Crash Pulse Characterization for Restraints System Performance Optimization 2015-26-0152

The vehicle crash signature (here on referred as crash pulse) significantly affects occupant restraints system performance in frontal crash events. Restraints system optimization is usually undertaken in later phase of product development. This leads to sub-optimal configurations and performance, as no opportunity exists to tune vehicle structure and occupant package layouts. In concept phase of development, crash pulse characterization helps to map occupant package environment with available structure crush space and stiffness. The crash pulse slope, peaks, average values at discrete time intervals, can be tuned considering library of restraints parameters. This would help to derive an optimal occupant kinematics and occupant-restraints interaction in crash event. A case study has been explained in this paper to highlight the methodology. The study has been undertaken for critical frontal crash load cases, considering library of single stage restraints components (airbags, seat belts). Crash pulse requirements have been derived for a stiffness range of these restraints components. To simplify the study, library of restraints components has been classified in three stiffness categories. Design of experiments (DOE), which forms an integral part of this study, helped to identify performance sensitive variables in concept crash pulse. Zones have been identified in crash pulse characteristic curve, which need further optimization, to achieve occupant restraints performance with adequate margins and robustness. The output from this study is a force vs displacement and force vs time characteristic curves. This is used to understand the stiffness and crush length requirements from the vehicle structure.