Time Frame

1 NCHRP_22_24 January 22 2007

Pre

kic

k off

meeti

ng 1

Time Frame

• CM/E finalised the vehicle and test object modelling documents (Parts 2&3) – These documents should be revised at regular

intervals

• Validation procedures still require research– Further analysis of the Round Robin data in

ROBUST is a necessary input – Difficult to predict the delivery of a draft

procedure – possibly 2007


Pre

kic

k off

meeti

ng 2

Validation.

• If we want to use CM for the certification of a system which are the requirements for a “validated” model?

• Validation should be based on a comparison between test and simulation using:– Severity indices.– Barrier performance:

• Deformation.• Failures.

– Vehicle trajectories.– Vehicle time histories (acceleration yaw ratio …)– …..

• Validation methods MUST be able to validate also tests repetition.


Pre

kic

k off

meeti

ng 3

Validation

• The problem is how to define an objective procedure to compare time histories.

• Direct comparison between avcceleration has been already demonstrated to be not applicable. Is not possible to find an objective way to compare such different curves.

• Other approaches:– Statistical approach (Chalmers software).– Velocity.

• Chalmers software:– Statistical comparison between a master and a signal to

be tested.– The comparison is based on 8 statistical indices.


Pre

kic

k off

meeti

ng 4

CFC 60

• 3 over 8. We could relax the limits. But with no statistical meaning.


Pre

kic

k off

meeti

ng 5

Filtered at 12.5 hz

• Always 3 over 80 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

-10

-5

0

5

10

15

20

25

30simulationtest


Pre

kic

k off

meeti

ng 6

Different experimental test

• Worse condition. Different requirements in the second phase?


Pre

kic

k off

meeti

ng 7

Only the first phase.Always the same problem.

• Minimum peak fails even if is less important.


Pre

kic

k off

meeti

ng 8

First phase.

• Only way to pass all the tests.• First part of the impact and relaxation of

limits.


Pre

kic

k off

meeti

ng 9

Two experimental tests

• 4 over 8!


Pre

kic

k off

meeti

ng 10

Other possibility

• Window obtained from test where simulation must be contained.

• Not easy to justify a window (delta time, delta g, filtering)

-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4-10

-5

0

5

10

15

20

25

30upper boundtest lower boundsimulation


Pre

kic

k off

meeti

ng 11

Other possibilty 3.Final consideration

• Compare two velocity time histories (experimental and numerical).

• If the difference between these two time histories become greather than X(t)% your model is validated until this time.

• After this time your model is not validated.• We are applying this approach also to the deformable barrier and

to other impacts


Pre

kic

k off

meeti

ng 12

Validation.

• Comparison based on local velocity components.– Reference frame is not inertial.– Accelerations evaluated on a reference system “mounted” on

the vehicle.– To proper evaluation of velocity relative mechanics should be

used.

• Comparison based on global velocity components.• Planar motion.

• Need of yaw rotation (not filtered).• Evaluation of global components of velocity

(interpretation less immediate)


Pre

kic

k off

meeti

ng 13

Vehicle rotation

Vy GlobalVy Local

x

yx

y

X

Y

αx

y

α

X X

αx

y

X


Pre

kic

k off

meeti

ng 14

Round Robin.

• Rigida barrier h=800 mm.• Tb11

– 900 kg– 20°


Pre

kic

k off

meeti

ng 15

Round Robin 1.

-0.2 0 0.2 0.4 0.6 0.8-2

0

2

4

6

8

10

12Vy global Unfiltered

AutostradeHut Cidaut Lier TRL

-0.2 0 0.2 0.4 0.6 0.816

18

20

22

24

26

28Vx global Unfiltered


-0.2 0 0.2 0.4 0.6 0.8-2.5

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2Vz global Unfiltered


Same new vehicle. Only exp. results


Pre

kic

k off

meeti

ng 16

Round Robin 2

• Different not new vehicles

-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6-2

0

2

4

6

8

10


-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6-3

-2

-1

0

1

2

3


-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.614

16

18

20

22

24

26



Pre

kic

k off

meeti

ng 17

Robust 4.3

– Two more tests on RR1

-0.2 0 0.2 0.4 0.6 0.8 1 1.2-2

0

2

4

6

8


-0.2 0 0.2 0.4 0.6 0.8 1 1.219

20

21

22

23

24

25

26

27


-0.2 0 0.2 0.4 0.6 0.8 1 1.2-1.5

-1

-0.5

0

0.5



Pre

kic

k off

meeti

ng 18

All the tests.

• Same rigid barrier.• Different vehicles.• 12 nominally identical.

-0.4 -0.2 0 0.2 0.4 0.6 0.8 1-2

0

2

4

6

8

10


-0.2 0 0.2 0.4 0.6 0.8 1 1.214

16

18

20

22

24

26


-0.4 -0.2 0 0.2 0.4 0.6 0.8 1-3

-2

-1

0

1

2

3



Pre

kic

k off

meeti

ng 19

Round Robin. Test and simulation

-0.4 -0.2 0 0.2 0.4 0.6 0.8 1-2

0

2

4

6

8

10


-0.2 0 0.2 0.4 0.6 0.8 1 1.214

16

18

20

22

24

26


-0.4 -0.2 0 0.2 0.4 0.6 0.8 1-3

-2

-1

0

1

2

3


– Not so bad.– Friction influence. (Not

understood from acceleration comparison).


Pre

kic

k off

meeti

ng 20

Rigid barrier results

• Components– Vy global: good agreement between tests– Vx global: scatter between tests (exit velocity is

different)– Vz global: less significative.

• Seems to work.


Pre

kic

k off

meeti

ng 21

Deformable barrier.

• Task 4.1 Robust.• N2 barrier (max 1500 kg 110 km/h 20°).• Different vehicles.• Gorund differences.


Pre

kic

k off

meeti

ng 22

Yaw angle

x

yx

y

X

Y

αx

y

α

X X

αx

y

X

Angle


Pre

kic

k off

meeti

ng 23

Yaw angle problems during tests

0 0.5 1 1.5 2 2.5 3-60

-40

-20

0

20

40

60Ay

0 0.5 1 1.5 2 2.5 3-100

-50

0

50

100

150

200

250Yaw rate

0 0.5 1 1.5 2 2.5 3-5

0

5

10

15

20

25

30Rotation

0 0.5 1 1.5 2 2.5 3 3.5-50

-40

-30

-20

-10

0

10

20

30

40rotation


Pre

kic

k off

meeti

ng 24

Comparison.

-1.5 -1 -0.5 0 0.5 1 1.5 20

2

4

6

8

10

12


-1.5 -1 -0.5 0 0.5 1 1.5 2 2.55

10

15

20

25


-1.5 -1 -0.5 0 0.5 1 1.5 2 2.50

0.5

1

1.5

2

2.5Vz global Unfiltered


Pre

kic

k off

meeti

ng 25

Comparison 1

• Dynamic deflection (ground)– Curve 1 (blue)=0.9m– Curve 3 (red)=0.7m– Difference 25%

-1.5 -1 -0.5 0 0.5 1 1.5 20

2

4

6

8

10

12


-1.5 -1 -0.5 0 0.5 1 1.5 2 2.512

14

16

18

20

22

24

26

28


-1.5 -1 -0.5 0 0.5 1 1.5 2 2.50

0.5

1

1.5

2



Pre

kic

k off

meeti

ng 26

Tests and simulation

-1.5 -1 -0.5 0 0.5 1 1.5 2 2.512

14

16

18

20

22

24

26

28


-1.5 -1 -0.5 0 0.5 1 1.5 2-2

0

2

4

6

8

10

12


-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5-1

-0.5

0

0.5

1

1.5

2



Pre

kic

k off

meeti

ng 27

Conclusion

• From Round Robin encouraging results.• From deformable barrier results not

acceptable.• Problem:

– With these results (deformable) window to accept simulation is too wide.

– According to 1317 these tests are equivalent. Means that a simulation with these differences is validated?

Time Frame

Documents