On the design and crashworthiness of a novel auxetic self-locking energy absorption system

Auxetic honeycombs and self-locking energy absorption systems/structures are promising candidates for protective applications. In the present work, a novel auxetic self-locking energy absorption system (ASLEAS) was proposed to utilize the superior properties brought by both the NPR effect and self-locking principle. The proposed ASLEAS consists of thin-walled tubes featuring an I-shaped cross-section which were arranged in a crisscross pattern to analogy to conventional anti-tetra-missing rib auxetic honeycomb. Structural discretization allows the system to be fabricated through cost-effective traditional manufacturing methods, a notable advantage over most auxetic meta-structures that often require expensive additive manufacturing (AM) technology. The proposed system can be conveniently assembled and disassembled to meet the requirement for flexible and responsive impact protection. The protective properties of the proposed system were then comprehensively investigated through numerical analysis under dynamic loading conditions. Results show that the proposed design exhibits evident NPR effects, outstanding self-locking stability and excellent energy absorption capacity as expected. Compared to existing integrated structures, including its integrated variant, it can more effectively reduces stress fluctuations and prevent the transfer of load to the protected object. Moreover, compared to many existing typical nonauxetic self-locking energy absorption systems, it has higher plateau stress and specific energy absorption (SEA). Based on the revealed underlying deformation mechanism, a theoretical model of the collapse stress under quasi-static, low-velocity, and high-velocity impacts were further developed. The present work paves a novel avenue to design protective devices with high performance and low-cost.