基于损伤力学的电厂主蒸汽管道蠕变损伤有限元分析

Finite Element Analysis on Creep Damage for Main Steam Pipelines in a Power Plant Based on Damage Mechanics

电厂主蒸汽管道在长期高温高压条件下会发生损伤,进行其蠕变损伤分析以及寿命评估至关重要。该文基于修正的卡恰诺夫–拉包特诺夫(Karchanov-Rabotnov)本构方程,编制了用于计算管单元和三维单元的用户子程序,并且与ABAQUS有限元分析软件耦合。通过540℃下10CrMo910管材的蠕变试验,得到蠕变损伤力学本构方程中的材料参数,对热电厂高温主蒸汽管线的蠕变损伤进行模拟计算,得到了整体损伤分布和最大损伤部位。同时对管线中的薄弱部位异径管进行蠕变损伤分析,得到其损伤分布,讨论了损伤过程中应力再分布,实现了对高温主蒸汽管道整体以及异径管的寿命评估。

Damage will occur in main steam pipelines subjected to high temperature and high pressure in the period of long-term service. Therefore, it is important to predict the damage and service life of the pipelines. Based on the modified Karchanov-Rabotnov constitutive equation, the user subroutines computing the damage of the pipe element and 3D solid element were compiled and coupled with ABAQUS finite element code. Creep tests were performed at serviced at 540 ℃ for 10CrMo910 pipe material, and the creep material constants in the modified creep damage constitutive equations were obtained by fitting the creep test data. Based on this, the creep damage prediction was carried out for the steam pipelines serviced at high temperature in a power plant. The damage distribution and maximum damage location of the pipelines were obtained. Furthermore, the local creep damage analysis of a taper pipe serviced at high temperature was also carried out because tapered pipe used in the main steam pipeline is one of weakness in the piping system. Damage distribution and evolution in the analyzed taper pipe were obtained, and stress redistribution in the period of creep damage was discussed. According to the results obtained above, the life evaluation of the pipeline and the taper pipe were performed.