增材制造镍钛仿生结构缓冲吸能及自恢复特性研究

Buffer energy absorption and self-recovery characteristics of NiTi bionic structure fabricated with additive manufacturing

蜂窝结构由于具有优异的可设计性、剪切模量、断裂韧性、抗冲击吸能等特性,在车辆碰撞、卫星着陆、军事装备等吸能结构设计和多功能优化方面具有巨大的应用潜力。以普通内凹蜂窝结构为基础,运用结构仿生学原理进行了仿生优化设计,建立了内凹蜂窝结构和仿花生壳结构的三维负泊松比承载结构,并利用有限元分析软件LS-DYNA进行数值仿真分析。同时以NiTi形状记忆合金这种有独特的形状恢复行为、低刚度、高强度、超弹性的材料为基材,运用选区激光融化技术制备了两种仿生结构样件,并对样件进行了准静态压缩试验。通过对比试验测试结果与数值仿真结果得出,两种结构在吸能减震方面均有着较好的应用前景。其中,3D仿花生壳承载结构有着更好的吸能承载特性。两种结构在5次13%的循环压缩试验后,经过水浴加热后均可达到99%以上的形状恢复效率,为未来具有自恢复功能的缓冲结构的设计提供了参考。

Due to their excellent designability,shear modulus,fracture toughness and anti-impact energy absorption,honeycomb structures have great application potential in design and multi-function optimization of energy-absorbing structures,such as,vehicle collision,satellite landing,military equipment and so on.Here,based on ordinary concave honeycomb structures,bionic optimization design was performed by using the principle of structural bionics,3 D negative Poisson’s ratio load-bearing structures for concave honeycomb structure and imitation peanut shell structure were established,and their numerical simulation analyses were performed by using the finite element analysis software LS-DYNA.Meanwhile,taking NiTi shape memory alloy having unique shape recovery behavior,low stiffness,high strength and hyper-elasticity as base material,two bionic structural specimens were fabricated with the selective laser melting technique,and quasi-static compression tests were conducted for the two specimens.By comparing test results and numerical simulation results,it was shown that the two structures have better application prospects in energy absorption and anti-impact;among them,3 D imitation peanut shell load-bearing structure has better energy absorption and load-bearing characteristics;after five times of 13% cyclic compression tests,shape recovery efficiencies of the two structures can reach more than 99% after water-bath heating;the study results can provide a reference for designing buffer structures with self-recovery function in future.