Micro-inertia effect and dynamic plastic Poisson's ratio of metallic foams under compression
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摘要: 采用三维Voronoi技术和显式有限元方法来研究闭孔和开孔两种泡沫金属的动态塑性泊松比问题和微惯性效应。细观数值模拟的结果表明：塑性泊松比随着轴向应变的增加而下降，塑性泊松比的峰值随着冲击速度的增加而下降；相对密度增加时，泡沫金属塑性泊松比增加；微惯性对平台应力的影响不大。该数值模拟结果能够解释侧向约束情况下闭孔泡沫金属的压溃应力随着加载速率的提高而下降的实验现象。Abstract: The three-dimensional Voronoi technique and the explicit finite element method were utilized to investigate the micro-inertia effect and dynamic plastic Poisson's ratio of closed-cell and opencell metallic foams.The simulation results indicate that the plastic Poisson's ratio decrease with increasing nominal strain, the peak value of which decreases as the impact velocity increases.And the Poisson's ratio increases with the increasing of relative density.The micro-inertia plays little role in enhancing the plateau stress of metallic foams.The above simulation results can explain the existent experimental phenomenon that the crushing stress decreases with increasing loading rates, which is endured by the closed-cell aluminum foam under lateral constraint.
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图 2 泡沫金属在不同冲击速度下的变形模式
Figure 2. Deformation modes of metallic foam under different impact velocities
图 3 泡沫金属的应力均匀性指标随冲击速度变化关系
Figure 3. Stress uniformity index varied with impact velocity for metallic foam
图 4 不同相对密度的泡沫金属的塑性泊松比随轴向应变的变化
Figure 4. Plastic Poisson's ratio varied with longitudinal strain for foams with different relative densities
图 5 不同冲击速度下泡沫金属塑性泊松比随轴向应变的变化
Figure 5. Plastic Poisson's ratio varied with longitudinal strain at different impact velocities
图 6 泡沫金属塑性泊松比峰值随冲击速度的变化
Figure 6. Peak value of plastic Poisson's ratio varied with impact velocity
图 7 泡沫金属微惯性参数随轴向应变的变化
Figure 7. Micro-inertia parameter varied with longitudinal strain for metallic foam
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