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Sheila A. Thibeault

Publications and source records attributed to Sheila A. Thibeault.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2022

Epoxy Resins with Reduced Viscoelastic Relaxation

The payloads of current space launch systems, e.g. rockets, are constrained to a small size due to aerodynamic, weight, and cost limitations. Deployable structures allow for a folded or stowed configuration during launch and deployment at the mission location. Polymer composites have shown both high weight savings over current metallic structure, as well as improved specific mechanical strengths overall. One issue encountered with polymer composite deployables, however, is stress relaxation of the polymer matrix in the stowed configuration. In this study, a range of different epoxy formulations were evaluated as potential matrix resins for deployable composites. A new multifunctional epoxy resin with a fortifying additive is predicted to show 70% less stress relaxation after 1 year as compared to a state-of-the-art aerospace epoxy matrix.

Ray S. Peterson↗
NASA NTRSDate not supplied

Modeling Radiation Sources for Experimental Validation

To build on previously completed experimental work, I have been working to implement a model of our lab’s Americium-Beryllium neutron source and Ludlum detection instruments computationally to provide secondary verification of our experimental results. This has been done using the radiation transport code MCNP6 (Monte Carlo N-Particle). I have developed files to calculate the mass ratio of various composite materials that we have exposed to the radiation source, as well as the components of the detection instruments and converted all of these into geometric coordinates that define the experimental setup. Identifying the proper energy distribution and detector efficiencies as well as the correct interpretation of the detector physics have proven to be the most difficult and time-consuming challenges of the work. It is currently too early for results based on the most updated and accurate models. With this experience, the next step is to develop another source model of a proton beam to simulate exposures on other composite targets. This will be developed based on existing experimental datasets, but not used to validate them. Each of these projects will further define the radiation shielding needs for humans in space radiation environments that astronauts will someday be exposed to beyond Low Earth Orbit.

Juliana Simon↗
NASA NTRSDate not supplied

Automating MISSE Specimens Image Analysis

The Materials International Space Station Experiment (MISSE) Project consists of experiments focused on the investigation of the effects that occur through the exposure of materials specimens in the space environment. To determine if there is a change in a specimen, the data obtained from the MISSE high-resolution photographic images can be monitored. For this, a compilation of folders was created to provide an organizational system. Each mission was divided into the specific direction in space, materials specimen, and date the image was taken. This organization helps to identify how a specimen behaves as a function of time in the space environment. Once the images were classified, a qualitative process was first used to detect an evolution in the materials of MISSE-9 - MISSE-14.

MISSE ISS Materials↗