Evaluation of finite element models of the advanced Pedestrian Legform Impactor

Abstract

According to the National Highway Traffic Safety Administration (NHTSA), 54,769 pedestrians were injured in the United States during 2020 (Stewart, 2023). Among these injured pedestrians, 12,623 experienced incapacitating injuries (National Center for Statistics and Analysis, 2022). To minimize such injuries, both physical and Finite Element (FE) representations of the advanced Pedestrian Legform Impactor (aPLI) are used in vehicle design to reduce the risk of serious injuries to the lower extremities. The physical aPLI is a mechanical representation of the human leg used to assess knee, tibia, and femur injury risk in crash testing. This project aimed to evaluate the performance of two different FE models of aPLIs in LS-DYNA by conducting dynamic validation tests. In addition, this project aimed to determine which FE aPLI model better correlated with physical test results using a Generic Vehicle Test Rig (GVTR) within the limitations set by this thesis. A dynamic validation test was conducted on a physical aPLI to ensure its validity. The test employed an energy absorber attached to a linearly guided sled, which im pacted the aPLI at 40 km/h. The resulting signal responses from sensors in the knee, tibia, and femur had to fall within a specified certification corridor for the physical aPLI to be considered valid. This test was then mimicked in the FE environment, and the performance of the FE aPLI models was evaluated based on how close to the physical test results they predicted. The two FE aPLI models were Humanetics v1.2.6 and ATD-models D02.11. A sensitivity study was conducted during this step of the project, in which the FE dynamic validation test was performed using the maximum and minimum tolerance limits to investigate if the signal responses from the FE aPLI models would diverge. The next step consisted of simulating impact tests with the GVTR and comparing the results to physical test results. The results showed that the Humanetics FE aPLI model demonstrated better and more consistent performance in the validation test. It was slightly more robust in the FE sensitivity study and produced results that correlated more closely with physical impact tests with the GVTR.