Online stress monitoring during laser-directed energy deposition based on dynamic contour method

Abstract

Deformation and cracking caused by internal stress have been a long-standing challenge in the field of metal additive manufacturing. This paper presents a novel method for real-time stress assessment of laser-directed energy deposition (LDED) based on the shrinkage phenomenon of deposition layer – the Dynamic Contour Method (DCM). It integrates machine vision, three-dimensional reconstruction based on actual morphology, and numerical simulation to calculate rapidly stress development during the LDED process. Meanwhile, a mapping relationship between the surface shrinkage of the deposition layer and stress is established, providing a theoretical basis for the DCM. Regarding the validation of this method, the DCM simulations are compared with the experimentally calibrated thermo-mechanical coupling simulations. The results show a high degree of consistency, demonstrating the feasibility and accuracy of the DCM. This method provides a new digital twin framework for additive manufacturing.

Keywords

• Laser-directed energy deposition
• residual stress
• internal stress monitoring
• digital twin
• machine vision
• numerical simulation