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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Damage Tolerance of Composites

Fracture control requirements have been developed to address damage tolerance of composites for manned space flight hardware. The requirements provide the framework for critical and noncritical hardware assessment and testing. The need for damage threat assessments, impact damage protection plans, and nondestructive evaluation are also addressed. Hardware intended to be damage tolerant have extensive coupon, sub-element, and full-scale testing requirements in-line with the Building Block Approach concept from the MIL-HDBK-17, Department of Defense Composite Materials Handbook.

Hodge, Andy↗
NASA NTRS2008

Future NTP Development Synergy Leveraged from Current J-2X Engine Development

This paper is a discussion of how the many long-lead development elements required for the realization of a future nuclear thermal propulsion (NTP) system can be effectively leveraged from the ongoing work being conducted on the J-2X engine program for the Constellation Program. Development studies conducted to date for NTP forward planning have identified a number of technical areas that will require advancement to acceptable technology readiness levels (TRLs) before they can be utilized in NTP system development. These include high-temperature, high-area ratio nozzle extension; long-life, low-NPSP. turbomachinery; and low-boiloff propellant management; and a qualified nuclear fuel element. The current J-2X program is working many of these areas that can be leveraged to support NTP development in a highly compatible and synergistic fashion. In addition to supporting technical development, there are other programmatic issues being worked in the J-2X program that can be leveraged by a future NTP development program. These include compliance with recently-evolved space system requirements such as human-rating, fault tolerance and fracture control. These and other similar mandatory system requirements have been adopted by NASA and can result in a significant technical impact beyond elevation of the root technologies required by NTP. Finally, the exploitation of experience, methodologies, and procedures developed by the J-2X program in the areas of verification, qualification, certification, altitude simulation testing, and facility definition will be especially applicable to a future NTP system. The similarities in system mission (in-space propulsion) and operational environment (vacuum, zero-gee) between J-2X and NTP make this highly synergistic. Thus, it can be $hown that the collective benefit of leveraging experience and technologies developed during the J-2X program can result in significant savings in development cost and schedule for NTP.

Ballard, Richard O.↗
NASA NTRS2008

Composites Damage Tolerance

This slide presentation reviews the development of MSFC-RQMT-3479 for requirements for fracture control of composites to be used in the Constellation program. This effort is part of the development of a revision of NASA-STD-5019(A), which will include MSFC-RQMT-3479. Examples of the requirement criteria and implementation are given.

Gregg, Wayne↗
NASA NTRS2004

NASGRO(registered trademark): Fracture Mechanics and Fatigue Crack Growth Analysis Software

This viewgraph presentation describes NASGRO, which is a fracture mechanics and fatigue crack growth analysis software package that is used to reduce risk of fracture in Space Shuttles. The contents include: 1) Consequences of Fracture; 2) NASA Fracture Control Requirements; 3) NASGRO Reduces Risk; 4) NASGRO Use Inside NASA; 5) NASGRO Components: Crack Growth Module; 6) NASGRO Components:Material Property Module; 7) Typical NASGRO analysis: Crack growth or component life calculation; and 8) NASGRO Sample Application: Orbiter feedline flowliner crack analysis.

Forman, Royce↗
NASA NTRS2011

The J-2X Fuel Turbopump - Turbine Nozzle Low Cycle Fatigue Acceptance Rationale

The J-2X Fuel Turbopump (FTP) turbine, which drives the pump that feeds hydrogen to the J-2X engine for main combustion, is based on the J-2S design developed in the early 1970 s. Updated materials and manufacturing processes have been incorporated to meet current requirements. This paper addresses an analytical concern that the J-2X Fuel Turbine Nozzle Low Cycle Fatigue (LCF) analysis did not meet safety factor requirements per program structural assessment criteria. High strains in the nozzle airfoil during engine transients were predicted to be caused by thermally induced stresses between the vane hub, vane shroud, and airfoil. The heritage J-2 nozzle was of a similar design and experienced cracks in the same area where analysis predicted cracks in the J-2X design. Redesign options that did not significantly impact the overall turbine configuration were unsuccessful. An approach using component tests and displacement controlled fracture mechanics analysis to evaluate LCF crack initiation and growth rate was developed. The results of this testing and analysis were used to define the level of inspection on development engine test units. The programmatic impact of developing crack initiation/growth rate/arrest data was significant for the J-2X program. Final Design Certification Review acceptance logic will ultimately be developed utilizing this test and analytical data.

Hawkins, Lakiesha V.↗
NASA NTRS2012

Composite Structures Damage Tolerance Analysis Methodologies

This report presents the results of a literature review as part of the development of composite hardware fracture control guidelines funded by NASA Engineering and Safety Center (NESC) under contract NNL04AA09B. The objectives of the overall development tasks are to provide a broad information and database to the designers, analysts, and testing personnel who are engaged in space flight hardware production.

Chang, James B.↗
NASA NTRS2013

Damage Tolerance Assessment Branch

The Damage Tolerance Assessment Branch evaluates the ability of a structure to perform reliably throughout its service life in the presence of a defect, crack, or other form of damage. Such assessment is fundamental to the use of structural materials and requires an integral blend of materials engineering, fracture testing and analysis, and nondestructive evaluation. The vision of the Branch is to increase the safety of manned space flight by improving the fracture control and the associated nondestructive evaluation processes through development and application of standards, guidelines, advanced test and analytical methods. The Branch also strives to assist and solve non-aerospace related NDE and damage tolerance problems, providing consultation, prototyping and inspection services.

Walker, James L.↗
NASA NTRS2013

Visit from JAXA to NASA MSFC: The Engines Element & Ideas for Collaboration

System Design, Development, and Fabrication: Design, develop, and fabricate or procure MB-60 component hardware compliant with the imposed technical requirements and in sufficient quantities to fulfill the overall MB-60 development effort. System Development, Assembly, and Test: Manage the scope of the development, assembly, and test-related activities for MB-60 development. This scope includes engine-level development planning, engine assembly and disassembly, test planning, engine testing, inspection, anomaly resolution, and development of necessary ground support equipment and special test equipment. System Integration: Provide coordinated integration in the realms of engineering, safety, quality, and manufacturing disciplines across the scope of the MB-60 design and associated products development Safety and Mission Assurance, structural design, fracture control, materials and processes, thermal analysis. Systems Engineering and Analysis: Manage and perform Systems Engineering and Analysis to provide rigor and structure to the overall design and development effort for the MB-60. Milestone reviews, requirements management, system analysis, program management support Program Management: Manage, plan, and coordinate the activities across all portions of the MB-60 work scope by providing direction for program administration, business management, and supplier management.

Greene, William D.↗
DOE OSTI2021

Deep reinforcement learning control of hydraulic fracturing

Hydraulic fracturing is a technique to extract oil and gas from shale formations, and obtaining a uniform proppant concentration along the fracture is key to its productivity. Recently, various model predictive control schemes have been proposed to achieve this objective. But such controllers require an accurate and computationally efficient model which is difficult to obtain given the complexity of the process and uncertainties in the rock formation properties. In this article, we design a model-free data-based reinforcement learning controller which learns an optimal control policy through interactions with the process. Deep reinforcement learning (DRL) controller is based on the Deep Deterministic Policy Gradient algorithm that combines Deep-Q-network with actor-critic framework. In addition, we utilize dimensionality reduction and transfer learning to quicken the learning process. We show that the controller learns an optimal policy to obtain uniform proppant concentration despite the complex nature of the process while satisfying various input constraints.

42 ENGINEERING↗
DOE OSTI2026

3D seismic imaging of a fracture damage zone controlling reservoir compartmentalization at the Raft River EGS using multi-azimuth walkaway VSP

Accurate imaging of steeply dipping fracture zones in crystalline enhanced geothermal systems (EGS) is critical for constraining permeability architecture and guiding stimulation design. However, such structures remain poorly resolved by conventional surface seismic methods. We present a fully three-dimensional (3D) elastic-waveform inversion-migration workflow applied to multi-azimuth walkaway vertical seismic profiling (VSP) data acquired in a deviated borehole at the Raft River EGS. The workflow integrates first-arrival traveltime tomography, multi-scale elastic waveform inversion (EWI), and elastic least-squares reverse-time migration (ELSRTM) to recover high-resolution compressional-and shear-wave velocity models and to image structural discontinuities in the crystalline basement. The results reveal a laterally continuous low-velocity anomaly, with shear-wave velocity reductions of 25-30%, consistent with fractureinduced mechanical weakening. Two steeply dipping discontinuities bound a 50-80 m wide fracture damage zone. Independent constraints from microseismic clustering and geochemical compartmentalization corroborate the geometry and structural significance of this feature. Synthetic modeling further confirms that structures of this scale are resolvable (~30 m). These findings indicate that the Narrows structure is a distributed fracture damage zone rather than a discrete fault plane. By resolving fracture-zone geometry at the tens-of-meters scale using a single borehole, this workflow provides a practical and transferable approach for improving structural characterization, reducing uncertainty in permeability architecture, and supporting reservoir modeling and stimulation design in fractured crystalline EGS reservoirs.

58 GEOSCIENCES↗
DOE OSTI2023

Gravity-driven controls on fluid and carbonate precipitation distributions in fractures

Abstract Many challenges related to carbon-dioxide ( $$\hbox {CO}_2$$ CO 2 ) sequestration in subsurface rock are linked to the injection of fluids through induced or existing fracture networks and how these fluids are altered through geochemical interactions. Here, we demonstrate that fluid mixing and carbonate mineral distributions in fractures are controlled by gravity-driven chemical dynamics. Using optical imaging and numerical simulations, we show that a density contrast between two miscible fluids causes the formation of a low-density fluid runlet that increases in areal extent as the fracture inclination decreases from 90 $$^\circ$$ ∘ (vertical fracture plane) to 30 $$^\circ$$ ∘ . The runlet is sustained over time and the stability of the runlet is controlled by the gravity-driven formation of 3D vortices that arise in a laminar flow regime. When homogeneous precipitation was induced, calcium carbonate covered the entire surface for horizontal fractures (0 $$^\circ$$ ∘ ). However, for fracture inclinations greater than 10 $$^\circ$$ ∘ , the runlet formation limited the areal extent of the precipitation to less than 15% of the fracture surface. These insights suggest that the ability to sequester $$\hbox {CO}_2$$ CO 2 through mineralization along fractures will depend on the fracture orientation relative to gravity, with horizontal fractures more likely to seal uniformly.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Planarizing Spalled GaAs(100) Surfaces by MOVPE Growth

III-V photovoltaic devices have demonstrated exceptional performance across various applications, with controlled crystal fracturing, known as controlled spalling, emerging as a promising method to reduce costs by enabling substrate reuse. Spalling GaAs(100) substrates, a commonly used substrate in III-V photovoltaics, results in faceted ridges that must be planarized to grow high-quality photovoltaic devices. Here, in this study, we demonstrate that a GaAs(100) wafer offcut toward [$0\bar{11}$] and spalled toward [$011$] can be efficiently planarized by growing C:GaAs by metal-organic vapor phase epitaxy (MOVPE) on the surface, with up to 95% of the nominally deposited material used to fill the valleys between ridges. We find that reducing the offcut to 2° enhances the planarizing capability of C:GaAs. A surface morphology model indicates that the density of surface dangling bonds significantly influences the growth evolution of undoped GaAs surfaces. In contrast, the model suggests that the effectiveness of C:GaAs as a smoothing layer stems from modifying the atomic surface structure and, consequently, the associated sticking coefficients of the facets, which can alter the evolution of surface morphology. Our findings provide guidelines for the epitaxial planarization of semiconductor surfaces and improve the understanding of MOVPE growth on nonplanar surfaces.

14 SOLAR ENERGY↗
NASA NTRS2018

Effect of Control Mode and Load Rate on Fracture Toughness of Brittle Ceramics

The effects of control mode and rate on the fracture toughness of ceramics were measured by using chevron-notched flexure specimen in accordance with ASTM C1421. The use of stroke control gave consistent results with about 2% variation in measured fracture toughness for a very wide range of rates (0.005 to 0.5 mm/min). Use of strain or CMOD control gave an approximately 5% variation over a very wide range of rates, with the measurements being a function of rate. However, the effect was eliminated by use of dry nitrogen, implying a stress corrosion effect rather than a stability effect. With the use of nitrogen for strain control, fracture toughness values were within about 1% over a wide range of rates (1 to 80 micro-epsilon/sec.). CMOD or strain control did allow stable crack extension well past maximum load, and thus is preferred for energy calculations. The effort is being used to confirm recommendations in ASTM International standard C1421 on fracture toughness measurement.

control mode↗
NASA NTRS2018

Effect of Control Mode and Test Rate on Fracture Toughness of Advanced Ceramics

The effects of control mode and rate on the fracture toughness of ceramics were measured by using chevron-notched flexure specimen in accordance with ASTM C1421. The use of stroke control gave consistent results with about 2% variation in measured fracture toughness for a very wide range of rates (0.005 to 0.5 mm/min). Use of strain or CMOD control gave ~5% variation over a very wide range of rates, with the measurements being a function of rate. However, the effect was eliminated by use of dry nitrogen, implying a stress corrosion effect rather than a stability effect. With the use of nitrogen for strain control, fracture toughness values were within about 1% over a wide range of rates (1 to 80 /s). CMOD or strain control did allow stable crack extension well past maximum load, and thus is preferred for energy calculations. The effort is being used to confirm recommendations in ASTM International standard C1421 on fracture toughness measurement.

fracture toughness↗
NASA NTRS1994

Fracture Behavior of Ceramics Under Displacement Controlled Loading

A Mode I fracture specimen and loading method has been developed which permits the observation of stable crack extension in monolithic and in situ toughened ceramics. The developed technique was used to conduct room temperature tests on commercial grade alumina (Coors' AD-995) and silicon nitride (Norton NC-132). The results of these tests are reported. Crack growth for the alumina remained subcritical throughout testing revealing possible effects of environmental stress corrosion. The crack growth resistance curve for the alumina is presented. The silicon nitride tests displayed a series of stable (slow) crack growth segments interrupted by dynamic (rapid) crack extension. Crack initiation and arrest stress intensity factors, K(sub Ic) and K(sub Ia), for silicon nitride are reported. The evolution of the specimen design through testing is briefly discussed.

Calomino, Anthony↗
DOE OSTI2021

Newly acquired core enhances geologic understanding of the northern Paradox Basin Cane Creek play, southeastern Utah

The Cane Creek interval is an emerging unconventional heterolithic play within the Pennsylvanian Paradox Formation of the northern Paradox Basin, southeastern Utah. Structural controls (basement uplifts, salt movement, faults, fractures) likely control production from the Cane Creek, where total oil production of ~10 MMBO is just a fraction of current estimates of the undiscovered resource (up to 1.2 BBOE). Oil production has been most successful from unstimulated horizontal wells in the Cane Creek Unit in the central play area, whereas areas to the north (Greentown and Gunnison Valley) have to date proven to be largely unproductive from vertical and horizontal wells drilled without the benefit of 3D seismic or the deployment of modern hydraulic fracturing techniques. However, the limited historical drilling has shown significant promise (e.g., significant shows). The lack of core data in the northern part of the play has impeded thorough assessment of reservoir quality, character, and lithological facies heterogeneity. The Cane Creek is informally divided into three distinct zones. The upper A and basal C zones are composed of fabric destructive and wavy bedded anhydrite, dolomitic mudstone, and organic-rich algal laminated mudstones (source rock). The middle B zone is generally wave rippled and burrowed, low-permeability sandstone-siltstone (reservoir) with subordinate displacive anhydrite. Recent potash cores collected from the Salt Valley anticline near Crescent Junction, Utah (but east of the main play area), show thicker reservoir sandstone/siltstone packages (~40 ft) in the B zone, and parts of the C zone, in the northern part of the Paradox Basin in comparison to the central (~35 ft) and southern (~30 ft) areas. Source rock analyses from northern core/cuttings also indicate that it is well positioned within the oil window (VRo ~0.8), with thin organic-rich mudstone beds containing up to 20 wt% TOC. Because the siliciclastic reservoir rocks have low permeabilities (0.009–0.202 mD) and variable porosities (6–17%) due to dolomite-anhydrite cement, naturally occurring and possibly stimulated fractures may be essential for hydrocarbon recovery. To better understand the northern part of the Cane Creek play, a new core was obtained from the research stratigraphic well State 16-2 (January 2021). Details from this new core will help characterize reservoir quality via core analyses, petrography, fracture orientations, geomechanics, and correlation of facies and depositional trends. Additionally, an evaluation of matrix porosity/permeability will be conducted to determine its contribution to productivity.

02 PETROLEUM↗