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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Development of Testing Methodologies for the Mechanical Properties of MEMS

This effort is to investigate and design testing strategies to determine the mechanical properties of MicroElectroMechanical Systems (MEMS) as well as investigate the development of a MEMS Probabilistic Design Methodology (PDM). One item of potential interest is the design of a test for the Weibull size effect in pressure membranes. The Weibull size effect is a consequence of a stochastic strength response predicted from the Weibull distribution. Confirming that MEMS strength is controlled by the Weibull distribution will enable the development of a probabilistic design methodology for MEMS - similar to the GRC developed CARES/Life program for bulk ceramics. However, the primary area of investigation will most likely be analysis and modeling of material interfaces for strength as well as developing a strategy to handle stress singularities at sharp corners, filets, and material interfaces. This will be a continuation of the previous years work. The ultimate objective of this effort is to further develop and verify the ability of the Ceramics Analysis and Reliability Evaluation of Structures Life (CARES/Life) code to predict the time-dependent reliability of MEMS structures subjected to multiple transient loads.

Ekwaro-Osire, Stephen↗
NASA NTRS1993

ASRM nozzle thermal analysis

This report describes results from the nozzle thermal analysis contract which has been performed to support NASA/Marshall Space Flight Center in the development of the Advanced Solid Rocket Motor (ASRM). The emphasis of this study has been directed to four potential problem areas of the nozzle. These areas are the submerged nozzle region containing the flex seal, the nozzle entrance region, the material interface region in the nozzle exit cone, and the aft region of the exit cone. This study was limited throughout by inadequate material response models, especially for the polyisoprene flex seal and the low density carbon phenolic used in the exit cone. Thermal response and particle erosion calculations were performed for each of the potential problem areas. Results from these studies showed excessive erosion (large negative safety margins) to occur in the flex seal and nozzle entrance regions. The exit cone was found to be marginally adequate (near zero safety margins) and the material interface region was found not to be a problem.

Strobel, Forrest↗
DOE OSTI2026

A cell-centered AMR-ALE framework for 3D multi-material hydrodynamics. Part I: Lagrangian and indirect Euler AMR algorithms

Many applications of physics and engineering involve wide ranges of time and spatial scales. The numerical simulation of localized small scales such as shock waves and material interfaces requires a large number of computational cells in these regions. For these applications, Lagrangian and Arbitrary-Lagrangian-Eulerian (ALE) related methods are engaging since the moving mesh feature naturally brings mesh cells on shock discontinuities and material interfaces are carefully captured. In addition, Adaptive-Mesh-Refinement (AMR) strategies aim to optimize computational resources by concentrating finer mesh cells only in areas of interest while using coarser cells elsewhere. A key but challenging AMR requirement consists in efficiently distributing the computational effort to achieve high accuracy without the prohibitive computational costs associated with uniformly fine grids. Here, in this document, the coupling of the p4est AMR library with a cell-centered Lagrangian scheme is presented with the goal to perform reliable 3D Lagrangian-AMR and indirect Euler-AMR multi-material simulations. In particular, it is shown that starting from a 3D indirect ALE code, the memory management and load balancing requirements can be delegated to an external library (here the p4est library) to unlock ALE-AMR capabilities. First, we present a strategy to transcribe the octant-based connectivity of the 3D AMR framework with that of an unstructured mesh of polygonal cells used in Lagrangian hydrodynamics. Then, we show how refinement and coarsening operations must be adapted to the particular Lagrangian framework to ensure the conservation of volume during those steps. Finally, several numerical test cases are presented that demonstrate the capabilities of the Lagrangian-AMR and indirect Euler-AMR algorithms.

3D cell-centered Lagrangian numerical scheme↗
NASA NTRS1985

Efficient Joints for Graphite/Epoxy Structures

Bonded joints perform well through wide temperature range. Tests indicate significant improvement in joint efficients available through geometric modifications and hybrid material additions at adherent interfaces. Material modifications consisted of placing S-glass polyimide fabric in joint between adherents. Most fabric interface specimens delaminated between two fabric plies as opposed to failing in base adherents.

Skoumal, D. E.↗
DOE OSTI2024

Editorial: Advanced in situ characterization of biological interfaces and materials

Rapid changes are occurring on this dynamic planet–in 2020 anthropogenic mass was reported to not only match but exceed the mass of natural origins (Elhacham et al., 2020). These indications do not bold well for humanity in the coming generations, as we face 2 degree overall temperature increases over the next 5 years, CO 2 is spewing into the atmosphere at the Gigatonne (Gt) rate per year without any signs of mitigation in the foreseeable future, ocean water levels are rising to incredible levels, drinking water availability is disappearing, humanity is heavily reliant on the “drill-and-fill” culture, and two wars are currently being fought in Gaza and Ukraine (Carr et al., 2024). And even with these pressures, humanity continues to eke out impressive scientific and technological achievements in the recent past including mRNA vaccines to counter a global pandemic (Hogan and Pardi, 2022) and the development of CRISPR-Cas9 drugs (Parums, 2024). All these developments are only possible from the incremental methodological improvements taking place presently.

36 MATERIALS SCIENCE↗
NASA NTRS2006

Using ABAQUS Scripting Interface for Materials Evaluation and Life Prediction

An ABAQUS script has been written to aid in the evaluation of the mechanical behavior of viscoplastic materials. The purposes of the script are to: handle complex load histories; control load/displacement with alternate stopping criteria; predict failure and life; and verify constitutive models. Material models from the ABAQUS library may be used or the UMAT routine may specify mechanical behavior. User subroutines implemented include: UMAT for the constitutive model; UEXTERNALDB for file manipulation; DISP for boundary conditions; and URDFIL for results processing. Examples presented include load, strain and displacement control tests on a single element model. The tests are creep with a life limiting strain criterion, strain control with a stress limiting cycle and a complex interrupted cyclic relaxation test. The techniques implemented in this paper enable complex load conditions to be solved efficiently with ABAQUS.

Powers, Lynn M.↗
NASA NTRS2008

Thermal Interface Comparisons Under Flight Like Conditions

Thermal interface materials are used in bolted interfaces to promote good thermal conduction between the two. The mounting surface can include panels, heat pipes, electronics boxes, etc.. . On Lunar Reconnaissance Orbiter (LRO) project the results are directly applicable: a) Several high power avionics boxes b) Several interfaces from RWA to radiator through heat pipe network

Rodriquez-Ruiz, Juan↗
NASA NTRS1993

A study of strength evaluations of EDNi/EDCu/NARloy-Z bonded joints

Dissimilar material interfaces can be found in many materials and structural bonds such as composite materials, welded parts, inclusion in matrix, bond between metallic and ceramic materials, and so forth. One of such structural bonds can be seen in the main combustion chamber (MCC) of the Space Shuttle Main Engine (SSME). In this study, from a practical sense, the primary concern is to understand the systems response of EDNi/EDCu/NARloy-Z bonded joints using stress values approximated by the finite element method to determine an influence of the variation of structural bond parameters on the bonded joints, and consequently main combustion chamber of the Space Shuttle Main Engine. The results presented in this study could be an appropriate indicator for a good bond of EDNi/DECu/NARloy-Z layers with the desired thickness of copper deposition in the SSME MCC manufacturing process. Furthermore, the results from this study appear to be applicable to any bonded joints that can be characterized by the parameters and assumptions used in this analysis.

Min, J. B.↗
DOE OSTI2025

Hydration and Restructuring of Polar Polymer Interfaces: Implications in Antifouling and Responsive Materials

Manipulating polymer interfaces is crucial for understanding how structure influences function in applications spanning biofouling prevention to energy storage. Moreover, observing how polymers adapt their microscopic structure to changes in their local environment can reveal essential properties that govern their performance in such applications, providing key insights into how to design more effective interfaces. Here, in this study, a series of “grafting-from” polymer brushes with side chains varying in charge, are probed by sum frequency generation (SFG) and modeled using all-atom molecular dynamics (MD) simulations to elucidate how chemical makeup and charge mediate interfacial restructuring in dry versus hydrated states. Results show that charge, in progressing from nonpolar to cationic to zwitterionic, results in dramatic changes in interfacial structure and overall hydration. While net neutral systems, regardless of bulk phase polarity, show minimal interfacial water structuring, the cationic species exhibits strong bulk water signals from the surface potential. Meanwhile, the polymer brushes themselves restructure in water differently independent of charge, impacting the functional groups that are presented to the aqueous phase. Nonpolar and cationic species for instance undergo a change in alkyl group orientations to accommodate hydrating water molecules, whereas the zwitterionic polymer becomes completely disordered in water. Overall, the structure-based behavior trends presented herein have implications in antifouling applications and responsive material interfaces.

biointerface↗
NASA NTRS2005

Voltage-induced broad-spectrum reflectivity change with surface-plasmon waves

Voltage-induced broad-spectrum reflectivity change with surface-plasmon waves is reported. When white light is incident at a metal/electro-optical material interface, surface-plasmon waves can be excited under phase match conditions. This surface-plasmon resonance depends on the dielectric constants of both the metal and the electro-optical material. Photons in the surface-plasmon resonance wavelength range are absorbed by the interface. Since metals have large imaginary parts of their dielectric constants, the surface-plasmon resonances are broad and may cover all visible wavelengths. Applying voltage to the electro-optical material to change its dielectric constant can result in a change in the reflectivity at the interface. Experimental results showed a reflectivity change from almost 0% to about 40% under an applied voltage using a liquid-crystal and nickel film structure, and the results had good agreement with theoretical calculations. The theoretical calculations also predicted a 90% reflectivity recovery by exciting surface-plasmon waves at a Rh-Al/electro-optical material interface. These results demonstrate that a high efficiency white light modulator can be built using surface-plasmon excitations.

white light modulator↗
NASA NTRS2001

Innovative Technologies for a Space Station Microgravity Furnace

Several Innovations were developed for a high gradient directional solidification vacuum furnace with quench capability, called the Quench Module Insert. The QMI hot zone employs advanced heater elements in a multiple zone configuration and uses a novel instrumentation approach for temperature control. A fiber interface material provides a low friction, high heat extraction interface between a reconfigurable cold zone and the science sample. The quench utilizes a metal phase change to provide rapid, resource efficient quenching of science samples. This paper provides conceptual details and performance data on these innovations.

Carswell, B.↗
NASA NTRS1990

A New Approximate Fracture Mechanics Analysis Methodology for Composites with a Crack or Hole

A new approximate theory which links the inherent flaw concept with the theory of crack tip stress singularities at a bi-material interface was developed. Three assumptions were made: (1) the existence of inherent flaw (i.e., damage zone) at the tip of the crack, (2) a fracture of the filamentary composites initiates at a crack lying in the matrix material at the interface of the matrix/filament, and (3) the laminate fails whenever the principal load-carrying laminae fails. This third assumption implies that for a laminate consisting of 0 degree plies, cracks into matrix perpendicular to the 0 degree filaments are the triggering mechanism for the final failure. Based on this theory, a parameter bar K sub Q which is similar to the stress intensity factor for isotropic materials but with a different dimension was defined. Utilizing existing test data, it was found that bar K sub Q can be treated as a material constant. Based on this finding a fracture mechanics analysis methodology was developed. The analytical results are correlated well with test results. This new approximate theory can apply to both brittle and metal matrix composite laminates with crack or hole.

Tsai, H. C.↗
DOE OSTI2025

Time-domain thermoreflectance

Time-domain thermoreflectance (TDTR) has been instrumental in measuring the heat transfer properties of bulk and nanostructured materials over the past two decades. In this Primer, we describe the optical and thermal aspects of TDTR, with an in-depth discussion on the theory, apparatus design and implementation. We present examples that illustrate the ability of TDTR to measure thermal conductivity tensors, thermal conductance across material interfaces, and volumetric heat capacity of thin films, 2D materials and bulk materials. The ability of TDTR to spatially resolve thermal properties is useful for studying heterogeneous material systems, such as materials processed in or subjected to extreme environments. We consider current limitations of pump–probe metrologies and discuss recent advancements of TDTR, such as time-resolved magneto-optic Kerr effect (TR-MOKE), beam-offset TDTR/TR-MOKE, steady-state thermoreflectance, frequency-domain thermoreflectance and laser-flash TDTR. Lastly, we present an outlook on anticipated technological developments to further expand the ability of TDTR to measure nanoscale thermal properties.

42 ENGINEERING↗
DOE OSTI2025

Low-Loss Charge Transfer Plasmons in Graphene/α-RuCl 3 Heterostructures Below 40 K

Charge transfer at material interfaces governs a wide range of physical properties, from electronic band structures to emergent collective excitations. In two-dimensional (2D) material heterostructures, charge transfer phenomena play important roles in enabling novel quantum phases, proximity effects, and tunable plasmonic responses. One representative charge transfer interface is formed between α-RuCl 3 , a van der Waals material with high electron affinity, and graphene. Significant charge transfer across this interface induces the formation of charge-transfer plasmon polaritons (CPPs), hybrid excitations between light and charge oscillations. However, previous studies found that as the charge transfer process takes place, α-RuCl 3 becomes lossy, which limits the quality factor of CPPs. Here, we investigate CPPs down to 10 K using a home-built scattering-type scanning near-field optical microscope (s-SNOM) optimized for low-temperature measurements. Our study reveals a dramatic suppression of plasmon loss channels below 40 K, contributing to a significant enhancement in the plasmonic quality factor. This reduction in loss is likely attributed to the blue shift of the correlation-induced Mott gap in α-RuCl 3 with decreasing temperature, along with the reduction of phonon scattering at low temperature. In conclusion, our results highlight the potential of using s-SNOM and CPPs to study complex 2D interfaces and reveal correlated electron dynamics in the underlying material.

36 MATERIALS SCIENCE↗
NASA NTRS2011

Thermal stir welding apparatus

A welding method and apparatus are provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

Ding, R. Jeffrey↗
NASA NTRS2012

Thermal Stir Welder

A welding apparatus is provided for forming a weld joint between first and second elements of a workpiece. The apparatus heats the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding mixer, to remove any dendritic-type weld microstructures introduced into the interface material during heating.

Ding, R. Jeffrey↗
NASA NTRS2012

Thermal stir welding process

A welding method is provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

Ding, R. Jeffrey↗
NASA NTRS2007

Rapid Fabrication of Carbide Matrix/Carbon Fiber Composites

Composites of zirconium carbide matrix material reinforced with carbon fibers can be fabricated relatively rapidly in a process that includes a melt infiltration step. Heretofore, these and other ceramic matrix composites have been made in a chemical vapor infiltration (CVI) process that takes months. The finished products of the CVI process are highly porous and cannot withstand temperatures above 3,000 F (approx.1,600 C). In contrast, the melt-infiltration-based process takes only a few days, and the composite products are more nearly fully dense and have withstood temperatures as high as 4,350 F (approx.2,400 C) in a highly oxidizing thrust chamber environment. Moreover, because the melt- infiltration-based process takes much less time, the finished products are expected to cost much less. Fabrication begins with the preparation of a carbon fiber preform that, typically, is of the size and shape of a part to be fabricated. By use of low-temperature ultraviolet-enhanced chemical vapor deposition, the carbon fibers in the preform are coated with one or more interfacial material(s), which could include oxides. The interfacial material helps to protect the fibers against chemical attack during the remainder of the fabrication process and against oxidation during subsequent use; it also enables slippage between the fibers and the matrix material, thereby helping to deflect cracks and distribute loads. Once the fibers have been coated with the interfacial material, the fiber preform is further infiltrated with a controlled amount of additional carbon, which serves as a reactant for the formation of the carbide matrix material. The next step is melt infiltration. The preform is exposed to molten zirconium, which wicks into the preform, drawn by capillary action. The molten metal fills most of the interstices of the preform and reacts with the added carbon to form the zirconium carbide matrix material. The zirconium does not react with the underlying fibers because they are protected by the interfacial material(s). The success of the melt-infiltration step depends on interface material selection and uniform coating of the fibers, infiltration with the correct amount of carbon, and careful control of temperature and rate of heating.

Williams, Brian E.↗