ADVANCED MATERIALS & PROCESSES | JULY/AUGUST 2024 24 As the aerospace industry has continued to evolve from the era of the Wright brothers, so too have aerospace structural materials. And it appears that a new inflection point requiring a new class of materials is fast approaching. From the modest origins of wood and cloth, the structural scaffolding of human-engineered flight has since progressed from aluminum alloys to fiberglass to carbon fiber- reinforced polymer (CFRP) composites. As humanity advances ever further into the final frontier, crewed deep-space exploration—such as missions to Mars— will require significantly lighter structural materials than have thus far been engineered in order to achieve sustainability in operations and cost. Currently, carbon nanotube (CNT) composites are the only known materials that could meet the challenge, although CNT composite materials have yet to be fully developed. Among the many requirements of the NASA Transition Authorization Act of 2017, one clause states NASA “shall develop a human exploration roadmap…to expand human presence beyond low-Earth orbit to the surface of Mars and beyond…”[1] Later, in 2022, NASA launched its Moon to Mars Objectives, built on three foundational pillars of science, inspiration, and national posture. In their published plans to accomplish the program’s objectives, NASA states, “We will NOVEL COMPOSITES FOR LIGHTWEIGHTING IN DEEP SPACE APPLICATIONS The evolution of carbon nanotube composites, as inspired by the Materials Genome Initiative, unlocks new potential for materials sustainability in challenging deep space applications. Benjamin Huebner,* United States Air Force, Macon, Georgia *Member of ASM International advanced materials twice as fast and at a fraction of the cost compared to traditional methods.”[4] Although not funded by MGI directly, US-COMP follows the philosophical framework of creating and fostering a community- led effort to share data as well as experimental and computational tools to accelerate novel materials innovation from low technology readiness levels to high. MATERIALS INNOVATION The excellent mechanical performance offered by composites requires a high degree of reinforcement alignment, low void and defect content, high fiber concentration, and a strong reinforcement-matrix interface. To achieve these properties, US-COMP selected commercially available CNT yarns and, with the help of simulation tools, three different aerospace resins for their potential compatibility with CNTs[5]. Additionally, three different impregnation techniques were tested. For achieving a high degree of alignment and dense packing, a special filament winding process was developed and later modified to deliver high quality, reproducible, and scalable unidirectional CNT composite laminates (Fig. 1). Due to the lack of an ASTM tensile testing standard for this type of material at the produced scale, the US-COMP team developed an intermediate scale method. Results revealed collaborate with our partners to… prepare for future human exploration of the Red Planet.”[2] Though NASA has already landed several rovers on Mars, astronauts will require much larger payloads of food, water, air, vehicles, and habitats, all of which will add significant mass that requires more fuel, which in turn adds even more mass— and so on until prohibitive costs are quickly reached. Enter the Institute for Ultra-Strong Composites by Computational Design (US-COMP), a NASA Space Technology Research Institute (STRI) awarded in 2017 to a partnership of 11 universities, two companies, and the Air Force Research Laboratory[3]. Directed by Gregory Odegard from Michigan Technological University, US-COMP’s overarching goal is “to establish the next generation of composite materials for manned deep-space missions” by focusing on computationally driven development using a holistic framework for accelerated development inspired by the Materials Genome Initiative (MGI). With the NASA grant expiring in August of this year, US-COMP has indeed succeeded in developing a novel composite material with mechanical properties per unit mass that exceed state-of-the-art structural composites. Established in 2011, MGI is a government-led initiative “for discovering, manufacturing, and deploying
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