Mr. Takahashi presented document GTR9-7-13. He explained that JASIC sees issues with the definition of the Biofidelic Assessment Interval (BAI) proposed by BASt. For some vehicles, the length of the interval could affect the maxima due to its definition. Here, due to the length of the interval, it does not seem to be biofidelic in all cases. In addition, in the beginning of the contact phase with the vehicle some local maxima may occur that could be misinterpreted when using the BAI. However, Mr. Takahashi stated JASIC may accept the interval as a solution for the current discussion as long as it is not called “Biofidelic Assessment Interval” but just “Assessment Interval”.
In response Mr. Zander presented document GTR9-7-15. He finalized to still see the biofidelity of the legform within this interval. For the local maxima at the beginning of the contact phase he proposed to exclude all peaks that still are in the corridors of the pre-contact phase as covered by agenda item 6.2.
Dr. Otubushin supported Mr. Takahashi’s opinion of the limited biofidelity but stated to see the BASt proposal as the best solution currently available. Mr. Gehring wondered whether biofidelic really refers to the human-like behavior. After some further discussion it was concluded that the proposal itself seems to be acceptable but that the name may be modified. The chair reminded the group that discussion is not finalized here and experts are invited to come up with a better proposal if possible.
Before concluding the subject Mr. Takahashi wondered whether the assessment should include the femur data since these are not needed for passing the FlexPLI requirements. Mr. Martin proposed to also develop femur criteria. The chair added that currently an assessment of the femur is not subject of the discussion. The idea here is to assess the human-like behavior of the legform during the rebound phase while a general human-like behavior may not be given for the femur of the FlexPLI. This may need to include other technical solutions in the future, such as e.g. an upper body mass. The chair also reminded the group that the aim was to finish the discussion preferably by the end of this year which may not be possible if a possibility to assess femur injuries needs to be developed. Mr. Martin responded that, however, if femur measurement results are taken into account a certification possibility should exist for the respective data channels.
Mr. Takahashi and Mr. Roth supported Mr. Damm regarding the tight timing of the work of this Informal Group. Dr. Otubushin wondered whether it would be possible to just develop a corridor e.g. for the time history curves. This may solve NHTSA’s concerns. Mr. Burleigh noted that the certification of the overall assembly is already done. So, there is no need to test the femur on its own. Mr. Zander added that static tests for both, the tibia and the femur, are already included in the draft gtr No 9 amendment. Mr. Martin suggested that it also may be sufficient to just define the common zero crossing.
After some further detailed discussion on pros and cons Dr. Konosu proposed that JARI could review the data to assess the issue (action item A-7-08). The chair noted that Mr. Zander will support JARI with BASt data. Also, the chair welcomed the activities but added that he somehow doubts whether there is a need for this especially since femur data are useless in their current form for any assessment. The chair finally emphasized that, if there were a problem, it would be questionable whether the Informal Group could stick to its schedule.
Finally, Mr. Hardy added that it should be made clear in the wording for the “Biofidelic Assessment Interval” that “maximum” refers to positive maxima and does not include negative maxima (meaning minima). In addition, he wondered whether in the BASt document on the BAI the wording “In the case of not all bending moments having a zero crossing during the common zero crossing phase…” should read “… the common femur and tibia zero crossing phases…” (document GTR9-6-07, page 14). It was agreed that BASt will check this (action item A-7-09).
(Note of the secretary: Since action item A-6-09 could not be closed it will be maintained for the 8th meeting.)
The presentation of BASt (document GTR9-6-07) was introduced by Mr. Zander. He explained that, according to his opinion, it would be more appropriate to define a biofidelic assessment interval that covers all possible cases as explained.
The chair invited the audience to discuss the issue. Discussion came up on when the rebound phase starts. Mr. Zander confirmed on request of Mr. Roth that the interval should be considered in which the FlexPLI behaves like the human or the human model respectively. Dr. Ries pointed out that then the interval proposed seems much too long since the legform is only for the first contact confirmed to be biofidelic. Also, this period may be different for tibia and knee. He and Mr. Roth wondered how BASt specified the length of their Biofidelic Assessment Interval and Mr. Zander responded that an objective method and automatic evaluation method was requested. There is no clue that the impactor biofidelity is limited to the pure contact phase with the vehicle only. The BAI can solve this issue. In addition, it covers all potential critical loadings during the test. Partly, the BAI interval is even shorter than the interval proposed by industry in document GTR9-5-30. This was demonstrated in document GTR9-6-07. The secretary reminded the attendees that some information on this had also been shown in the TF-BTA meeting held on 18 March 2013 and that the information is already available on the website. (Note of the secretary: The documents referred to were presented in the 3rd meeting of the Task Force Bumper Test Area as documents TF-BTA-3-03, TF-BTA-3-07 and TF-BTA-3-08 and are available on the respective UNECE website.)