Abstract Stress concentration and residual stress have a significant influence on fatigue life of welded joints. In order to reduce the stress concentration of welded joints, a mathematical design method of tensile triangles (MTT) based on bionics was applied to weld shape design. Accordingly, the stress concentration of various weld beads in the corner boxing welded joint and the fillet welded T-joint was dissected using our in-house FEM software JWRIAN. It was found that there existed a large stress concentration in the conventional welded joints, whereas those welded joints with elongated weld bead were accompanied by a lower stress concentration, especially for elongated weld bead with MTT design. Furthermore, among the weld shapes of the corner boxing fillet welded joint, the rectangle shape of weld bead had the minimum stress concentration factor (1.05). For the fillet welded T-joint with MTT design, the stress concentration of weld toe decreased dramatically with the increase of the index of designed shape, but there was a minor difference of stress concentration at weld root between the weld beads with MTT design. In addition, application of low transformation temperature (LTT) weld metal utilizing martensitic transformation to the fillet welded T-joints can produce compressive residual stress at weld toe.

中文翻译：

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一种降低焊接接头应力集中和残余应力的拉伸三角形和低相变温度焊缝金属设计方法

摘要 应力集中和残余应力对焊接接头的疲劳寿命有显着影响。为了减少焊接接头的应力集中，将基于仿生学的拉伸三角形（MTT）数学设计方法应用于焊缝形状设计。因此，使用我们的内部 FEM 软件 JWRIAN 剖析了角箱焊接接头和角焊 T 接头中各种焊道的应力集中。研究发现，传统焊接接头存在较大的应力集中，而细长焊道的焊接接头应力集中较低，特别是对于采用MTT设计的细长焊道。此外，在角箱角焊缝的焊缝形状中，矩形焊道的应力集中系数最小（1.05）。对于采用MTT设计的角焊T型接头，随着设计形状指标的增加，焊趾应力集中显着降低，但采用MTT设计的焊道之间在焊根处的应力集中存在微小差异。此外，将利用马氏体转变的低转变温度 (LTT) 焊接金属应用于角焊 T 型接头会在焊趾处产生残余压应力。