【作者】 郑翔宇；

【导师】 金志江；

【作者基本信息】 浙江大学 ， 化工过程机械， 2008， 硕士

【摘要】 未焊透缺陷是工业压力管道系统中广泛存在的一种焊接缺陷,国内外对此类压力管道缺陷的研究较少。鉴于管道材料韧性较好,管道的破坏常表现为塑性极限载荷控制失效。本文以工业中常用的低碳钢压力管道为研究对象,采用有限元分析和试验研究相结合的方法,研究了缺陷深度、环向长度、轴向长度和管道径比等因素在纯内压、纯弯矩以及内压弯矩组合作用下对压力管道塑性极限载荷的影响,主要研究成果和创新点如下:(1)建立了含未焊透缺陷压力管道的有限元计算模型,编制出了适合本课题需要的有限元APDL参数设计程序。(2)对含未焊透缺陷压力管道的影响因素进行了简化,采用正交实验法制定计算方案,通过有限元分析,得到了不同尺寸未焊透缺陷压力管道在单一内压作用下的极限内压、单一弯矩作用下的极限弯矩以及在一定内压作用下的极限弯矩,研究了其塑性极限载荷随缺陷深度、环向长度、轴向长度和管道径比等影响因素的变化规律,分析了其塑性区扩展情况和失效模式。(3)在有限元分析得到的结果的基础上,分别拟合出了单一内压和单一弯矩作用下的含未焊透缺陷压力管道的极限载荷估算公式。(4)设计加工了组合载荷作用下压力管道的极限载荷试验装置,进行了极限载荷试验测试,试验结果与有限元计算结果基本一致,表明有限元建模和计算是正确的,用有限元方法计算含未焊透缺陷压力管道是可行的。(5)在有限元计算结果和试验结果的基础上,提出了含未焊透缺陷低碳钢管道在内压和弯矩作用下的安全评定方法。更多还原

【Abstract】 Incomplete penetration defect is one of common defects in industrial pressure piping system, few researches was reported at home and abroad. As the good toughness of pressure pipes, general failure mode of the pipes is plastic failure. By means of the non-linear FEA and experiments, the influence of the incomplete penetration defect of pressure piping under combined loads of internal pressure and bending moment was researched in this paper. The main research achievements and creative ideas are as follows:(1) The finite element models of pressure piping contain incomplete penetration defect was established. The APDL procedures suitable for the subject were made.(2) According orthogonal experimental design, worked out computational scheme. By simplifying the effect factors of plastic limit load, the plastic limit load of different defect size under simplex loads or combined loads were gained. Meanwhile, the relation between the plastic limit loads and main effect factors was studied, and the failure mode was presented.(3) Based on the results of FFA, a fitted formula for plastic limit load of pressure piping contain incomplete penetration defect was given.(4) An experimental system used for testing the limit load of pressure piping under combined loads was designed. Using the self-designed limit load test system, the experiments of pressure piping containing incomplete penetration defect ware carried out. The experimental results are consistent with those from FEA, which indicate that the modeling method and calculation of FEA are correct and it is effective to calculate the limit load by FEA.(5) On the base of results of FEA and experiments, a safety evaluation method for pressure piping containing incomplete penetration defect under combined loads is proposed.更多还原