Dynamic-compression mechanical properties and energy-absorption capability of fly-ash cenospheres-reinforced 1199Al-matrix composite foam
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摘要: 利用分离式霍普金森压杆（split Hopkinson pressure bar，SHPB）系统对空心微珠体积分数为0.4的空心微珠/1199Al复合泡沫在1 700~2 900s-1应变率范围内的动态压缩力学性能、吸能性能进行了研究，还利用SEM扫描电镜对压缩试件断口进行微观组织分析，与准静态条件下材料的压缩力学性能及压缩变形机制进行了对比。结果表明，空心微珠/1199Al复合泡沫是一种应变率敏感材料，与准静态结果相比，在高应变率下复合材料的流动应力和塑性应变有明显的增大，应变率硬化效应对复合材料的流动应力的影响明显大于应变硬化的影响。复合材料的准静态和动态压缩变形机制存在一定差异，动态载荷作用下，空心微珠/1199Al复合泡沫内部空心微珠的压缩和基体材料的充填同时发生，组分之间具有良好的协调变形能力。
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关键词:
- 固体力学 /
- 动态压缩力学性能 /
- 分离式霍普金森压杆 /
- 空心微珠/1199Al复合泡沫 /
- 吸能特性
Abstract: The fly-ash cenospheres-reinforced 1199Al-matrix composite foam was prepared by the pressure infiltration technique, in which containing the 80-μm-sized fly-ash cenospheres with the volume fraction of 0.4.Dynamic compression experiments were performed with a split Hopkinson pressure bar(SHPB)setup to investigate the dynamic compression properties and energy-absorption capability of the prepared composite foam in the strain rate range from 1 700s-1 to 2 900s-1.And the fractured surfaces of the compressed specimens were observed by a scanning electron microscopy.Moreover, the energy-absorption capability and the deformation mechanism of the prepared composite faom in dynamic compressions were compared with those of it in quasi-static compressions by an Instron 5569 tensile machine.The results show that the cenospheres-reinforced 1199Al-matrix composite foam is a strain-rate sensitive material.Its flow stress and plastic strain at the high strain rates are obviously higher than those under the quasi-static conditions.And the strain-rate hardening effect can more markedly influence the flow stress of the cenospheres-reinforced 1199Al-matrix composite foam than the strain-hardening effect.Furthermore, there are some differences between the quasi-static and dynamic compressive deformation mechanisms in the cenospheres-reinforced 1199Al-matrix composite foam.Under dynamic loadings, the fly-ash cenospheres in the cenospheres-reinforced 1199Al-matrix composite foam can be simultaneously compressed when the Al-matrix material is being filled, and there lies a good coordinate deformation capacity between the components. -
图 3 准静态及动态压缩应力应变曲线
Figure 3. Stress-strain curves at quasi-static and dynamic loading conditions
图 4 在不同的塑性应变下，流动应力与应变率的关系曲线
Figure 4. Flow stress varied with strain rate at different plasitc strains
图 5 不同应变率时，塑性应变与应变率敏感率之间的关系
Figure 5. Strain-rate sensitivity varied with plastic strain at different stain rates
图 6 不同应变率时吸能效率与压缩应力的关系曲线
Figure 6. Energy-absorption efficiency as a function of compressive stress at different stain rates
图 7 不同应变率时理想吸能效率与压缩应力的关系曲线
Figure 7. Ideal energy-absorption efficiency as a function of compressive stress at different stain rates
图 8 复合泡沫试件准静态压缩变形过程中宏观变形及微观组织
Figure 8. Macroscopic deformation and microstructure of composite foam specimen undergoing quasi-static compression
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