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Lightweight Spacecraft Structures & Materials

"The Lightweight Materials and Structures project will develop advanced materials and structures technology to enable lightweight systems to reduce mission cost."

Lightweight Materials

The LMS project has two major technical elements. The objective of the first element, Solar Array Structures (SAS), is to mature one or more deployable solar array designs for the 300 kW-class Solar Electric Propulsion (SEP) tugs to TRL 5. These solar arrays will be approximately 1500 m2 in total area which is about an order-of-magnitude larger than the huge 160 m2 solar array blankets on the International Space Station. The project will initially conduct a workshop to quantify the challenges to be overcome and the technology gaps, to identify possible approaches for overcoming these challenges and gaps, and to develop design requirements. The project will identify and address the most-challenging aspects of developing deployable solar array structures, including aspects related to: compact stowage, reliable deployment, high deployed strength and stiffness, robustness to dynamic docking and maneuver loads, modularity, reusability, and ground validation. A NASA team will analyze and ground test key aspects of the solar array structural systems developed in this project. These ground tests will likely use scale models of the SAS because of the extreme sizes envisioned for the full-scale solar arrays. Analyses will be performed to ensure that scale models of the SAS are designed and manufactured with sufficient quality to validate the new technologies comprising each proposed solar array concept.

The object of the second element, Inflatable Structures (INS), is to understand the behavior of pressurized structures with different restraint layer configurations before and after damage is induced. The goal is to develop models capable of predicting global and local stresses and deflections with a high degree of accuracy, and conduct damage mode experiments to assess damage physics and the ability of analysis models to predict the observed behavior. This element involves two separate tasks. The first task is to evaluate the viscoelastic behavior of the inflatable materials and to verify the ‘creep’ characteristics of the structural restraint layer material. Creep is a viscoelastic response of a material as function of time, temperature, and stress. It is necessary to understand creep behavior in order to design inflated structures with long operational lifetimes to prevent creep rupture. Accelerated creep test methods will be used to predict the long-term viscoelastic response under certain loading conditions. Long-term creep testing will be used to validate accelerated tests data. For the second task, damage tolerance tests will be performed to verify the structural integrity of the full scale inflated units and to verify the load distribution of the structural restraint layer following pressurization, before and after inducing damage to the structural restraint layer. Analysis methods will also be developed and validated to better understand the performance and damage tolerance of the inflatable structures.

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