ECC疲劳损伤规律及微观结构研究

Fatigue damage pattern and microstructure study of ECC

为研究工程水泥基复合材料(ECC,engineered cementitious composites)的疲劳规律并探究其损伤原因,利用疲劳试验机对ECC试件进行单轴拉伸循环加载试验,分析其疲劳规律及损伤界面微观形态。研究结果表明:ECC试件破坏规律与其累积轴向应变速率有关,在加载初始阶段,累积轴向应变会随着循环荷载作用次数增加而明显增大,随后进入稳定变形阶段;进一步加载将导致累积轴向应变快速增长,并最终导致试件断裂破坏;ECC的裂纹宽度发展呈现出中间低、两端高的趋势;ECC试件在循环荷载过程中初次开裂后,不会迅速进入破坏阶段,是因为纤维仍然具有抗拉能力,可继续承受循环荷载加载;通过对纤维-基体界面的微观分析发现,纤维与基体结合较好,可整体耗散能量,为ECC具有高疲劳性能的主要原因。

In this paper,the uniaxial tensile cyclic loading test was carried out on engineered cementitious composites(ECC)specimens using a fatigue testing machine to investigate the fatigue pattern and the damage reason of the ECC.The results show that the damage pattern of ECC specimens is related to its cumulative axial deformation rate.At the initial stage of loading,the cumulative axial deformation amplifies significantly with the number of cyclic loads increasing,and then enters a stable deformation phase.Further loading will result in a rapid increase of the cumulative axial deformation and eventually leads to fracture of the specimen.The crack width of ECC development,shows a trend of low in the middle and high at both ends.ECC specimens will not rapidly crack after the initial cracking in the cyclic loading process,mainly because the fibers are still tensile and can continue to withstand cyclic loading.Microscopic analysis of the fiber-matrix interface reveals that the fibers are well bonded to the matrix and can dissipate energy as a whole,which is the main reason for the high fatigue performance of ECC.