Impact resistance analysis and multi-objective optimization of polyurea-coated auxetic honeycomb sandwich panels

To investigate the protective capacity and mechanism of polyurea-coated auxetic honeycomb sandwich structures under impact loading. The mechanical properties of a sandwich panel under the action of a cylindrical punch is numerically simulated by LS-DYNA. Firstly, the impact of different coating positions on the protective properties of sandwich panels is analyzed and concluded which coating method is most effective. Then, the mechanism of the impact resistance of sandwich panels strengthened by the thickness, grading and orientation of the auxetic honeycomb cores is discussed by outline volume analysis. Finally, a multi-objective optimization of the sandwich panel's internal concave hexagonal structural parameters with the best impact resistance is carried out. It is shown that the coating of polyurea elastomers can effectively increase the impact protection performance of sandwich panels. The best impact resistance is achieved by the back side coated sandwich panel (type B). Increasing the wall thickness of auxetic honeycomb and the thickness of the upper graded honeycomb core can effectively increase the impact resistance of the type B sandwich panel. Optimized type B sandwich panel has a 6.2% reduction in maximum deflection (D) compared to the unoptimized version. The findings of this research provide a reference for the study and design of polyurea-coated sandwich panels.