The pedestrian protection given by a vehicle is assessed according to four independent impact test procedures, related to different body segments. Four impactors were developed specifically:​ leg, upper-leg, child head and adult head. These impactors, which are thrown against specific zones of the front face of the vehicle, allow the measurements of biomechanical criteria simulating the injury risk during the impact .Such test procedures are used by Euro NCAP and by the European regulation on pedestrian protection.

Concerning the leg, the first impactor used was the TRL impactor, but since 2014, the TRL impactor was replaced by the FLEX-PLI impactor for the Euro NCAP tests. The conception and the biomechanical criteria are different between the TRL and the FLEX-PLI. A specific study is carried out, to quantify behavioural differences between these two impactors tests.

In the first part of this study, various tests are performed with FLEX-PLI and TRL impactors on vehicles with different heights of front face. In these tests we check if vehicles that respect the Euro NCAP criteria with the TRL impactor, also respect the Euro NCAP criteria with the FLEX-PLI impactor. These tests are carried out with the cooperation of UTAC CERAM.

Then, in the second part, after analysis of the tests results, we identify the least favourables front face geometries for the FLEX-PLI impactor for the respect of the Euro NCAP requirements. Then using numerical simulations, we identify design and conception levers that allow to improve the results for the FLEX-PLI test for this kind of front face geometries. The numerical study is conducted with the cooperation of ACTOAT company.