Mr. Takahashi also presented the document on the biofidelity issues. He concluded that, compared to the EEVC LFI, biofidelity has improved significantly. First, the risk of bone fracture is evaluated over the entire length of the tibia. As the peak stress of the bone is generally located below the impact point, the injury risk could not be addressed using the EEVC LFI accordingly. Second, an elongation of the cruciate ligaments is caused by both shear and valgus bending which is addressed accordingly by the FlexPLI while the EEVC LFI is using two separate thresholds for the knee shear displacement and the knee bending angle.

For the tibia fracture prediction, Mr. Takahashi had presented results for three different vehicle front ends (passenger car, SUV with low lower bumper reference line and SUV with high lower bumper reference line) in their original state as well as in a modified state. Mr. Zander wondered why for vehicles A and B the performance with the EEVC LFI was worse while it improved for vehicle C. Mr. Takahashi explained that vehicles A and B had relatively soft front ends and were modified to be stiffer while vehicle C already had a stiff front end and was modified to become softer. This explains the different results.

Also, Mr. Zander asked which simulation models were used. Mr. Takahashi stated that the human model was developed jointly by Honda and JARI. Detailed information on the human model is available in the references listed in the document GTR9-1-05. The vehicle models are simplified vehicle models and the derivation is described in detail in the reference paper (see list of references at the end of document GTR9-1-05) of Konosu et al. from the IRCOBI 2009 conference.

Mr. Bilkhu added that the EEVC LFI had been developed to address knee injuries. So, one should not be surprised that the performance regarding tibia injuries is limited. However, also with the FlexPLI the correlation of the knee response with the human model is not yet perfect compared to that of the tibia. Mr. Takahashi replied that they are aware of this and plan to study this in more detail in the future. On request he confirmed that this should not affect the design of the current impactor.

Besides, Mr. Bilkhu stated that both impactors do not seem to be very good for knee injury prediction (r value below .8) Mr. Takahashi answered this being one of the limitations of the legform only representing the isolated human leg. He stated that JARI is currently working on a study to incorporate the upper body mass effect. However, the study is at a too early stage for conclusions.

Ms. Versailles added that the US also had shown in their document GTR9-1-12 that the performance had been improved. Mr. Kinsky stated that however the presentation of the US may cover a mistake in its conclusions: due to the fact that the FlexPLI has an overload protection device (the steel cables along the long bones) and the EEVC LFI does not have such a device it is not possible to compare test results well above the limits. This was confirmed by Mr. Been (Humanetics).

Mr. Takahashi promised to also provide an updated version of this presentation that will include some slight corrections (see doc. GTR9-1-05r1).