Non-Destructive Evaluation of Lunar Regolith Metal Matrix Composites fabricated via Twin Rod Additive Friction Stir Deposition for In-Space Manufacturing

The remote and austere nature of space exploration poses significant logistical challenges associated with the fabrication of in-space infrastructure at the point of need. Sustainable in-space manufacturing solutions, with in situ resource utilization (ISRU) at the core, will need to be advanced to further development of the space economy. In situ resource utilization (ISRU) can produce metal matrix composites with on-site lunar regolith matrixed with in-space material waste or scrap material. This work uses twin-rod additive friction stir deposition (TR - AFSD), a nascent additive manufacturing technique proven capable of utilizing the in-space material waste or available in-site resources, to fabricate lunar regolith metal matrix composites. Once fabricated, in-space manufactured tools, infrastructure, repairs, or near net shape lunar regolith metal matrix composites need to be evaluated for defects and material uniformity. Material performance and lifetime assessment of the composites can be directly tied to NDE characterization parameters. This work investigates the use of ultrasonic testing (UT) and X-ray computed tomography (CT), to characterize the quality and uniformity of the lunar regolith metal matrix composites at increasing weight percentages of regolith content. UT was used to map the speed of sound of the composite material, showing increased speed of sound in regions with increased regolith content. X-ray CT was used to validate the UT findings, as well as provide insights on the dispersion patterns of the regolith in the metal matrix.