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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2007

Effect of Electron Beam Freeform Fabrication (EBF3) Processing Parameters on Composition of Ti-6-4

The Electron Beam Freeform Fabrication (EBF3) process developed at NASA Langley Research Center was evaluated using a design of experiments approach to determine the effect of processing parameters on the composition and geometry of Ti-6-4 deposits. The effects of three processing parameters: beam power, translation speed, and wire feed rate, were investigated by varying one while keeping the remaining parameters constant. A three-factorial, three-level, fully balanced mutually orthogonal array (L27) design of experiments approach was used to examine the effects of low, medium, and high settings for the processing parameters on the chemistry, geometry, and quality of the resulting deposits. Single bead high deposits were fabricated and evaluated for 27 experimental conditions. Loss of aluminum in Ti-6-4 was observed in EBF3 processing due to selective vaporization of the aluminum from the sustained molten pool in the vacuum environment; therefore, the chemistries of the deposits were measured and compared with the composition of the initial wire and base plate to determine if the loss of aluminum could be minimized through careful selection of processing parameters. The influence of processing parameters and coupling between these parameters on bulk composition, measured by Direct Current Plasma (DCP), local microchemistries determined by Wavelength Dispersive Spectrometry (WDS), and deposit geometry will also be discussed.

Lach, Cynthia L.↗
NASA NTRS2004

Processing Robustness for A Phenylethynyl Terminated Polyimide Composite

The processability of a phenylethynyl terminated imide resin matrix (designated as PETI-5) composite is investigated. Unidirectional prepregs are made by coating an N-methylpyrrolidone solution of the amide acid oligomer (designated as PETAA-5/NMP) onto unsized IM7 fibers. Two batches of prepregs are used: one is made by NASA in-house, and the other is from an industrial source. The composite processing robustness is investigated with respect to the prepreg shelf life, the effect of B-staging conditions, and the optimal processing window. Prepreg rheology and open hole compression (OHC) strengths are found not to be affected by prolonged (i.e., up to 60 days) ambient storage. Rheological measurements indicate that the PETAA-5/NMP processability is only slightly affected over a wide range of B-stage temperatures from 250 deg C to 300 deg C. The OHC strength values are statistically indistinguishable among laminates consolidated using various B-staging conditions. An optimal processing window is established by means of the response surface methodology. IM7/PETAA-5/NMP prepreg is more sensitive to consolidation temperature than to pressure. A good consolidation is achievable at 371 deg C (700 deg F)/100 Psi, which yields an RT OHC strength of 62 Ksi. However, processability declines dramatically at temperatures below 350 deg C (662 deg F), as evidenced by the OHC strength values. The processability of the IM7/LARC(TM) PETI-5 prepreg was found to be robust.

Hou, Tan-Hung↗
NASA NTRS2008

Electron Beam Freeform Fabrication: A Fabrication Process that Revolutionizes Aircraft Structural Designs and Spacecraft Supportability

The technological inception and challenges, as well as current applications of the electron beam freeform fabrication (EBF3) process are outlined. The process was motivated by the need for a new metals technology that would be cost-effective, enable the production of new alloys and that would could be used for efficient, lightweight structures. EBF3 is a rapid metal fabrication, layer-additive process that uses no molds or tools and which yields properties equivalent to wrought. The benefits of EBF3 include it near-net shape which minimizes scrap and reduces part count; efficiency in design which allows for lighter weight and enhanced performance; and, its "green" manufacturing process which yields minimal waste products. EBF3 also has a high tensile strength, while a structural test comparison found that EBF3 panels performed 5% lower than machined panels. Technical challenges in the EBF3 process include a need for process control monitoring and an improvement in localized heat response. Currently, the EBF3 process can be used to add details onto forgings and to construct and form complex shapes. However, it has potential uses in a variety of industries including aerospace, automotive, sporting goods and medical implant devices. The novel structural design capabilities of EBF3 have the ability to yield curved stiffeners which may be optimized for performance, low weight, low noise and damage tolerance applications. EBF3 has also demonstrated its usefulness in 0-gravity environments for supportability in space applications.

Taminger, Karen M.↗
NASA NTRS2008

Wide-Band Microwave Receivers Using Photonic Processing

In wide-band microwave receivers of a type now undergoing development, the incoming microwave signals are electronically preamplified, then frequency-up-converted to optical signals that are processed photonically before being detected. This approach differs from the traditional approach, in which incoming microwave signals are processed by purely electronic means. As used here, wide-band microwave receivers refers especially to receivers capable of reception at any frequency throughout the range from about 90 to about 300 GHz. The advantage expected to be gained by following the up-conversion-and-photonic-processing approach is the ability to overcome the limitations of currently available detectors and tunable local oscillators in the frequency range of interest. In a receiver following this approach (see figure), a preamplified incoming microwave signal is up-converted by the method described in the preceeding article. The frequency up-converter exploits the nonlinearity of the electromagnetic response of a whispering gallery mode (WGM) resonator made of LiNbO3. Up-conversion takes place by three-wave mixing in the resonator. The WGM resonator is designed and fabricated to function simultaneously as an electro-optical modulator and to exhibit resonance at the microwave and optical operating frequencies plus phase matching among the microwave and optical signals circulating in the resonator. The up-conversion is an efficient process, and the efficiency is enhanced by the combination of microwave and optical resonances. The up-converted signal is processed photonically by use of a tunable optical filter or local oscillator, and is then detected. Tunable optical filters can be made to be frequency agile and to exhibit high resonance quality factors (high Q values), thereby making it possible to utilize a variety of signal-processing modalities. Therefore, it is anticipated that when fully developed, receivers of this type will be compact and will be capable of both wide-band and narrowband signal processing. Thus, one compact receiver of this type would afford the functionality that, heretofore, could have been obtained only by use of multiple heterodyne microwave receivers.

Matsko, Andrey↗
NASA NTRS2009

System and method for deriving a process-based specification

A system and method for deriving a process-based specification for a system is disclosed. The process-based specification is mathematically inferred from a trace-based specification. The trace-based specification is derived from a non-empty set of traces or natural language scenarios. The process-based specification is mathematically equivalent to the trace-based specification. Code is generated, if applicable, from the process-based specification. A process, or phases of a process, using the features disclosed can be reversed and repeated to allow for an interactive development and modification of legacy systems. The process is applicable to any class of system, including, but not limited to, biological and physical systems, electrical and electro-mechanical systems in addition to software, hardware and hybrid hardware-software systems.

Hinchey, Michael Gerard↗
NASA NTRS2007

Processing AIRS Scientific Data Through Level 2

The Atmospheric Infrared Spectrometer (AIRS) Science Processing System (SPS) is a collection of computer programs, denoted product generation executives (PGEs), for processing the readings of the AIRS suite of infrared and microwave instruments orbiting the Earth aboard NASA s Aqua spacecraft. AIRS SPS at an earlier stage of development was described in "Initial Processing of Infrared Spectral Data' (NPO-35243), NASA Tech Briefs, Vol. 28, No. 11 (November 2004), page 39. To recapitulate: Starting from level 0 (representing raw AIRS data), the PGEs and their data products are denoted by alphanumeric labels (1A, 1B, and 2) that signify the successive stages of processing. The cited prior article described processing through level 1B (the level-2 PGEs were not yet operational). The level-2 PGEs, which are now operational, receive packages of level-1B geolocated radiance data products and produce such geolocated geophysical atmospheric data products such as temperature and humidity profiles. The process of computing these geophysical data products is denoted "retrieval" and is quite complex. The main steps of the process are denoted microwave-only retrieval, cloud detection and cloud clearing, regression, full retrieval, and rapid transmittance algorithm.

Oliphant, Robert↗
NASA NTRS2010

Computer-Controlled Cylindrical Polishing Process for Large X-Ray Mirror Mandrels

We are developing high-energy grazing incidence shell optics for hard-x-ray telescopes. The resolution of a mirror shells depends on the quality of cylindrical mandrel from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation software is developed to model the residual surface figure errors of a mandrel due to the polishing process parameters and the tools used, as well as to compute the optical performance of the optics. The study carried out using the developed software was focused on establishing a relationship between the polishing process parameters and the mid-spatial-frequency error generation. The process parameters modeled are the speeds of the lap and the mandrel, the tool s influence function, the contour path (dwell) of the tools, their shape and the distribution of the tools on the polishing lap. Using the inputs from the mathematical model, a mandrel having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. The preliminary results of a series of polishing experiments demonstrate a qualitative agreement with the developed model. We report our first experimental results and discuss plans for further improvements in the polishing process. The ability to simulate the polishing process is critical to optimize the polishing process, improve the mandrel quality and significantly reduce the cost of mandrel production

Khan, Gufran S.↗
NASA NTRS2011

Space Shuttle Systems Engineering Processes for Liftoff Debris Risk Mitigation

This slide presentation reviews the systems engineering process designed to reduce the risk from debris during Space Shuttle Launching. This process begins the day of launch from the tanking to the vehicle tower clearance. Other debris risks (i.e., Ascent, and micrometeoroid orbital debit) are mentioned) but are not the subject of this presentation. The Liftoff debris systems engineering process and an example of how it works are reviewed (i.e.,STS-119 revealed a bolt liberation trend on the Fixed Service Structure (FSS) 275 level elevator room). The process includes preparation of a Certification of Flight Readiness (CoFR) that includes (1) Lift-off debris from previous mission dispositioned, (2) Flight acceptance rationale has been provided for Lift-off debris sources/causes (3) Lift-off debris mission support documentation, processes and tools are in place for the up-coming mission. The process includes a liftoff debris data collection that occurs after each launch. This includes a post launch walkdown, that records each liftoff debris, and the entry of the debris into a database, it also includes a review of the imagery from the launch, and a review of the instrumentation data. There is also a review of the debris transport analysis process, that includes temporal and spatial framework and a computational fluid dynamics (CFD) analysis. which incorporates a debris transport analyses (DTA), debris materials and impact tests, and impact analyses.

Mitchell, Michael↗
NASA NTRS2011

Cryogenic Quenching Process for Electronic Part Screening

The use of electronic parts at cryogenic temperatures (less than 100 C) for extreme environments is not well controlled or developed from a product quality and reliability point of view. This is in contrast to the very rigorous and well-documented procedures to qualify electronic parts for mission use in the 55 to 125 C temperature range. A similarly rigorous methodology for screening and evaluating electronic parts needs to be developed so that mission planners can expect the same level of high reliability performance for parts operated at cryogenic temperatures. A formal methodology for screening and qualifying electronic parts at cryogenic temperatures has been proposed. The methodology focuses on the base physics of failure of the devices at cryogenic temperatures. All electronic part reliability is based on the bathtub curve, high amounts of initial failures (infant mortals), a long period of normal use (random failures), and then an increasing number of failures (end of life). Unique to this is the development of custom screening procedures to eliminate early failures at cold temperatures. The ability to screen out defects will specifically impact reliability at cold temperatures. Cryogenic reliability is limited by electron trap creation in the oxide and defect sites at conductor interfaces. Non-uniform conduction processes due to process marginalities will be magnified at cryogenic temperatures. Carrier mobilities change by orders of magnitude at cryogenic temperatures, significantly enhancing the effects of electric field. Marginal contacts, impurities in oxides, and defects in conductor/conductor interfaces can all be magnified at low temperatures. The novelty is the use of an ultra-low temperature, short-duration quenching process for defect screening. The quenching process is designed to identify those defects that will precisely (and negatively) affect long-term, cryogenic part operation. This quenching process occurs at a temperature that is at least 25 C colder than the coldest expected operating temperature. This quenching process is the opposite of the standard burn-in procedure. Normal burn-in raises the temperature (and voltage) to activate quickly any possible manufacturing defects remaining in the device that were not already rejected at a functional test step. The proposed inverse burn-in or quenching process is custom-tailored to the electronic device being used. The doping profiles, materials, minimum dimensions, interfaces, and thermal expansion coefficients are all taken into account in determining the ramp rate, dwell time, and temperature.

Sheldon, Douglas J.↗
NASA NTRS2012

Finite Element Models for Electron Beam Freeform Fabrication Process

Electron beam freeform fabrication (EBF3) is a member of an emerging class of direct manufacturing processes known as solid freeform fabrication (SFF); another member of the class is the laser deposition process. Successful application of the EBF3 process requires precise control of a number of process parameters such as the EB power, speed, and metal feed rate in order to ensure thermal management; good fusion between the substrate and the first layer and between successive layers; minimize part distortion and residual stresses; and control the microstructure of the finished product. This is the only effort thus far that has addressed computer simulation of the EBF3 process. The models developed in this effort can assist in reducing the number of trials in the laboratory or on the shop floor while making high-quality parts. With some modifications, their use can be further extended to the simulation of laser, TIG (tungsten inert gas), and other deposition processes. A solid mechanics-based finite element code, ABAQUS, was chosen as the primary engine in developing these models whereas a computational fluid dynamics (CFD) code, Fluent, was used in a support role. Several innovative concepts were developed, some of which are highlighted below. These concepts were implemented in a number of new computer models either in the form of stand-alone programs or as user subroutines for ABAQUS and Fluent codes. A database of thermo-physical, mechanical, fluid, and metallurgical properties of stainless steel 304 was developed. Computing models for Gaussian and raster modes of the electron beam heat input were developed. Also, new schemes were devised to account for the heat sink effect during the deposition process. These innovations, and others, lead to improved models for thermal management and prediction of transient/residual stresses and distortions. Two approaches for the prediction of microstructure were pursued. The first was an empirical approach involving the computation of thermal gradient, solidification rate, and velocity (G,R,V) coupled with the use of a solidification map that should be known a priori. The second approach relies completely on computer simulation. For this purpose a criterion for the prediction of morphology was proposed, which was combined with three alternative models for the prediction of microstructure; one based on solidification kinetics, the second on phase diagram, and the third on differential scanning calorimetry data. The last was found to be the simplest and the most versatile; it can be used with multicomponent alloys and rapid solidification without any additional difficulty. For the purpose of (limited) experimental validation, finite element models developed in this effort were applied to three different shapes made of stainless steel 304 material, designed expressly for this effort with an increasing level of complexity. These finite element models require large computation time, especially when applied to deposits with multiple adjacent beads and layers. This problem can be overcome, to some extent, by the use of fast, multi-core computers. Also, due to their numerical nature coupled with the fact that solid mechanics- based models are being used to represent the material behavior in liquid and vapor phases as well, the models have some inherent approximations that become more pronounced when dealing with multi-bead and multi-layer deposits.

Chandra, Umesh↗
NASA NTRS2007

A Decision Tool that Combines Discrete Event Software Process Models with System Dynamics Pieces for Software Development Cost Estimation and Analysis

The development process for a large software development project is very complex and dependent on many variables that are dynamic and interrelated. Factors such as size, productivity and defect injection rates will have substantial impact on the project in terms of cost and schedule. These factors can be affected by the intricacies of the process itself as well as human behavior because the process is very labor intensive. The complex nature of the development process can be investigated with software development process models that utilize discrete event simulation to analyze the effects of process changes. The organizational environment and its effects on the workforce can be analyzed with system dynamics that utilizes continuous simulation. Each has unique strengths and the benefits of both types can be exploited by combining a system dynamics model and a discrete event process model. This paper will demonstrate how the two types of models can be combined to investigate the impacts of human resource interactions on productivity and ultimately on cost and schedule.

Mizell, Carolyn Barrett↗
NASA NTRS2013

Evolution of International Space Station Program Safety Review Processes and Tools

The International Space Station Program at NASA is constantly seeking to improve the processes and systems that support safe space operations. To that end, the ISS Program decided to upgrade their Safety and Hazard data systems with 3 goals: make safety and hazard data more accessible; better support the interconnection of different types of safety data; and increase the efficiency (and compliance) of safety-related processes. These goals are accomplished by moving data into a web-based structured data system that includes strong process support and supports integration with other information systems. Along with the data systems, ISS is evolving its submission requirements and safety process requirements to support the improved model. In contrast to existing operations (where paper processes and electronic file repositories are used for safety data management) the web-based solution provides the program with dramatically faster access to records, the ability to search for and reference specific data within records, reduced workload for hazard updates and approval, and process support including digital signatures and controlled record workflow. In addition, integration with other key data systems provides assistance with assessments of flight readiness, more efficient review and approval of operational controls and better tracking of international safety certifications. This approach will also provide new opportunities to streamline the sharing of data with ISS international partners while maintaining compliance with applicable laws and respecting restrictions on proprietary data. One goal of this paper is to outline the approach taken by the ISS Progrm to determine requirements for the new system and to devise a practical and efficient implementation strategy. From conception through implementation, ISS and NASA partners utilized a user-centered software development approach focused on user research and iterative design methods. The user-centered approach used on the new ISS hazard system utilized focused user research and iterative design methods employed by the Human Computer Interaction Group at NASA Ames Research Center. Particularly, the approach emphasized the reduction of workload associated with document and data management activities so more resources can be allocated to the operational use of data in problem solving, safety analysis, and recurrence control. The methods and techniques used to understand existing processes and systems, to recognize opportunities for improvement, and to design and review improvements are described with the intent that similar techniques can be employed elsewhere in safety operations. A second goal of this paper is to provide and overview of the web-based data system implemented by ISS. The software selected for the ISS hazard systemMission Assurance System (MAS)is a NASA-customized vairant of the open source software project Bugzilla. The origin and history of MAS as a NASA software project and the rationale for (and advantages of) using open-source software are documented elsewhere (Green, et al., 2009).

Ratterman, Christian D.↗
NASA NTRS2013

Elevated Temperature, Notched Compression Performance of Out of Autoclave Processed Composites

Curved honeycomb sandwich panels composed of carbon fiber reinforced toughened-epoxy polymer facesheets are being evaluated for potential use as payload fairing components on the NASA heavy-lift space launch system (HL-SLS). These proposed composite sandwich panels provide the most efficient aerospace launch structures, and offer mass and thermal advantages when compared with existing metallic payload fairing structures. NASA and industry are investigating recently developed carbon fiber epoxy prepreg systems which can be fabricated using out-of autoclave (OOA) processes. Specifically, OOA processes using vacuum pressure in an oven and thereby significantly reducing the cost associated with manufacturing large (up to 10 m diameter) composite structures when compared with autoclave. One of these OOA composite material systems, CYCOM(R) 5320-1, was selected for manufacture of a 1/16th scale barrel portion of the payload fairing; such that, the system could be compared with the well-characterized prepreg system, CYCOM(R) 977-3, typically processed in an autoclave. Notched compression coupons for each material were obtained from the minimum-gauge flat laminate [60/-60/0]S witness panels produced in this manufacturing study. The coupons were also conditioned to an effective moisture equilibrium point and tested according to ASTM D6484M-09 at temperatures ranging from 25 C up to 177 C. The results of this elevated temperature mechanical characterization study demonstrate that, for thin coupons, the OHC strength of the OOA laminate was equivalent to the flight certified autoclave processed composite laminates; the limitations on the elevated temperature range are hot-wet conditions up to 163 C and are only within the margins of testing error. At 25 C, both the wet and dry OOA material coupons demonstrated greater OHC failure strengths than the autoclave processed material laminates. These results indicate a substantial improvement in OOA material development and processing since previous studies have consistently reported OOA material strengths on par or below those of autoclave processed composite laminates.

Grimsley, Brian W.↗
NASA NTRS2014

Human Integration Design Processes (HIDP)

The purpose of the Human Integration Design Processes (HIDP) document is to provide human-systems integration design processes, including methodologies and best practices that NASA has used to meet human systems and human rating requirements for developing crewed spacecraft. HIDP content is framed around human-centered design methodologies and processes in support of human-system integration requirements and human rating. NASA-STD-3001, Space Flight Human-System Standard, is a two-volume set of National Aeronautics and Space Administration (NASA) Agency-level standards established by the Office of the Chief Health and Medical Officer, directed at minimizing health and performance risks for flight crews in human space flight programs. Volume 1 of NASA-STD-3001, Crew Health, sets standards for fitness for duty, space flight permissible exposure limits, permissible outcome limits, levels of medical care, medical diagnosis, intervention, treatment and care, and countermeasures. Volume 2 of NASASTD- 3001, Human Factors, Habitability, and Environmental Health, focuses on human physical and cognitive capabilities and limitations and defines standards for spacecraft (including orbiters, habitats, and suits), internal environments, facilities, payloads, and related equipment, hardware, and software with which the crew interfaces during space operations. The NASA Procedural Requirements (NPR) 8705.2B, Human-Rating Requirements for Space Systems, specifies the Agency's human-rating processes, procedures, and requirements. The HIDP was written to share NASA's knowledge of processes directed toward achieving human certification of a spacecraft through implementation of human-systems integration requirements. Although the HIDP speaks directly to implementation of NASA-STD-3001 and NPR 8705.2B requirements, the human-centered design, evaluation, and design processes described in this document can be applied to any set of human-systems requirements and are independent of reference missions. The HIDP is a reference document that is intended to be used during the development of crewed space systems and operations to guide human-systems development process activities.

Boyer, Jennifer↗
NASA NTRS2015

Mars Soil-Based Resource Processing and Planetary Protection

The ability to extract and process resources at the site of exploration into products and services, commonly referred to as In Situ Resource Utilization (ISRU), can have significant benefits for robotic and human exploration missions. In particular, the ability to use in situ resources to make propellants, fuel cell reactants, and life support consumables has been shown in studies to significantly reduce mission mass, cost, and risk, while enhancing or enabling missions not possible without the incorporation of ISRU. In December 2007, NASA completed the Mars Human Design Reference Architecture (DRA) 5.0 study. For the first time in a large scale Mars architecture study, water from Mars soil was considered as a potential resource. At the time of the study, knowledge of water resources (their form, concentration, and distribution) was extremely limited. Also, due to lack of understanding of how to apply planetary protection rules and requirements to ISRU soil-based excavation and processing, an extremely conservative approach was incorporated where only the top several centimeters of ultraviolet (UV) radiated soil could be processed (assumed to be 3% water by mass). While results of the Mars DRA 5.0 study showed that combining atmosphere processing to make oxygen and methane with soil processing to extract water provided the lowest mission mass, atmosphere processing to convert carbon dioxide (CO2) into oxygen was baselined for the mission since it was the lowest power and risk option. With increased knowledge and further clarification of Mars planetary protection rules, and the recent release of the Mars Exploration Program Analysis Group (MEPAG) report on "Special Regions and the Human Exploration of Mars", it is time to reexamine potential water resources on Mars, options for soil processing to extract water, and the implications with respect to planetary protection and Special Regions on Mars.

Sanders, G. B.↗
NASA NTRS2016

Functional Fault Model Development Process to Support Design Analysis and Operational Assessment

A functional fault model (FFM) is an abstract representation of the failure space of a given system. As such, it simulates the propagation of failure effects along paths between the origin of the system failure modes and points within the system capable of observing the failure effects. As a result, FFMs may be used to diagnose the presence of failures in the modeled system. FFMs necessarily contain a significant amount of information about the design, operations, and failure modes and effects. One of the important benefits of FFMs is that they may be qualitative, rather than quantitative and, as a result, may be implemented early in the design process when there is more potential to positively impact the system design. FFMs may therefore be developed and matured throughout the monitored system's design process and may subsequently be used to provide real-time diagnostic assessments that support system operations. This paper provides an overview of a generalized NASA process that is being used to develop and apply FFMs. FFM technology has been evolving for more than 25 years. The FFM development process presented in this paper was refined during NASA's Ares I, Space Launch System, and Ground Systems Development and Operations programs (i.e., from about 2007 to the present). Process refinement took place as new modeling, analysis, and verification tools were created to enhance FFM capabilities. In this paper, standard elements of a model development process (i.e., knowledge acquisition, conceptual design, implementation & verification, and application) are described within the context of FFMs. Further, newer tools and analytical capabilities that may benefit the broader systems engineering process are identified and briefly described. The discussion is intended as a high-level guide for future FFM modelers.

Verification↗
NASA NTRS2018

Robust Bonding Through Process Control

Process control has been proven to be the most reliable means of safeguarding the quality of adhesive bonds according to Federal Aviation Administration (FAA). A method for implementing process control for reduction in risk in a bonded joint fabrication process is demonstrated in this study using a selected bonding system. The stepwise method included risk analysis to identify defects with the highest impact and likelihood to occur, evaluation of various pre-bond surface analysis tools to monitor for the selected defects, and demonstration of the benefits of in-process monitoring utilizing threshold limits determined from bond performance tests. The bonded system selected for investigation was an aerospace carbon fiber epoxy composite substrate surface prepared with random orbital sanding using 180 grit aluminum oxide sand paper. A series of portable, pre-bond surface analysis tools were investigated for their ability to be used for in-line bond process control. Results and threshold limits are presented from roughness, ballistic water contact angle (WCA), color, gloss, and Fourier transform infrared spectroscopy (FTIR) surface analysis tools. Results demonstrated how in-process inspection methods can be used to ensure quality of a surface preparation for a selected bonding system. A framework is provided for implementation of bond process control for robust bonding.

Kutscha, Eileen O.↗
NASA NTRS2016

Functional Fault Model Development Process to Support Design Analysis and Operational Assessment

A functional fault model (FFM) is an abstract representation of the failure space of a givensystem. As such, it simulates the propagation of failure effects along paths between the origin ofthe system failure modes and points within the system capable of observing the failure effects. Asa result, FFMs may be used to diagnose the presence of failures in the modeled system. FFMsnecessarily contain a significant amount of information about the design, operations, and failuremodes and effects. One of the important benefits of FFMs is that they may be qualitative, ratherthan quantitative and, as a result, may be implemented early in the design process when there ismore potential to positively impact the system design. FFMs may therefore be developed andmatured throughout the monitored system's design process and may subsequently be used toprovide real-time diagnostic assessments that support system operations. This paper provides anoverview of a generalized NASA process that is being used to develop and apply FFMs. FFMtechnology has been evolving for more than 25 years. The FFM development process presented inthis paper was refined during NASA's Ares I, Space Launch System, and Ground SystemsDevelopment and Operations programs (i.e., from about 2007 to the present). Process refinementtook place as new modeling, analysis, and verification tools were created to enhance FFMcapabilities. In this paper, standard elements of a model development process (i.e., knowledgeacquisition, conceptual design, implementation & verification, and application) are describedwithin the context of FFMs. Further, newer tools and analytical capabilities that may benefit thebroader systems engineering process are identified and briefly described. The discussion isintended as a high-level guide for future FFM modelers.

Melcher, Kevin J.↗