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Wednesday November 22nd 2017

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Standardized braking test – Tests

A vehicle which ABS and EBS could be disconnected and selective front/rear/all axles braking was used. The vehicle has a front axle weight of 9352.9N and the rear axle weight of 7506.5N

Four braking points were selected in the MIRA test track to perform the braking tests. Not all the points had the same track conditions; therefore they are shown and explained:

MIRA_test_track_testing_brake_zones

Point

Conditions

1

Dry and Smooth Tarmac

2

Dry and Smooth Tarmac

3

Dry and Rough Tarmac

4

Damp and Rough Tarmac

5

Damp and Smooth Tarmac

 


The following tests were performed until full locking of one axle was achieved.

 

Test 1 – All brakes, ABS and EBD disabled

9 Stops from 40mph. Table of results:

Target Pressure [psi]

Target Pressure [Mpa]

Actual Average Pressure [Mpa]

Average Acceleration [m/s2]

Average Rate of Braking [g]

Braking Point

Observations

200

1.379

1

Not valid, file was overwritten

400

2.758

1.905

-3.120

0.318

2

600

4.137

3.402

-5.288

0.539

3

800

5.516

4.489

-6.359

0.648

4

1000

6.895

5.921

-8.066

0.822

5

1200

8.274

7.305

-9.063

0.924

1

Locking of both rear wheels

Test 2 – All brakes, ABS and EBD operational

6 Stops from 40mph. Table of results:

Target Pressure [psi]

Target Pressure [Mpa]

Actual Average Pressure [Mpa]

Average Acceleration [m/s2]

Average Rate of Braking [g]

Braking Point

Observations

1100

7.584

6.854

-6.635

0.676

3

1200

8.274

7.130

-7.636

0.778

2

1300

8.963

7.790

-7.925

0.808

4

1400

9.653

8.648

-7.228

0.737

5

Locking of front wheels (ABS intervention).

Emergency Stop

7.404

-8.113

0.827

1

Locking of all four wheels. (ABS intervention)

 

Test 3 – Front brakes only, ABS and EBD disabled

9 Stops from 40mph. Table of results:

Target Pressure [psi]

Target Pressure [Mpa]

Actual Average Pressure [Mpa]

Average Acceleration [m/s2]

Average Rate of Braking [g]

Braking Point

Observations

200

1.379

0.727

-1.573

0.160

2

400

2.758

3.319

-3.053

0.311

3

600

4.137

4.317

-4.639

0.473

1

800

5.516

4.423

-5.290

0.539

5

1000

6.895

5.797

-6.155

0.627

2

1100

7.584

6.054

-6.692

0.682

3

1200

8.274

7.474

-4.922

0.502

3

Locking of both front wheels

 

Test 4 – Rear brakes only, ABS and EBD disabled

9 Stops from 30mph. Table of results:

Target Pressure [psi]

Target Pressure [Mpa]

Actual Average Pressure [Mpa]

Average Acceleration [m/s2]

Average Rate of Braking [g]

Braking Point

Observations

400

2.758

1.878

-1.009

0.103

4

600

4.137

3.855

-2.107

0.215

5

800

5.516

4.844

-2.499

0.255

1

1000

6.895

6.044

-2.886

0.294

2

1200

8.274

7.190

-3.429

0.350

4

1300

8.963

7.850

-3.071

0.313

5

Locking of both rear wheels (damp).

1300

8.963

8.140

-3.120

0.318

1

Locking of both rear wheels (dry). Slight vehicle deviation

 

A sample deceleration and pressure trace from test D1 is shown to illustrate how the mean values were determined. The target pressure for this test was 400psi (2.758Mpa), however the driver averaged 1.905MPa.

deceleration_trace_pressure_rate_braking_g_MPa

Following figure shows test 1 and test 2 comparison

standardized_braking_test_test_rate_braking

Following figure shows test 3 and test 4 comparison.

test_standarized_braking_rate

 

 

 

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