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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 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS2026

Fatigue Life of Flow-Formed Aluminum 2195 and 6061 Alloys

The successful design and fabrication of metallic cryotanks for commercial aviation applications require lightweight, durable materials capable of withstanding high pressures and cryogenic temperatures through tens of thousands of thermomechanical refueling cycles. Flow forming is an advanced manufacturing technique that offers high-rate production and scalability for fabricating integrally stiffened cylinders suitable for cryotank applications. This work establishes the durability of flow-formed aluminum alloys by characterizing their fatigue life performance under conditions that mimic cryotank refueling cycles. Residual stresses in flow-formed aluminum-lithium (Al-Li) 2195-T6 cylinders were assessed using the contour method and found to be minimal. Fatigue life testing was conducted on flow-formed Al-Li 2195-T6 at room temperature and cryogenic temperatures (-321°F [-196°C]), with wrought Al-Li 2195-T6 serving as a baseline for comparison. Results showed that flow-formed materials exhibited fatigue performance comparable to or better than wrought materials, with no statistically significant differences observed between different specimen orientations relative to processing directions. Fractography revealed reduced delaminations in the flow-formed Al-Li 2195 samples as compared to wrought, indicating potential improvement to the microstructure that could result in improved service properties. Texture analysis using electron backscattered diffraction (EBSD) indicated recrystallization during heat treatment, potentially contributing to reduced delamination susceptibility. These findings demonstrating flow-formed material durability coupled with the high manufacturing efficiency of flow forming, makes flow forming an attractive process to produce aircraft cryotanks.

EBF3↗
NASA NTRSDate not supplied

Evaluations of Additively Manufactured Superalloy Lattice Blocks

Cast lattice block structures made up of high-temperature superalloys were previously shown to offer advantages in density, efficiency, and tailored properties. However, inconsistencies in casting die-fill, composition, and microstructure were identified as persistent issues with the casting process path. Three candidate lattice designs were screened through additive manufacturing of a superalloy. Laser powder bed fusion was applied with superalloy powder to produce lattice blocks for three-dimensional octahedral unit-cell designs of three heights. Properties of the structural designs versus additively manufactured lattices were compared, including structural dimensions, densities, defects, grain structures, crystallographic texture, and surface residual stresses. Findings indicate this concept could produce useful superalloy structures for high-temperature-capable static components requiring tailored density, and thermophysical and mechanical properties.

superalloy↗
NASA NTRS2026

Beyond Melting: Amorphous Bonding for Joining and Consolidation

Crystallization may be the hidden constraint in thermoplastic composite manufacturing. It requires tightly controlled cooling, induces residual stresses through shrinkage, and introduces path-dependent behavior that complicates predictive modeling yet remains essential for structural performance. This work asks: can bonding be achieved without relying on melt-driven crystallization? To address this, thin (5–20 μm) polyetherimide (PEI) interlayers are pre-healed to slow-cooled polyaryletherketone (PAEK) in two contexts. The first, Thermabond®, is sub-melt joining of low melt-PAEK laminates. Results show that bond quality is governed primarily by processing (i.e., adequate healing and film handling) rather than modest changes in interlayer thickness. This concept is then extended to laminate-scale manufacturing through an architecture known as OATMEAL (Out-of-autoclave Amorphous/semicrystalline Thermoplastic Material for Energy-efficient Aerospace-grade Laminates). PEI is healed to carbon fiber reinforced polyetheretherketone (PEEK) at the prepreg and excess PEI is then ablated from the surface. Crystallinity is developed off-line during prepreg fabrication, while subsequent consolidation occurs below the melt temperature to preserve it. Cross-ply warpage experiments show that, contrary to intuition, repeated amorphous interfaces reduce global curvature by lowering the effective stress lock-in temperature and eliminating crystallization shrinkage from the lamina response. Correspondingly, laminate behavior is accurately predicted using classical laminate theory (CLT) with a single effective stress-free temperature, whereas conventional CF/PEEK requires accounting for crystallization-driven effects. By decoupling interfacial healing from crystallization, OATMEAL enables sub-melt consolidation, reduces energy consumption by up to 75%, and increases manufacturing throughput by fivefold. These results demonstrate that amorphous bonding is not only a joining strategy, but a pathway to more predictable and scalable thermoplastic composite manufacturing.

solidification↗
DOE OSTI2016

US Progress on Property Characterization to Support LEU U-10 Mo Monolithic Fuel Development

The US High Performance Research Reactor program is pursuing development and qualification of a new high density monolithic LEU fuel to facilitate conversion of five higher power research reactors located in the US (ATR, HFIR, NBSR, MIT and MURR). In order to support fabrication development and fuel performance evaluations, new testing capabilities are being developed to evaluate the properties of fuel specimens. Residual stress and fuel-cladding bond strength are two characteristics related to fuel performance that are being investigated. In this overview, new measurement capabilities being developed to assess these characteristics in both fresh and irradiated fuel are described. Progress on fresh fuel testing is summarized and on-going hot-cell implementation efforts to support future PIE campaigns are detailed. It is anticipated that benchmarking of as-fabricated fuel characteristics will be critical to establishing technical bases for specifications that optimize fuel fabrication and ensure acceptable in-reactor fuel performance.

Characterization↗
DOE OSTI2016

Advances in Neutron Radiography: Application to Additive Manufacturing Inconel 718

Reactor-based neutron radiography is a non-destructive, non-invasive characterization technique that has been extensively used for engineering materials such as inspection of components, evaluation of porosity, and in-operando observations of engineering parts. Neutron radiography has flourished at reactor facilities for more than four decades and is relatively new to accelerator-based neutron sources. Recent advances in neutron source and detector technologies, such as the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, TN, and the microchannel plate (MCP) detector, respectively, enable new contrast mechanisms using the neutron scattering Bragg features for crystalline information such as average lattice strain, crystalline plane orientation, and identification of phases in a neutron radiograph. Additive manufacturing (AM) processes or 3D printing have recently become very popular and have a significant potential to revolutionize the manufacturing of materials by enabling new designs with complex geometries that are not feasible using conventional manufacturing processes. However, the technique lacks standards for process optimization and control compared to conventional processes. Residual stresses are a common occurrence in materials that are machined, rolled, heat treated, welded, etc., and have a significant impact on a component s mechanical behavior and durability. They may also arise during the 3D printing process, and defects such as internal cracks can propagate over time as the component relaxes after being removed from its build plate (the base plate utilized to print materials on). Moreover, since access to the AM material is possible only after the component has been fully manufactured, it is difficult to characterize the material for defects a priori to minimize expensive re-runs. Currently, validation of the AM process and materials is mainly through expensive trial-and-error experiments at the component level, whereas in conventional processes the level of confidence in predictive computational modeling is high enough to allow process and materials optimization through computational approaches. Thus, there is a clear need for non-destructive characterization techniques and for the establishment of processing- microstructure databases that can be used for developing and validating predictive modeling tools for AM.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Freestanding, heat resistant microporous film for use in energy storage devices

Preferred embodiments of a freestanding, heat resistant microporous polymer film (10) constructed for use in an energy storage device (70, 100) implements one or more of the following approaches to exhibit excellent high temperature mechanical and dimensional stability: incorporation into a porous polyolefin film of sufficiently high loading levels of inorganic or ceramic filler material (16) to maintain porosity (18) and achieve low thermal shrinkage; use of crosslinkable polyethylene to contribute to crosslinking the polymer matrix (14) in a highly inorganic material-filled polyolefin film; and heat treating or annealing of biaxially oriented, highly inorganic material-filled polyolefin film above the melting point temperature of the polymer matrix to reduce residual stress while maintaining high porosity. The freestanding, heat resistant microporous polymer film embodiments exhibit extremely low resistance, as evidenced by MacMullin numbers of less than 4.5.

25 ENERGY STORAGE↗
DOE OSTI2018

Effect of Inter-layer Cooling Time on Distortion and Mechanical Properties in Metal Additive Manufacturing (AM)

Laser Metal Deposition with wire (LMD-w) is one of the novel Direct Energy Deposition (DED) processes that is gaining attention in aerospace industry due to the potential cost and lead time reductions for large-scale components. However, improving process parameters (for example, laser power, wire feed rate, robotic travel speed, inter-layer cooling time, etc.) is still under development. These parameters affect thermal gradients that cause residual stresses that in-turn influence distortion. These parameters also affect mechanical properties. Inter-layer cooling time, specifically, is one of the main factors for total production time, and it is used to help mitigate distortion. Therefore, this paper investigated the effects of different inter-layer cooling times on both distortion and mechanical properties. Distortion of deposited Ti-6Al-4V walls was measured automatically using a laser scanner. Finally, suitable recommendations are discussed to optimize the inter-layer cooling time to fabricate components with desired mechanical properties.

Bandari, Yashwanth Kumar↗
DOE OSTI2017

Role of Cyclic Phase Transitions in Additive Manufacturing of Metals and Alloys - Lessons Learned from Welding Science

Additive manufacturing (also known as 3D printing) of metals is considered to be a disruptive technology, able to produce limited number of high value components with topologically optimized geometries and functionalities. Realization of the above potential for real-world applications is stifled by lack of standard computational design tools; component certifications, varied starting powder feed stock compositions, methods to probe thermomechanical processes, microstructural homogeneity, residual stress, as well as, anisotropic static- and dynamic-material properties. Detailed research of direct energy deposition, laser- and electron-powder bed additive manufacturing demonstrates that the underlying physics of these processes are very similar to welding, except for complex boundary conditions. This paper will review published literature and on-going research with reference to fundamental aspects of heat and mass transfer, solidification under large (103 to 105 K/m) thermal gradients and (10-3 to 100 m/s) liquid solid-interface velocities, as well as, solid->solid transformation under repeated thermal excursions. Case studies on model based qualification of Ni- and Ti- alloy builds made by additive manufacturing (AM), based on the above fundamental knowledge will be discussed.

Babu, Sudarsanam Suresh↗
DOE OSTI2019

Nanomaterial assisted bonding method to produce curved surfaces

A method of fabricating a curved surface bonding technique using low melting temperature nanoparticles or nanofilms/nanoparticles of reactive metals as eutectic compounds. The ability of nanomaterials to melt at low temperature lowers the bonding temperature and reduces/eliminates the residual stresses generated in bulk material during the bonding process of two materials with different coefficients of thermal expansion. The nanoscale materials will then be integrated and the new bond will assume properties of the bulk material, including its higher melting temperature.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Modeling Time-Dependent Surrogates of Additive-Manufactured Nuclear Fuels Processes

Additive manufacturing (AM) technology is being increasingly adopted in a wide variety of application areas for its ability to rapidly produce, prototype, and customize designs. Recently, a hybrid AM technique was successfully developed at Idaho National Laboratory (INL) to manufacture nuclear fuels [1]. Despite the advantages, this AM technique needs optimization due to defects from a highly complex melting and sintering process. The complex metallurgical phenomena during AM processes are strongly related to parameters such as applied laser power, traveling speed, and scan style, which could lead to differences in density, residual stress, crystallographic texture, and mechanical properties. In addition, stochastic variations in laser energy interaction and associated multiscale/multiphysics phenomena cause variations in microstructure evolution and mechanical properties. Currently, researchers at INL are focusing on developing a comprehensive modeling framework, leveraging INL’s simulation tools MOOSE/MARMOT/BISON/RAVEN [2-4] to describe all steps of this AM process across multiple length scales. Although this advanced framework plays a critical role in enabling enhancements to traditional trial and error approaches for design and optimization of nuclear fuel materials, it remains computationally intense, limiting its use in sensitivity and optimization analysis. In this case, an accurate and inexpensive surrogate becomes an effective tool for providing a tractable approximation of the underlying underline physics. Surrogate models generally not based on the physics of a system are purely mathematical models used to capture the relationships between specific system inputs and outputs. Popular approaches, including neural networks [5], response surfaces [6], and subspace-based reduced order models [7], have been applied to a wide range of disciplines, such as nuclear reactor design, aerospace design and automotive design. In this summary, we employ advanced time-dependent surrogate models such as high-dimensional model representation (HDMR) [8] and physics-informed deep neural network (PINNs) [9] to accelerate the design and optimization of AM process.

42 ENGINEERING↗
DOE OSTI2016

DIRECT LASER DEPOSITION OF POROUS STRUCTURES AND GRADIENT METAL-CERAMIC COMPOSITE COATINGS

Direct laser deposition is an additive manufacturing technique capable of producing complex geometries, bond different materials, repair broken parts, and add protective coating. In the present study it is used to make micro-porous scaffolds and apply protective vanadium and niobium carbide coatings. Micro-porous metal filters are a difficult thing to make but are required for many applications. In this study it was hypothesized that laser engineering net shaping (LENS) could be used to make porous Ti6Al4V scaffolds with an interconnected micro-porous structure. This proved to be true with cylinders made to have 15.9% porosity, and a pore size less than 100μm. These structures were made by only altering processing parameters, which yielded a scaffold with obstructed random pore interconnectivity. The scaffolds had a compressive strength of 645-556MPa and martensitic like α' grains. Another study was done to apply hard niobium and vanadium carbide surface coatings to stainless steel. The objective was to used LENS to deposit stainless steel coatings with added carbides to eventually make a gradient coating with increased protective qualities. Parts that have suffered material loss from abrasive wear or cavitation could have material added back as well as add a protective coating at the same time. Compositions ranging from 5% to 100% of the carbides were mixed with stainless steel. The coatings were then deposited on a stainless steel 304 substrate individually, as well as in a series to make a gradient structure. These coatings all increased hardness, wear resistance, and 100%VC significantly increased the materials resistance to damage from abrasive water. The carbides integrated into the SS304 matrix on the grain boundaries making a metal ceramic composite. These precipitates left residual stress in the structure which increased the hardness and wear resistance. The study proved that the addition of these carbides did increase the protective qualities and could make a gradient coating with properties tailored to the user’s preference.

13 HYDRO ENERGY↗
DOE OSTI2016

In-Situ Synchrotron and Neutron Radiation at International User Facilities Take Welding Research to a New Level

Over the past century the principal method for understanding the effects of welding on the mechanical and physical integrity of the final joint has been post-weld microstructure analysis, and it’s the interpretation of these microstructures that sets welding metallurgy apart from other related scientific fields. In conjunction with heat flow analysis, thermodynamics, and kinetics, post-weld visual observations have provided the framework for interpreting the events that lead to the final weld microstructure. However, without direct and confirming evidence of the actual phases that exist during welding, or measurement of invisible weld properties such as crystal structure and residual stress, multiple interpretations for microstructural evolution of welds are possible. For these reasons, new methods are being developed for the direct observation of phase transformations that occur both during and as a result of welding, using modern synchrotron and neutron user research facilities.

36 MATERIALS SCIENCE↗
DOE OSTI2022

FEMTOSECOND LASER DRILLING OF SILICON NITRIDE

Ceramics are employed in various engineering applications including electronics, semiconductors, automotive and aerospace industry, among others. Ceramics are desirable materials due to their high hardness, thermal resistance, chemical, thermal, and mechanical properties. A drawback of engineering ceramics is the manufacturing process. Ceramics are hard and brittle and conventional drilling or cutting methods can damage the material. These challenges in manufacturing have limited the application of ceramics in certain engineering applications. The non-contact machining of ceramics through ultrashort pulsed laser drilling offers a possible solution to the manufacturing issues. The advantage of laser drilling is the ability to machine hard and brittle materials. A laser, pulsed in the time regime of femtoseconds (fs), drills/machines sharp and well-defined holes and cuts. Additionally, the short pulse width results in limited melting, cracking, or heat transfer to the surrounding material, as well as no residual stresses. This non-contact process can greatly aid in the machining of hard materials. This study focuses on drilling into silicon nitride to produce zero-taper through holes. With this, other thicknesses can be explored, to achieve zero-taper holes.

Femtosecond laser ablation, Ceramics, Silicon Nitr↗
DOE OSTI2022

Quarterly Management Document – FY22, 3rd Quarter, Multi-pass Hybrid Laser Arc Welding of Alloy 740H

During the 3rd quarter of FY22, progress was made on modeling and simulation of deep penetration laser welding of Alloy 740H. Advances in the modeling of residual stress development arising from the calculated temperature field of the solidifying weld pool were made to understand the development of solidification cracking. Additionally, preliminary modeling of the temperature field within the weld pool of a wobbling laser heat source was performed. The maximum temperature of the weld pool was found to vary with time. These result will allow modeling of deep penetration laser welding using a wobbling laser to mitigate weld defects and cracking. Also, additional characterization of hybrid laser arc welds indicated that these welds were not defect-free as originally thought and the current HLA welds would not be acceptable under criteria outlined in the ASME Boiler and Pressure Vessel Code, Section IX. Therefore, additional welding trails with variation of the welding parameters and HLA welding configurations are required to produce welds acceptable under the Section IX criteria. It was shown that considerable reduction of HLAW defects had been achieved with each successive welding campaign. Therefore additional variation of HLAW parameters may still yield the desired defect-free welds, however, options for alternate HLAW configurations as well as plate preheating are outlined as contingency plans to obtain suitable welds. These additional (unplanned) HLAW trial may prevent subsequent milestones from being achieved within the original budget.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Extended Finite Element Based Approach in Additive Manufacturing Modeling for Optimizing Highly Complex Manifold in Protonic Ceramic Electrochemical Cells

The objective of this project is to develop a novel numerical approach based on the extended finite element method (XFEM) for modeling moving boundaries of material deposited in additive manufacturing (AM) process with improved accuracy and reduced computational cost. One of the major challenges in simulating AM processes is that the boundaries of the computational domain need to change as material is deposited. Previous approaches have achieved this by activating new finite elements, but this requires a high level of mesh refinement to capture small movement of the boundary. XFEM allows the solution boundary to move independently of the mesh, permitting smooth representation of the evolution of the boundary as material is deposited. As a result, this new method will significantly improve the simulation accuracy while reducing the computational cost compared with existing approaches. Furthermore, this project will bring significant improvements for the design and AM process optimization in an iterative fashion among numerical simuation, parameter optimization, and experimental validation. Specifically, this project will support the protonic ceramic electrochemical cells (PCEC) stack development at INL by providing insights into the density, residual stress, thermal and mechanical properties of the PCEC manifold and interconnect, which is critical in enhancing the system lifetime and reducing the overall cost. Upon the success of proposed development and validation of the proposed approach, simulation will be applied to determine an optimal set of AM process parameters for the PCEC manifold production. This project will consolidate Idaho National Laboratory (INL)’s simulation capabilities provided by the MOOSE framework and the Valhalla AM simulation application, with encouraging expansion to emerging PCEC applications and AM technologies at INL and beyond.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

ADDITIVE MANUFACTURING AND REGULATORY TESTING OF CANISTERS FOR SPENT NUCLEAR FUEL MANAGEMENT

The back end of the fuel cycle focuses on the interim storage, transportation, and final disposition of the spent nuclear fuel from nuclear reactors. Commercial light water nuclear power stations across the United States operate with fuel assemblies being irradiated for up to 6 years (planned) in the reactor pressure vessel. After their planned irradiation, the fuel assemblies are moved to a spent fuel pool within the facility complex. After the spent nuclear fuel is removed from the fuel pool, it is typically inserted into a welded metal canister that can be transferred between overpacks for storage, transportation and possibly disposal. Most dry storage systems being used by industry today use dual purpose canisters (DPCs), designed for use in storage and transportation overpacks, but not specifically designed for disposal. Triple purpose-canisters, designed for disposal in addition to storage and transportation, have also been researched. Traditional manufacturing methods for spent fuel canisters involve fusion welding along the length or circumference of the canister which results in high tensile residual stresses in the joint weld zone (WZ) and heat affected zone (HAZ). In this paper, spent fuel canister designs were printed by wire arc additive manufacturing (AM) using the 316L SS welding wire to demonstrate: 1. Feasibility of spent nuclear fuel canister fabrication using this advanced manufacturing method, 2. Dynamic response of the additive manufacture canister design when subjected to the federally mandated Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC) physical tests for Type B packages. This paper will focus on the canister printing design and structural tests. The AM 3D printed design, regulatory testing, and post-test evaluation of the canister tested to the 10 CFR 71.71 and 10 CFR 71.73 requirements will be presented. One AM canister design was subjected to the penetration, free drop, and puncture test. Before and after the dynamic structural tests, the AM canister design was scanned with a handheld scanner to capture a 3D CAD geometry to compare to the 3D printed canister design in the deformed shape. The scanned geometry was sectioned in areas with deformation and the cross-section profile was measured to determine accurate and repeated results of the deformed shape of the AM canister design.

Martinez, Oscar↗
DOE OSTI2021

Additive manufacturing of power poles using bamboo-polymer composites: A quick solution for power grid restoration

Polymer additive manufacturing (AM) technology is rapidly growing and its transition to become an advanced manufacturing technique now offers possibilities for unconventional applications. One of these potential applications is on site additive manufacturing of power poles. During natural incidents such as storms and hurricanes, power lines can be severely damaged and there may not be sufficient spare power poles to replace. In such situations, additive manufacturing of power poles on site can offer a fast, temporary solution during emergencies. The ability of freeform manufacturing of parts with complex geometries makes large scale AM attractive for various applications; however, due to residual stress build up and need for different mechanical requirements for different applications, reinforcement of the AM feedstock is necessary. In addition to carbon and glass fibers, bio-derived fibers can also be used as a reinforcing phase, both to utilize the natural resources at the emergency area and in terms of long-term sustainability. In this project, design and additive manufacturing of a 13.1 m power pole was demonstrated. Three different feedstock material options (polystyrene, cellulose ester and polycarbonate reinforced with glass and bamboo fibers) and two different pole designs were investigated. As-printed part tensile properties both in printing and interlayer directions were measured and a power pole was printed as six pieces and put together successfully. Finally, a conceptual design of a portable power pole manufacturing approach was proposed.

Tekinalp, Halil↗
DOE OSTI2024

Atomistic Modeling of Irradiation-Induced Defects and Clusters in Additively-Manufactured Austenitic Stainless Steel

Understanding the progression of irradiation-induced defects in real materials and alloys requires insight into the interaction between point defects, defect clusters, and the existing microstructure. This is particularly true when it comes to additively manufactured (AM) materials with complicated microstructures and residual stresses. In this work, we employ molecular dynamics (MD) to simulate the creation of point defects via primary radiation damage modeling and point defect interactions with extended defects such as voids and dislocations using simplified but representative alloy compositions. We analyze the effect of alloying elements on the formation energies of the defect clusters and measure interactions such as sink strengths and binding energies. This study provides insight into the unique behaviors of irradiation damage in AM materials and information necessary to bridge the gap in length and time scales to connect the atomistic behavior of defects to longer length scale simulations such as cluster dynamics.

36 MATERIALS SCIENCE↗