Examination of Different Bumper System Using Hybrid II, RSPD Subsystem and Cadavers

Analysis of the results of previous simulations of pedestrian collision performed with different commercial dummies have indicated that test results do not always correspond with observations in simulations with cadavers. It seems that determining the risk of injury to pedestrians from these dummy tests may be very difficult.

To study injury-related parameters in connection with mechanical dummies, 21 crash tests were performed at the Institute of Forensic Medicine at the Medical University of Hannover. Various front structures and velocities of vehicles were simulated. Two measuring tools were used for verification: a standard Hybrid II dummy, and the lower part of a Rotationally Symmetrical Pedestrian Dummy (RSPD) with no representation of the upper body. RSPD was previous developed at the Department of Injury Prevention at Chalmers University in Göteborg. Results from these mechanical tests were compared with previous cadaver tests performed at the Institute of Forensic Medicine at the Medical University of Hannover. In all the tests particular emphasis was put on the lower extremities. The tests confirmed that it is possible to design front structures consisting of the standard bumper plus an additional structure below the bumper, which reduces the severity of injuries to the knee region and the leg.

Results from our study confirm the previous indications that in crash tests for the assessment of car-front aggressivity to pedestrian lower extremities it is necessary to use a specially designed mechanical tool for measurement of injury-related parameters. To date none of the systems used give a complete description of the risks of leg and knee injuries. There are at least four parameters that are essential for satisfactory information about loading of the knee joint and the leg: impact force (contact force between car-structures and pedestrian leg) and its distribution, shear force and bending moment transferred through the knee region. It is very important that future tools used for testing of car fronts enable the measurement of all these parameters.