高速冲击下负泊松比金属蜂窝夹芯结构塑性动力响应机理研究

The auxetic honeycomb core shows unique auxetic characteristics when the sandwich structure under high velocity impact, resulting to superior impacting-resistance performances compared with the conventional solid monolithic structure and sandwich structure with positive Poisson’s ratio honeycomb core, and its dynamic plastic response is the key issue and difficulty of this research field. This project will mainly concern about these aspects: (1) To establish an analytical model for the dynamic crushing stress of auxetic honeycomb to characterize the relationship between plastic deformation of honeycomb cell and dynamic crushing stress; (2) to study the auxetic deformation mechanism of honeycomb core based on the high velocity impacting experiments and numerical simulations; (3) to put forward the dynamic plastic limit yield criterions of sandwich beam by using the experimental results and the analytical model for dynamic crushing stress of auxetic honeycomb, and then a theoretical model for the dynamic plastic response of sandwich beam with auxetic honeycomb core under high velocity impact will be constructed to reveal the relationship between the crushing deformation of auxetic honeycomb core and dynamic response of sandwich beam. This project is expected to obtain original achievements in the analytical model for dynamic crushing stress of auxetic honeycomb and the dynamic plastic theoretical model of sandwich beam, which will provide significant guidance for the fields of aeronautics, astronautics and national defense, etc.

负泊松比金属蜂窝夹芯结构冲击过程中芯层发生独特的负泊松比变形，比传统单层实体结构和正泊松比金属蜂窝夹芯结构具有更优秀的抗冲击性能，其塑性动力响应是该领域基础研究的热点和难点问题。本项目拟(1)建立负泊松比金属蜂窝动态压缩应力理论模型，揭示其胞元塑性变形与动态压缩应力之间的内在机理；(2)基于高速冲击实验和数值计算方法研究负泊松比金属蜂窝夹芯结构冲击过程中蜂窝芯层的负泊松比变形动态演化规律；(3)基于实验结果和动态压缩应力模型提出夹芯结构动态塑性极限屈服准则，并构建高速冲击下负泊松比金属蜂窝夹芯梁结构的塑性动力响应理论模型，从而揭示芯层压缩变形与夹芯结构整体冲击变形之间的内在机理。通过本项目的研究，期望在负泊松比金属蜂窝动态压缩应力理论模型及其夹芯结构冲击塑性动力响应模型与机理等方面获得突破，为其在航空航天和国防等领域的应用提供理论指导。

负泊松比金属蜂窝夹芯结构冲击过程中芯层发生的收缩变形，比传统单层实体结构和正泊松比金属蜂窝夹芯结构具有更复杂的抗冲击特性，其塑性动力响应是该领域基础研究的难点问题。本项目建立了泊松比金属蜂窝动态压缩应力理论模型，揭示其胞元变形与压缩应力之间的内在机理，首次发现高速压缩过程中负泊松比结构新的收缩变形机制，通过理论证明已有的分析方法会低估其真实的压缩应力。基于高速冲击实验和数值计算方法研究了冲击过程中芯层的负泊松比变形动态演化规律，揭示芯层压缩变形与夹芯结构整体冲击变形之间的内在机理，发现芯层在冲击变形过程中并不是一直发生收缩，而是先收缩后膨胀，然后收缩和膨胀变形交替转换，这些原创性研究成果能够为应用在航空航天和国防装备上提供理论指导。