Thermo-mechanical analysis of Wire and Arc Additive Layer Manufacturing process on large multi-layer parts

Wire and Arc Additive Layer Manufacturing (WAALM) is rapidly gaining prominence for producing large custom-made metal workpieces due to its high deposition rates. This study investigates the thermo-mechanical behavior of multi-layer wall structures produced through the WAALM process, highlighting the significant residual stresses and distortions that arise from the high input power of the welding process. A comprehensive methodology involving a 3D thermo-elastic-plastic transient model and an advanced steady-state thermal analysis model was employed to simulate temperature variations and predict distortions. The validation of the simulation results was carried out by comparing them with experimental data obtained from thermo-couples and laser scanners, alongside residual stress measurements using the neutron diffraction strain scanner ENGIN-X. Findings indicate that the stresses across the deposited walls remain uniform with minimal influence from prior layers, while a notable redistribution of stress occurs upon unclamping, particularly showing lower values at the top of the wall compared to the interface, attributed to bending distortions. Furthermore, the steady-state thermal model demonstrated significant efficiency gains in computational time analysis.