Description: This Phase I project aims to assess the feasibility of disassembling and reassembling thermoplastic composite joints in space by thermo-mechanically debonding and bonding the joint interface. By harnessing this fundamental operation, space structures can be reconfigured into vastly different geometries depending on mission needs using the same set of structural elements. Repurposing thermoplastic composite structures has the potential to significantly reduce the amount of materials to be delivered to space as payloads. In our proposed concept, the original and the repurposed structures are trusses consisting of composite joints and struts. The joint-strut interfaces are pre-inserted with a conductive composite adhesive layer made of the same thermoplastic matrix as the adherend composite parts and embedded with nanostructured carbon fillers. By forming an electrically and thermally conductive network, the carbon fillers act as an in-situ resistance heater to bring the thermoplastic matrix to the processing temperature for interface debonding by mechanical forces. The disassembled struts and joints are reassembled to the repurposed configuration via resistance welding using the same or additional conductive adhesive layers. The proposed in-situ heating and reassembly method enables spacecraft components to be reutilized, which greatly reduces the logistical footprint to deliver technologies to space. Current spacecraft components are still largely designed for single-use missions, which are costly and not scalable. The ability to repurpose spacecraft components maximizes their useful service life and lowers the cost of building new infrastructure on planetary surfaces. In Phase I, the power and tooling requirements to make the proposed technology viable will be established using multiphysics simulations and analyses of the full reassembly operation.

Benefits: Repurposable thermoplastic composite structures have the benefit of significantly reducing the amounts of materials to be delivered to space as payloads to construct infrastructure. The ability to repurpose spacecraft components maximizes their useful service life and lowers the cost of building new infrastructure on planetary surfaces. The proposed innovation directly addresses the NASA need stipulated under Topic T12.09: Thermoplastic Composites for Repurposable Aerospace Applications. Being lightweight and stiff, thermoplastic composites are excellent candidates for building mechanical structures such as reflectors and solar arrays, where the performance improves with their surface area. Because of the volume constraints of launch fairings, deployable structures must be used, but this approach is hitting technological barriers such as deployment complexity and lack of shape accuracy. The proposed joining method will lead to a new on-orbit manufacturing strategy that provides large, lightweight, dimensionally stable mechanical structures at lower cost than existing deployable solutions. This project closely aligns with NASA's priorities of building persistent platforms for science missions and human presence in space and driving innovations for deep space exploration. The outcome directly contributes to many areas in NASA's technology portfolio outlined in the 2020 Technology Taxonomy (TX), including TX01.4.1: Solar Sails, TX03.1.1: Photovoltaic Solar Arrays, TX05.1.2: Large Apertures, TX05.2.6: Innovative Antennas, TX07.2.2: In-Situ Manufacturing, TX07.2.4: Micro-Gravity Construction and Assembly, TX08.2.2: Structures and Antennas, TX 12.1.1: Lightweight Structural Materials, TX12.2.1: Lightweight Concepts, and TX12.4.1: Manufacturing Processes. In particular, the proposed technology sits within On-orbit Servicing, Assembly and Manufacturing (OSAM). Disassembly and reassembly of lightweight but stiff thermoplastic composites is a capability that can improve current composite manufacturing processes for fields such as electronics, sports, and automotive industries. Present large composite structures manufacturing is costly and has substantial logistical footprint. In addition, reprocessing of the structures is difficult due to the thermoset polymer matrices being used. The proposed technology presents a new manufacturing route that is low in logistical footprint and cost while allowing for repurposing. Potential non-NASA commercial applications also include the same applications as those listed above, but in the commercial space industry, military (Space Force, etc.), and other government space agencies (ESA, DLR, etc.). Besides space-related applications, there are potential uses in aerospace more broadly, as well as defense, automotive, marine, energy, electronics, sporting goods, and medical devices, etc., especially where simulation tools can improve utilization possibilities for high-performance thermoplastics. These applications extend beyond simulation and into repair for thermoplastics in these industries as well. Additional benefits include but are not limited to: - Better engineering and qualification of next generation lightweight structures made from thermoplastics. - Validated design and analysis tools for the industrial realization of thermoplastic composites (space, aerospace, energy/wind, automotive, marine, consumer products, etc.) -Better designs for high-performance prosthetics, fishing rods, golf clubs, and other sports and recreational equipment, etc. -Reduced cost and time that companies spend in design, trial-and-error testing, and manufacturing of high performance thermoplastic composite structures thanks to the improved predictive capabilities for these structures. -Improvements in repairs/reconfigurations for thermoplastics used in high-performance applications.