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On the impact of undercuts and lack of penetration of cruciform joints from fatigue tests
International Journal of Fatigue ( IF 6 ) Pub Date : 2022-06-23 , DOI: 10.1016/j.ijfatigue.2022.107093
Helen Bartsch , Markus Feldmann

The assumption of the detail categories in EN1993-1-9 is the presence of a certain weld quality level. In order to find out the sensitivity of the resulting fatigue strength for cases where a worse or better quality level compared to the selected level of EN ISO 5817 is achieved, in this paper, special fatigue experiments are presented. The experiments refer to the load-carrying cruciform joint with lack of penetration and root fusion as well as undercuts. The performed fatigue investigations on cruciform joints are based on and accompanied by further fatigue test results of literature, documented in a detailed fatigue database containing 147 test series. Detailed information on mechanical properties, fabrication and metallurgical characteristics of the cruciform specimens are given. Extensive 3D laser scans of the specimens and ultrasonic testing as well as magnetic particle testing have been performed in order to analyse the imperfection sizes and scatters. The fatigue test results of the cruciform joints show, that undercuts lead to lower fatigue strength at the weld toe, as was to be expected. When reducing the fatigue resistance, undercuts could however be tolerated at secondary structural elements or marginally fatigue stressed components. A lack of penetration and/or root fusion can be tolerated, if the fatigue verification at the weld root is performed. A verification at the weld root can only be neglected in case of lack of penetration and/or root fusion, if the weld toe is decisive due to undercuts or large enough weld angels, here shown for 45°.



中文翻译:

疲劳试验对倒扣和十字接头未穿透的影响

EN1993-1-9 中详细类别的假设是存在一定的焊接质量水平。为了找出与 EN ISO 5817 所选水平相比质量水平更差或更好的情况下产生的疲劳强度的敏感性,在本文中,提出了特殊的疲劳实验。实验是针对缺乏穿透和根部融合以及咬边的承载十字形接头。对十字形接头进行的疲劳研究基于并附有文献的进一步疲劳测试结果,记录在包含 147 个测试系列的详细疲劳数据库中。给出了十字形试样的机械性能、制造和冶金特性的详细信息。为了分析缺陷尺寸和散射,已经对样本进行了广泛的 3D 激光扫描和超声波检测以及磁粉检测。十字形接头的疲劳试验结果表明,咬边会导致焊趾处的疲劳强度降低,这是意料之中的。然而,当降低抗疲劳性时,可以在二级结构元件或轻微疲劳应力的部件处容忍底切。如果在焊根处进行疲劳验证,则可以容忍缺少熔透和/或根部熔合。如果焊趾由于咬边或足够大的焊接角度(此处显示为 45°)而具有决定性,则只能在未熔透和/或根部熔合的情况下忽略焊缝根部的验证。

更新日期:2022-06-23
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