ENERGY ABSORPTION DEVICE AND ENERGY ABSORPTION SYSTEM (EMBODIMENTS) FOR VEHICLE

摘要

A vehicle bumper energy absorber system includes a foam energy absorber (EA) for transverse mounting forward of a bumper and having a plurality of cavities formed therein. Variable-stiffness elements are located within the cavities and embedded within the EA. The variable-stiffness elements are formed from open-cell foam treated with magneto-rheological fluid. Electromagnetic devices are co-located with the respective elements and are energized to create magnetic fields acting on the magneto-rheological the elements and thereby increase the stiffness of the elements. When energized, the elements increase the overall stiffness of the EA/element system. When the electromagnetic devices are not energized, the stiffness of the EA by itself is relatively low to meet pedestrian protection goals. At speeds where pedestrian protection is not required but low-speed damageability goals are important, the electromagnetic devices are energized to stiffen the EA/element system.