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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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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Overcoming obstacles to the exchange of information between risk tools

Our work to date in connecting risk tools hs had successes, but also has revealed there to be significant impediments to information exchange between them. These impediments stem from the well-known phenomenon of 'semantic dissonance' - mismatch between conceptual assumptions made by the separately developed tools. This issue represents a fundamental challenge that arises regardless of the mechanism of information exchange. This paper explains the issue and illustrates it with reference to our experiences to date connecting several risk tools. We motivate this work, present and discuss the solutions we have adopted to surmount these impediments, and the implications this work has for future efforts to integrate risk tools.

semantic dissonance↗
NASA NTRS2017

Analysis of Alerting System Failures in Commercial Aviation Accidents

The role of an alerting system is to make the system operator (e.g., pilot) aware of an impending hazard or unsafe state so the hazard can be avoided or managed successfully. A review of 46 commercial aviation accidents (between 1998 and 2014) revealed that, in the vast majority of events, either the hazard was not alerted or relevant hazard alerting occurred but failed to aid the flight crew sufficiently. For this set of events, alerting system failures were placed in one of five phases: Detection, Understanding, Action Selection, Prioritization, and Execution. This study also reviewed the evolution of alerting system schemes in commercial aviation, which revealed naive assumptions about pilot reliability in monitoring flight path parameters; specifically, pilot monitoring was assumed to be more effective than it actually is. Examples are provided of the types of alerting system failures that have occurred, and recommendations are provided for alerting system improvements.

aviation accidents↗
NASA NTRS2019

The Analysis of Adhesive Residue Failure

Adhesives have always been, and will continue to be, a crucial component of assembling flight hardware. Unfortunately, adhesives have a long standing history of being a source of costly contaminations. There are currently no existing documents that can aid a technician in discerning the proper adhesive/substrate combinations, nor the optimal solvent to use when removing adhesive residue. This project seeks to evaluate the performance of adhesive tapes on various flight hardware substrates in order to create an easy-to-use guide for spacecraft ground processing. The analyses performed were the adhesive/solvent solubility, SEM examinations, and peel adhesion tests. The solubility tests showed that amyl acetate, acetone, and MEK were the most successful in dissolving the adhesives. The SEM data gives preliminary insight into the morphology of the residues. Lastly, the peel adhesion testing proved that there is no relationship between the length of time the adhesive was applied and its adhesive strength.

Smiley, Adrienne↗
NASA NTRSDate not supplied

Trends in Human Spaceflight: Analysis of Observed Propulsion Failure Modes Following NASA’s Artemis I Mission

In 2022, NASA’s Artemis program returned the agency to lunar space, propelled by the Orion European Service Module (ESM). Through rigorous ground test campaigns for Artemis I and II and the collection and transmission of operational data during the Artemis I flight, the Safety and Mission Assurance (S&MA) team created and maintained a robust database of component nonconformances. This study analyzes in-flight and ground processing findings on the Artemis ESM propulsion subsystem to track reliability and safety metrics, as well as comparing the data to that of previous human spaceflight programs, Apollo and Space Shuttle. In drawing a comparison to the Artemis I flight, recommendations can be made for the Artemis II crewed mission to ensure best practices for flight safety, including redundancy and failure tolerance in the system. The results reinforce a need for robust safety standards and caution against the complacency of a single successful test flight.

human spaceflight safety↗
NASA NTRSDate not supplied

Trends in Human Spaceflight: Analysis of Observed Propulsion Failure Modes Following NASA’s Artemis I Mission

In 2022, NASA’s Artemis program returned the agency to lunar space, propelled by the Orion European Service Module (ESM). Through rigorous ground test campaigns for Artemis I and II and the collection and transmission of operational data during the Artemis I flight, the Safety and Mission Assurance (S&MA) team created and maintained a robust database of component nonconformances. This study analyzes in-flight and ground processing findings on the Artemis ESM propulsion subsystem to track reliability and safety metrics, as well as comparing the data to that of previous human spaceflight programs, Apollo and Space Shuttle. In drawing a comparison to the Artemis I flight, recommendations can be made for the Artemis II crewed mission to ensure best practices for flight safety, including redundancy and failure tolerance in the system. The results reinforce a need for robust safety standards and caution against the complacency of a single successful test flight.

human spaceflight safety↗
NASA NTRSDate not supplied

Testing and Analysis Correlation of a Large-Scale Composite Sandwich Longitudinal Bonded Joint for Space Launch Vehicle Structures

The NASA Composite Technology for Exploration (CTE) Project is developing and demonstrating critical composite technologies with a focus on composite bonded joints; incorporating materials, design/analysis, manufacturing, and tests that utilize NASA’s expertise and capabilities. The project has goals of advancing composite technologies and providing lightweight structures to support future NASA exploration missions. In particular, the CTE project will demonstrate weight-saving, performance-enhancing composite bonded joint technology for Space Launch System (SLS)-scale composite hardware. Advancements from the CTE project may be incorporated as future block upgrades for SLS structural components. This paper discusses the details of the development of a composite sandwich bonded longitudinal joint for a generic space launch vehicle structure called the CTE Point Design. This paper reports on the large-scale longitudinal bonded joint test articles that were fabricated and tested under axial compressive loading conditions to test the capability of the bonded joint design for buckling and joint failure. Test and analysis correlation of an as-manufactured undamaged longitudinal bonded joint panel are presented in the paper for tests to the onset of buckling and panel failure. Analysis predictions for buckling initiation and panel failure were both within 10% of the longitudinal bonded joint panel test results. This testing and analysis provide confidence in the potential use of composite bonded joints for future launch vehicle structures.

David W Sleight↗
NASA NTRS2016

Reliability and Maintainability Analysis for the Amine Swingbed Carbon Dioxide Removal System

I have performed a reliability & maintainability analysis for the Amine Swingbed payload system. The Amine Swingbed is a carbon dioxide removal technology that has gone through 2,400 hours of International Space Station on-orbit use between 2013 and 2016. While the Amine Swingbed is currently an experimental payload system, the Amine Swingbed may be converted to system hardware. If the Amine Swingbed becomes system hardware, it will supplement the Carbon Dioxide Removal Assembly (CDRA) as the primary CO2 removal technology on the International Space Station. NASA is also considering using the Amine Swingbed as the primary carbon dioxide removal technology for future extravehicular mobility units and for the Orion, which will be used for the Asteroid Redirect and Journey to Mars missions. The qualitative component of the reliability and maintainability analysis is a Failure Modes and Effects Analysis (FMEA). In the FMEA, I have investigated how individual components in the Amine Swingbed may fail, and what the worst case scenario is should a failure occur. The significant failure effects are the loss of ability to remove carbon dioxide, the formation of ammonia due to chemical degradation of the amine, and loss of atmosphere because the Amine Swingbed uses the vacuum of space to regenerate the Amine Swingbed. In the quantitative component of the reliability and maintainability analysis, I have assumed a constant failure rate for both electronic and nonelectronic parts. Using this data, I have created a Poisson distribution to predict the failure rate of the Amine Swingbed as a whole. I have determined a mean time to failure for the Amine Swingbed to be approximately 1,400 hours. The observed mean time to failure for the system is between 600 and 1,200 hours. This range includes initial testing of the Amine Swingbed, as well as software faults that are understood to be non-critical. If many of the commercial parts were switched to military-grade parts, the expected mean time to failure would be 2,300 hours. Both calculated mean times to failure for the Amine Swingbed use conservative failure rate models. The observed mean time to failure for CDRA is 2,500 hours. Working on this project and for NASA in general has helped me gain insight into current aeronautics missions, reliability engineering, circuit analysis, and different cultures. Prior my internship, I did not have a lot knowledge about the work being performed at NASA. As a chemical engineer, I had not really considered working for NASA as a career path. By engaging in interactions with civil servants, contractors, and other interns, I have learned a great deal about modern challenges that NASA is addressing. My work has helped me develop a knowledge base in safety and reliability that would be difficult to find elsewhere. Prior to this internship, I had not thought about reliability engineering. Now, I have gained a skillset in performing reliability analyses, and understanding the inner workings of a large mechanical system. I have also gained experience in understanding how electrical systems work while I was analyzing the electrical components of the Amine Swingbed. I did not expect to be exposed to as many different cultures as I have while working at NASA. I am referring to both within NASA and the Houston area. NASA employs individuals with a broad range of backgrounds. It has been great to learn from individuals who have highly diverse experiences and outlooks on the world. In the Houston area, I have come across individuals from different parts of the world. Interacting with such a high number of individuals with significantly different backgrounds has helped me to grow as a person in ways that I did not expect. My time at NASA has opened a window into the field of aeronautics. After earning a bachelor's degree in chemical engineering, I plan to go to graduate school for a PhD in engineering. Prior to coming to NASA, I was not aware of the graduate Pathways program. I intend to apply for the graduate Pathways program as positions are opened up. I would like to pursue future opportunities with NASA, especially as my engineering career progresses.

Dunbar, Tyler↗
NASA NTRS1989

Thermoplastic matrix composites - Finite-element analysis of mode I and mode II failure specimens

A finite-element analysis was conducted to evaluate the stress distributions within mode I and mode II failure specimens, assuming both isotropic and orthotropic elastic material properties. The effects of anisotropy on both the magnitude and the location of the highest stress concentration at the vicinity of the crack tip are significant. The results from modeling realistic blunt crack tip geometry and resin-rich zones imply that local variations in the microstructure strongly influence the stress state near the crack tip and therefore the measured fracture properties. In addition, the features of a viscoelastic model for thermoplastic matrices are described. This model will be used in future investigations of matrix-dominated failure phenomena.

Bankert, Ray J.↗
DOE OSTI2025

Safety Hazards of Batteries and Hydrogen Storage Systems in Proximity

This report addresses the safety concerns and mitigations for battery failures and their impact on hydrogen storage systems. Through an analysis of failure modes, this report highlights the risks posed by thermal runaway and chemical emissions caused by batteries. Although rare, battery thermal failure events may prompt the opening of the relief valve on the hydrogen tank. Strategies such as battery management systems, thermal management systems, and multiple thermally activated pressure relief devices can mitigate these risks. Potential simulations and experiments to better quantify the unique risks posed by lithium-ion batteries near tanks are suggested. Improving safety standards will enable integration of batteries and hydrogen storage systems in various energy storage technologies.

08 HYDROGEN↗
NASA NTRS1977

Reliability measurement during software development

Measurement of software reliability was carried out during the development of data base software for a multi-sensor tracking system. Every run made during this project was scored as success or failure, and supporting data were collected on forms for further analysis. The failure ratio (number of failures per calendar interval divided by total number of runs) and failure rate (number of failures divided by CPU time for the interval) were found to be consistent measures, on a month-to-month basis as well as from module to module, and therefore considered valid indicators of reliability in this environment. Trend lines could be established from these measurements that provide good visualization of the progress on the job as a whole as well as on individual modules. Over one-half of the observed failures were due to factors associated with the specific run submission rather than with the code proper.

Hecht, H.↗
NASA NTRS2006

A Perspective on DSN System Performance Analysis

This paper discusses the performance analysis effort being carried out in the NASA Deep Space Network. The activity involves root cause analysis of failures and assessment of key performance metrics. The root cause analysis helps pinpoint the true cause of observed problems so that proper correction can be effected. The assessment currently focuses on three aspects: (1) data delivery metrics such as Quantity, Quality, Continuity, and Latency; (2) link-performance metrics such as antenna pointing, system noise temperature, Doppler noise, frequency and time synchronization, wide-area-network loading, link-configuration setup time; and (3) reliability, maintainability, availability metrics. The analysis establishes whether the current system is meeting its specifications and if so, how much margin is available. The findings help identify the weak points in the system and direct attention of programmatic investment for performance improvement.

Deep Space Network (DSN)↗
NASA NTRS2000

Human versus automation in responding to failures: an expected-value analysis

A simple analytical criterion is provided for deciding whether a human or automation is best for a failure detection task. The method is based on expected-value decision theory in much the same way as is signal detection. It requires specification of the probabilities of misses (false negatives) and false alarms (false positives) for both human and automation being considered, as well as factors independent of the choice--namely, costs and benefits of incorrect and correct decisions as well as the prior probability of failure. The method can also serve as a basis for comparing different modes of automation. Some limiting cases of application are discussed, as are some decision criteria other than expected value. Actual or potential applications include the design and evaluation of any system in which either humans or automation are being considered.

NASA Discipline Space Human Factors↗
NASA NTRS2015

Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations under Flexure Loads

An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and facesheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

Damage↗
NASA NTRS2015

Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. Fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a strength reduction of 10 percent due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

Tolerance↗
NASA NTRS2015

Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

Tolerance↗