This study investigates the low-cycle fatigue (LCF) behavior of two types of dissimilar steel welded joints (DSWJs): AISI 1035 & S550Q and AISI 1020 & S550Q. Digital image correlation (DIC) and finite element analysis (FEA) were used to analyze the heterogeneous strain distribution. The results reveal that the location of maximum strain, which is load-dependent and related to strength mismatch, corresponds to the fracture location of the LCF specimens. Specifically, the crack initiation site shifts from the weld toe to the base metal as strain increases. Moreover, the weld reinforcement of the DSWJs significantly affects the failure site transition, introducing strain concentration at lower stress levels while enhancing deformation resistance at higher stress levels, as evidenced by DIC strain measurements and FEA. These findings highlight the importance of joint reinforcement profile, strength mismatch and external load level in designing DSWJs for wind turbine towers against LCF failure.

中文翻译：

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风电机组塔架异种钢焊接接头的低周疲劳性能及断裂位置过渡机制


这项研究调查了两种类型的不同钢焊接接头（DSWJs）的低周疲劳（LCF）行为：AISI 1035 & S550Q和AISI 1020 & S550Q。采用数字图像相关 （DIC） 和有限元分析 （FEA） 分析非均质应变分布。结果表明，最大应变的位置与载荷相关，与强度失配有关，对应于 LCF 试样的断裂位置。具体来说，随着应变的增加，裂纹萌生部位从焊趾转移到母材。此外，DSWJs 的焊缝加固显着影响失效部位的过渡，在较低应力水平下引入应变集中，同时在较高应力水平下增强抗变形能力，DIC 应变测量和 FEA 证明了这一点。这些发现强调了接头加固剖面、强度不匹配和外部载荷水平在设计风力涡轮机塔架 DSWJ 以抵御 LCF 失效时的重要性。