梯度金属泡沫夹芯复合结构的爆炸冲击能量吸收机理

Research objectives of this project are energy-absorption mechanisms of lightweight sandwich plates comprised of density-graded metallic foam cores and composite facesheets under blast loading. Firstly, based on three-dimensional mesoscale finite element modeling of the density-graded metallic foams and experimental results, the relationship between the material dynamic properties and its average porosity as well as the density-graded constitutive law is established. At the same time, with theoretical and numerical analysis as well as experimental tests, the dynamic deformation behavior, damage and failure patterns of the lightweight sandwich plates with density-graded metallic foam cores and composite facesheets subjected to blast loading are investigated. Correspondingly, in view of the law of energy absorption of composite facesheets and density-graded metallic foam cores as well as coupled effect and interation between composite facesheets and density-graded metallic foam cores, the dynamic failure patterns of the lightweight sandwich plates are presented. Furthermore, the law of energy-absorption of the lightweight sandwich plates is revealed, which illustrates that the macroscopic dynamic responses of the lightweight sandwich plates are closely associated with the microstructure damage mechanism of density-graded metallic foams and damage patterns in composite facesheets. It is expected that this project can provide a theoretical and technical foundation for design of the lightweight sandwich structures having high energy absorption capability and endurable impact property in protective engineering.

复合材料面板-梯度金属泡沫夹芯结构是一种新型轻质结构，本项目拟研究该类轻质夹心结构的爆炸冲击吸能机理。从梯度金属泡沫三维细观模型出发，结合实验结果分析，建立其动态力学性能与平均孔隙率及梯度密度间的关系。采用实验研究、理论和数值模拟方法，研究复合材料-梯度金属泡沫夹芯结构在爆炸冲击载荷作用下变形、损伤、破坏过程，研究夹芯复合结构的面板及芯材等各组成部分的能量耗散机理及对夹芯结构吸能特性的影响，分析复合材料面板和梯度金属泡沫芯体之间的相互作用及耦合机制，给出其动力失效模式，揭示轻质夹芯结构的能量吸收机理，阐明复合材料层合面板内部损伤模式、梯度金属泡沫材料细观结构破坏形态和轻质夹芯结构宏观动态响应之间的关系。研究成果可为高效吸能、耐冲击的梯度金属泡沫夹芯复合结构设计提供理论基础，为防护工程与公共安全提供有关技术支撑。

本研究工作采用理论分析、实验和数值模拟方法。基于显微CT断层扫描影像信息，逆向重建了闭孔泡沫铝的三维细观有限元模型，定量研究了泡沫金属在多轴压缩载荷作用下的大变形力学行为及其唯象弹塑性本构参数的确定方法。采用泡沫金属子弹撞击加载（模拟冲击波）试验研究了碳纤维复合材料面层-泡沫铝夹芯结构的冲击响应，得到了夹芯结构的变形与失效模式。针对传统名义应变无法准确描述梯度泡沫金属在准静态压缩过程中全部材料压溃之前存在明显的未变形区域的问题，提出了瞬态名义应变的表达式，并据此导出压溃应力的计算式，建立了瞬态名义应力-应变关系表达式，基于该表达式分析了梯度泡沫金属材料的能量效率，研究了密度梯度变化对其能量效率的影响规律。进一步建立了复合材料面层-梯度泡沫金属夹芯板的振动方程和描述梯度泡沫金属夹芯结构局部压入行为的理论模型，分析了梯度泡沫金属芯层密度梯度变化对夹芯板振动特性和响应的影响，研究了正、负梯度泡沫金属夹芯结构的局部变形和整体变形的关系。针对神舟飞船返回舱着陆过程中与地面碰撞的减震问题，基于以上理论模型，建立了双自由度弹簧-阻尼-梯度泡沫金属材料的碰撞模型，研究了梯度泡沫金属作为吸能缓冲材料对返回舱外壳和内部被保护结构振动响应的影响，并研究了梯度泡沫金属材料密度分布变化对内部被保护结构冲击过程中加速度峰值的削减规律，研究结果发现，梯度泡沫金属夹芯结构比传统的均质泡沫金属夹芯结构具有更好的抗冲击、吸能性能。