PSI - Issue 53

Benjamin Möller et al. / Procedia Structural Integrity 53 (2024) 190–202 Author name / Structural Integrity Procedia 00 (2023) 000–000

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structure using APPD process and encapsulate this structure by WAAM aluminum again, Fig. 1 left. This results in an additive manufacturing process of the single steps: 1. aluminum base hollow structure (WAAM) 2. adding ceramics isolators and copper conductors with APPD 3. encapsulating conductors by aluminum (WAAM) The aluminum base structure is mainly responsible for carrying the loads. With respect to fatigue, which is a relevant aspect for the design, two main load cases have been identified: lifting the motorbike and braking. Both are 3-dimensional (bending) load cases with respect to the mid axis of the handlebar, where the load introduction is close to the ends of the handlebar, Fig. 1 right. A focus of this investigation is set on the braking load case.

Fig. 1. CAD-model of the motorcycle handlebar including functional integration.

1.3. Realization of the WAAM process and specimen design The material used for the wire arc additive manufacturing (WAAM), Fig. 2a, of the motorcycle handlebar was the aluminum welding wire AA6063 (AlMgSi0,5). Using WAAM, single seam welds accumulate to a hollow structure shown in Fig. 2b. The cross-section is not a circular hollow section, but an aerodynamic triangular shape. The track of one WAAM layer is shown in Fig. 2c. Functional integration will be realized based on the hollow sections as described in section 1.2.

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Fig. 2. (a) WAAM process; (b) WAAM AA6063 structure for specimen extraction; (c) track of one WAAM layer.

Straight specimens including the triangular hollow sections have been manufactured separately representing the section between the mid part and end of the handlebar. Twenty specimens of approx. 160 mm length were cut from ten straight WAAM structures for fatigue testing. The wall thickness of the hollow structure specimens varies from approx. 4 mm to 6 mm. Porosity analysis on micrographs from section cuts show a porosity far below 1 %.