Syntactic foam core metal matrix sandwich composite under bending conditions

Highlights: • Flexural properties of A356 matrix syntactic foam core sandwich are studied. • Alumina hollow particle filled syntactic foam is combined with carbon fabric skins. • Flexural strength of 91.2 MPa and flexural stiffness of 20.6 GPA are measured. • Failure mode is included as tensile skin fracture and crack propagation in the core. • Cracks pass through the particles instead of crack tip blunting or bowing. - Abstract: The present work aims at characterizing a metal matrix syntactic foam core sandwich composite under three-point bending conditions. The sandwich comprises alumina hollow particle reinforced A356 alloy syntactic foam with carbon fabric skins. Crack initiation in the tensile side of the specimen causing failure of the skin, followed by rapid failure of the core in the direction applied load, is observed as the failure mechanism. Crack propagation through the alumina particles is observed in the failed specimens instead of interfacial failure. The average maximum strength, flexural strain and stiffness were measured as 91.2 ± 5.6 MPa, 0.49 ± 0.06% and 20.6 ± 0.7 GPa respectively. The collapse load is theoretically predicted using mechanics of sandwich beams. Experimental values show good agreement with theoretical predictions.