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Benchtop Brake Material Screening: Can we correlate with full scale AK Master? Patrick Markus, Bruker Nano Surfaces Tribology Days 2017, Vattenfall, Älvkarleby

Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

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Page 1: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Benchtop Brake Material Screening:

Can we correlate with full scale AK Master?

Patrick Markus,Bruker Nano Surfaces

Tribology Days 2017, Vattenfall, Älvkarleby

Page 2: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

This is why we all need good brakes ……

2

Page 3: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 3

The standard in predicting vehicle stopping

performance is a full-scale Dynamometer test

– COF can be measured under a given set of

conditions

– This information is key in evaluating brake pad

materials

– Equipment and tests are expensive and time-

consuming

– Protocol follows AK Master (SAE J2522)

standards

Development phase before release

Page 4: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 4

Dynamometer output data

Page 5: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 5

A benchtop developmentUMT Tribolab - Brake Material Tester

Collaboration with Greening Inc, ITT and Southern Illionois University

Page 6: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential

Replicating the Dyno Conditions

6

5 Key Tribology-elements:

• Materials

• Contact Geometry

• Loading

• Motion

• Environment

UMT Tribolab - Brake Material Tester

Page 7: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential

• Use same Materials as used in Dyno Test

7

1. Materials

Page 8: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 8

Minimum Contact Size due to Non Homogenous Nature of Material

0.5 mm

Choose button sample size to be 25x

larger than area shown in this image, to

capture inhomogeneous mixture

Use three buttons from each pad

to further get “average”

representation of material

<- Finish rotor to 320 grit, as in Dyno testing

2. Contact Geometry

Page 9: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 9

• Calculate same contact stress on pads as from Dyno, by

using:

• Hydraulic line pressure = most sequences run at 3 MPa

• Piston size (48 mm diameter), and

• Pad area (~ 300 mm2)

• Gives 1MPa contact pressure

• With the UMT TriboLab sample dimensions: 1 MPa = 380 N

3. Loading

Page 10: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential

Need to replicate car brake pad sliding speed on UMT TL test pads

Wheel

Diameter

Rotor Effective

Radius

UMT

radius

4. Motion - Velocity

Vehicle velocity (km/h)

π x tire diameter (m/rev) Wheel rpm = x (103 m/km) x (h/60 min)

Wheel rpm x π x rotor diameter (m/rev) x (min/60 sec)Sliding Velocity

at Brake Rotor

(m/sec)

= =

Sliding Velocity

at button sample

(m/sec)

sliding velocity at button (m/sec)

π x button path diameter (m/rev) UMT rpm = x (60 sec/min)

Page 11: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 11

• Provide artificial “deceleration” based on that from Dyno

tests

• Benchtop test has no inertial flywheels, only drive motor, so a

full brake application would stop test immediately

• Calculate stopping time (or time to final, lower velocity in

snub tests) from deceleration and initial velocity

• Program this deceleration into benchtop tester

• Example: Dynamometer simulating a vehicle stop of:

• 120 km/hr -> 40 km/hr @ 0.4g decel

• Sliding speed of 15.6 m/s -> 5.25 m/s

• Assume constant deceleration

• Time required: 5.7 seconds

4. motion c’td – Velocity Profile

Page 12: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 12

• Dry, Humidity

• Temperature of pad measured

• Temperature of rotor measured

• Test initiation dictated by rotor temperature

• Test sequences 6.3, 6.4, 6.5 and 6.8 are all

conducted using Initial Braking Temperature (IBT) of

100 C or less

• Benchtop tester programmed to begin each

measurement in these sequences with IBT < 100 C

5. Environment

Page 13: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 13

How does it look like and what do you get …

0 2 4 6 8 10 12 140

100

200

300

400

500F

z: F

orc

e (

N)

Fz

V

Tpad

Trotor

Tz0

500

1000

1500

2000

2500

Deceleration

V: S

pee

d (

rpm

)

0

20

40

60

80

100

120

140

Tpad (

°C)

0

20

40

60

80

100

120

140

Tro

tor (°

C)

0

2

4

6

Tz: T

orq

ue

(N

*m)

Varying the speed from 2089 to 787 rpm (80-30 km/h) in 5.5

s, under an applied force of 300N (0.75 MPa contact

pressure). Force and speed are controlled, while torque and

temperatures are monitored. Typically, torque increases

while speed is reduced at constant contact pressure

Page 14: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 14

UMT TriboLAB - Brake Material Tester

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Co

eff

icie

nt o

f F

rictio

n

0

50

100

150

200

250

300

350

400

Ro

tor

Tem

pe

ratu

re (

°C)

1 2 3 4 5 6

Dynamometer

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Co

eff

icie

nt o

f F

rictio

n0

50

100

150

200

250

300

350

400

Ro

tor

Tem

pe

ratu

re (

°C)

1 2 3 4 5 6

UMT-TL

The data collected during the tests show good correlation between the full-scale and the

benchtop tests, not only from the calculated average coefficient of friction (CoF), but also

in the behavior of the torque that has similar trend and shape.

CoF

Page 15: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 15

UMT TriboLAB - Brake Material Tester

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Coe

ffic

ient of F

riction

0

50

100

150

200

250

300

350

400

Roto

r T

em

pera

ture

(°C

)

0.3

3

0.6

6

0.9

9

1.3

2

1.6

5

1.9

8

2.3

1

2.6

4

Contact Pressure [MPa]

Dynamometer

0.0

0.1

0.2

0.3

0.4

0.5

0.6

300

0 k

Pa

flu

id

200

0 k

Pa

flu

id

Coe

ffic

ient of F

riction

400

0 k

Pa

flu

id

* * *

0

50

100

150

200

250

300

350

400

Roto

r T

em

pera

ture

(°C

)

0.3

9

0.5

2

0.6

5

0.7

8

0.9

1

1.0

4

1.1

7

1.3

0

Contact Pressure [MPa]

UMT-TL

Contact Pressure

shows step 6.4.2 aimed to measure the sensitivity to applied brake pressure when

testing the system at snubs of 80-40kmh

Page 16: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 16

UMT Tribolab - Brake Material Tester

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Coeffic

ient of F

riction

0

50

100

150

200

250

300

Roto

r T

em

pe

ratu

re (

°C)

1 2 3 4 5 6

Dynamometer

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Coeffic

ient of F

riction

0

50

100

150

200

250

300

Roto

r T

em

pe

ratu

re (

°C)

1 2 3 4 5 6

UMT-TL

CoF Cold Application

Good correlation between dyno and UMT-TL results testing materials at 40°C (“Cold

Application”, step 6.6), the values of CoF were very close

Page 17: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 17

UMT Tribolab - Brake Material Tester

0.0

0.1

0.2

0.3

0.4

0.5Rec. 1 (µF1)

Fade 1 (µF1)

Cold (µT40)

Char. 2 (µ0P61)

µ120 120-80

80-40

40-5

Char. 1 (µ0P61)

Burnish 1

Green µ

Dynamometer Material A

UMT Material A

Most of the values are within 10% difference – Good correlation according to industry experts

Comparison in the CoF for each step

Page 18: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential

Can UMT-Tribolab do more then only brakes?

18

Page 19: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 19

UMT-Tribolab Lower Drive Types

Linear & Reciprocating Drives

Max. Stroke 25 mm

Min. Stroke 0.1 mm

Position resolution 1µm

Speed 0.1 to 60 Hz

Max. Load 2,000 N

Stroke vs Frequency60 Hz @ 2 mm

20 Hz @ 25 mm

Reciprocating Drive Technical Specifications

Page 20: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 20

UMT-Tribolab Lower Drive Types

Rotary & Block-on-Ring Drives

Speed 0.1 to 5,000 rpm

Max. Torque >5 Nm @ 100 rpm, 2.5 Nm @ 5,000 rpm

Max. Load 2,000 N

Rotary Drive Technical Specifications

Speed 0.1 to 5,000 rpm

Max. Torque >5 Nm @ 100 rpm, 2.5 Nm @ 5,000 rpm

Max. Load 2,000 N

Block-on-Ring Drive Technical Specifications

Page 21: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential

UMT-Tribolab Force Sensors

21

Fz

Fx

SPECS\MODEL FVL-G FL-G DFM-0.5-G DFM-1-G DFM-2-G DFH-5-G DFH-10-G DFH-20-G DFH-50-G DFH-100-G DFH-200-G

Low 1mN 5mN 0.05N 0.1N 0.2N 0.5N 1N 2N 5N 10N 20N

High 100mN 500mN 5N 10N 20N 50N 100N 200N 500N 1,000N 2,000N

Resolution 10µN 50µN 0.25mN 0.5mN 1mN 2.5mN 5mN 10mN 25mN 50mN 100mN

FL series DFM series DFH series

Page 22: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential 22

Wide Range of Advanced Sensors for Environmental

and Test Characterization

• Advanced Sensors are field-installable, and easy to configure to add increased test characterization and accuracy of the UMT-Tribolab system.

• Advanced Sensors available include:

• Acoustic Emission

• Electrical Contact Resistance

• Temperature

• Humidity

• Micro-Wear, Deformation

Acoustic Emission Sensor Used to Detect Coating Delamination

Page 23: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

Bruker Confidential

UMT-Tribolab Product Selector Guide

Main Unit and Lower Drive Accessories

L-DRIVE

23

ROT-DRIVE

ROT-400

ROT-1000

ROT-HUMID/COOL

REC-350

REC-1000

REC-HUMID/COOL

REC-DRIVEBOR-DRIVE

BOR-150

Page 24: Benchtop Brake Material Screening: Can we correlate with .../file/Tribodays... · • Example: Dynamometer simulating a vehicle stop of: • 120 km/hr-> 40 km/hr@ 0.4g decel • Sliding

April 11-13, 2017 24Bruker Confidential18. Dezember 2017 24© Copyright Bruker Corporation. All rights reserved