Integration of annealing into the inherent strain simulation of wire arc additive manufacturing

In wire arc additive manufacturing, residual displacements represent a common challenge. Simulations act as a tool for predicting this deformation, consequently reducing scrap rates. This paper aims to present the use of the inherent strain simulation for rapid and quantitatively satisfactory displacement predictions in the wire arc additive manufacturing process. The inherent strain method inserts layer-wise a strain tensor into the part. The inherent strain tensor results from the thermal expansion and contraction cycles. In this work, the activation of elements to model the material deposition has been investigated by simulating a reactivation area representing the remelting and annealing of the previously deposited material. Accordingly, three activation models were calibrated on the basis of experiments and validated based on two very different structures. While the conven-tional activation model proves unfeasible, the second activation model of partial removal of the stress and strain history in the previously deposited material is able to reproduce the displacement field with respect to the mod-eling limitations of the inherent strain model. Furthermore, the penetration depth for this annealing effect is a displacement-sensitive parameter and can be estimated semi-analytically. For industrial purposes, the simulated and experimental displacements of the validation bodies were in good agreement, implying that the predicted displacement can be considered in design processes and welding trajectory planning.