Energy-Absorbing Polyurethane Foam to Improve Vehicle Crashworthiness

Federal legislation mandates that automotive OEMS provide occupant protection in collisions involving front and side impacts This legislation, which is to be phased-in over several years, covers not only passenger cars but also light-duty trucks and multipurpose passenger vehicles (MPVs) having a gross vehicle weigh rating (GVWR) of 8,500 lb (3,850 kg) or less.

During a frontal impact, occupants within the vehicle undergo rapid changes in velocity. This is primarily due to rapid vehicle deceleration caused by the rigid nature of the vehicle's metal frame components and body assembly. Many of today's vehicles incorporate deformable, energy-absorbing (EA) structures within the vehicle structure to manage the collision energy and slow the deceleration which in turn can lower the occupant velocity relative to the vehicle. Occupant velocities can be higher in light-duty trucks and MPVs having a full-frame structure resulting in increased demands on the supplemental restraint system (SRS). In these types of vehicles an energy management system can be installed between the bumper and the vehicle structure to help absorb some of the collision energy and reduce occupant velocities.

This paper describes an energy management system based on polyurethane foam to improve the crash signature of light-duty trucks and MPVs. The design and development requirements for this system are detailed as are material evaluations and full-scale impact testing. Development of a polyurethane material to meet the design requirements is also outlined. The test results demonstrate that vehicle crashworthiness can be improved by using energy-absorbing polyurethane foam to modify a vehicle's crash signature.