These slides were presented at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

Wire arc additive manufacturing (WAAM) holds significant promise for transforming industries such as aerospace and energy, offering large-scale printing capabilities with high deposition rates and exceptional material and energy efficiency. Despite its promise, inconsistent and inferior mechanical properties of WAAM-built parts'”often due to defects and unfavourable microstructures under certain process conditions'”remain a barrier to its wider adoption in critical engineering applications. Addressing this challenge is crucial to unlocking the full potential of WAAM. Inter-layer mechanical working, such as rolling, has emerged as an effective solution, significantly reducing porosity, refining microstructures, and alleviating residual stresses and distortions. Inter-layer rolling not only enhances the mechanical properties of WAAM-built parts but also enables higher performance and reliability. At the core of these improvements lies rolling-induced deformation, a critical factor in driving or amplifying the beneficial effects. However, understanding and optimising the rolling process require a detailed exploration of the deformation mechanisms, which is difficult to achieve by experimental methods alone due to the complexities of real-time measurement and evolving geometries inherent in WAAM. This study addresses the challenge of simulating rolling-induced large deformation in multi-layer deposition by WAAM and aims to gain deeper insights into the deformation mechanisms and their implications. A novel finite element analysis (FEA) approach is proposed to simulate the large, evolving deformation caused by inter-layer high-pressure rolling during WAAM. This approach overcomes a critical issue in FEA: mesh distortion in large-deformation scenarios. By developing a series of rolling models for each WAAM-deposited layer, the simulation framework uses solution mapping to incorporate the previously deformed geometry, along with stress and strain histories, into the next model with a new updated mesh. This stepwise simulation provides a robust framework to capture the progressive effects of rolling on WAAM-built parts. The capabilities of this approach are demonstrated and validated through its application to aluminium alloy walls, revealing the accumulation and stabilisation of rolling-induced deformations during WAAM. Key insights include the evolution of lateral widening and plastic yielding across layers, as well as the discovery of folding deformation when the contact angle of the deposited layer is large. The increase in layer width after rolling affects the geometric accuracy and the plastic strain and layer folding have significant implications for the final mechanical properties of WAAM-built parts, underscoring the critical role of modelling in advancing understanding and optimisation. The findings from this research represent a step forward in addressing large-deformation modelling challenges in the integrated process of WAAM and mechanical working. Beyond advancing the understanding of the deformation mechanisms, the results would provide guidance for selecting and optimising mechanical working processes to improve WAAM deposition quality. By bridging the gap between experimental limitations and practical implementation, this modelling work contributes to the development of high-performance WAAM parts for demanding engineering applications, further solidifying WAAM'™s position as a cornerstone technology for the future of manufacturing.