Knowledge Management System of Institue of Mechanics, CAS
| 平台用高强度钢多次补焊及TIG熔修的疲劳分析 | |
刘海涛
| |
| Thesis Advisor | 柳春图 |
| 1999 | |
| Degree Grantor | 中国科学院研究生院 |
| Place of Conferral | 北京 |
| Subtype | 硕士 |
| Degree Discipline | 固体力学 |
| Keyword | 疲劳实验 补焊 多次补焊 Tig熔修 补焊熔修 威布尔分布 Fatigue Test Repairing Weld Multiple Repairing Weld Tig Dressing Repairing Dressing Weibull Distribution |
| Other Abstract | 海洋石油平台在服役期内，由于受到各种环境载荷的交变作用，其受力的焊接构件不可避免地会出现疲劳裂纹。对出现的疲劳裂纹进行补焊修复，可以延长平台的使用期，带来巨大的经济和社会效益。本文通过实验研究，考察了多次补焊对海洋平台用高强度钢焊接接头疲劳性能的影响，以及是否可以通过TIG熔修工艺的采用提高补焊构件的疲劳寿命，达到延长补焊后平台的使用寿命，减少补焊次数的目的。本文涉及的主要研究内容如下：1、考察了多次补焊对焊接接头疲劳寿命的影响。通过对平台用高强度钢焊接接头初焊试样，以及重复三次补焊试样的疲劳实验，得到了各次补焊试样在对数正态分布和威布尔分布下的寿命估算式和考虑了存活率的R-S-N曲线。对实验结果进行了比较和分析，从而考察了多次补焊对焊接接头疲劳性能的影响。2、在每次补焊后，由于焊趾外移造成了焊趾角的变化，使得焊趾处的应力集中系数发生了变化。本文采用有限元方法计算了试样的应力场分布，得到了焊趾处的应力集中系数与焊趾角的关系。考虑到应力集中系数的变化后，对多次补焊试样疲劳实验的实验数据进行了重新处理。3、考察了多次补焊熔修对焊接接头疲劳寿命的影响。本文通过对平台用高强度钢焊接接头补焊及补焊熔修试样的疲劳实验，得到了多次补焊和补焊熔修试样对数正态分布和威布尔分布下的寿命估算式和考虑了存活率的R-S-N曲线。对实验结果进行了比较和分析，从而考察了补焊后采用TIG熔修工艺对焊接接头疲劳性能的影响。4、一次补焊后进行熔修处理可以极大的改善试样的疲劳性能，提高试样的疲劳寿命。但这一结果是在平焊位条件下得出了。为了将这一结果用于实际，还要考察实际操作中大量采用的立焊位条件下熔修的效果。本文完成了立焊位条件下补焊及补焊熔修试样的疲劳实验，得到了相应的S-N曲线。5、疲劳实验数据的处理中，大量采用威布尔分布作为数据统计的分布类型。但由于威布尔分布具有三个参数，给求解带来一定的困难。本文提出一种以在威布尔坐标纸上，数据分布的线形相关系数作为判据的求解威布尔参数的方法，并通过程序加以实现。为了对疲劳实验数据的处理更加方便和直观，编制了“疲劳实验数据处理程序“，将对疲劳实验数据的编辑、分布参数的求解、不同存活率下的疲劳寿命估算和各种分布类型图以及R-S-N曲线的绘制工作包括在该程序中。; Due to the alternate effects of various environmental loads, fatigue cracks inevitably appear in the welded parts of ocean platform during its service period. Repairing weld on fatigue crack can extend the life of platforms, thus bring great economic and social results. In this dissertation, the effects of multiple repairing weld on the fatigue property of high strength steel welded joints used in platform have been investigated, and whether the fatigue life of repairing welded component can be extended using TIG dressing technique, thus prolong the platform's life, reduce the times of repairing weld, has been examined. The main contents of this dissertation includes the following aspects: 1、The effect of multiple repairing weld on the fatigue life of welded joint has been investigated. Through the fatigue tests on primary welded samples and three times repairing welded samples, the life estimating formula and the R-S-N curves considering reliability of these samples under the condition of normal distribution and Weibull distribution have been obtained. By comparison and analysis tests' results of each time, the effect of multiple repairing welds on welded joints is discussed. 2、After each time of repairing weld, the stress concentration factors of weld toe change because of changes of toe angles induced by outward-move of toe. In this dissertation, stress field of the samples has been calculated using finite element method; the relation between stress concentration factors and toe angles has been obtained. Considering the changes of stress concentration factors, the fatigue test data of multiple repairing weld samples is reprocessed. 3、The effects of multiple repair dressing on the life of welded joint. Through the fatigue tests on high strength welded joint samples and repair dressing samples, the life estimating formula and the R-S-N curves considering reliability under the condition of logarithmic normal distribution and Weibull distribution are obtained. By comparison and analysis tests' results of each time, the effect of TIG dressing on welded joints is discussed. 4、The fatigue property of the first repairing welded samples have been improved greatly by TIG dressing technology. For the practical purpose, the experiments of vertical position welding samples has been finished, and the corresponding S-N curves have been obtained. 5、To deal with the data of fatigue tests, Weibull distribution is in common use. In this dissertation, a method to solve Weibull parameters by the linear correlative coefficient is performed. |
| Call Number | 29855 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://dspace.imech.ac.cn/handle/311007/23422 |
| Collection | 力学所知识产出(1956-2008) |
| Recommended Citation GB/T 7714 | 刘海涛. 平台用高强度钢多次补焊及TIG熔修的疲劳分析[D]. 北京. 中国科学院研究生院,1999. |
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