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摘要: 构建了三维随机分布球形泡孔模型，模拟开、闭孔混合结构泡沫铝材料的微细观结构，并通过有限元方法计算了10~104 s-1应变率范围内、孔隙率35%~65%泡沫铝材料的率相关性以及应变率和相对密度变化对泡沫铝动态压缩力学性能的影响。研究表明：中、低应变率下，泡沫铝材料率相关性能主要取决于基体材料的应变率敏感性；高应变率下，泡沫铝材料率相关性能受基体材料的应变率敏感性以及微结构惯性联合作用，且相对密度较低泡沫铝材料的微结构惯性效应更显著。
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关键词:
- 固体力学 /
- 率相关 /
- 三维随机球形泡孔模型 /
- 泡沫铝 /
- 有限元
Abstract: To examine the rate-dependent properties of aluminum foams, three-dimensional random spherical cell models were constructed to simulate the microstructures of aluminum foams, and the dynamic deformations of aluminum foams at the strain rates of 10-10 000 s-1 were calculated by using the ANSYS/LS-DYNA commercial code.Obtained results show that at moderate and low strain rates, the rate-dependent properties of aluminum foams originate mainly from the strain-rate sensitivities of their matrix materials.At high strain rates, the rate-dependent properties of aluminum foams are dominated by the combining action of the strain rate sensitivity of cell materials and the microstructure inertia of cells, and the microstructure inertia effects are more remarkable for aluminum foams with low relative density than for those with high relative density. -
图 2 泡沫模型初始弹性模量随相对密度的分布
Figure 2. Initial elastic modulus of foams versus foam relative densities
图 3 基体材料率相关泡沫模型动态压缩应力应变曲线
Figure 3. Dynamic compressive stress-strain curves of foam models with rate-dependent cell material
图 4 基体材料率无关泡沫模型动态压缩应力应变曲线
Figure 4. Dynamic compressive stress-strain curves of foam models with rate-independent cell material
图 5 动态压缩下泡沫铝流动应力与相对密度关系
Figure 5. Flow stresses of aluminum foams versus foam relative densities under dynamic compressive loadings
表 1 拟合结果
Table 1. Fitting results of parameters
${\dot \varepsilon }$/s-1 a n 10 0.698 1.72 100 0.784 1.72 1 000 0.942 1.72 2 500 1.03 1.68 5 000 1.13 1.66 10 000 1.27 1.64 
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表 2 泡沫模型及其基体材料强度的变化
Table 2. Variation of flow stress for foams and its cell material
${{\dot \varepsilon }_2}$/s-1 αf/% αs/% ρ=0.35 ρ=0.50 ρ=0.65 5 000 12.04 11.24 10.66 8.34 10 000 28.59 26.77 25.44 18.25
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