厚钢板疲劳裂纹扩展前缘应力状态试验与数值仿真
发布时间：2018-12-15 02:49
【摘要】：复杂的环境载荷不可避免地会造成海洋结构物的疲劳损伤,而高强度厚钢板典型的三向应力状态会增加结构脆性,更加缩短结构的疲劳寿命。为研究厚板裂纹前缘应力状态沿板厚方向的分布,完成了3组36 mm板厚Q370QE高强度钢的标准疲劳裂纹扩展速率试验,得到了材料参数C,m以及应力强度因子门槛值。接着,应用有限元方法分别基于线弹性分析和塑性分析计算裂纹尖端应力强度因子和裂纹尖端局部约束因子,并解释试验中裂纹前缘由倾斜趋于平直的现象。计算所得裂纹尖端应力强度因子可描述板厚中心部分裂纹前缘的应力状态,但在试件表面处结果失真,而裂纹前缘局部约束因子因考虑了厚板的厚度效应,故沿板厚方向分布的裂纹尖端局部约束因子可有效量化裂纹尖端的应力状态分布。
[Abstract]:Complex environmental loads will inevitably cause fatigue damage of offshore structures, while the typical triaxial stress state of high strength thick steel plates will increase the structural brittleness and shorten the fatigue life of the structures. In order to study the distribution of crack front stress state along the thickness direction of thick plate, three groups of standard fatigue crack growth rate tests of 36 mm thick Q370QE high strength steel have been completed. The material parameter Cumm and the threshold value of stress intensity factor have been obtained. Then the stress intensity factor and the local constraint factor at the crack tip are calculated based on the linear elastic analysis and the plastic analysis, respectively, and the phenomenon that the cause of the crack tends to be straight is explained in the experiment. The calculated stress intensity factor at the crack tip can describe the stress state of the crack front in the thick center of the plate, but the results are distorted on the surface of the specimen, and the thickness effect of the thick plate is taken into account in the local constraint factor of the crack front. Therefore, the stress state distribution at the crack tip can be effectively quantified by the local constraint factor distributed along the plate thickness direction.
【作者单位】： 武汉理工大学交通学院;
【基金】：国家自然科学基金资助项目(51009111) 中央高校基本科研业务费专项资金资助项目(135202006)
【分类号】：U661.4
本文编号：2379825
[Abstract]:Complex environmental loads will inevitably cause fatigue damage of offshore structures, while the typical triaxial stress state of high strength thick steel plates will increase the structural brittleness and shorten the fatigue life of the structures. In order to study the distribution of crack front stress state along the thickness direction of thick plate, three groups of standard fatigue crack growth rate tests of 36 mm thick Q370QE high strength steel have been completed. The material parameter Cumm and the threshold value of stress intensity factor have been obtained. Then the stress intensity factor and the local constraint factor at the crack tip are calculated based on the linear elastic analysis and the plastic analysis, respectively, and the phenomenon that the cause of the crack tends to be straight is explained in the experiment. The calculated stress intensity factor at the crack tip can describe the stress state of the crack front in the thick center of the plate, but the results are distorted on the surface of the specimen, and the thickness effect of the thick plate is taken into account in the local constraint factor of the crack front. Therefore, the stress state distribution at the crack tip can be effectively quantified by the local constraint factor distributed along the plate thickness direction.
【作者单位】： 武汉理工大学交通学院;
【基金】：国家自然科学基金资助项目(51009111) 中央高校基本科研业务费专项资金资助项目(135202006)
【分类号】：U661.4
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，本文编号：2379825
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