1. Pre kick off meeting 1 1 NCHRP_22_24 January 22 2007 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

2. Pre kick off meeting 2 2 NCHRP_22_24 January 22 2007 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.

3. Pre kick off meeting 3 3 NCHRP_22_24 January 22 2007 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.

4. Pre kick off meeting 4 4 NCHRP_22_24 January 22 2007 CFC 60 3 over 8. We could relax the limits. But with no statistical meaning.

5. Pre kick off meeting 5 5 NCHRP_22_24 January 22 2007 Filtered at 12.5 hz Always 3 over 8

6. Pre kick off meeting 6 6 NCHRP_22_24 January 22 2007 Different experimental test Worse condition. Different requirements in the second phase?

7. Pre kick off meeting 7 7 NCHRP_22_24 January 22 2007 Only the first phase. Always the same problem. Minimum peak fails even if is less important.

8. Pre kick off meeting 8 8 NCHRP_22_24 January 22 2007 First phase. Only way to pass all the tests. First part of the impact and relaxation of limits.

9. Pre kick off meeting 9 9 NCHRP_22_24 January 22 2007 Two experimental tests 4 over 8!

10. Pre kick off meeting 10 10 NCHRP_22_24 January 22 2007 Other possibility Window obtained from test where simulation must be contained. Not easy to justify a window (delta time, delta g, filtering)

11. Pre kick off meeting 11 11 NCHRP_22_24 January 22 2007 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

12. Pre kick off meeting 12 12 NCHRP_22_24 January 22 2007 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)

13. Pre kick off meeting 13 13 NCHRP_22_24 January 22 2007 Vehicle rotation Vy Global Vy Local x y x y X Y α x y α X X α x y X

14. Pre kick off meeting 14 14 NCHRP_22_24 January 22 2007 Round Robin. Rigida barrier h=800 mm. Tb11 –900 kg –20°

15. Pre kick off meeting 15 15 NCHRP_22_24 January 22 2007 Round Robin 1. Same new vehicle. Only exp. results

16. Pre kick off meeting 16 16 NCHRP_22_24 January 22 2007 Round Robin 2 Different not new vehicles

17. Pre kick off meeting 17 17 NCHRP_22_24 January 22 2007 Robust 4.3 –Two more tests on RR1

18. Pre kick off meeting 18 18 NCHRP_22_24 January 22 2007 All the tests. Same rigid barrier. Different vehicles. 12 nominally identical.

19. Pre kick off meeting 19 19 NCHRP_22_24 January 22 2007 Round Robin. Test and simulation –Not so bad. –Friction influence. (Not understood from acceleration comparison).

20. Pre kick off meeting 20 20 NCHRP_22_24 January 22 2007 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.

21. Pre kick off meeting 21 21 NCHRP_22_24 January 22 2007 Deformable barrier. Task 4.1 Robust. N2 barrier (max 1500 kg 110 km/h 20°). Different vehicles. Gorund differences.

22. Pre kick off meeting 22 22 NCHRP_22_24 January 22 2007 Yaw angle x y x y X Y α x y α X X α x y X Angle

23. Pre kick off meeting 23 23 NCHRP_22_24 January 22 2007 Yaw angle problems during tests

24. Pre kick off meeting 24 24 NCHRP_22_24 January 22 2007 Comparison.

25. Pre kick off meeting 25 25 NCHRP_22_24 January 22 2007 Comparison 1 Dynamic deflection (ground) –Curve 1 (blue)=0.9m –Curve 3 (red)=0.7m –Difference 25%

26. Pre kick off meeting 26 26 NCHRP_22_24 January 22 2007 Tests and simulation

27. Pre kick off meeting 27 27 NCHRP_22_24 January 22 2007 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?