Use of Aluminum Foam to Increase Crash Box Efficiency

Aluminum foams have been of interest to automotive designers for some time due to their extreme light weight (0.3 to 0.5 g/cm₃) and their potential to absorb energy during impact.

The current paper describes the use of stabilized aluminum foams produced by the melt method from Metal Matrix Composites (MMC) in automotive front-end crash box applications. Performance of an existing design crash box using hollow aluminum extrusions will be compared to the same extrusions filled with MMC foams of varying densities. Methods of manufacture and control of the physical and the related mechanical properties of the foam will be described

The existing and composite crash boxes were tested using standard methods. Test data including energy absorption per unit mass and per unit length will be discussed. The mechanism of energy absorption will also be discussed. Results indicate significant improvements in both these areas allowing a meaningful reduction in crash box length for a given energy absorption.