In Japan, a new legform impactor for pedestrian protection testing has been developed during the past 10 years. This legform is called “Flexible Pedestrian Legform Impactor” (FlexPLI). Compared to the existing legform currently used in Europe, the FlexPLI is intended by its developers to better reflect the behavior of a human leg during an impact with a vehicle. In addition to a more humanlike knee section, the new impactor provides for the possibility to also assess injuries of the pedestrian's tibia.

In the first development phase, the legform was considered to be very biofidelic but testing robustness was limited. In its further development, the impactor was modified to better address the needs of a certification tool:​ The latest version of the legform is more robust than pre-versions, the handling is acceptable, the repeatability of test results seems to be acceptable and the legform fits into the current sub-system test scenario of the global technical regulation (gtr) No 9 on pedestrian safety.

Common vehicle designs use a forward-moved lower structure of the bumper as a load path to reduce the knee bending. However, these structures may cause higher strains in the tibia area of the FlexPLI (and consequently may indicate a risk for tibia injuries in real-world accidents). Therefore, for many vehicles the bumper systems designed to meet the requirements for the lower legform currently used in Europe will need to be redesigned to fulfill the FlexPLI targets.

Nevertheless, the FlexPLI has already been proposed to be used as certification tool in gtr No 9. The study presented below provides first results of tests in a manufacturer’s lab with different vehicles of different categories and identifies general concepts for optimization towards FlexPLI requirements’ fulfillment. The intention of this paper is to summarize the experiences gained for use as information for future vehicle developments