About Legforms

Legforms have been developed both as independent manikin body segments and as components of full dummies. In both these forms they are used to test vehicles to record and evaluate the effects of leg-vehicle interaction. The primary advantage to using these legs in pedestrian impact testing is to evaluate the effects of leg-vehicle impacts under controlled kinematic conditions without variable input from the entire dummy body (Flex PLI and TRL leg forms).
These pedestrian legforms are designed to give data on bone bending and ligament dislocation at the knee. Legforms have also been developed to enhance the biofidelity of existing full dummies (THOR leg form). These legs have given the engineer the ability to test leg-vehicle interior interactions with better biofidelic response in tests requiring a complete dummy. Injury to the legs can be very debilitating and these leg forms aid in the development of protective measures for leg-vehicle interactions.

Why We Test With Legforms

The THOR-LX and THOR-FLX legforms are designed for use on Hybrid III and THOR dummies. They give the Hybrid III enhanced biofidelic response and they are part of the overall design of the THOR dummy. These legforms are used in tests involving the complete dummy in the vehicle.
The Flex-PLI legforms are designed to be launched at the front of the vehicle to measure forces and strains caused by leg-vehicle interaction in a simulated pedestrian incident. Their design allows the estimation of bone bending and ligament dislocation. Since they are used independently of a dummy the data is focused on the critical interaction at the vehicle front.
The TRL legforms are also designed for specific simulation of leg impacts with the front of the vehicle.

History of Legforms

The THOR legforms have been developed under the NHTSA advanced dummy effort. Work on the THOR has been ongoing for approximately 20 years to enhance the biofidelic responses of various parts of the dummy as a next step from the Hybrid III to a Hybrid IV advanced crash test dummy.
The TRL pedestrian legforms were developed in conjunction with the EEVC WG 17 (European Enhanced Vehicle Safety Committee) in 1998 and are applied in Directive 2003/102/EC. FLEX-PLI legform development was started in 2002 by JAMA and JARI (the Japan Automobile Manufacturers Association and the Japan Automotive Research Institute). The final version, the FLEX-GTR was developed by FTSS, one of Humanetics predecessor companies. The first prototypes were launched in 2008 and were subsequently tested by the FLEX Technical Evaluation Group (FLEX-TEG). The FLEX-GTR is intended for use in Global Technical Regulation GTR9. The FLEX-GTR is available at Humanetics.

Legforms and Their Use in Regulations

The legforms are possibly to be included in EEC regulations.

Future Legforms

The Flex PLI legforms were developed to improve upon the responses of the TRL legs in areas that were found to be deficient in biofidelic response. Future work in characterizing the injury pathways in the legs and information relating to injury in pedestrian incidents may lead to modifications in existing leg form designs or to the development of new legforms with even better injury predictive capabilities than the current models.

Legform Review

Legforms are used on full dummies and as separately launched or impacted body components to test the interior of vehicles and the front of vehicles for leg interactions and leading to injury. Their use is instrumental in improving protective capabilities for the human leg in current vehicle designs.