Dynamic behaviors of sandwich panels with 3D-printed gradient auxetic cores subjected to blast load

This study experimentally and numerically investigated the blast resistance of sandwich panels composed of steel face sheets and 3D-printed gradient auxetic chiral core. Five gradient strategies were utilized in the design of auxetic core, including uniform gradient, positive gradient, negative gradient, center positive gradient and center negative gradient. Varying blast loadings were applied by adjusting the masses of explosive charges. The deformation/failure modes of sandwich panels were obtained in the experiments, in terms of the face sheets and gradient auxetic core. The effects of impulse and gradient type of auxetic core on dynamic responses of specimens were examined. In addition, the numerical simulation was employed to clarify the deformation process of sandwich panel, and to analyze the deformation mode of auxetic cores under sufficient compression. It was shown that higher impulse was associated with increased plastic deformation in the face sheet and more serious shear and tensile tearing within the auxetic core. The auxetic cores of varying gradient types displayed distinct compress deformation behaviors. Among them, the negative gradient variant exhibited the least permanent deflection, and the superior negative Poisson's ratio effect, indicating enhanced blast resistance. This work not only contributes to a strategy for designing gradient auxetic cores with enhanced blast resistance, but also provides valuable insights into experimentally understanding the response of complex auxetic configurations under blast loads.