Currently, there are critical and controversial issues in side impact safety including biofidelity of different side impact dummies and two different injury criteria in the United States and Europe. More fundamental research is still needed to get a better understanding of biomechanical responses, injury mechanisms, and effective injury countermeasures in real-world side impacts.

The purposes of this study were (1) to develop test methodologies for the study of spacing and padding effects in real-world side impacts, (2) to determine thoracic injury mechanisms of the human thorax under those test conditions, and (3) to find the best injury criterion which faithfully predicts the thoracic injury observed in a range of spacing padding and conditions. For this study, two new test methodologies have been conceived and successfully developed:​ (1) limited-stroke, high-energy linear impactor and (2) sledto-sled side impact subsystem.

The limited-stroke, high-energy linear impactor was developed to replicate the important parameters demonstrated by the intruding door in a real-world side impact. The linear impactor was pneumatically driven such that impact velocity did not decrease too much during impact and the stroke was limited to simulate realistic door intrusions. Using the linear impactor, eighteen BioSID runs, six SID runs, and four cadaver tests were run for five different choices of 102 mm (4 inches) thick padding to investigate thoracic responses to lateral velocity pulse impacts. Candidate side impact injury criteria:​ TTI, ASA, VC_max, C_max, Contact force (F_max and F_avg), F_avg*C_max, Stored Energy Criterion (SEC), and Energy Storing Rate Criterion (ESRC) were critically evaluated. This experimental study is the first ever performed and only a test series such as this can legitimately determine the validity of various thoracic injury criteria in real-world side impacts.

In BioSID and cadaver runs, it has been shown that acceleration-based T i l and deflection-based Cnuw have opposite trends when stiff padding is introduced. SID peak response was quite different than BioSID response. These initial cadaveric study showed the contact force (R² = 0.996 for F_max and R² = 0.927 for F_avg) was the best injury criterion and C_max was a better injury index than TTI.

The sled-to-sled side impact subsystem test simulated a pulse quite similar to the door velocity in a real-world side impact. Three SID tests were run using this velocity pulse for three different choices of padding. The SID runs showed promise in demonstrating the effects of spacing and door padding that can occur in a real-world side impact. This study will help clarify critical and controversial issues in side impact crash protection and hopefully contribute to the acceptance of one thoracic injury criterion for side impact throughout the world.