轴向变密度铝泡沫件的动态和静态压缩实验与有限元模拟分析

Dynamic and static compression tests and FEA analyses of aluminum foam specimen with variable density in the loading direction

针对工程中常见的厚度方向变密度的闭孔铝泡沫材料,该文通过动态和静态压缩实验与模拟分析,探讨了大尺度变密度铝泡沫部件变形与吸能特性分析的有限元模型构建方法。对变密度铝泡沫大试样的准静态压缩和冲击压缩实验研究表明:厚度方向变密度铝泡沫材料的压缩过程呈现从低密度层开始的逐层屈服变形伴随整体变形的特性,与密度均匀的铝泡沫材料的变形特性显著不同。该文建立了变密度铝泡沫大试样的分层变密度变尺度有限元模型和近似的密度和尺度均匀的有限元模型,计算结果对比分析表明:分层变密度变尺度有限元模型能够模拟实际材料的逐层屈服变形特性,计算的试样准静态和冲击压缩变形与吸能特性等与实验结果相符;而基于均匀模型的计算结果则不能模拟逐层变形特性,与实验结果及理论特性明显不相符。分层变密度变尺度有限元模型的单元尺度会影响逐层屈服变形特性模拟结果,基于单元尺度接近实际铝泡沫材料胞元尺度的分层有限元模型的计算结果与实验结果一致性较好。这些研究结果对各种结构的铝泡沫材料应用研究具有重要意义。

Closed-cell aluminum foams with variable densities in the loading direction are widely used.A finite-element mode（FEM）is used to model the foam deformation and energy absorption characteristics with dynamic and quasi-static compression tests.The results show that large aluminum foam specimens with variable densities have density-dependent layered deformation characteristics,which differ from uniform-density aluminum foams.Predictions of an FEM model with a layered variable density and layered element sizes are compared with those of a conventional FEA model with uniform density and element size.The computation results show that the layered gradual deformation characteristics can be simulated by the layered models with quasi-static and dynamic compression simulation results agreeing well with experimental data.The uniform model cannot accurately predict the layered gradual deformation characteristics.The element size of the layered models influences the simulated layered gradual deformation characteristics with simulation results using the layered model with element sizes equal to the foam cell diameter agreeing best with the experimental data.These results will improve engineering designs using aluminum foam materials.