Topology design optimisation and manufacturing of aircraft frame considering the maximum overhang angle in wire arc additive manufacturing

Abstract

Topology optimisation (TO) is a popular method for lightweight design in the aircraft and aerospace industries. Wire arc additive manufacturing (WAAM) offers advantages such as high deposition rates and low costs, facilitating the manufacture of large-scale structures. However, this technique struggles to produce intricate shapes redesigned by the TO. In tandem with this, this study initially establishes an expected-value method to identify the optimal process parameters that yield the maximum overhang angle (MOA). Components fabricated below MOA exhibit compromised dimensional accuracy and poor surface quality. A variable density method is then employed to optimise the aircraft semi-frame component topologically. The modified inherent strain method is applied to determine the optimal strategy by minimising deformation at the assembly points. Based on the MOA constraint and the defined strategy, the aircraft semi-frame is re-optimised to guarantee that all regional forming angles meet or exceed the MOA threshold. Therefore, the topologically optimised model is fabricated via WAAM, with a forming error of within 3 mm. The findings indicate that the WAAM can successfully manufacture topologically optimised components when the MOA is considered, thus achieving a high level of forming accuracy.