Experimentally examining the mechanical behaviour of nap-core sandwich material – A novel type of structural composite

Experimental investigation of the nap-core sandwich is presented in detail, in which the nap-core is based on knitted fabric, being impregnated with a thermoset resin, formed to create cup-shaped naps, and stabilized to assume a permanent 3D contour. The material is a novel type of lightweight sandwich-structured composite which has good specific strengths and possesses various properties crucial for engineering applications, but its exploitation is still restricted due to insufficient research and understanding. The sample preparation is first described, being followed by the test implementation and outcomes. The results obtained from typical tests demonstrate high performance of the nap-core sandwich samples under different cases of loading. They also reveal the sandwich’s essential behaviours which are similar to those of a common shell structure, giving it a great potential of being computationally modelled with finite element software.