SMA-ECC 抗多次冲击动态力学性能试验研究

When components such as concrete pier columns are subjected to multiple impact loads，they may fail，potentially leading to overall collapse. To improve the impact resistance of components，a novel self-healing material，SMA-ECC，was proposed. Multiple impact tests were conducted on the SMA-ECC specimens with different SMA fiber contents under various impact pressures using a split Hopkinson pressure bar，and PVA-ECC and conventional concrete specimens were also tested as comparative specimens. The variation of failure modes，crack widths，stress-strain curves，dynamic elastic modulus，peak stresses and toughness of SMA-ECC specimens with the number of impacts were obtained. The test results show that the specimens with SMA fiber volume fraction of 0. 7% exhibit excellent resistance to multiple impacts. Under low impact pressure，the impact resistance of specimen with SMA fiber volume fraction of 0. 7% is 1. 9-2. 8 times that of PVA-ECC specimen and 18. 7-21. 3 times that of concrete specimen. When damaged，both PVA-ECC and SMA-ECC specimens maintain good integrity，while concrete specimens completely fracture. The crack width of PVA-ECC specimen at its maximum impact resistance is 3. 4 times and 7. 0 times that of specimen with SMA fiber volume fraction of 0. 7% under the same number of impacts. The total energy absorption of specimen with SMA fiber volume fraction of 0. 7% is 1. 9-2. 3 times that of PVA-ECC specimen and 12. 6-13. 1 times that of concrete specimen. However，the advantages of SMA-ECC specimens decrease significantly with the impact pressure increased.