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Christophe Thiry TVM Vibration Mechanics

High speed rolling in Abaqus Explicit

Transient Dynamics Method

Tire Vehicle Mechanics Applications

September 2011


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Table of content

TVM department in Global Tire Performance Prediction

NVH Comfort performance

High speed rolling over a cleat

9 Experimental cleat test : setup

9 Cleat impact simulation : approach, damping

9 Ride and Comfort indicators

9 Post-processing of data : Example of application and validation

Cleat impact simulation as input to Vehicle model

Other application

9Blocked force approach sensitivity versus cleat size


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TVM a global department

Akron Luxembourg

Engineering

Technology Lab (ETL)

Tire-Vehicle Test

Research Lab

GIC*A GIC*L


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TVM, our 3 teams

TVM Competencies

New predictive test method development Tire-vehicle modelling Advanced instrumented vehicle and tire testing Performance knowledge & guidelines (trade-offs & optimization) Support product development performance prediction needs

TVM Competencies

New predictive test method development Tire-vehicle modelling Advanced instrumented vehicle and tire testing Performance knowledge & guidelines (trade-offs & optimization) Support product development performance prediction needs

Vehicle dynamicsLifecycle mechanicsVibration mechanics


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Input Tire Vehicle Driver Subjective

Comfort

Tire

Approval



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Vibration path

Perception pathpassenger



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Objective comfort characterization

Tire alone Tire on vehicle

Fixed hub cleat test ondrum

Modal analysis

Static tests

Vehicle cleat test ondrum or on road

Test on rough roads

Admittance Tire/Vehicletest or prediction

Vehicle modal analysis


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Experimental cleat test

Tire mounted on a specific rim

Inflation

Tire deflected on the drum with the specified load

Drum rotating at a constant speed and driving the tire

Tire impacted by a small cleat fixed on the drum (10 x 25 mm)

The procedure is repeated for several

drum speeds : usually 20 km/h to 100

km/h by step of 10 km/h.

Measurement of hub forces by means

of sensors located in the hub : 3

directional forces and two moments


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Time signature in terms of hub force in the vertical and fore/aft directions for the tire rolling

at 20 and 60 km/h.

Two phenomena governing the response :

- tire is enveloping the cleat

- tire is vibrating after impact

The oscillations rapidly decrease with time due to viscoelastic behavior of tire components

The importance of each phenomenon is speed dependent



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Give information on the frequencies that are excited by road irregularities.

For instance, one eigenfrequency located at 78 Hz in vertical direction and two

eigenfrequencies located at 32 and 89 Hz in fore/aft direction

The frequency range is usually divided in three parts in order to isolate the different modes

Low frequency range 0 25 Hz

Medium frequency range 25 55 Hz (dominated by the major fore/aft mode)

High frequency range 55 130 Hz (dominated by the vertical mode)



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Cleat impact simulation Flow chart

Drawing of tire

cross section

Materials and

weight of tire

components

Cleat Impact

Prediction Post-Processing

Predicted RideIndicators including

Dynamic Load

Factors

+ other quantities

Cleat impact simulation Flow chart


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RMS Values

Ride & Comfort indicator : RMS Value

Time Signature

Frequencydomain

Root Mean Square

FFT

3 frequency ranges

The lower the RMS Value, the lower the energy transmitted to the vehicle,

the better the tire comfort

Tire ATire B


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Measurements Predictions

Hub reaction forces in vertical are very accurately predicted :

- The prediction levels are very close to measurement levels

- The ranking between the 6 conditions is well captured (R2 of 0.98 in 0-25Hz range)

Validation of Front Tires : 255/50R19 and 255/45R20

Cleat impact simulation Example of Validation


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Conclusions

Conclusions

Transient Dynamics Method can be used to predict ride and comfort

indicators

Quantitative : simulation results in line with classical measurements

Qualitative : allow distinguishing different constructions

Results are easily post-processed by means of a GUI

Different tire constructions can be assessed by means of indicators especially

dedicated to Ride & Comfort performance

The tool has been validated (different tire concepts covering design space,

different tire sizes)

Cleat Impact Prediction can be used in tire design process


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Cleattest front axle impact avg

0

2

4

6

8

10

12

14

16

18

20

CR9164

CR9165

CR9175

ED0229

ED0230

ED0231

ED0241

EH0326

ED0228

CR9005

CR9171

CR9174

CR9002

CR9004

CR9167

CR9168

CR9176

CR9202

RankStwheelaccrms25-55Hz[ms-2]

Audi

BMW

Mercedes

vehicle A

vehicle B

vehicle C

Example shows ranking of tires on three different vehicles Ranking based on rms-values in steering column resonance frequency range (25-55Hz)

Ranking

Rms25-5

5Hzstwheelaccelerations[ms-2

]

Vehicle cleat test

Vehicle effect makes a tremendous difference on tire performanceVehicle effect makes a tremendous difference on tire performance

Importance of vehicle in ride comfort performance

Tire1

Tire2

Tire3

Tire4

Tire5

Tire6

Tire7

Tire8

Tire9

Tire10

Tire11

Tire12

Tire13

Tire14

Tire15

Tire16

Tire17

Tire18


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Vehicle Lab Cleat test

Objective Comfort Tests Vehicle tests

Vehicle Road Cleat test

Vehicle Road test on Comfort Lanes forother types of excitation (Pave road,

rough road, )

Vehicle is instrumented with

accelerometers and microphones(Steering Wheel, Seat, Driver hears,)

WheelHubVertical 44G11

44G16

Vehicle response is analyzed in the frequency domain andmetrics are used to compare (rank) tire constructions

INPUTS

OUTPUTS


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Provide advanced tire/vehicle NVH performance prediction capability

Vehicle Model + Tire model = Advanced Tire/Vehicle Predictions

Use vehicle model (experimental or predictive) coupled with a high fidelity finite-element (based)tire model to develop optimal vehicle-specific tire designs for ride and structure-born noise

Tire/vehicle interaction has a high impact on tire performance

Improvement of tire design process with the vehicle included

What ?

Why ?

How ?

Vehicle comfort performance is predicted for candidate tire designs in early

development phase

Tire Vehicle system prediction : Objectives

Tire A

Tire B

Tire C


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Three different cases are simulated using the Transient Dynamics Method in Explicit

Blocked force approach sensitivity versus cleat size

Case 1 : Typical blocked force test Case 2 : Typical vehicle cleat test

Case 3 : The cleat is removedfrom the case 2

The excitation is given by the

vertical and fore/aft forces

applied to the hub, which

come from the case 1

Kv = 20 N/mm

C v = 2 Ns/mm

Kf= 300 N/mm

C f= 0.5 Ns/mm


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Blocked force approach is supposing that case 2 and case 3 are

equivalent.

The purpose is to show how differences between the case 2 and the

case 3 are linked to the cleat shape (width and height).

Purpose

=?=


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RMS on 0 130 Hz Error = difference between case 2 and case 3

Correlation between error and cleat size

[%]

RelativeAbsolute

Mass node


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GIC*A GIC*L

Thank you for your attention

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