Toward a smart wire arc additive manufacturing system: A review on current developments and a framework of digital twin

In recent years, Wire Arc Additive Manufacturing (WAAM) has attracted increasing scientific attention. With the rise of Industry 4.0 and smart manufacturing, Digital Twin (DT) has become an emerging technology that is finding increased acceptance in Additive Manufacturing (AM) processes. This paper aims to provide a systematic review of current developments of DT in AM processes and then derive a suitable DT for the WAAM system. Firstly, DT developments in AM processes are introduced from supervisory, control, and predictive aspects. This provides a reference and inspiration for designing process DTs by reviewing their structures, algorithms, and methodologies. Secondly, the current research on process planning, monitoring, modeling, online control, and simulation in WAAM is reviewed. Particular attention is given to intelligent algorithms, such as machine learning. Thirdly, the challenges to building a WAAM-DT are introduced step-by-step. Finally, the paper con-cludes by proposing a framework of WAAM-DT as a hybrid and intelligent solution for monitoring, modeling, control, and simulation.