套管法兰是换流变压器阀侧套管的薄弱部位，承受着换流变振动等复杂环境动力，易因长期机械载荷作用出现疲劳开裂，导致换流变压器停运。应力集中是导致结构疲劳开裂的主要因素，但现在少有针对法兰应力分布和疲劳的研究。为优化套管法兰根部结构、提高法兰疲劳强度，采用有限元仿真方法分析法兰应力分布，研究不同根部结构下法兰应力集中特征，并采用模态分析和响应谱分析研究振动载荷下法兰应力分布。研究发现：应力集中在法兰拐角位置并随法兰拐角曲率半径增加而降低；套筒上与法兰盘连接的加强筋能明显降低法兰拐角应力，降低幅度随加强筋宽度和高度增加而提升；三角形加强筋在靠近应力集中位置时能明显降低法兰拐角应力，降低幅度随加强筋安装角度增加而减小；连接的加强筋还对套管受竖直方向和轴向振动时法兰拐角最大应力有明显抑制作用。
Abstract
Bushing flange is the weak part of side bushing of converter transformer valve, it is subjected to complex environmental dynamic forces, such as, vibration of converter transformer, and it is easy to have fatigue cracking due to long-term action of mechanical load, and cause shutdown of converter transformer. Stress concentration is the main factor leading to structural fatigue cracking, but there are few studies on stress distribution and fatigue of flanges. Here, in order to optimize root structure of bushing flange and improve its fatigue strength, the FE simulation method was used to analyze stress distribution of flange, and study stress concentration characteristics of flange under different root structures. The modal analysis and response spectrum analysis were used to study stress distribution of flange under vibration load. The study results showed that stress is concentrated at flange corner and decreases with increase in curvature radius of flange corner; the stiffener connected with flange on bushing can obviously reduce flange corner stress, and the reduction amplitude increases with increase in width and height of stiffener; triangular stiffener can obviously reduce flange corner stress near stress concentration position, and the reduction amplitude decreases with increase in installation angle of stiffener; the maximum stress at flange corner of the bushing subjected to vertical and axial vibrations is obviously suppressed by the connected stiffener.
关键词
中换流变压器阀侧套管 /
法兰 /
有限元分析 /
应力集
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Key words
side bushing of converter transformer valve /
flange /
finite element (FE) analysis /
stress concentration
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