Response of the Worldwide Side Impact Dummy (WorldSID) to Localized Constant-Speed Impacts

The objective of this study was to evaluate WorldSID constant-speed shoulder and thorax impact responses in terms of impact force, external and internal deflection (1D and 2D IR-Tracc response) for two velocities (1 m/s and 3 m/s), at three impact levels (shoulder, upper thorax and mid thorax) in three impact directions (lateral, +15° posterolateral, -15° anteraolateral). In addition, the impact force and external deflection were compared to previously published cadaver data. Each impact condition was repeated twice. A total of 42 tests were performed. The WorldSID's lowest peak impact force and external deflection were found for impact at shoulder level regardless of impact direction. Maximum force and deflection were found for impact at mid thorax. Comparison between WorldSID and PMHS showed similar external chest deflections for impacts at 3 m/s. The peak impact force response with respect to impact level was found to be reversed for the WorldSID compared to the PMHS, for which shoulder impact resulted in the highest peak force. External time history responses for the WorldSID compared to the one PMHS impacted at 1 m/s in lateral impact direction showed a significant difference in both timing and magnitude. External deflections at upper and mid thorax were approximately twice as high as the internal 1D deflection measured by the IR-Tracc. However, taking into account the rotation of the rib, the calculated 2D deflection response at the posterior impact direction was closer to the external deflection, and thus also to the PMHS deflection response at 3 m/s. These findings emphasize the need of 2D deflection measurement.