Dynamic crushing of uniform and functionally graded origami-inspired cellular structure fabricated by SLM

• The dynamic mechanical properties and energy absorption characteristics were obtained by low-velocity impact tests. • Finite element analysis was carried out in LS-DYNA to obtain an accurate refined simulation method. • The dynamic constitutive models of AM SS304L considering the fabrication orientations were obtained. • Proposed the gradient design of this cellular structure and assessed its validity. This paper investigated the dynamic crushing of a novel periodic origami-inspired cellular structure. The large-scale multi-layer metallic specimens considered geometry, anisotropy and gradient design were fabricated by an SLM system. Mechanical properties and energy absorption characteristics under dynamic load were investigated through drop hammer impact test. The results show that this novel structure has obvious negative Poisson's ratio (NPR) effect and relatively balanced mechanical properties in the three orientations under impact load. Among them, the z-axis orientation was the best bearing orientation. Three gradient modes of this structure were designed and tested for the first time. Results showed the gradient design effectively improved the energy absorption performance of this structure. Besides, high-speed tensile tests on the additively manufactured metallic coupons showed the strain rate effect and anisotropy of AM stainless steel 304L were significant. Corresponding Cowper-Symonds models were fitted. The numerical simulation reproduction based on LS-DYNA was validated to be well-matched with the test results. Parametric analysis showed that the initial folding angle was the crucial factor for the initial peak force, and the gradient growth rate can significantly affect the energy absorption of the structure.