Cervical human spine loads during traumatomechanical investigations

The last decade's improvements in automotive safety resulted into a significant decrease of fatal injuries. However, due to the use of belts and airbags it can be observed that cervical spine injuries, non-severe and severe, have become more important. It seems that inertial loading of the neck by the head is an important loading mechanism causing these injuries. Until now local deformations and load paths in the cervical spine can not be determined accurately from cadaver experiments due to the lack of adequate measuring techniques. At this moment the loads at the occipital condyles can be estimated by analyzing high-speed film and the linear and angular accelerations of the head. These loads show a correlation with (local) cervical spine injuries in car crashes. The head-neck response, the neck loads and the sustained injuries obtained from human cadaver experiments in the frontal, lateral and rear-end collisions were investigated to increase the knowledge of the traumatomechanics of the cervical spine. The severity of these experiments, e.g., sled deceleration, varies from 11 to 15 g for frontal, and 7 g for rear-end collisions; for lateral impacts, the shoulder was accelerated with 100 to 130 g through the intruded side wall of the car. It was observed, that rotational accelerations of 1000 rad/sec²do not lead to recognizable injuries during postmortem loadings, while rotational accelerations of 2000 - 3000 rad/sec²or bending moments of 80 - 100 Nm can lead to injuries of ligaments, intervertebral discs and compression fractures of vertebral bodies. Shear forces in frontal collisions of 1000 - 1500 N at the level of the occipital condyles cause strength of the joints in this region. The resultant acceleration at the head center of gravity varies from 20 to 45 g

Evaluation of the performance of the THOR-alpha dummy

47th Stapp Car Crash Journal, , , -Six European laboratories have evaluated the biomechanical response of the new advanced frontal impact dummy THOR-alpha with respect to the European impact response requirements. Me results indicated that for many of the body regions (e.g. shoulder, spine, thorax, femur/knee) the THOR-alpha response was close to the human response and more biofidelic than die Hybrid111. In addition, the durability, repeatability and sensitivity for some dummy regions have been evaluated. Based on the tests performed, it was found that the THOR-alpha is less durable than the Hybrid-III. The Jack in durability of the THOR-alpha caused a problem in completing the full test program and in evaluating the repeatability of the dummy. Results have demonstrated that the assessment of frontal impact protection can be greatly improved with a more advanced frontal impact dummy. Regarding biofidelity and injury assessment capabilities, 'the THOR-alpha is a good candidate however it needs to be brought up to standard in other areas. Based on the results obtained recommendations were defined for the improvement of the THOR-alpha dummy. Mots clés libres :performance, biofidelity, thor-alpha, HYBRID-III