Evaluation of near-side oblique frontal impacts using THOR with SD3 shoulder.

OBJECTIVE

Within the EC Seventh Framework project THORAX, the Mod-Kit THOR was upgraded with a new thorax and shoulder. The aim of this study was to investigate whether the THOR ATD met a set of prerequisites to a greater extent than Hybrid III and by that measure whether the dummy could serve as a potential tool for future evaluation of serious head and chest injuries in near-side oblique frontal impacts.

METHOD

A small-overlap/oblique sled system was used to reflect occupant forces observed in oblique frontal crashes. The head and thoracic response from THOR was evaluated for 3 combinations: belt only with no deformation of the driver's side door (configuration A), belt only in combination with a predeformed door (configuration B), and prepretensioning belt and driver airbag (PPT+DAB) in combination with a predeformed door (configuration C). To evaluate head injury risk, the head injury criterion (HIC) and brain injury criteria (BrIC) were used. For evaluation of the thoracic injury risk, 3 injury criteria proposed by the THORAX project were evaluated: Dmax, DcTHOR, and strain (dummy rib fractures).

RESULTS

Unlike Hybrid III, the THOR with SD3 shoulder interacted with the side structure in a near-side oblique frontal impact. HIC values for the 3 test configurations corresponded to a 90% (A) and 100% (B and C) risk of Abbreviated Injury Scale (AIS) 2+ head injury, and BrIC values resulted in a 100% risk of AIS 2+ head injury in configurations A and B. In C the risk was reduced to 75%. The AIS 2+ thoracic injury risks based on Dmax were similar (14-18%) for all tests. Based on DcTHOR, AIS 2+ injury risk increased from 29 to 53% as the predeformed door side was introduced (A to B), and the risk increased, to 64%, as a PPT+DAB was added (C). Considering the AIS 2+ injury risk based on strain, tests in A resulted in an average of 3 dummy rib fractures (17%). Introducing the predeformed door (B) increased the average of dummy fractures to 5 (39%), but in C the average number of dummy rib fractures decreased to 4 (28%).

CONCLUSIONS

THOR with an SD3 shoulder should be the preferred ATD rather than the Hybrid III for evaluating head and thorax injuries in oblique frontal impacts. Thoracic interaction with the predeformed door was not well captured by the 3D IR-Traccs; hence, use of deflection as an injury predictor in oblique loading is insufficient for evaluating injury risk in this load case. However, injury risk evaluation may be performed using the strain measurements, which characterize loading from seat belt and airbag as well as the lateral contribution of the structural impact in the loading condition used in this study.