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基于剖球模型,利用LS-DYNA有限元软件,研究了开孔泡沫金属在冲击载荷作用下的动态力学行为。重点分析了冲击速度、相对密度对泡沫金属的变形模式以及平台应力的影响。结果表明:泡沫金属材料的整体变形模式本质上是微观棱壁的不同变形模式在宏观尺度上的体现,与相对密度和冲击速度有着密切的联系。在不同冲击速度下,材料会出现逐层压溃、混合变形、均匀压缩3种变形模式。材料在逐层压溃和混合变形模式的中后期,会出现局部失稳带,削弱材料的承载能力,导致整体应力水平显著下降。随着材料相对密度的增加,不同变形模式之间的转变速度也随之增大。此外,相对密度、变形模式和惯性效应均会影响到平台应力的改变,从而呈现出相对复杂的变化趋势。
The dynamic mechanical behavior of open-cell foam metal under impact load was studied by using the LS-DYNA finite element software based on the shot-peening model. The impact of impact velocity and relative density on the deformation mode of foam metal and the stress of platform are analyzed emphatically. The results show that the overall deformation mode of the foam metal material is essentially the reflection of different deformation modes of the micro-ribbed wall at the macroscopic scale, which is closely related to the relative density and the impact velocity. At different impact velocities, the material will appear layer by layer crush, mixed deformation, uniform compression of three deformation modes. In the middle and later stages of the layer-by-layer crush and the mixed deformation mode, the local buckling zone appears, which weakens the bearing capacity of the material and leads to a significant decrease in the overall stress level. As the relative density of the material increases, the rate of change between different deformation modes also increases. In addition, relative density, deformation mode and inertial effect will affect the change of platform stress, showing a relatively complex trend.