PSI - Issue 18

Benjamin Möller et al. / Procedia Structural Integrity 18 (2019) 556–569 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 6. Fatigue test results and evaluated Wöhler curves of laser beam welded lap joints without and with control of the penetration depth

In Möller et al. (2017), the comparison of Wöhler curves for lap joints with a single and a triple weld seam has already shown that the influence of the welding process parameters and the resulting local weld geometry, i.e. weld width and penetration depth, are the dominating effects for a fatigue assessment, in contrast to the number of weld seams. However, this is not true for designed adapters due to the symmetric loading situation of this type of specimen. Therefore, laser beam welded adapters of variant 1 (V1) with six weld seams resulted in a higher fatigue life compared to lap joints, even though the width-to-depth ratio is decreased. Fatigue testing has been performed on a further development of the adapter to variant 2 in the same test setup as that in which lap joints were investigated, but with a free length between the upper and lower clamping of 40 mm. The fatigue strength then increases from F a ( N f = 2ꞏ10 6 ) = 1.31 kN (V1) to F a ( N f = 2ꞏ10 6 ) = 3.63 kN for a compact second variant V2, as shown in Fig. 7. Furthermore, a discussion of possible definitions for a stress-based assessment of such laser beam welded adapters was made by Albrecht (2019).

Fig. 7. Fatigue test results and evaluated Wöhler curves for laser beam welded adapters of variant 1 and 2