An experimental study on dynamic mechanical property ofultra-light aluminum foam under high temperatures
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摘要: 对传统的分离式Hopkinson压杆装置加以改进，设计了一种长杆直接撞击Hopkinson杆的实验方案，检测出低波阻抗材料在高温动态加载下的应力均匀性。对轻质泡沫铝材料的实验表明，在同一撞击速度下，温度越高，试件两端的应力均匀性越差，增加温度与提高撞击速度均会导致泡沫铝材料冲击端与支撑端的应力不均匀性。根据高温下应力均匀性的实验结果，确定高温下试件均匀变形对应的冲击速度，再通过传统的分离式Hopkinson压杆实验得出泡沫铝在高温动态下的力学性能。Abstract: An improved split Hopkinson pressure bar device was applied and a direct impact Hopkinson experimental program with long bullets was designed to measure the dynamic properties of closed-cell aluminum foam under high temperatures. Stress-time curves of both ends of aluminum foam specimens were obtained. It is found that the temperature markedly influence the stress uniformity of the specimens. As the temperature increases, the stress non-uniformity in the specimen becomes serious under the same impact velocity. Thus, both the increment in the test temperature and the impact velocity will cause stress non-uniformity of aluminum foam specimens. For aluminum foams, homogeneous deformation mode is dominant when the impact velocity is low, and the meso-scopic deformation pattern may vary but the stress field of the foam specimen is macroscopically homogeneous. Finally, the SHPB experiment is used to obtain the stress-strain curve under high temperature and high strain rate, after ensuring homogeneous deformation of the specimen.
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Key words:
- solid mechanics /
- stress uniformity /
- Hopkinson bar /
- ultra-light aluminum foam /
- high temperature /
- dynamic
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图 4 不同撞击速度下的两端应力曲线(25 ℃)
Figure 4. Stress curves of two ends under different impact velocity (25 ℃)
图 5 不同撞击速度下的两端应力曲线(350 ℃)
Figure 5. Stress curves of two ends under different impact velocity (350 ℃)
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