陈立明^*， 张建， 杜冰

（  重庆大学航空航天学院，非均质材料力学重庆市重点实验室，重庆 400030；  ）

摘要： 以拉伸主导型(全三角)和弯曲主导型（六边形）为例，建立了两种典型点阵圆柱壳结构的有限元模型，改变几何参数研究了相对密度对点阵圆柱壳结构压溃性能的影响规律，以归一化塑性耗散能作为吸能性的评价指标，发现当相对密度小于6%时，低速压溃下增加相对密度能提高吸能性,高速压溃下则完全相反；当相对密度大于6%时,相对密度的改变对吸能性的影响不明显，因此结合功能梯度材料的思想，在压溃方向引入密度梯度从而提出了梯度点阵圆柱壳结构。研究结果表明，在低速压溃下，圆柱壳结构表现出多种不同的压溃模式，当压溃应变大于60%时梯度点阵圆柱壳较均匀点阵圆柱壳吸能性更优；高速压溃下，圆柱壳结构均为"I"型压溃模式，引入正梯度使结构吸能性先上升后降低，而引入负梯度则相反。对比点阵圆柱壳和点阵夹芯圆柱壳的SEA（第一次出现要具体名称）后发现，蒙皮的引入能大幅度提升结构的吸能性。对于全三角点阵夹芯圆柱壳，当胞壁蒙皮厚度比大于1时，结构的SEA变化趋于平稳；对于六边形点阵夹芯圆柱壳，当胞壁蒙皮厚度比接近1时，结构的SEA最优。低速压溃，芯层引入密度梯度对全三角点阵夹芯圆柱壳的SEA有显著影响；高速压溃下，芯层引入密度梯度对六边形点阵夹芯圆柱壳的SEA有显著影响。
关键词： 动态压溃；吸能性；密度梯度；点阵圆柱壳

Chen Liming^*， Zhang Jian， Du Bing

（  Chongqing Key Laboratory of Heterogeneous Material Mechanics, College of Aerospace Engineering, Chongqing University, Chongqing 400030；  ）

Abstract： Cylindrical lattice shells with two kinds of typical configurations which are stretching-dominated and bending-dominated were modeled. The influence of changing relative density on the dynamic crushing of cylindrical lattice shells was investigated, normalized plastic energy dissipation was used to be the evaluation indexes of the energy absorption. it was noted that increasing relative density can improve energy absorption under low velocity crushing while depress it at high velocity crushing when the relative density belows 6%. When the relative density was bigger than 6%, the relative density didn't influence the energy absorption much. We also investigated the energy absorption of density gradient cylindrical lattice shells which featured a density gradient along crushing direction, it was found that introducing density gradient can improve energy when the crushing strain was higher than 60% at low crushing velocity, and at high crushing velocity, positive density gradient can enhance energy absorption at first while negative density gradient decreased energy absorption at first because of their crushing mode was "I" shape. It was noted that the SEA of sandwich cylindrical lattice shell was significantly higher than that of cylindrical lattice shell. After investigating the crushing of sandwich cylindrical lattice shell, it was found that the SEA of triangular sandwich cylindrical lattice shell was started to level off when the ratio of cell wall and skin thickness exceeded 1 and the SEA of hexagonal ones was optimal when the ratio of cell wall and skin thickness was close to 1. Introducing density gradient had significant influence on the energy absorption of triangular sandwich cylindrical lattice shell at low crushing velocity and hexagonal sandwich cylindrical lattice shell at high crushing velocity.

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