Evaluation of THUMS Human FE Model in Oblique Frontal Sled Tests against Post Mortem Human Subject Test Data

Abstract

Last year 319 people were killed in traffic accidents in Sweden. The majority of these were car drivers and passengers. In order to minimize the number of people killed in traffic, vehicle safety is very important. Crash tests are frequently used to develop safety systems in cars. Both mechanical testing with crash dummies and simulations with mathematical models of the crash dummies are used. However, a disadvantage with the crash dummies is that they have limited biofidelity in order to be durable for repeatable testing. Therefore there is a difference between their kinematics in a collision compared to the kinematics of humans. To be able to predict the response of a human body, mathematical human body models have recently been developed, e.g. the Total HUman Model for Safety (THUMS). Since THUMS is a relatively new model there have been limited validation done to establish its kinematic performance. In pure frontal impact some validations have been done, by means of pendulum and sled tests, but in oblique frontal impacts, a rather common crash situation, no evaluation have been done. The aim of this project is to evaluate the kinematics of THUMS version 2.21 against Post Mortem Human Subjects (PMHS) in oblique frontal collisions. Two sled test series with belted PMHS and Hybrid III 50th percentile male (HIII) dummies have been used in the project. The velocities in the tests were approximately 30 km/h and the acceleration pulses in the sleds were approximately 13 g. The two sled setups have been modelled and simulated with an HIII dummy model and with THUMS. The HIII simulations were used to validate the sled environment and then THUMS was evaluated against the PMHS data. The results consist of belt force, acceleration and displacement comparisons between the mechanical test results and the mathematical model predictions. The results from the HIII simulations shows good conformity with the HIII dummy test results for both sled environments. In the THUMS evaluation there are issues with THUMS interaction with the simulated seat belt. The belt elements entangle with the elements in the neck and the chest of THUMS and the belt therefore get stuck. However, THUMS replicates post mortem human kinematics even though THUMS appears to be somewhat stiffer than the PMHS.