Processing, compression response and finite element modeling of syntactic foam based interpenetrating phase composite (IPC)

The feasibility of processing lightweight interpenetrating phase composite (IPC) foam is demonstrated. The composite is produced by infiltrating uncured epoxy-based syntactic foam into an open-cell aluminum preform, resulting in an IPC foam with improved compression characteristics relative to conventional syntactic foams. Different IPC foam varieties are prepared by varying the volume fraction of microballoons in the syntactic foam from 20% to 40% while keeping the volume fraction of the metallic network the same. Two variations of these IPC foam are produced using the aluminum preform in (a)'as-is' condition and (b) after coating it with silane to increase adhesion between the metallic network and polymer foam. The IPC foam samples in general and the silane coated ones in particular show significant improvement in elastic modulus,yield stress and plateau stress values when compared to the corresponding syntactic foam of the same volume fraction of microballoons. The increase in plateau stress of IPC foam samples is about eight times that of an unfilled preform and approximately 42% higher than that of the corresponding syntactic foam. Up to 50% higher energy absorption by the silane treated IPC foam relative to the corresponding syntactic foam is also achieved. A Kelvin cell based 3-D elasto-plastic finite element model capable of capturing both linear and nonlinear characteristics of the IPC foams is also presented. (C) 2008 Elsevier B.V. All rights reserved.