Comparison of Thorax Responses between the Belted Elderly Occupant Human Body and THOR-50M FE Models under Typical Frontal Crash Test Conditions

摘要

In Japan the ratio of traffic accident fatalities of elderly people has been increasing, and the main factor is thorax injury. An elderly human body model (HBM) has been developed to evaluate the vehicle safety systems. At the same time, Test device for Human Occupant Restraint (THOR) ATD that has high bio-fidelity is being used in frontal crash tests including lateral vehicle motion. This paper describes the comparison of the thorax response between an elderly human and THOR 50th percentile male (THOR-50M) under a simulated frontal crash including lateral vehicle motion, and clarifies whether there is the correlation between them, especially, the correlation between the rib fractures of the elderly HBM and the thorax deformation of the THOR-50M. The elderly HBM and THOR-50M model were compared under the condition of a driver seat position in a left-handed midsized sedan vehicle equipped with a three-point seat belt, a driver airbag, a knee airbag, and a side curtain airbag. The frontal crash motions of Full Width Rigid Barrier (FWRB) at 56 km/h, Offset Deformable Barrier (ODB) at 64 km/h, Small Overlap Test (SOT) at 64 km/h and Oblique Moving Deformable Barrier (OMDB)-to-vehicle crash test at 90 km/h were applied. From the results the thorax responses and deformation were investigated respectively. The kinematics of each body component was in same trend between the elderly HBM and THOR-50M model in each test condition. For the elderly HBM and THOR-50M model in all the test conditions, the thorax deformation at the upper right was largest among four measurement locations, and that of the elderly HBM and THOR-50M model showed good correlation. In the elderly HBM, the locations of rib fractures were roughly assorted into three regions on the ribcage. The upper left ribs around the belt path in all test conditions, the right ribs around the belt path in FWRB and OMDB, and the lower left ribs in SOT and OMDB were fractured. The R~2 (correlation coefficient) between the number of fractured ribs of the elderly HBM and the overall peak resultant deformation (R_(max)) of THOR-50M was high as 0.83 for total rib fractures over all regions, while that wasn't high as 0.7 or less for those of each region. The structural differences between the elderly human and THOR-50M such as the ribcage, spine and shoulder were considered to affect the differences of the kinematics and thorax deformation between them under frontal loading with lateral and vertical input. The comparison results showed a certain correlation between the rib fractures of the elderly HBM and the thorax deformation of THOR-50M, and several differences of the partial thorax responses due to structural differences between humans and THOR-50M. The results of this study suggested that further study for the methods to evaluate detailed thorax injury using THOR-50M should be needed in order to correlate any other indices and possible thorax injuries in the crash conditions with lateral motion.