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The purpose of this study is to help understand the thoracic response and injury mechanisms in high-energy, limited-stroke, lateral velocity pulse impacts to the human chest wall. To impart such impacts, a linear impactor was developed which had a limited stroke and minimally decreased velocity during impact. The peak impact velocity was 5.6 ± 0.3 m/s. A series of BioSID and cadaver tests were conducted to measure biomechanical response and injury data. The conflicting effects of padding on increased deflection and decreased acceleration were demonstrated in tests with BioSID and cadavers. The results of tests conducted on six cadavers were used to test several proposed injury criteria for side impact. Linear regression was used to correlate each injury criterion to the number of rib fractures. This test methodology captured and supported a contrasting trend of increased chest deflection and decreased TTI when padding was introduced.

Heidelberg-type side impact sled tests were conducted using SID side impact dummies. These tests were run under similar conditions to a series of cadaveric sled tests funded by the Centers for Disease Control in the same lab. Tests included 6.7 and 9 m/s (15 and 20 mph) unpadded and 9 m/s padded tests. The following padding was used at the thorax: ARSAN, ARCEL, ARPAK, ARPRO, DYTHERM, 103 and 159 kPa (15 and 23 psi) crush strength paper honeycomb, and an expanded polystyrene. In all padded tests the dummy Thoracic Trauma Index, TTI(d) was below the value of 85 set by federal rulemaking (49 CFR, Part 571 et al., 1990). In contrast, cadavers in 9 m/s sled tests did not tolerate ARSAN 601 (MAIS 5) and 23 psi (159 kPa) paper honeycomb (MAIS 5), and 20 psi (138 kPa) Verticel™ honeycomb (MAIS 4), but tolerated 15 psi (103 kPa) paper honeycomb (average thoracic MAIS 2.3 in six tests).

Seventeen Heidelberg type cadaveric side impact sled tests, two sled-to-sled tests, and forty-four pendulum tests have been conducted at Wayne State University, to determine human responses and tolerances in lateral collisions. This paper describes the development of a simplified finite element model of a human occupant in a side impact configuration to simulate those cadaveric experiments. The twelve ribs were modeled by shell elements. The visceral contents were modeled as an elastic solid accompanied by an array of discrete dampers. Bone condition factors were obtained after autopsy to provide material properties for the model. The major parameters used for comparison are contact forces at the level of shoulder, thorax, abdomen and pelvis, lateral accelerations of ribs 4 and 8 and of T12, thoracic compression and injury functions V*C, TTI and ASA.

Traumatic brain injury (TBI) continues to be a major health problem, with over 500,000 cases per year with a societal cost of approximately $85 billion in the US. Motor vehicle accidents are the leading cause of such injuries. In many cases of TBI widespread disruption of the axons occurs through a process known as diffuse axonal injury (DAI) or traumatic axonal injury (TAI). In the current study, an in vivo TAI model was developed using spinal nerve roots of adult rats. This model was used to determine functional and structural responses of axons to various strains and displacement rates. Fifty-six L5 dorsal nerve roots were each subjected to a predetermined strain range (<10%, 10-20% and >20%) at a specified displacement rate (0.01 mm/sec and 15 mm/sec) only once. Image analysis was used to determine actual strains on the roots during the pull.