基于连续损伤力学的UHTCC疲劳损伤扩展模型研究

FATIGUE DAMAGE PROPAGATION MODELS FOR ULTRA-HIGH TOUGHNESS CEMENTITIOUS COMPOSITES WITH CONTINUUM DAMAGE MECHANICS

为研究超高韧性水泥基复合材料的损伤扩展规律,该文对该材料的预制单边切口试件进行了三点弯曲疲劳试验。基于连续损伤力学,建立两种疲劳损伤扩展模型:一是以J积分作为自变量的双对数线性模型,二是以疲劳应力水平作为自变量的单对数线性模型。结果表明,两种模型计算结果与试验结果吻合良好。但J积分取值很大程度上依赖于试件的几何特征,导致模型1受试件形状影响较大;实际应用中,由于疲劳应力水平的获得相对直观方便,故模型2更加实用。

The damage propagation property of Ultra-high toughness cementitious composites（UHTCC） was studied using three-point flexural fatigue tests on single-notched specimens. Based on the continuum damage mechanics and the flexural fatigue damage model, two fatigue damage propagation models were built. One was a bi-logarithmic linear model with J-integral range as its independent variable. The other was a semi-logarithmic linear model with fatigue stress level as its independent variable. Results from the two models fit well with experimental results. However, because the J-integral is strongly dependent on the specimens＇ geometry, the first model was affected significantly by the specimens＇ shape. The second model is expected to be more applicable in engineering practice since the fatigue stress level is easy to obtain.