IR Thermography Based Real-time In-situ Defect Detection and Elimination of Defect Propagation for In-Space Additively Manufactured Structures

The ability to perform In-Space Manufacturing (ISM) is critical for sustainable, flexible missions in orbit, in transit, and on the surface of the Moon or Mars. ISM offers on-demand fabrication of necessary supplies, such as tools, bolts, brackets, wire clamps, and other items needed for mission logistics and maintenance/repair of critical systems. Additive manufacturing (AM) was first performed and demonstrated on the International Space Station in 2014. Since then, numerous parts have been 3D printed in space using polymers. NASA is considering using lunar regolith as a local material for lunar infrastructure. One of the potential ways to print infrastructure with regolith-polymer mixture is to use a 3D print head that heats and extrudes the mixture to generate a desired geometry. While this approach is a game changer for prototype development of a single component, mass production of such infrastructural parts needs to overcome quality issues encountered in traditional extrusion-based AM. One of the major challenges going forward with ISM is verifying that the printed parts meet requirements. Currently, in-space inspection capabilities are limited to post-build visual inspection of the part. But the goal is to be able to inspect the part in-situ, during the build process, so that the part is “born certified.” On Earth, infrared (IR) thermography is one of the most common nondestructive evaluation methods used for defect detection in materials. Thermography can be used on nearly all material types, and not only can it detect surface flaws, but it can also generate real-time images of structural components, which is essential to verify structural integrity. In this project, a system for in-situ defect detection and elimination of defect propagation using IR thermography will be developed. It is proposed to integrate a traveling, non-contact, IR camera with the extruder head to detect defects in the part in real time as it is being printed.