PSI - Issue 79

Benjamin Möller et al. / Procedia Structural Integrity 79 (2026) 493–500

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Tensile tests under symmetrical loading of the laser-welded adapters have been performed in order to draw conclusions about the mechanical load capacity, fracture behavior, and weld seam quality. Due to the symmetrical loading, the tensile force acts evenly on both sides of the adapter, resulting in a homogeneous stress distribution within the welded joint. As a result, force-displacement curves show max. tensile forces F t for the adapters in the range of approximately 35 kN. The test results (≥ 3) show low dispersion and, thus, high reproducibility. However, final failure occurs in the connecting fillet weld using GMAW from aluminum T-profile to the aluminum sheet belonging to the superstructure – and not within the adapter at the intersection of steel and aluminum. Figure 4 presents example fracture patterns of an adapter tested under symmetrical tensile loading. Since the final failure of the adapters occurs primarily in the area of the weld metal and the heat-affected zone of the weld seam between the welded plate and the aluminum adapter, a positive effect of both the microstructure and the form fit due to their characteristics becomes obvious, which results in high tensile strength.

Figure 4. Exemplary fracture patterns of laser-welded adapters under (symmetric) tensile loading.

Due to its excellent corrosion resistance and formability, the naturally hard aluminum alloy AA5083 is often used in shipbuilding. For this reason, the tensile force at the yield point of this aluminum alloy ( t =8mm) is used for comparison. The maximum tensile force of approximately F t =35kN corresponds to an exceedance of the yield strength of the aluminum alloy AA5083 by approximately 37 %. Fatigue testing and results 4. Fatigue testing and results Fatigue testing under constant amplitude loading (CAL) has been performed on the adapters produced through the developed laser beam welding process. Each tested adapter comprised the form fit, had a thickness of 15 mm and was designed without connecting fillets welds to the ship structure, Figure 5 (left). The hydraulic-driven, uni-axial test setup is shown in the middle of Figure 5. Crack initiation, crack propagation and final fracture are observed by camera tracking on the front side of each adapter to be used for digital image correlation (DIC).

Figure 5. Fatigue test setup for adapters investigated in air and under corrosive media.