
On June 4, 2014, NHTSA posted a report to Docket No. NHTSA-2008-0145 entitled, Technical Evaluation of the Flexible Pedestrian Leg Impactor (FLEX-PLI). Published last month by NHTSA, the report draws the conclusion that the Flex-PLI is an appropriate test tool for evaluating pedestrian lower extremity protection in vehicle bumper impacts.
The report abstract reads as follows:
The objective of this study was to evaluate the production version of the Flex-PLI (known as FlexGTR) pedestrian legform. Testing & analysis were done to examine the biofidelity, injury criteria, repeatability, reproducibility, durability, injury criteria efficacy, and sensitivity to vehicle design. Various bumper configurations from thirteen vehicles were tested with the Flex-PLI, in addition to multiple qualification tests, to evaluate these aspects of the legform. The primary findings from this evaluation were that the Flex-PLI legform is:
• Durable, as it didn’t sustain any significant structural damage in 30+ vehicle bumper impacts at 40 km/h. Many of these vehicles were far from complying with the proposed GTR injury limits.
• Biofidelic, as the legform maintained conformance with qualification corridors derived from biomechanical data
• Repeatable, with percent coefficients of variation (%CV) below 5% for all channels and below 2% for all injury channels (MCL and tibia 1 bending moment) in vehicle bumper tests
• Reproducible, with %CV 10% or below for three different legforms in vehicle bumper tests and below 4% in pendulum qualification tests without vehicle or test setup-related variance
• Sensitive to vehicle design, as demonstrated through testing a large range of compliant and non-compliant bumper systems. The Flex-PLI discriminated between systems containing pedestrian countermeasures, such as the lower bumper stiffener and modular energy absorber, and older model year, non-GTR compliant systems present in the U.S. fleet
In addition to these positive aspects of the Flex-PLI, testing with the legform led to a better understanding of (a) the feasibility of producing a bumper system that can comply with both GTR and bumper damageability requirements, (b) the differences expected from using the Flex-PLI instead of the EEVC leg, and (c) the current performance of the U.S. fleet with respect to the GTR. In summary, this assessment demonstrated that the Flex-PLI is an appropriate test tool for evaluating pedestrian lower extremity protection in vehicle bumper impacts.