On the high-temperature crushing of metal foams

Abstract

This work focuses on understanding and quantifying the effect of high temperatures on the compressive response of open-cell aluminum foams. Foam specimens with different cell-size are compressed within an environmental chamber under a range of temperatures 20 °C ≤ T ≤ 300 °C. The localization and evolution of collapse is monitored and analyzed using Digital Image Correlation (DIC) and the overall force–displacement response is measured. The results indicate that increasing temperatures significantly affect all mechanical properties of the foam. Both the limit and plateau stresses were found to decrease linearly with temperature. More importantly, their drop does not follow directly with the corresponding one in the base material's yielding stress. The densification strain, that is a measure of the plateau extension, also follows a linear trend albeit in an increasing manner. This increase is attributed to changes of the collapse mechanism, which at high temperatures involves localization in different zones within the foam, as well as increased compaction at the cell-level caused by the base material softening. Finally, we measure the reduction in the strain energy absorption capacity of the foam caused by high temperatures.