梯度铝蜂窝夹芯板的力学行为

梯度分层铝合金蜂窝板是一种有效的吸能结构,本工作在梯度铝蜂窝结构的基础上根据梯度率的概念,通过改变蜂窝芯层的胞壁长度,设计了4种质量相同、梯度率不同的铝蜂窝夹芯结构。通过准静态压缩实验,并结合非线性有限元模拟准静态及冲击态下梯度铝蜂窝夹芯结构的变形情况及其力学性能,分析对比了相同质量下梯度铝蜂窝夹芯结构在准静态下的变形模式以及冲击载荷下分层均质蜂窝结构和不同梯度率的分层梯度蜂窝结构的动态响应和能量吸收特性。结果表明:在准静态压缩过程中,铝蜂窝梯度夹芯板的变形具有明显的局部化特征,蜂窝芯的变形为低密度优先变形直至密实,层级之间的密实化应变差随芯层密度的增大而逐渐减小;在高速冲击下,梯度蜂窝板并非严格按照准静态过程中逐级变形直至密实,而是在锤头冲击惯性及芯层密度的相互作用下整体发生的线弹性变形、弹性屈曲、塑性坍塌及密实化;另外,在本工作所设计的梯度率中,当梯度率为γ₁=0.0276时,梯度蜂窝夹芯板的吸能性达到最好,相较于同等质量下的均质蜂窝夹芯板,能量吸收提高了10.63%。

Mechanical behavior of gradient aluminum honeycomb sandwich panels

Gradient aluminum honeycomb structure is an effective energy-absorbing structure.According to the concept of gradient rate,four types of aluminum honeycomb sandwich components with the same mass and different gradient rates were designed by changing the cell wall length of the honeycomb core layer.On the basis of the same mass,the deformation mode of gradient aluminum honeycomb sandwich structure under quasi-static state,as well as the dynamic response and energy absorption characteristics of layered homogeneous honeycomb structure under impact load and layered gradient honeycomb structure with different gradient rates were compared by combining quasi-static compression experiments and the deformation and mechanical properties of gradient aluminum honeycomb sandwich structures under quasi-static and impact states,which were simulated by nonlinear finite element.The results show that during the quasi-static compression process,the deformation of the aluminum honeycomb gradient sandwich panel has obvious localization characteristics.The deformation of the honeycomb core is preferentially low density until compaction,and the densification strain difference between the layers is gradually decreased as the core layer density is increased.Besides,under high-speed impact,the gradient honeycomb panel is not strictly deformed step by step in the quasi-static process until it is densified.It is the linear elastic deformation,elastic buckling,plastic collapse and compaction that occur as a whole under the interaction of the hammer head inertia and the core layer density.In addition,during the range of the gradient rate designed in this paper,when the gradient rate isγ₁=0.0276,the energy absorption of the gradient honeycomb sandwich panel is the best.Compared with a homogeneous honeycomb sandwich panel of the same mass,the energy absorption is improved by 10.63%.