Parametric Analysis of Rollover Occupant Protection Using a Deformable Occupant Compartment Testing Device

Occupant kinematics during rollover inverted impacts has been the subject of significant research. Controlled experiments have utilized complete vehicles, partial vehicles and seat/restraint systems attached to various platforms. The Deformable Occupant Compartment Impact Tester (DOCIT) was developed to incorporate functions similar to previous methods, but has added a roof capable of deforming under impact. These roof deformation characteristics can be reset without the destruction of a complete vehicle. The DOCIT simulates an occupant compartment (roof, seat, restraint system) in which an ATD is placed and subjected to a repeatable inverted dynamic impact environment. Several test series are reviewed, in which standard of value tests, based upon real-world rollover accidents, are compared with alternate design systems under the same impact environments. 5th and 50th percentile Hybrid III ATD’s are utilized to assess neck and head injury criteria. Alternate designs for roof structures and restraint systems are tested to determine the effectiveness of each. The DOCIT accommodates rapid parametric analysis of occupant injury criteria relative to various occupant, restraint and roof configurations in a dynamic loading environment and enables evaluation of restraint system performance and injury potential under impacts with controlled initial/residual head clearance and repeatable pre-determined roof profiles. Test variations in restraint systems or roof performance can be correlated with other component and full vehicle tests without the need for the destruction of many vehicles. This research indicates that for reasonably restrained occupants, roof crush preceded head to roof contact and peak neck forces. Reducing roof crush also reduced neck injury measures and therefore neck injury potential. In many cases, reducing roof crush and optimizing restraint designs eliminated interaction with the roof and provided correspondingly negligible injury measures.