mf swift v5 - tno...

1

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

MF-Tyre/MF-Swift

Dr. Antoine Schmeitz

Copyright TNO, 2013

Introduction

TNO’s tyre modelling toolchain

Dr. Antoine SchmeitzMF-Tyre/MF-Swift

2

Identification Simulation

parameter fitting+

database

MF-Tool

TYDEX files

tyre propertyfile

tyre modelMF-TyreMF-Swift

MBSsolver

tyre (virtual) testing

signalprocessing

Measurement

2

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Introduction

What is MF-Tyre/MF-Swift?

MF-Tyre/MF-Swift is an all-encompassing tyre model

for use in vehicle dynamics simulations

This means:

emphasis on an accurate representation of the generated (spindle) forces

tyre model is relatively fast

can handle continuously varying inputs

model is robust for extreme inputs

model the tyre as simple as possible, but not simpler for the intended

vehicle dynamics applications


3

Copyright TNO, 2013

Introduction

Model usage and intended range of application

All kind of vehicle handling simulations:

e.g. ISO tests like steady-state cornering, lane changes, J-turn, braking, etc.

Sine with Dwell, mu split, low mu, rollover, fishhook, etc.

Vehicle behaviour on uneven roads:

ride comfort analyses

durability load calculations (fatigue spectra and load cases)

Simulations with control systems, e.g. ABS, ESP, etc.

Analysis of drive line vibrations

Analysis of (aircraft) shimmy vibrations; typically about 10-25 Hz

Used for passenger car, truck, motorcycle and aircraft tyres


4

3

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Modelling aspects and contents (1)

1. Basic tyre properties and constitutive relations

for tyre radii, contact patch size, stiffness, rolling resistance

nonlinear, effects of loads, velocity, inflation pressure

2. Inclusion of measured tyre steady-state slip char acteristics

described by load and inflation pressure dependent Magic Formula

responses to sideslip, longitudinal slip, camber and turn slip

3. Tyre transients / relaxation length properties

carcass compliance

proper contact transient properties due to finite contact length

4. Inclusion of belt dynamics

primary natural frequencies (rigid ring modes) and gyroscopic effects

5. Tyre rolling over uneven road surface

tyre deformation on obstacles, arbitrary uneven roads


5

Copyright TNO, 2013

Modelling aspects and contents (2)

6. Model usage and availability

selection of complexity level

road definition

7. Model parameterisation

measurement requirements

MF-Tool

8. Concluding remarks


6

4

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

1. Basic tyre properties and constitutive relations


7

Copyright TNO, 2013

Some definitions

• free tyre radius RΩ

• loaded radius Rl

• effective rolling radius Re

• tyre deflection ρ• forward velocity Vx

• wheel spin velocity Ω• longitudinal slip velocity Vsx

• lateral slip velocity Vsy

• longitudinal force Fx

• lateral force Fy

• vertical force Fz

• overturning moment Mx

• rolling resistance moment My


8

• self aligning moment Mz

• inclination angle γ

FxMx

FyMy

Mz

FzVx

normal to the road

Vsx Vsy

ReRl

γ

C

S

RΩΩ

ρ

For a freelyrolling wheel:

Ω= x

e

VR

lRR −= Ωρ

5

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Constitutive relations

Tyre radii, stiffness, contact patch dimensions, rolling resistance, etc. are non-

constant for different operating conditions (load, velocity, etc.)

In MF-Swift nonlinear empirical relations are used to describe these basic tyre

properties

Examples:

vertical force


9

( )iyxz pFFfF ,,,,Ω= ρ

( ) 01

2

02

01

2

0

2

00

02

1

1

ziFzFzFz

z

yFcy

z

xFcxvz

FdppR

qR

q

F

Fq

F

Fq

V

RqF

+

+

⋅

−

−Ω+=

ρρ

coefficient from curve fitting

Fz

Copyright TNO, 2013

Constitutive relations

effective rolling radius


10

+

−= Ω

00

0 arctanz

zreff

z

zreffreff

z

ze F

FF

F

FBD

c

FRR

Ω+=Ω

2

0

0100 V

RqqRR vre

Fz

coefficient from curve fitting

6

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

2. Inclusion of measured tyre steady-state slip characteristics ( magic formula)


11

Copyright TNO, 2013

Magic Formula

Descriptions are available for the three steady-state modes of slip

Equations depend on vertical load Fz, inclination angle γ and inflation

pressure pi ; [Fx, Fy, Mx, My, Mz] = MF (Fz, κ, α, γ, ϕ, pi, V)


12

side slip

α

Mz

V

Fy

α0 0.1 0.2 0.3

0

Mz

Fy

t

turn slip+ camber

R

V Mz Fy

aϕ = a/R

spin

0 0.1 0.2 0.3

Mz

Fy

κ0 0.1 0.2 0.3

Fx

longitudinal slip

FxVsx

+ combinations

x

ex

x

rx

x

sx

V

RV

V

VV

V

V

Ω−−=

−−=−=κ

=

x

sy

V

Varctanα Vt

ψϕ &−=

Vx

Vsy

ψ&

VxΩ

7

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Magic Formula

Notion: the base tyre characteristics Fx=f(κ), Fy=f(α) and Mz=f(α) have a

sinusoidal shape, with a “stretched” horizontal axis for large values of slip

This consideration is the basis for a tyre model known as “Magic Formula ”

Some notes:

First versions developed by Egbert Bakker (Volvo) and prof. Pacejka (TU

Delft, TNO)

MF-Tyre software developed and distributed by TNO since 1996

Probably the most popular tyre model for vehicle handling simulations

(worldwide!)


13

Copyright TNO, 2013

Base Magic Formula


14

Note:

• C determines the limit value when x→∞

• BCD determines the slope near the origin

• B, E & C determine the location of the peak

H

f

x

F

D

SV

S

arctan(BCD) X

X : input, e.g.α or κF : output, e.g.F or Fxy

D : peak factor

C : shape factor

B : stiffness factor

E : curvature factor

SH,V : hor./vert. shift

f = D sin[ C arctan Bx – E( Bx – arctan(Bx) ) ]

F(x) = f(x) + SV

x = X + SH

f∞

8

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Stretching the sine…


15

parameters in this example:

B=8, C=1.5, D=5500, E=-2

Copyright TNO, 2013

Example: pure longitudinal slip characteristics

where:

note:

• Kx = Cfκ: longitudinal slip stiffness

• Bx is calculated from Cx, Dx and Kx

• equations simplified for educational reasons…


16

• coefficients p are determined in curve fitting process

• scaling coefficients λ:• equal 1 during fitting

process• may be used to adjust

tyre characteristics• vertical load increment:

• Fz0 is nominal load0

0

z

zzz F

FFdf

−=

9

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Example: pure longitudinal slip characteristics

result after fitting coefficients: ⇒

data reduction:

495 measurement points ⇒ 11 coefficients

interpolation/extrapolation (load, braking/driving):


17

Copyright TNO, 2013

Magic Formula

Similar equations exist for Fx, Fy, Mx, My and Mz

Combined slip: reduction of Fx and Fy by applying a

weighting function G to the ‘pure’ characteristics

Example:

In total 144 parameters that are curve fitted

using an automated process;

typical fit errors of a few percent


18

0xxx FGF ⋅= α

Fz

Fx

Fy

Mx

My

Mz

κ

pi

Vx

ϕt

α

γ

vertical force

longitudinal slip

side slip angle

inclination angle

forward velocity

inflation pressure

longitudinal force

lateral force

overturning moment

rolling resistance moment

self aligning moment

turn slip

MagicFormula

parameters: general (4), Fx (29), Fy (50), Mx (15), My (8), Mz (38)

10

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

3. Tyre transients / relaxation length properties


19

Copyright TNO, 2013

Tyre transients

Measure step response to

side slip angle

Procedure:

1. Apply steering angle of 1 deg.

2. Load the tyre

3. Start rolling the track at low

velocity (e.g. 0.05 m/s)


20

11

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Tyre transients

• Tyre cannot instantaneously react to changes in slip

• Travelled distance required to build up forces

• Relaxation effects exist for all modes of slip

This is due to:

1. carcass compliance

2. finite contact length

In MF-Swift both are considered:

1. carcass stiffness → springs

2. contact patch slip model

(Magic Formula (MF) slip model and

contact patch transients)


21

*V_

α*

belt

wheel plane

ϕ*

ϕ γ

αV_

c

C

ψ.-

Copyright TNO, 2013

Simplified example carcass stiffness

• Assume linear tyre model for small slip angles:

• Create dynamic tyre model by accounting for tyre sidewall stiffness:

• Dynamic side slip angle:

• Introducing the relaxation length σ (=C/k) and V≈u:


22

αCFy =

uv−=α

εα kCFy =′= . .εα kC =′

.

u

v εα +−=′

.ααασ =′+′

V α ′= CFy

ααα =−=+′u

v

uk

C&

1 ′contact patch

wheel plane

12

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013


• First order dynamics between lateral force and side slip angle input, transfer

function:

• Relaxation length σ does not depend on forward velocity V:

• response time reduces when increasing V;

• travelled distance required to build up the lateral force remains the same.


23

1)(,

+=

sV

CsH

yF σα time constant:

Vσ

Copyright TNO, 2013


step response (α = 1 deg, C = 1000 N/deg, σ = 0.5 m)


24

13

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Tyre relaxation effects

• Experiments show that relaxation length

depends on:

• vertical load Fz

• slip level

• inflation pressure

• Thus also relaxation effects when Fz is

changed at e.g. constant side slip

Modelling

Slip and vertical load dependency can be

included by using nonlinear slip characteristics

(MF) and load and inflation pressure

dependent carcass stiffness


25

processed measurements:relaxation lengths σ

αfrom

small changes in side slip angle (∆α = 0.5°)

Copyright TNO, 2013

Contact patch slip model

• For shorter wavelengths λ (0.1 < λ < 5 m) of e.g. side slip, the finite length of

the contact patch needs to be considered

• Important for aligning torque response to sideslip and for turn slip

MF-Swift contact patch slip model:

• Contact patch has stiffness (stiffness of tread elements)

• From physical brush model derived differential equations for contact patch

transients (relaxation lengths depend on slip and tread stiffness)

• Nonlinear slip characteristics from Magic Formula model

(basically the brush model slip characteristics are replaced by the more

accurate Magic Formula characteristics)


26

14

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013


In total 7 nonlinear 1st-order differential equations (derived from brush model):

• one 1st-order differential equation for κc’

• two 1st-order differential equations for αc’ and αt’

• four 1st-order differential equations for ϕc’


27

κc’, αc’, αt’, ϕc’inputs into

Magic Formula

s

Fy

s0

0s

Fx

s0

0

κ α

s

-Mz

s0

0

α

s

Fy

s0

0

ϕ

s

Mz

s0

0

ϕ

κ α ϕcontact patch step responses

Copyright TNO, 2013



28

carcass forces, moments

contactpatchdynamics

slip forces and moments

first-ordercontacttransientslipequations

deflection angle

transient slipquantities

tyre carcass compliance

MagicFormula

-βst

+

αc

contact patchslip quantitiesκ

c

α'

κ'c

F

My

z

Fx

-βα

Fy

αc

V

-Mz

15

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Wheel load oscillations at constant side slip


29

V = 0.6 m/sα = 5oFzo= 4000N Fzv= 2000NF = F +F sin(2π s/λ)zvzoz

0.2 0.4 0.6 0.8 12

3

4

5

6

[kN]

00.2 0.4 0.6 0.8 10

150

[Nm]

100

50

0

test

2

3

4

5

6

[kN]

150

Fy -Mz

yF -Mz

[Nm]

100

50

0

model

s/λ s/λ

moment

1.20.60.3

2.4m

λ =side force

Copyright TNO, 2013

4. Inclusion of belt dynamics


30

16

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

MF-Swift: inclusion of belt dynamics

• First mode shapes are rigid belt vibrational modes

• Below about 100 Hz we can suffice considering these modes


31

Rigid ring / tread band

Road surface (flat)

Sidewall stiffness &damping (6 DOF)

Rim

Residualstiffness &damping

Magic Formulaslip model

Copyright TNO, 2013

Residual stiffness

Residual stiffness elements ( ccz, ccy, ccΨ, ccx) between belt and contact patch

• assure correct overall tyre stiffness resulting in correct loaded radius vs.

vertical force and correct relaxation lengths

• describe the effects of the modes that lie above the maximum frequency of

interest (high-frequency modes, i.e. non rigid belt modes)


32

vertical

ccz

beltrim

-zcr

ccx

belt

xcr

Msx

Fsy FsxMsy

FNMsz

rim

tangentiallateral and yaw

ycr

ψcr

ccyccψ

belt

wheelplane

contactpatch

17

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

In-plane modes and natural frequencies


33

vertical 80Hzin-phase 33Hz anti-phase 76Hz longitudinal 100Hz

longitudinal 74Hzrotational 0Hz vertical 74Hz torsional 78Hz

free

loaded

featured by model at stand-stillafter having fitted parameters from tests on loaded and rolling tyre

Copyright TNO, 2013

Out-of-plane modes and natural frequencies


34

yaw 46Hz camber 46Hz

free

loaded

lateral 42Hz

camber 44Hz yaw 46Hz lateral 103Hz

featured by model at stand-stillafter having fitted parameters from tests on loaded and rolling tyre

18

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Validation: dynamic braking

longitudinal force response


35

0 20 40 60 80 100 0 20 40 60 80 100

200

0

180

0

-180

90

-90

0

180

0

-180

90

-90

30belt

dynamicsslip stiffness

relaxation length

experimentmodel

V = 25 km/hFz = 4000 N

Fxκ

Fx

MB

[1/m] [N]

n [Hz] n [Hz]

to brake torque variations to wheel slip variations

φ φ

Copyright TNO, 2013

Validation: yaw oscillation

side force and moment

response to yaw

oscillations at

different speeds


36

100 101

105

106

104

Frequency [Hz]100 101

Frequency [Hz]

102

103

104

105

106

amplitude ratio F ψy amplitude ratio M ψz

V = 110 km/h

V = 20 km/h

V = 110 km/h

V = 20 km/h

ExperimentSimulation

Note: splitting of single peak at low velocity into two peaks (camber and yaw mode) due to gyroscopic action

19

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013


side force and moment response to yaw

oscillations at different speeds


37

experiments

φ ψF

[ ]o

Fyψ

φ ψM

Mzψ

106

105

104

180

90

0

-90

-180

106

104

102

180

90

0

-90

-180

Nrad

Nmrad

100 101 100 101n [Hz] n [Hz]

[ ]o

side force moment

φ ψF

[ ]o

Fyψ

φ ψM

Mzψ

106

105

104

180

90

0

-90

-180

106

104

102

180

90

0

-90

-180

Nrad

Nmrad

100 101 100 101n [Hz] n [Hz]

[ ]o

side force moment

simulations

25 km/h59 km/h92 km/h

V =xα = 0o

Note: splitting of single peak at low velocity into two peaks (camber and yaw mode) due to gyroscopic action

Copyright TNO, 2013


side force and moment response to yaw

oscillations at different slip angles


38

V =59km/hx

φ ψF

[ ]o

Fyψ

φ ψM

Mzψ

106

105

104

180

90

0

-90

-180

106

104

102

180

90

0

-90

-180

Nrad

Nmrad

100 101 100 101n [Hz] n [Hz]

[ ]o

side force moment

φ ψF

[ ]o

Fyψ

φ ψM

Mzψ

106

105

104

180

90

0

-90

-180

106

104

102

180

90

0

-90

-180

Nrad

Nmrad

100 101 100 101n [Hz] n [Hz]

[ ]o

side force moment

0

31

5

oooo

α = 0

experiments simulations

20

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Validation: step changes in brake pressure

responses to

successive step

changes in brake

pressure versus time


39

[rad/s]

20

23

22

21

0

1000

2000

3000simulation

time [s] time [s]0 2.5 0 2.5

simulation

experiment

0 20

23

22

21

20

Ω

experiment

[N]

-Fx

zF xV= 4000N, = 25km/h

brake force wheel speed of rev.

Note:• steps in brake pressure

up to wheel lock; then brake released

• vibrations (about 28 Hz) attributed to the in-phase rotational mode of the system with the brake and axle inertia included

Copyright TNO, 2013

Validation: step changes in brake pressure

responses to successive step changes in brake pressure versus longitudinal

wheel slip


40

experimentsimulation

0 2 4 6-κ [%] 8 10

3000

2000

1000

012

[N]

-Fx

brake force

wheel slip

zF xV= 4000N, = 25km/h

Note:• similarity with longitudinal slip characteristics• maximum friction in experiment earlier reached

21

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Validation: step changes in steering angle

side force response to

successive step changes in

steer angle versus time


41

[N]

4000

3000

1000

0

Fyexperiment

z =3700N, =25km/hF xV

2000

[N]

4000

3000

1000

0

Fy

2000simulation

=0ψ

1

2

3

45

6 7 8

o

o

o

o

oo o o

0 1 2 3 4time [s]

1 2 3 4time [s]0

o

sideforce

Note:• vibrations attributed to

yaw/camber mode with frequency of about 40 Hz

• decrease overall relaxation length at larger sideslip angles

Copyright TNO, 2013

Validation: step changes in steering angle

aligning moment response to

successive step changes in steer

angle versus time


42

0

[Nm]

200

100

0

-100

-200

-Mz

0 1 2 3 4time [s]

1 2 3 4time [s]

[Nm]

200

100

0

-100

-200

-Mz

simulationmoment

experiment

z =3700N, =25km/hF xV

22

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

5. Tyre rolling over uneven road surface


43

Copyright TNO, 2013

Summarising

So far:

excitation of the tyre via axle motions or braking/steering on a flat road

surface

Next:

tyre dynamics can also be excited via the road;

for short wavelength unevenness (e.g. short obstacles/cleats) the tyre

enveloping behaviour is important:


44

23

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Enveloping example: rolling over short obstacle

Constant axle height experiment

Three distinct responses:

• variations in vertical force

• variations in longitudinal force

• variations in wheel spin velocity

Note:

• tyre touches obstacle before and after

wheel centre is above the obstacle!

• shape of the response is totally

different from obstacle shape


45

Copyright TNO, 2013

Phenomena enveloping behaviour


46

lengtheningresponse

swallowingobstacles

filtered responseat axle

road profile

filteringunevenness

24

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

The effective road surface

Assumptions

• The tyre contact zone, where the large deformations due to envelopment of

the unevenness occur, dynamically deforms mainly in the same way as it

does quasi-statically

• Local dynamic effects can be neglected

• Rigid ring model takes care of the tyre dynamics

Approach

• A special road filter has been developed to take care of the enveloping

properties

• This filtered road surface is called the effective road surface

• Instead of the actual road surface, this effective road surface is the input of

the rigid ring model


47

Copyright TNO, 2013

The effective road surface

The concept of the effective road surface

is that for each axle position an

effective road plane can be defined the position

and orientation of which is governed by the

resulting tyre force.

Definition

• Vertical position w of eff. road plane

varies according to vertical axle movement zaxle

at constant vertical load FV.

• Slopes βy (and βx for 3D) of the eff. road plane

according to orientation of the resulting tyre force

FN when moving over frictionless surface (µ = 0).


48

w FN

β y

FV

2-D

= ∆ zaxle

constant

z axle

FH

µ = 0

25

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Tandem-cam enveloping model


49

cam

cam

ls

wheelcentre

w-βy

F

cam

cam

ls

Copyright TNO, 2013

3D Tandem-cam enveloping model

Four effective road input quantities

Road curvature dβy /dx used for extra variation of the eff. rolling radius


50

−βx−βy

w

z

xy

xβd

d+ y

ISO

contact patch width

26

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

3D Tandem-cam enveloping model

For higher accuracy on short obstacles one might introduce:

• for w and βy:

• more parallel

tandems

(multi-track)

• for βx:

• intermediate

cams at the

side edges


51

'6x5' cams= 18 cams

Copyright TNO, 2013

Example of validation result


52

27

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Example of validation result


53

Copyright TNO, 2013

Low speed perpendicular and inclined cleat tests


54

28

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

MF-Swift: 3D road unevenness


55

Rigid ring (6 DOF)

Enveloping model with elliptical cams

Effective road plane

Sidewall stiffness& dampingRim

Residualstiffness &damping

Slip model

Cleat

ff

Copyright TNO, 2013

Validation: various obstacle shapes


56

29

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Validation:


57

-0.05 0 0.05 0.1 0.15 0.2 0.25-4000

-2000

0

2000

4000

∆Fz

[N]

0 50 100 1500

50

100

150

200

PS

D √

(SF

zFz)

-0.05 0 0.05 0.1 0.15 0.2 0.25-1

-0.5

0

0.5

1x 10

4

∆Fx

[N]

0 50 100 1500

100

200

300

400

500

PS

D √

(SFx

Fx)

-0.05 0 0.05 0.1 0.15 0.2 0.25-10

-5

0

5

10

Time [s]

∆Ω [r

ad/s

]

0 50 100 1500

0.2

0.4

0.6

0.8

Frequency [Hz]

PS

D √

(SΩ

Ω)

vertical mode

in-phase rotational mode

in-phase rotational mode

10 15

100 290 105mm 237 120 221 50

15 10

∆Fz

∆Fx

∆Ω

time [s] frequency [Hz]Fz0 = 4000 N, V = 39 km/h

simulationsmeasurements

Copyright TNO, 2013

Validation: Strip 10x50 mm, 34 °, Fz0 = 4 kN


58

measurement model

0 20 40 60 80 100 120 140 160 180 2000

0.05

0.1

0.15

0.2

Frequency [Hz]

√(S

ΩΩ

)

-0.05 0 0.05 0.1 0.15 0.2 -4

-2

0

2

4

Time [s]

Ω [

rad/s

]

0 20 40 60 80 100 120 140 160 180 2000

50

100

150

√(S

KxK

x)

-0.05 0 0.05 0.1 0.15 0.2 -4000

-2000

0

2000

4000

∆ Kx [

N]

0 20 40 60 80 100 120 140 160 180 2000

10

20

30

40

√(S

KzK

z)

-0.05 0 0.05 0.1 0.15 0.2 -500

0

500

1000

1500

∆ Kz

[N]

∆Fz

∆Fx

∆Ω

rotational mode

rotational mode

Vdrum= 39 km/h

time [s] frequency [Hz]

30

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Validation: Strip 10x50 mm, 34 °, Fz0 = 4 kN


59

measurement model

0 20 40 60 80 100 120 140 160 180 2000

2

4

6

Frequency [Hz]

√(S

TxT

x)

-0.05 0 0.05 0.1 0.15 0.2 -100

-50

0

50

100

Time [s]

∆ Tx [

Nm

]

0 20 40 60 80 100 120 140 160 180 2000

1

2

3

√(S

TzT

z)

-0.05 0 0.05 0.1 0.15 0.2 -100

-50

0

50

100

∆ Tz

[Nm

]

0 20 40 60 80 100 120 140 160 180 2000

5

10

15

20

√(S

KyK

y)

-0.05 0 0.05 0.1 0.15 0.2 -500

0

500

∆ Ky [

N]

camber mode

yaw mode

camber mode

camber

∆Fy

∆Mz

∆Mx

time [s] frequency [Hz]

Copyright TNO, 2013

Validation: running over pothole while braking

constant axle height

constant speed


60

free rolling medium brake torque

large brake torque

-4

-3

-1

0

1

2

3

0.0 0.20.1 0.0 0.20.1 0.0 0.20.1time [s]

[kN]

∆FX

-2

500mm15mm

F = 4000NVo

V = 35km/h

measurements simulations

31

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Road load simulation example

Durability load calculation at Nissan, Japan

SAE paper 2011-01-0190


61

OpenCRG file4x4 mm grid sizebinary, 273 MB

Adams modelflexible bodyrigid suspensionMF-Swift 6.1.2

durability roaddigitised 4x4 mm grid9.7 GB

Copyright TNO, 2013


Validation: front left shock absorber force


62

32

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013


Validation: lower link ball joint forces


63

Copyright TNO, 2013

6. Model usage and availability


64

33

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Using the tyre model

Tyre model parameters

Tyre property file (*.tir)

Result of MF-Tool

Road surface definition

Road data file (*.rdf, *.crg)

Select model complexity

Operating or use mode


65

Copyright TNO, 2013

Complexity level of the model can be changed

The most complex model is not always needed (dynamics mode)

Within validity range simulation results are identical


66

< 1 Hz < 10 Hz, linear < 10 Hz, nonlinear < 60-100 Hz, nonlinear

massless tyre model tyre model includes mass of the belt

34

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Complexity level of the model can be changed

The most complex contact model is not always needed

• Depending on the wavelength of the obstacles/unevenness a contact method

can be selected

• For enveloping the number of contact points and cams can be chosen

• 2D/3D enveloping is generally combined with rigid ring dynamics because of

the high frequency excitation


67

single point 2D enveloping 3D enveloping

Copyright TNO, 2013

Road definition

• Road definitions inside the tyre model

• predefined road profiles with limited set of parameters

(e.g. flat, plank, sine, polyline, drum + cleat)

• 3D measured road profiles (OpenCRG®)

• In many packages it is also possible to use the native road definition, coming

along with the simulation package.


68

OpenCRG® is on:http://www.opencrg.org

35

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Model availability

MF-Tyre/MF-Swift is available for all major simulation packages used in

vehicle dynamics


69

Copyright TNO, 2013

7. Model parameterisation


70

36

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Tire modelling toolchain


71

measurement parameteridentification

simulation

cost $savings $

Virtual Prototyping

accumulating error determines accuracy

Copyright TNO, 2013

Measurement requirements

MF-Tyre can be parameterised using the following tests:

Geometry, mass and inertia measurements

Force and moment measurements (Magic Formula dataset)

Loaded radius and rolling radius measurements

Footprint measurements

Stiffness measurements

Additionally for MF-Swift

(enveloping and rigid ring components)

Cleat experiments


72

37

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Measurement requirements

Source:

German OEM

AK 3.5.1


73

geometrical data,stiffnesses,cleat tests, inertias

specific data forcomplex tire models. e.g. belt angle, cord stiffness ...

force & momentand transient tests

Copyright TNO, 2013

MF-Tool

Fitting of current and

historical tyre models

(including MF 5.2)

Database and

plotting functionality

Software is able to

make estimates

Available at all major

tyre manufacturers

Due to the model’s semi-empirical nature different aspects of the tyre

behaviour can be handled separately in (relatively) small optimisation steps

and represented with maximum accuracy


74

38

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

8. Concluding remarks


75

Copyright TNO, 2013

Concluding remarks

The TNO Delft-Tyre toolchain (MF-Tyre/MF-Swift and MF-Tool) offers a

versatile, high quality and cost efficient solution for tyre modelling:

MF-Tyre leading Magic Formula implementation and unique features

MF-Swift extension of MF-Tyre (rigid ring, enveloping, turn slip)

MF-Tool provides independent parameter identification possibilities

MF-Tyre/MF-Swift is one model for many applications

implementations for all main simulation packages

little measurements required

computationally efficient

MF-Tyre (Magic Formula) part is free of charge for many packages

TNO provides parameter identification, training and consultancy

well validated and open/accessible theory (many scientific publications)


76

39

MF-Tyre/MF-Swift

Copyright TNO, 2013

Copyright TNO, 2013

Roles & responsibilities and contact information

• Model development is done by TNO (large independent research and

technology organisation in The Netherlands)

• Worldwide sales and distribution of Delft-Tyre products (MF-Tyre/MF-Swift

and MF-Tool) is done by TASS (TNO Automotive Safety Solutions), which is a

TNO subsidiary

Website:

http://www.tassinternational.com/delft-tyre

TNO, Delft-Tyre, P.O. Box 756, Helmond, The Netherlands

Willem Versteden (product manager) [email protected]

Dr. Antoine Schmeitz (technical leader) [email protected]


77

Copyright TNO, 2013

Further reading

MF-Swift theory extensively described in book:

Hans Pacejka , Tire and Vehicle Dynamics ,

third edition, Butterworth-Heinemann, 2012


78

mf swift v5 - tno...

Documents