Research on a Hybrid Manufacturing Process for Aerospace Structures

This paper presents a multi-axis hybrid Laser Aided Manufacturing Process (LAMP) to fabricate aerospace structures. This system integrates multi-axis laser deposition and material removal processes to produce aerospace structures with machining accuracy. Automated process planning issues are investigated and developed to automatically generate motion codes for the integrated hybrid process. The LAMP system fully utilizes multi-axis capability to minimize the usage of support structures by fabricating non-uniform thickness layers and changes the building direction as needed. The input of LAMP process is an STL model as the geometry models and generates a description that specifies contents and sequences of operations. The tasks for process planning of the LAMP system involve multi-axis adaptive slicing, 2-D deposition tool path generation, overhang and hollow structure process, integration between two processes handling non-uniform (thickness) layer building and overall process sequence. In order to fully understand the metal deposition process, models are developed to understand the powder delivery system and melt pool during deposition processes. An extensive understanding of the powder stream characteristics, such as concentration of powders, and velocity of powder are needed in determining operational parameters. The commercial software FLUENT is used in the LAMP process to study the effects of gas flow settings. Stochastic tracking predicted the particle path based on coupled particle-gas interactions. A comprehensive model is developed to simulate the laser deposition process, and it incorporates several important aspects which take place in the process, including phase changes phenomena, effects of powder injection, evolution of free surface of melt pool, momentum balance on the top free surface, fluid flow and temperature distribution in the melt pool and adjacent regions, and residual stress distribution analysis