Flexural performance of sandwich panels comprising polyurethane core and GFRP skins and ribs of various configurations

An equivalent material formulation for sinusoidal corrugated cores of structural sandwich panels

Sandwich composite materials are characterized by high strength and low weight benefits. Traditional applications of sandwich structures primarily utilize polymeric foams and honeycomb as core materials. The primary concern with traditional core sandwich is however, the dissimilarity of the facesheet and core material, core to facesheet delamination under low velocity impact and space inaccessible core. This research presents multifunctional sandwich composites where the core is designed to incorporate functions such as sound/vibration damping and ability to route wires or embed sensors. The multifunctional sandwich composite used in this study has number of curved core piles in the z-direction which are woven to the facesheets at top and bottom. In the present study, the low velocity impact (LVI) response of the 3-D sandwich composites with hollow core and a polyurethane (PUR) foam filled core is studied. Impact response is interpreted in terms of incipient damage point and maximum load point for each case. The mode of failure for the unfoamed specimens was primarily the buckling of the core piles and the rupture of the facesheets, while for the foamed specimens, the foam core crushing along with the core piles failure were the primary modes of failure. The foam filled specimens could withstand the energies up to 70 J with a complete punch through for 73 J of impact energy.

Q.H. Cheng

Papers

A numerical analysis approach for evaluating elastic constants of sandwich structures with various cores