Ultra-lightweight Core Materials for Efficient Load-Bearing Composite Sandwich Structures

Objectives The NASA Game Changing Development program under the Space Technology Mission Directorate focuses on advancing and maturing mid-level technologies (as defined by NASA Technology Readiness Levels) for use in advancing the NASA Strategic Space Technology Investment Plan. Part of that investment plan is the development of lightweight space structures as an enabling and advancing technology for human and robotic space exploration. The overall goals of this NRA are to investigate and mature fabrication approaches, joining techniques, analytical and experimental processes, ancillary structural benefits, and cost estimates of materials that can serve as core structures in composite sandwich structures. Dynetics is pleased to propose the maturation of the LaserLatticeTM technology as a path forward to meeting the requirements of the NRA and greater NASA objectives. Methods and Techniques The LaserLatticeTM process follow four basic steps to create the flat and curved core materials outlined in the NRA requirements: 1. A substrate material is placed into a pressurized chamber filled with a precursor gas – selected to deposit the desired material onto the substrate when thermally decomposed. A laser is focused on the substrate, locally heating it, decomposing the precursor gas, and depositing solid material on that spot. A solid base mesh is created in this way by translating the laser beam over the substrate 2. Fibers are then constructed by translating the focused laser spot from mesh intersections in the vertical direction to the desired thickness. A series of vertical and diagonal fibers are created from the base mesh as deemed necessary to provide the structural strength and density desired of the final core sample. 3. A thin composite face sheet (selected to be compatible with NASA face sheets) is then attached to the vertical fiber array with a thin layer of adhesive. 4. The vertical fiber array is immersed in a shallow pool of adhesive to provide reinforcement to the base material and create stress-distributing fillets at the fiber junctions. Significance LaserLatticeTM technology has the potential to provide game-changing technology leaps in four specific areas relevant to NASA objectives: Structures: LaserLatticeTM will enable the development of ultra-light launch vehicle and spacecraft structures, decreasing the cost and increasing payload capabilities of those vehicles. The ability to embed boron or other radiation-absorbing materials will increase the radiation tolerance of electronics and other sensitive equipment. This allows faster adoption and implementation of terrestrial low-power electronics and equipment. Thermal Protection Systems: LaserLatticeTM will provide a manufacturing process for exotic materials such as tantalum hafnium carbine to be utilized as high temperature, light weight ablative heat shields. Reductions in mass for these atmospheric entry bodies allow greater payloads, personnel, and scientific equipment to be carried back to Earth from orbit or for planetary exploration. Propulsion: LaserLatticeTM's ability to produce radiation and heat-tolerant materials will be critical for the development of next-generation nuclear thermal rocket engines. These engines, with much higher efficiencies, thrust, and power densities of current deep-space propulsion options will enable advanced and higher-power solar system exploration missions. In-Space Fabrication: LaserLatticeTM technology can be applied to environments such as in-space fabrication, where components are manufactured from raw materials either available from raw-materials delivery from Earth or from in-situ materials found on bodies of exploration. Dynetics feels that LaserLatticeTM technology will provide game-changing materials for use by NASA and industry to advance robotic and manned space exploration. Our NRA response provides a path to mature the technology and provide NASA with the tools to continue its mission. More »