Flexural behavior of stiffened syntactic foam core sandwich composites

Sandwich composite with phenolic syntactic foam as a core and glass polymeric laminates as face skins are widely used in ship hull structures because of its high specific properties and buoyant nature. In the present work, syntactic foam is prepared by uniform mixing of cenosphere and phenolic resin in equal proportions. The effect of stiffening the syntactic foam core by resin-impregnated paper honeycomb structure on flexural behavior of sandwich composites is experimentally investigated under flatwise and edgewise loading configuration. Microscopic features of fractured coupons are also investigated to predict the failure mode. The results reveal that use of resin-impregnated paper honeycomb structure in syntactic foam to form the core leads to considerable improvement in the flexural properties of sandwich composites in both flatwise and edgewise loading configurations. The span of sandwich composite has significant role in altering the magnitudes of core shear strength, skin bending strength and mode of failure. Coupons under edgewise configuration failed in progressive failure mode; however, in flatwise configuration coupons failed in sudden brittle mode.