啄木鸟敲击树木时，头部受到很高的减速度（1200-1500g），却不会产生脑损伤。与此相比，人体头部能承受的减速度不足啄木鸟的百分之一。因此，研究啄木鸟头部抗冲击的机理，可以为头盔等人体保护装备、以及精密微电子器件的减震和缓冲装置设计提供理论依据和技术指导。这是一个非常有趣的科学问题，但同时也具有非常现实的应用价值和工程意义。 当前的研究大多是从生态学的角度出发，提供一些观测数据或生物习性方面的分析，但还不足以回答其抗冲击这个核心问题。申请人拟采用试验、理论建模和数值计算相结合的方法，从冲击动力学角度研究啄木鸟在冲击下的耗能机理。内容包括啄木鸟与树木之间的相互作用、头骨的等效材料特性、结构在减震方面的作用。目标是：1）明确啄木鸟受到的脉冲载荷；2）建立其头骨的等效材料模型并分析其波传播特性；3）建立简化的多刚体理论分析模型；4）利用物质点法（MPM）对啄木鸟敲击树干进行数值模拟。

The woodpecker's head need to bear high deceleration, up to 1200-1500g, but it does not produce any brain injures. But the human head can only withstand deceleration level less than one percent of the woodpecker's. Therefore, it is necessary to study the mechanism of woodpecker's response under impact, which will provide useful information in the design of body protection equipment, e.g., helmet; or energy dissipation equipments protecting the microelectronic devices. This is an interesting scientific problem, but also important in applications. Most of the previous researches are concentrated in ecology, which will provide observational data or biological behavior of woodpeckers, but can't give the principle of its impact resistances. From the impact dynamics point of view, the applicant prepares to combine the experimental, theoretical modeling and numerical methods, to study the energy dissipation principle of woodpecker hammering trunks. The contents will include the interaction between woodpecker and trunk, the equivalent material properties of the bones, and the energy absorption effect of the structures. The objectives are: 1) to get the interaction pulse between the woodpecker and the trunk; 2) to get the equivalent material properties of the bones and the corresponding wave propagation characteristics; 3) to establish a simplified analytical model; 4) using the material point method (MPM) to simulate the process of the woodpecker hammering the trunk.