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• Comparative impact tests of novel FHCB were performed. • Foam filling enhances impact resistance. • Gradient design can optimize foam energy absorption. Auxetic structures have attracted a lot of attention as they can meet the requirements of impact resistance and lightweight performance of protective structures in aerospace and defense industries. To enhance the impact resistance and improve the capacity of energy absorption of auxetic structures, foam-filled hybrid-chiral honeycomb beams (FHCB) were designed and fabricated through SLM (Selective laser melting) printing method and foaming method. The localized impulse loading was generated through the impact from foam projectile, accelerated by light gas gun. The dynamic responses of EHCB (empty hybrid-chiral honeycomb beam) and FHCB were compared. In the experimental results, FHCB showed enhanced impact resistance and higher SEA (specific energy absorption) value than EHCB. A validate finite element model was used to study the influence of cell-wall thickness on the impact resistance of EHCB and FHCB. Results indicated that by changing the cell-wall thickness, the potential energy absorption capacity of the filled foam can be fully utilized. Furthermore, the impact resistance of FHCB can be effectively improved by using a gradient cell-wall thickness arrangement. This study can provide reference for the optimal design of blast mitigation and impact resistant structures. [ABSTRACT FROM AUTHOR]

• The dynamic responses and energy absorption characteristics of aluminium honeycomb sandwich panels under ice wedge impact are investigated. • A three-dimensional nonlinear finite element model of AHSP under ice impact is established. • The ice wedge impact tests of AHSPs were conducted. • The plastic deformation energy absorption and ice facture energy dissipation mechanism is revealed. In this paper, the dynamic responses and energy absorption characteristics of aluminium honeycomb sandwich panels (AHSPs) under ice wedge impact are numerically and experimentally investigated. A three-dimensional nonlinear finite element model of AHSP under ice impact is established based on a concrete constitutive ice model in the commercial package ANSYS/LS-DYNA. The impact force-displacement curves and energy absorption properties as well as the crushing process of ice wedge are numerically achieved. In addition, the ice wedge impact tests of AHSPs were conducted by using a horizontal impact experimental apparatus. Furthermore, the effects of impact parameters and structural parameters on the dynamic responses and energy absorption are performed. Results show that the numerical results of ice wedge-AHSP impact dynamic responses are consistent well with the experimental results. The permanent deformation profiles of face sheets are approximately axisymmetric about the vertical and horizontal centerline. The ice impact energy is mainly converted into the plastic deformation energy of AHSP and rebound kinetic energy of ice wedge as well as the fracture energy of ice wedge. With the increase of the impact energy and thickness of face sheets, the energy dissipation ratio of ice broken increases dramatically and the energy dissipation by ice wedge makes an increasingly contribution to the impact energy absorption. [ABSTRACT FROM AUTHOR]

Abstract: Energy absorption characteristics of regular polygonal columns and angle elements under dynamic axial compression are investigated by using non-linear explicit finite element code LS-DYNA. The influence of central angle on deformation mode and mean crushing force of angle elements is studied. Based on two types of deformation mechanisms known by experiments, two types of initial indentation triggers are introduced. By assuming appropriate boundary condition on the edges, a simplified finite element model is adopted in the analysis of angle elements and validated by comparing with full polygonal column model. Numerical investigations are also carried out to study the influence of angle on angle elements with three and four panels by using the simplified model. Several useful conclusions are drawn about the axial crushing of polygonal columns and angle elements and can be used to guide the design of crashworthiness structures. In addition, a comparison is conducted between the numerical results and theoretical predictions of the mean forces of some special angle elements. Good agreement is obtained. [Copyright &y& Elsevier]