Surface

velocities,

applied

load and

surface

radii

Film thickness, friction

force, efficiency,

extrapolated equation

Elasto-hydrodynamic lubrication

Contact footprint and

direction of angled flow

Instantaneous contact footprint

orientation with respect to direction

of lubricant entrainment

Pressure Distribution and Film Thickness

pinion angle Load [N]

Magnitude of Velocity [m/s] Velocity Along Minor Axis [m/s] Velocity Along Major Axis [m/s] Surface Radius in Minor Axis [m] Surface Radius in Major Axis [m] 0.5027 744.5161 18.0398 7.9751 16.1813 0.0157 1.0067

pinion angle Load [N] Velocity [m/s] Magnitude of

Velocity Along Minor Axis

[m/s]

Velocity Along Major Axis

[m/s] in Minor Axis [m] Surface Radius in Major Axis [m] Surface Radius

0.9582 5764.1 15.7962 8.9823 12.9938 0.0180 1.2578

Film thickness comparison to

other known methods

Friction coefficient variation

during the meshing cycle

Literature

- Cheng, Y., Lim, T.C. (2001), Vibration analysis of hypoid transmission applying an exact geometry based gear mesh theory, Journal of Sound and

Vibration, 240(3), pp. 519-543

- Cheng, Y, Lim, T.C. (2003), Dynamics of hypoid gear transmission with non-linear time-varying mesh characteristics, Trans. ASME, Journal of

Mechanical Design 125, pp.373-382.

- Wang, J., Lim, T.C., Li, M. (2007), Dynamics of a hypoid gear pair considering the effects of time-varying mesh parameters and backlash nonlinearity, Journal of Sound and Vibration, 229(2), pp.287-310.

- Vaishya, M., Singh, R. (2003), Strategies for modelling friction in gear dynamics, Trans. ASME, J of Mech Design, 125, pp. 383-393

- Kar, C. and Mohanty, A.R. (2007), An algorithm for determination of time-varying frictional force and torque in a helical gear system, Mechanism

and Machine Theory, 42, pp. 482-496

- Xu, H. and Kahraman, A. (2007), Prediction of friction-related power losses of hypoid gear pairs, Proc, IMechE, J. Multibody Dyn. 221, 387-400 - Vijayakar, S. 1998, Tooth Contact Analysis Software: CALYX, Advanced Numerical Solutions, Hilliard, OH

- Gosselin, G., Guertin T., Remond, D., and Jean, Y. 2000, Simulation and experimental measurement of the transmission error of real hypoid gears

under load, Journal of Mechanical Design, 122, pp.109-122

- Borner, J., Houser, D., 1996, Friction and Bending Moments as Gear Noise Excitations, SAE paper 961816

- M. Mohammadpour, S. Theodossiades and H. Rahnejat. Elastohydrodynamic lubrication of hypoid gear pairs at high loads. Proc. of the Inst. of

Mech. Eng. Part J: Journal of engineering Tribology, 2012, 226(3), 183-198.

- I. Karagiannis, S. Theodossiades and H. Rahnejat. On the dynamics of lubricated hypoid gears. Mech. and Mach. Theory, 2012, 48, 94-120. - G. Koronias, S. Theodossiades, H. Rahnejat and T. Saunders. Axle whine phenomenon in light trucks: a combined numerical and experimental investigation. Proc. of the Inst. of Mech. Eng. Part D: Journal of Automobile Engineering, 2011, 225 (7), 885-894.

- Rahnejat, H. (Ed.) Tribology and dynamics of engine and powertrain, Woodhead Publishing Ltd., Cambridge, UK, 2010 - Denny, C.M., “Mesh friction in gearing”, AGMA, Technical Paper No. 98FTM2, 1998

- Michlin, Y. and Myunster, V., “Determination of power losses in gear transmissions with rolling and sliding friction incorporated”, Mech.Mach.

Theory, 37, 2002, pp. 167-174

- Benedict, G.H. and Kelly, B.W., “Instantaneous coefficients of gear tooth friction”, Trans. ASLE, 4, 1960, pp. 59–70

- Velex, P. and Cahouet, V.“Experimental and numerical investigations on the influence of tooth friction in spur and helical gear dynamics”, Trans.

ASME, J. Mechanical Design, 122, 2000, pp. 515–522.

- Velex, P. and Sainsot, P. “An analytical study of tooth friction excitations in errorless spur and helical gears”, Mechanism and Machine Theory, 37,

2002, pp. 641–658.

- Litvin, F. L., Fuentes, A., Fan, Q. and Handschuh, R. F. “Computerized design, simulation of meshing, and contact and stress analysis of face-milled formate generated spiral bevel gears”, Mech. & Mach. Theory, 37, 2002, pp. 441–459

- Kolivand, M., Li, S. and Kahraman, A. “Prediction of mechanical gear mesh efficiency of hypoid gear pairs”, Mech. & Mach. Theory,45, 2010, pp.

1568–1582

- Simon, V., Influence of machine tool setting parameters on EHD lubrication in hypoid gears, Mech. & Mach. Theory, 44, 2009, pp. 923–937 - Vaishya, M. and Singh, R. “Analysis of periodically varying gear mesh systems with Coulomb friction using Floquet theory”, JSV., 243, 2001, pp. 525-545

- Akin, L. S., “EHD lubricant film thickness formulae for power transmission gears”, Trans. ASME, J. Lubn.Tech., 1974, pp.426-431

- Naruse, C., Haizuka, S., Nemoto, R., and Umezu, T.,“Limiting loads for scoring and frictinal loss of hypoid gear”, Bull. JSME, 29(253), 1986, pp.

2271-2280

Impact induced vibrations in vehicular drivelines promoting

Clonk (or Clunk!) Noise

Shuffle and Shunt

Shuffle

is the first rigid body torsional vibration mode of the entire powertrain system.

It is in the range 3-7 Hz.

It can be noted with sudden throttle tip-in from coast to drive condition, or conversely in

back-out by sudden release of throttle (tip-out) from drive to coast.

It is usually noted by the coupled fore and aft motion of the vehicle, referred to as

shunt

(a translational motion at the same frequency as the shuffle response).

Shuffle can also be induced by sudden clutch engagement or release.

It also manifests itself when negotiating a speed breaking bump.

It is most prominent at low road speeds and in low gear.

1st clonk

Time

Torque

2nd clonk

3rd clonk

shuffle

frequency 3-7 Hz

The shuffle action of the drivetrain leads to torque reversals as impact action takes

place in transmission and differential meshing teeth, as well as in the propshaft joints,

Clonk

accompanies shuffle with sudden demands in throttle tip-in/tip out or with abrupt

clutch in low gear and at low engine speed actuation (1.5-5KHz).

Clonk

is an audible and tactile response from the driveline, which may occur under

several different driving conditions, as follows:

Tip-in clonk

, when the throttle is rapidly applied from coast.

Tip-out clonk

, when the throttle is abruptly released from drive.

Clutch engagement clonk

may occur after gear selection, if the clutch is rapidly

engaged. It is more noticeable during low speed creep manoeuvres and low gear.

Shift clonk

may occur during a gear up-shift.

The resulting torsional impulse delivered to the driveline gives rise to a short duration

vehicle jerk and an accompanying metallic clonk or thud noise.

Important parameters affecting shuffle and clonk are:

- Lash zones in the drivetrain: transmission gear pairs, differential unit gears and

splined joints.

- Sources of compliance in the system, such as the dual mass flywheel torsional

stiffness, the torsional stiffness of the clutch, the presence of any clutch system

pre-damper, the stiffness of the rear-axle half-shafts and driveshafts in rear wheel drives,

the longitudinal stiffness of the tyre.

- The clonk response refers to coincidence of structural waves with modes of

acoustic cavities, such as in the transmission bell housing, the hollow driveshaft

tubes and the differential unit cavity.

Experimental results

-150

-100

-50

0

50

100

Time

A c c e le ra tio n

A p p lie d

to rq u e

Torque

1 - 2 ms impact

50 ms decay transient

The three-piece

driveline

experimental rig

A: Accelerometer Location L: Laser Location M: Microphone Location A

M

M

M

L

L

L

A A A Driveshaft(2)

Transmission Driveshaft(3) Differential Motor Driveshaft(1) Clutch Pedal Centre Bearing(1) Centre Bearing(2)

Positions of all

monitoring

equipment

Solid flywheel configuration – Wavelets of the clonk noise signal for the (a) front, (b) middle and (c) rear shafts

(a)

(b)

(c)

Clonk

accelerative noise (impact)

Ringing noise

Clonk

accelerative noise

(impact)

Clonk

accelerative noise (impact)

(a)

(b)

Clonk

accelerative noise (impact)

Ringing noise

Clonk

accelerative noise (impact)

Driveline Tubes

Rear Wheel Axles

Input-Output Shafts

Flexible

Components

Introduced by FEA

Techniques and

applying the

component mode

synthesis method

Clonk Investigation in a light truck

Transmission

(Helical Gears)

Differential

(Hypoid Gears)

Calculation of the developed forces between mating teeth pairs

during the meshing cycle through external code and introduction

in the model in real time (elastodynamics, elastohydrodynamics)

3.6E+008 3.9E+008 4.2E+008

φ ( ω

₁

t),

₁

pinion

gear

φ ( , ω

₂

t)

₂

k t)

(

R

₁

R

₂

pinion

gear

b

b

Line of Action

0.05 0.1 0.15 0.2 440 442 444 446 448 450 452

Gear Meshing Stiffness (N/μm) Variation with Respect to the Roll

Angle (rad) (Second Gear Set - One Cycle, Unmodified Gears).

0.05 0.1 0.15 0.2 0.25 420 425 430 435 440 445

Gear Meshing Stiffness (N/μm) Variation with Respect to the Roll

Angle (rad) (Second Gear Set - One Cycle, Modified Gears).

Any public or commercial use requires the agreement of the author.

Mode shapes of the main breathing modes observed in clonk noise measurements and numerical results

1830 Hz

1838 Hz

2312 Hz

2338 Hz

2454 Hz

2457 Hz

2502 Hz

2678 Hz

2871 Hz

3348 Hz

2718 Hz

2857 Hz

3540 Hz

3634 Hz

Literature

- R. Krenz, Vehicle response to throttle tip-in/tip-out. SAE Technical Paper Series 850967 (1985).

- A. Laschet, Computer simulation of vibrations in vehicle powertrains considering nonlinear effects in clutches and manual transmissions. SAE Technical Paper Series 941011 (1994).

- S. J. Hwang, J. L. Stout and C. C. Ling, Modeling and analysis of powertrain torsion response. SAE Technical Paper Series 980276 (1998). - M. Menday, H. Rahnejat and M. Ebrahimi, Clonk: an onomatopoeic response in torsional impact of automotive drivelines. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 213 (1999) 349-357.

- S. Vafaei, M. Menday and H. Rahnejat, Transient high-frequency elasto-acoustic response of a vehicular drivetrain to sudden throttle demand. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 215 (2001) 35-52.

- A. Farshindiafar, M. Ebrahimi, H. Rahnejat and M. Menday, High frequency torsional vibration of vehicular driveline systems in clonk. International Journal of Vehicle Design 9 (2002) 127-149.

- J. W. Biermann and B. Hagerodt, Investigation into the clonk phenomenon in vehicle transmission-measurement, modelling and simulation. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 213 (1999) 53-60.

- F. Petrone, G. Fichera and M. Lacagnina, A numerical model to analyze the dynamic response of a vehicle to variations in torque transmitted by the driveline. SAE Technical Paper Series 2001-01-3334 (2001).

- C. K. Chae, Y. W. Lee, K. M. Won and K. T. Kang, Experimental and analytical approach for identification of driveline clunk source and transfer path. SAE Technical Paper Series 2004-01-1231 (2004).

- Theodossiades, S., Gnanakumarr, M., Rahnejat, H. and Kelly, P. On the effect of dual mass flywheel upon impact induced noise in vehicular powertrain systems. Proc. of the Inst. of Mech. Eng. Part D: Journal of Automobile Engineering, 2006, 220 (6), 747-761.

- Theodossiades, S., Gnanakumarr, M. and Rahnejat, H. Root cause identification and physics of impact induced driveline noise in vehicular powertrain systems. Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2005, 219, 1303-1319. - Gnanakumarr, M., Theodossiades, S., Rahnejat, H. and Menday, M. Impact Induced Vibration in Vehicular Driveline Systems: Theoretical and Experimental Investigations. Proc. of the Inst. of Mech. Engineers Part K: Journal of Multi-body Dynamics, 2005, 219, 1-12.

- M. Gnanakumarr, S. Theodossiades, H. Rahnejat and M. Menday, Elasto-multibody dynamic simulation of impact induced high frequency vehicular driveline vibrations. Proceedings of the ASME IMECE 2003, Washington, USA, 2003.

- S. Theodossiades, M. Gnanakumarr, H. Rahnejat and M. Menday, Mode identification in impact-induced high-frequency vehicular driveline vibrations using an elasto-multibody dynamics approach. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 218 (2004) 81-94.

- K. R. Fyfe and F. Ismail, An investigation of the acoustic properties of vibrating finite cylinders. JSV, 128(3) (1989) 361-375.

- Moetakef, M., Bresky, A., Zilberman, M., Pham, T. et al., "Reducing High Frequency Driveshaft Radiated Noise by Polymer Liners“, SAE Technical Paper 2005-01-3554, 2005, doi:10.4271/2005-01-3554.

- Nitin Y. Wani, Vinod K. Singh, Greg Falbo and Vincent D. Monkaba, “Finite Element Model Correlation of an Automotive Propshaft with Internal and External Dampers”, SAE Technical Paper 2004-01-0862