A Hybrid Method for the Online Evaluation of Stress Fields in Metal Additive Manufacturing

Background: Metal additive manufacturing has extensive application prospects in the aerospace, precision instrument, and biomedical fields, etc. However, the low manufacturing quality of key components is a bottleneck restricting the further development and application of this technology. Because of the extremely complex manufacturing environment, a real-time and online monitoring technology for the manufacturing quality remains lacking. Objective: For laser engineered net shaping (LENS), a mainstream technology of metal additive manufacturing, a hybrid method for the online evaluation of stress fields during laser cladding is developed in this paper that combines the real-time measured temperature field, three-dimensional deformation field and finite element method. Methods: The proposed method first designed the synchronous measurement optical paths of the temperature field and three-dimensional deformation field of the substrate, and the positions of the temperature and deformation field images were matched. A finite element model was established based on the printing parameters such as the layer thickness and printing speed, and the temperature field and three-dimensional deformation field synchronously measured at each moment were incorporated into the model as boundary conditions to obtain the deformation and stress information inside the model. Results: We compared the stress field obtained at the end of printing with the XRD (X-ray diffraction) measurement results to verify the effectiveness of the proposed method. The proposed method can obtain the three-dimensional stress distribution and evolution of the substrate and printed component. Conclusion: The proposed method can realize the online characterization of the three-dimensional stress field in the LENS printing process and provide important experimental guidance and data for the quality control of 3D printing.