"Electronics Shielding and Reliability Design Tools"
J.W. Wilson1, P.M. O’Neill2,T.A. Zang1, J.E. Pandolf1, Steven L. Koontz2, P. Boeder3, B. Reddell3, C. Pankop3
1NASA Langley Research Center
2NASA Johnson Space Center
3The Boeing Company
It is well known that electronics placement in large-scale human-rated systems provides opportunity for optimization of electronics shielding through materials choice and geometric arrangement. For example, several hundred single event upsets (SEUs) occur within Shuttle avionic computers during a typical mission but an order of magnitude less than would occur with bad placement in the Shuttle design. In those studies, basic physics models (LET, track structure, Auger recombination) were combined with limited SEU cross section measurements allowing accurate evaluation of target fragment contributions to Shuttle avionics memory upsets. Electronics shielding design on humanrated systems provides opportunity to minimize radiation impact on critical and noncritical electronic systems. Implementation of shielding design tools requires adequate methods for evaluation of design layouts, guiding qualification testing, and an adequate follow-up on final design evaluation including results from a systems/device testing program tailored to meet design requirements. Provision of such design methods is critical to the use of low-cost commercial-off-the-shelf (COTS) electronic devices and systems with their, often, high radiation sensitivity and manufacture variability. A similar shield design tool activity development for human protection already includes evaluation of natural and induced environments mapped throughout the vehicle design to assure astronaut safety providing most of the software framework required for electronics shield design and evaluation including charge buildup in dielectric components. Preliminary software has likewise been prepared for JPL’s Team X multidisciplinary environment. The present project will prepare modified software tools for use in electronics shield design with appropriate NASA mandated verification and validation processes that will use Shuttle and ISS flight data. This provides a well validated tool to use in Crew Exploration Vehicle first flight design validation. User-friendly design engineering interfaces for use in multidisciplinary design processes allowing optimization and reliability design methods supported by high-speed computational procedures will be discussed.
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