Energy Absorption of Integrated Functionally Gradient Syntactic Foam

Abstract

Functionally gradient syntactic foams (FGSFs) are fabricated using a layer-over-layer integrated technique in five different layer sequences. Four different types of glass microballoons, with similar outer diameters but different inner diameters are used to fabricate individual layers in integrated FGSFs (IFGSFs). The volume fraction of microballoons in each IFGSF layer is kept constant at 60% to maintain uniformity in the structure. The different layers of IFGSFs are integrated before major solidification takes place. IFGSFs are investigated for flat-wise and edge-wise compression properties on a MTS-810 servo hydraulic machine. Compared to plain syntactic foams with a similar density, it is found that the energy absorption of flat-wise and edge-wise IFGSFs increase by more than 200% and 20%, respectively. Also, the IFGSFs show a dramatic increment in compressive properties compared to adhesively bonded FGSFs. Furthermore, IFGSFs are compared to one another to examine the effect of layer sequencing on flat-wise and edge-wise compressive behavior. The layer sequencing effect on crack propagation behavior of IFGSF is carefully monitored and analyzed with an optical microscope (OM) and a scanning electron microscope (SEM).