Measurement and comparison of thoracic viscous response between the Chinese anthropomorphic test device and hybrid III.

OBJECTIVE: Anthropomorphic test devices (ATDs) are essential tools for estimating occupant injury risks under controlled impact conditions. Viscous response (VC) is one of the important criteria for assessing the risk of thoracic injury. However, the thoracic displacement sensor in the existing Hybrid III ATD cannot directly measure or calculate VC. This article aims to establish general methods for measuring the thoracic VC of ATDs, and to obtain and compare the thoracic VC of an ATD representing the 50th percentile Chinese adult male (CN-50M) with that of the Hybrid III 50th percentile male ATD (HIII-50M). METHODS: Thoracic VC is calculated from external chest deformation, which includes the viscoelastic properties of the thoracic skin. Two methods for measuring external chest deformation during thoracic impact tests are proposed: (1) External deformation is obtained by subtracting the dummy's shoulder displacement from the impactor displacement, both measured using a high-speed camera. (2) External deformation is obtained by subtracting the dummy's thoracic spine displacement, measured using a string potentiometer, from the impactor displacement, measured using a high-speed camera. A total of nine impact tests were conducted on two CN-50M and three HIII-50M dummies on the thoracic calibration test bench. The pendulum mass was 19.78 kg for the CN-50M tests and 23.36 kg for the HIII-50M tests, with an impact velocity of 6.7 m/s in both cases. RESULTS: The average peak internal thoracic VC of the CN-50M was 0.8019 m/s, which is 19.63% higher than that of the HIII-50M (0.6703 m/s), while the peak external thoracic VC of the CN-50M was comparable to that of the HIII-50M. The recommended values of the external-to-internal VC scaling factor for the CN-50M and HIII-50M are 1.63 and 2.03, respectively. CONCLUSIONS: The proposed methods can effectively measure the thoracic VC of the ATDs. Under lower impact energy, the internal thoracic deformation velocity and peak VC of the CN-50M were both significantly higher than those of the HIII-50M.