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摘要: 利用传统分离式霍普金森压杆（SHPB）对低密度、低波阻材料进行测试时，存在透射信号弱、试样在加载时间内难以达到受力变形均匀的不足。采用嵌入压电石英晶体技术测试微弱的透射信号，并监测试样两端应力平衡。实验测试了一种低密度聚氨酯泡沫，结果表明嵌入压电石英晶体技术可以大幅提高透射信号的幅值和信噪比，所测试的材料在应变率范围1 000~4 000 s-1内应变率效应不明显。Abstract: During testing low impedance materials (so-called soft materials) by a conventional split Hopkinson pressure bar (SHPB), the transmission strain pulse is too weak to be collected correctly. In addition, the soft material specimen will not deform homogeneously during the testing, which makes it impossible to get valid data. In this paper, a polyurethane foam material was tested by SHPB using a quartz transducer technique. The stress equilibrium in the specimen was monitored by quartz transducer mounted at two end faces of the specimen. Experimental results showed that the amplitude of transmitted signals were increased greatly. Meanwhile, we used a pulse-shaper technique to increase the rise time of the incident pulse, which could ensure stress equilibrium and homogeneous deformation in the specimen. Compressive stress-strain behaviors of the foam showed that there was little effects of strain rates on the material properties at strain-rate of 1 000~4 000 s-1.
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Key words:
- SHPB /
- quartz transducer /
- soft material /
- high strain rate
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