As basements of offshore wind turbines (OWTs) in deep water (>50 m), jacket structures are an economic alternative to monopiles. For this reason, the structural durability of jackets has become more important. In such structures, welded tubular joints are weak points for fatigue design. The harmful effect of tensile residual stresses in welding joints is well known. For these reasons, the residual stresses and the loading stresses of offshore jacket structures were determined by X-ray diffraction (XRD) using a mobile diffractometer. This allows us to directly determine the load stress at the fatigue-critical locations, namely at the weld toe at the testing rig. High tensile residual stresses up to 250 MPa were determined in a welded (and unloaded) condition. At a loaded structure (10,000 load cycles), a lower residual stress level was determined. During loading, a local increase in the stress at the welded joint that is between 1.4 and 4 times higher than the applied nominal stress was determined. Furthermore, it is shown that additional treatment (grinding and clean blasting) influences the local stress state significantly.

中文翻译：

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通过 X 射线衍射测定海上导管架结构的载荷和残余应力

作为深水 (>50 m) 海上风力涡轮机 (OWT) 的基底，导管架结构是单桩的经济替代方案。因此，夹克的结构耐用性变得更加重要。在此类结构中，焊接管接头是疲劳设计的薄弱环节。焊接接头中残余拉应力的有害影响是众所周知的。由于这些原因，海上导管架结构的残余应力和加载应力是通过使用移动衍射仪的 X 射线衍射 (XRD) 来确定的。这使我们能够直接确定疲劳关键位置处的负载应力，即测试台上焊趾处的负载应力。在焊接（和卸载）条件下测定了高达 250 MPa 的高残余拉伸应力。在负载结构（10,000 个负载循环）下，确定了较低的残余应力水平。在加载过程中，焊接接头处的应力局部增加，比所施加的标称应力高 1.4 至 4 倍。此外，结果表明，附加处理（研磨和清洁喷砂）显着影响局部应力状态。