Evaluations of aluminum foams show they can be efficient energy absorbers. They are especially interesting because they have virtually no rebounding characteristics. The load-compression response characteristics of the foam can be controlled by variations of alloy composition and foam density, thereby controlling foam strength and ductility. This makes foamed metals attractive candidates for a number of automotive energy-absorption applications.
The energy-absorption properties of a number of aluminum alloy foams have been studied under low and medium speed impact, up to 25 mph. The foam density, volume, and size required for a 5 mph “single shot” impact shock absorber have been determined for two automotive weight classes.
Nonshearing, columnar, high-density foam structures have been developed to withstand basal compressive loads. These columns have potential for multi-impact shock-absorbing applications.
Work is currently under way to define foamed aluminum properties and design required for use in bumpers for 50 mph barrier and pole impacts.