PSI - Issue 57

J. Baumgartner et al. / Procedia Structural Integrity 57 (2024) 618–624

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J. Baumgartner et al. / Structural Integrity Procedia 00 (2023) 000–000

from the various W orking G roups (WG) within Commission XIII, b) papers presented and discussed during the A nnual A ssembly of IIW that are published in the journal W elding in the W orld and c) publications in other journals. The IIW-recommendations have reached a worldwide impact that can be identified by the currently 38.000 accesses and nearly 400 references in journal papers for the 2016 version. One reason for its success is the fact, that the recommendations are compiled from scientific results achieved by the leading researchers in fatigue. Therefore, the document is based on a current scientific basis and is, beyond that, unrelated to any industrial branches. With this, a broad application in various industries is possible. The work on the update started in 2017. The publication of the new IIW-recommendations is expected in 2024. In the following, an overview on the most relevant changes is provided and references to the source of the changes is given.

Nomenclature

r ref Reference radius m General slope of an S-N curve m σ Slope of S-N curve for normal stresses m τ Slope of S-N curve for shear stresses t Wall thickness n Thickness correction exponent N Number of cycles

2. Most important changes

2.1. Nominal stress approach

Due to evaluations of available data in literature, some changes of FAT-classes within the nominal stress approach have been made, Table 1. Main important changes are the addition of laser-beam welded butt joints with a FAT80 for steel and an increase in FAT-class of high-quality butt joints ground flush with additional requirements.

Table 1. Changes made in the structural details for the nominal stress approach

DetailNo.

Changes made

121 211

Added FAT-class for aluminum sheets with machine gas cut or sheared edges.

A reevaluation of S-N data [4] showed a higher fatigue for high-quality butt joints ground flush. FAT125 is recommended for a max. misalignment of 5% and FAT112 for 10%. The slope is changed to k σ = 5. The detail ”Transverse laser-welded butt welds” was added with FAT80 for steel and FAT28 for aluminum. The detail ”Transverse sti ff ener with weld toes ground” was increased to FAT90 and FAT32 for steel and aluminum resp. to be in line with the recommendations on the new assessment approach on post-weld treated joints.

216a

411

2.2. Notch stress approach and thin welded joints

One of the major changes in the updated IIW-recommendations is the consideration of smaller reference radii for the assessment of thin-welded joints with thicknesses t ≤ 10 mm [2]. The choice of the reference radii depends on the