Quasi-static bending response and energy absorption of a novel sandwich beam with a reinforced auxetic core under the fixed boundary at both ends

Abstract

Although the auxetic structure exhibits excellent mechanical properties, the low stiffness, and strength still limit its development. Considering the high stiffness and strength of the sandwich structure, a novel sandwich beam with an enhanced auxetic core (SCH SWB) was proposed in this paper. The accuracy of the finite element (FE) modeling was first verified by quasi-static bending experiments. Then, based on FE simulation, the deformation modes and energy absorption were explored. The results showed that local indentation and global bending deformation coexisted under the mid-span loading, and the core can absorb the most energy. Furthermore, using the analogy method, and based on the yield criterion and indentation response of the foam sandwich beam, a theoretical model was established to predict the force response, which considered the influence of local indentation on the overall bending, and the double-plateau characteristic of the auxetic core. The theoretical results were basically consistent with the simulation. Subsequently, the influence of the key parameters of the core and faces on the mechanical responses was discussed in depth, and it was found that changing the key geometric parameters and the material combination of the faces and the core can significantly vary the energy absorption capacity. Finally, several sandwich beams with different auxetic cores were compared, and the results proved that SCH SWB exhibited superior bending resistance and higher energy absorption. This paper presents a new idea and theoretical basis for studying the mechanical response of auxetic sandwich beams. The results show that the auxetic sandwich beam has great potential in aerospace, automobile crash, impact protection of key engineering structures, etc.