Process-property-performance in large-scale robotic 3D printing for aerospace applications

A 6-axis robotic arm-based 3D printing system has been developed by integrating Fused Deposition Modeling (FDM) hardware with a UR16e robotic arm for large-scale aerospace structure manufacturing. The 6-axis enables manufacturing large-scale and complex shape aerospace structures. The influence of process parameters on the structural properties of fabricated structures is studied. First, small rectangular strips coupons with unidirectional printing path along the length direction are conducted and tested. The influence of extruder nozzle temperature, extruder travel speed and material feed rate on strength, stiffness and apparent density is studied. The material deposition paths are generated using RoboDK, which discretized the 3D model into parametric toolpath synchronized with the robot’s multi-axis motion. The customized robotic 3D printer’s performance was evaluated experimentally by varying extruder travel speed (20–125 mm/s), material feed rate (8–13.3 RPM), and nozzle temperature (200–250°C) with raster orientation 0o. Experimental parametric studies have shown that the combined process parameters of travel speed of 55 mm/s, material feed rate of 13 RPM, and temperature above 250°C produce samples with superior strength properties. The material properties obtained from the coupon tests and the printing directional path are both studied for investigating load-carrying capacity of airplane wing models. To complement the experiments using parametric studies, finite element simulations were conducted in Abaqus/Explicit to study the load-carrying capacity of cantilever plate which is manufactured under different raster orientations and process conditions. Four different printing directional paths are considered: [0/90], [15/-75], [30/-60], and [45/-45]. From numerical parametric studies, it is found that the process parameter condition with [45/-45] raster orientation, 230°C nozzle temperature, 15 RPM feed rate and 50 mm/s travel speed that exhibits the best condition for the manufactured coupons with highest load carrying capacity. Study results reveal the impact of process parameters and the printing path direction have a significant influence on structural loading carrying capacity. The robotic 3D printer has been successfully utilized to manufacture large-scale airfoil wing model, which will be used to print the designed plate model under optimized process parameters, whose test results will be used to validate the process-properties-performance relationship studied in this work. Furthermore, the data-driven prediction models using the coupons’ experimental results for mass and flexural strength were developed using ridge regression and singular value decomposition (SVD), both demonstrating high predictive accuracy, which will be used to further investigate the best process parameters and the printing directional path for high-performance aerospace applications.