Large deflection response of sandwich beams with layered-gradient foam cores subjected to low-velocity impact

The sandwich structures with gradient cores perform a wide application prospect due to their good design po-tential. Herein, an analytical model of fully clamped sandwich beams (SBs) with layered-gradient foam core (LGFC) under low-velocity heavy-mass impact was formulated, where the interactions between the bending and stretching were incorporated. The dynamic solutions for deflection response of three-layer graded core SBs were attained by introducing the newly developed yield criteria and were quantitatively confirmed by the corre-sponding numerical simulations and experiments, which allows for parametric study of the influence of core strength on load-bearing capacity of SBs. It demonstrates that the impact resistance of the uniform core SBs is superior to that of layered-gradient core SBs. Except for the top core layer of the positive gradient SBs, the in-crease in core layer strength will greatly enhance the load-bearing capacity of SBs in large deflection response situations, where membrane force plays a dominant role. Finally, the minimum mass design chart was con-structed using the derived analytical formula to give the geometric optimization paths.