焊接结构对某型金属波纹管使用寿命的影响分析

Analysis of the Influence of Welding Structure on the Service Life of aCertain Metal Bellows

针对某补偿器波纹管出现的疲劳泄漏问题,开展了焊接结构对波纹管使用寿命的影响分析研究。首先,利用微结构分析的方法研究焊接结构形貌特性,并分析裂纹扩展机理,建立焊接结构的有限元模型;然后,利用子模型方法,对不同厚度焊缝的工作应力进行了计算分析,并提出波纹管焊接结构优化方案;最后,基于计算结果和疲劳寿命理论,对原始、改进波纹管焊接结构抗疲劳能力进行了分析。结果表明:1)原始焊接状态下,波纹管上封头连接环处易出现焊接缺陷,厚、薄焊缝处最大应力分别为462.84MPa和816.81MPa,超出了材料的疲劳极限,是波纹管低周疲劳破坏的主要原因;2)理想无焊接缺陷状态下,该型波纹管上封头连接环焊缝区的最大应力大约为260MPa,安全系数约为2;3)改进型波纹管连接环焊缝焊趾区最大应力为113MPa,安全系数约为4。本文的研究可为金属类波纹管的焊接结构优化和耐久性分析提供参考。

For the fatigue leakage problem of a certain compensator bellows,the influence of welding structure on the service life of bellows is studied in the current work.First,the microstructure analysis method is used to study the morphology of the welded structure,and the crack propagation mechanism is analyzed to establish the finite element model;Then,the working stress of the weld with different thickness is calculated and analyzed by using the sub-model method,and the optimization program of the welded structure is developed;Finally,based on the numerical results and fatigue theory,the fatigue resistance of the original and new welded structure is analyzed.The results show that:1)Under the original welding condition,the welding defects are easy to appear at the upper joint ring of the bellows.The maximum stresses of the thick and thin welds are 462.84 MPa and 816.81 MPa respectively,both of which exceed the fatigue limit of the material and are responsible for the low cycle fatigue of the bellows;2)Under no welding defects condition,the maximal stress at the joint zone is around 260 MPa,and the safety life coefficient is less than 2;3)The maximum stress in the weld toe of the improved bellows joint is 113 MPa,and the safety life coefficient is 4.This research provides a reference for the welding structure optimization and durability analysis of metal bellows.