梯度泡沫金属填充管的耐撞性和吸能模块设计

Metallic foams and tubular structures have stable dynamic crushing characteristics and excellent energy absorption capacity. Introducing graded metallic foams to filling tubular structures may improve the space utilization and the structural crashworthiness, but unreasonable design may bring negative effects. Some studies have focused on the dynamic impact behavior of graded metallic foams with a given density/strength distribution, but few studies carried out the gradient design from the view of crashworthiness requirements. Studies to guide the crashworthiness design of metallic foam-filled tubular structures from the perspective of stress wave propagation characteristics have not available in the literature. Hence a new conceptual design method will be proposed in this project which aims to develop new-type lightweight composite structures with graded metallic foam as the filling material from the perspective of the stress wave propagation characteristics and the crashworthiness requirements, taking the advantage of using graded foam to control the crushing process. It also aims to reveal the interaction mechanism of meso-structures and suggest the design method of energy-absorbing modules. This project focuses on the construction methods of tubular structures, the optimization of the graded metallic foam filling and the installation method of energy-absorbing modules. The crashworthiness of composite structures under different loading conditions will be evaluated and energy-absorbing units, which can be adapted to a wide range of engineering applications, will be developed by a combination of theoretical analysis, finite element simulations and experimental investigation. The research of this project is of great significance to the engineering application of lightweight composite structures.

泡沫金属和管状结构都具有稳定的动态压溃特性和优异的能量吸收能力，引入梯度泡沫金属填充管结构可改善空间利用率和提高结构耐撞性，但不合理的设计可能带来负面的影响。已有的研究主要集中在探讨已知密度或强度分布的梯度泡沫金属的动态冲击行为，较少从耐撞性需求角度指导梯度的设计，未见有研究从应力波传播特性的角度指导梯度多胞金属填充管结构的耐撞性设计。本项目提出一种新概念设计方法，拟从应力波传播特性和耐撞性需求的角度以及可利用梯度泡沫调控压溃过程的优势，发展以梯度泡沫金属作为填充材料的新型轻质复合结构，揭示细观结构的相互作用机制，探讨吸能模块的设计方法。重点探讨填充管的构造方式、梯度泡沫金属填充的优化和吸能模块的安装方式。通过理论分析、数值模拟和实验研究相结合的方法，对复合结构在各种冲击情形下的耐撞性进行评估，进而发展可适应于多种工程应用的吸能单元。本项目的研究对轻质复合结构的工程应用具有重要的意义。

引入梯度泡沫金属填充管结构可改善吸能结构的空间利用率和提高结构耐撞性，但不合理的设计可能带来负面的影响，亟需从耐撞性需求的角度指导梯度的设计。本项目以理论分析、数值模拟和实验测试相结合的方法，深入探讨了泡沫金属的率敏感性本构模型、梯度泡沫金属填充结构的耐撞性设计方法和吸能模块在实际碰撞中的新概念设计及应用，取得了预期的研究成果。.(1) 发现了多胞材料椭圆屈服面的变椭圆率行为，改进了Deshpande-Fleck泡沫本构模型；发展了计及应变率敏感性的单轴压缩细观统计本构模型，提出了材料参数的实验测试方案。.(2) 提出了非等长内外管、“外方内圆”双管以及双方管等泡沫填充结构设计，降低了初始峰值力，提高了轴压平均力及比吸能等，增强了复合结构的抗斜压能力。.(3) 发展了计及率敏感性的梯度多胞材料的耐撞性反向设计方法，提出了密度分布的显式渐近级数解，数值模拟和冲击实验验证了该设计方法的简便性、精准性和实用性。.(4) 提出了梯度泡沫金属填充管的动态压溃行为的理论分析模型及耐撞性反向设计方法，建立了梯度泡沫填充圆管的抗爆理论分析模型，阐明了梯度参数与管壁厚对变形模式的影响规律。.(5) 探讨了泡沫金属填充结构作为吸能模块在车辆正碰和侧碰中的新概念设计与应用，提出了前防撞吸能盒、座椅横梁及门槛元件的填充设计，显著地提高了结构的抗弯能力和耐撞性。.(6) 揭示了均匀、密度梯度和形状梯度多胞结构中的弹性应力波传播规律，建立了理论分析模型并获得了解析解，阐明并揭示了密度和形状梯度分布对波传播的调控作用和机理。.相关成果发表在 Int. J. Impact Eng., Int. J. Mech. Sci., Acta Mech. Sin., Int. J. Crashworthiness 等国内外重要期刊上。该课题的研究为根据耐撞性要求的主动设计提供新思路，对轻质复合结构的工程应用具有重要的意义。