Structural Damages in Syntactic Metal Foams Caused by Monotone or Cyclic Compression

Abstract

Closed cell, high strength metallic foams, like ceramic hollow spheres filled metal matrix foams are promising materials to build lightweight but high specific strength structural parts. The aim of this study is to investigate the damage of the foam structure during monotone or cyclic compression. The tested metal matrix syntactic foams were produced by inert gas pressure infiltration. Four different alloys as matrix and two different ceramic hollow spheres as filler material were applied. The cylindrical specimens were investigated in quasi-static and high strain rate compression and in cyclic compression. The higher strain rates were ensured by a Split-Hopkinson pressure bar system, while the fatigue tests were performed on a closed loop universal hydraulic testing machine. The failure modes of the foams have explicit differences showing barreling and shearing in the case of quasi-static and high strain rate compression respectively. In the case of the fatigue loading, there was a significant difference between the damage mechanisms of the unalloyed and the Si alloyed matrix syntactic foams. This can be explained by the difference between the yield strength of the matrix material and the ceramics hollow spheres.