Compressive response of 3D printed graded foams

The syntactic foams are widely used in aeronautics, underwater vehicle structures, and oil drilling applications. These foams are being extensively utilized in naval applications wherein they are subjected to the compressive forces that are depth-dependent. Developing graded foams with better compressive behavior using three-dimensional printing (3DP) permits realizing complex geometrical structures with numerous advantages compared to conventional processing routes. The present work deals with 3DP of syntactic foams and their graded configuration by embedding (20, 40, and 60 vol%) glass microballoons (GMBs) in high density polyethylene (HDPE). It is noted that the modulus increases with the filler content. Specific properties of the graded foams exhibited superior response as compared to neat HDPE. Among functionally graded foams (FGFs), FGF-2 (20–40–60) showed the highest modulus and yield strength. FGFs exhibited better energy absorption among all the tested samples. GMBs are observed to be intact, and a seamless interface is seen in micrographs of 3D printed graded foams, making them candidate materials for lightweight structural applications.