锈蚀钢丝疲劳断口分析与寿命预测

发布时间：2018-03-23 15:56

本文选题：桥梁工程　切入点：高强度钢丝　出处：《中国公路学报》2017年04期

【摘要】：为了研究桥梁锈蚀高强度钢丝的疲劳性能以及疲劳断裂机理,并为基于断裂力学理论的锈蚀高强度钢丝疲劳寿命评价提供试验依据,以服役10余年的漂浮结构体系的拱桥吊杆退役钢丝及人工加速腐蚀钢丝为试验样本,对这2类钢丝进行了不同应力幅下的疲劳试验;利用扫描电镜分析了锈蚀钢丝的疲劳断口形貌特征以及疲劳断裂失效过程,对比分析了2类锈蚀钢丝疲劳源的蚀坑尺寸;考察了2类锈蚀钢丝初始裂纹应力强度因子及剩余断裂韧性,并与既有的钢丝疲劳阈值和断裂韧性指标进行了比较;采用三参数公式对锈蚀钢丝应力-寿命(S-N)曲线进行了拟合,对比了不同锈蚀程度钢丝S-N曲线的差异;针对锈蚀钢丝高应力幅的疲劳寿命特征,运用线弹性断裂力学方法对其进行了分析。结果表明:随着腐蚀程度的增加,钢丝的疲劳性能下降;表面蚀坑分布较密时,容易诱发多源裂纹并表现出不规则的裂纹扩展规律;萌生主裂纹的蚀坑阈值条件主要由疲劳裂纹扩展阈值ΔK_(th)控制;锈蚀钢丝S-N曲线在低应力范围下出现拐点,符合三参数公式的拟合规律;锈蚀钢丝的裂纹扩展寿命所占比例较大,基于一定初始裂纹尺寸假设得到的疲劳裂纹扩展寿命SN曲线能较好地反映锈蚀钢丝中等寿命区的平均疲劳行为。
[Abstract]:In order to study the fatigue performance and fatigue fracture mechanism of corroded high strength steel wire of bridge, and to provide experimental basis for fatigue life evaluation of corroded high strength steel wire based on the theory of fracture mechanics. The fatigue tests of these two kinds of steel wires under different stress amplitudes were carried out by taking the retired steel wire of suspension rod of arch bridge and the artificial accelerated corrosion steel wire as test samples which were used in floating structure system for more than 10 years. The fatigue fracture morphology and fatigue fracture failure process of corroded steel wire were analyzed by SEM, and the corrosion pit sizes of two kinds of corroded steel wire fatigue sources were compared and analyzed. The initial crack stress intensity factor and residual fracture toughness of two kinds of corroded steel wire were investigated and compared with the existing fatigue threshold and fracture toughness index of the corroded steel wire, and the stress-life curve of corroded steel wire was fitted by using the three-parameter formula. The S-N curve of steel wire with different corrosion degree is compared, and the fatigue life characteristics of corroded steel wire with high stress amplitude are analyzed by means of linear elastic fracture mechanics method. The results show that the fatigue life of corroded steel wire increases with the increase of corrosion degree. The fatigue property of steel wire decreases, when the surface corrosion pit distribution is dense, it is easy to induce multi-source cracks and show irregular crack propagation law, and the threshold condition of corrosion pit where the main crack originates is mainly controlled by fatigue crack propagation threshold 螖 K _ (th). The S-N curve of corroded steel wire appears inflection point in low stress range, which accords with the fitting rule of three-parameter formula, and the crack propagation life of corroded steel wire accounts for a large proportion. The SN curve of fatigue crack propagation life based on the assumption of certain initial crack size can well reflect the average fatigue behavior of corroded steel wire in the medium life region.
【作者单位】：浙江大学土木工程学系;昆明理工大学土木工程系;武义县公路管理段;金华市公路管理局;
【基金】：国家自然科学基金项目(51378460)
【分类号】：U443.38

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