Abstract
The aim of the present research is to check the accuracy of the Modified Wöhler Curve Method (MWCM) in estimating the fatigue strength of friction stir (FS) welded tubular joints of Al 6082-T6 subjected to in-phase and out-of-phase multiaxial fatigue loading. The welded samples being investigated were manufactured by equipping an MTS I-STIR process development system with a retracting tool that was specifically designed and optimised for this purpose. These specimens were tested under proportional and non-proportional tension and torsion, the effect of non-zero mean stresses being also investigated. The validation exercise carried out by using the generated experimental results allowed us to prove that the MWCM (applied in terms of nominal stresses) is highly accurate in predicting the fatigue strength of the tested FS welded joints, its usage resulting in estimates falling with the uniaxial and torsional calibration scatter bands.
Highlights
Friction stir (FS) welding is a solid-state joining process that results, if applied correctly, in connections characterised by high mechanical performance
The aim of the present research is to check the accuracy of the Modified Wöhler Curve Method (MWCM) in estimating the fatigue strength of friction stir (FS) welded tubular joints of Al 6082-T6 subjected to in-phase and out-of-phase multiaxial fatigue loading
The validation exercise carried out by using the generated experimental results allowed us to prove that the MWCM is highly accurate in predicting the fatigue strength of the tested FS welded joints, its usage resulting in estimates falling with the uniaxial and torsional calibration scatter bands
Summary
Friction stir (FS) welding is a solid-state joining process that results, if applied correctly, in connections characterised by high mechanical performance. [7] and references reported therein), examination of the state of the art suggests that no systematic theoretical/experimental work has been carried out so far in order to formalise and validate specific criteria suitable for performing the multiaxial fatigue assessment of this type of welded connections. In this complex scenario, this paper summarises a part of a large programme of work on the issue of multiaxial fatigue design for FW welded tubular structures
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