温度对PVA/ECC动态压缩性能影响

为研究不同温度、不同聚乙烯醇(PVA)纤维体积掺量和不同应变率对高延性纤维增强水泥基复合材料(PVA/ECC)动态压缩性能的影响，采用直径50 mm分离式霍普金森压杆(SHPB)，对高温浸水冷却后的PVA/ECC进行了冲击压缩试验，结果表明：当温度≥250℃，PVA/ECC试件冲击破坏后的整体性变差，应力-应变曲线更趋于扁平，其动态峰值应变提高不明显但动态峰值应力、冲击韧度显著降低，且高温对较大纤维体积掺量PVA/ECC动态峰值应力、冲击韧度的劣化效应更明显；温度≤150℃时，增大PVA纤维体积掺量，PVA/ECC动态峰值应力、峰值应变和冲击韧度均明显提高，但当温度≥250℃时，增大PVA纤维体积掺量，PVA/ECC动态峰值应变增大，而冲击韧度的提高幅度显著降低且动态峰值应力下降；高温水冷后的PVA/ECC仍具有明显的应变率效应，但温度≥150℃后，其抗压强度的应变率敏感性有所降低。

Effect of temperature on dynamic compression properties of PVA/ECC

In order to study the effects of different temperatures, different polyvinyl alcohol (PVA) fiber contents by volume and different strain rates on the dynamic compressive properties of engineered fiber reinforced cementitious composite (PVA/ECC), impact compression tests were conducted on PVA/ECC after the high-temperature and water-cooled by using a 50 mm diameter split Hopkinson compression bar (SHPB). The results show that when the temperature is greater than or equal to 250℃, the integrity of PVA/ECC specimens becomes worse after impact damage and the stress-strain curves tend to be flatter. The dynamic peak strain doesn’t increase obviously but the dynamic peak stress and impact toughness decrease remarkably. Furthermore, the deterioration effect of high temperature on the dynamic peak stress and impact toughness of PVA/ECC with larger fiber contents by volume is more obvious. When the temperature is less than or equal to 150℃, the dynamic peak stress, peak strain and impact toughness of PVA/ECC improve significantly with increasing the PVA fiber contents by volume. When the temperature is greater than or equal to 250 ℃, the dynamic peak strain increases with increasing the PVA fiber contents by volume, but the improvement extent of impact toughness reduces significantly and the dynamic peak stress decreases. PVA/ECC still has a significant strain rate effect after the high temperature and water-cooled. While when the temperature is greater than or equal to 150 ℃, the strain rate sensitivity of compressive strength reduces.