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At least 1,189 records · Page 66

Next-Generation Materials Design: Quantum Mechanics and Data-Driven Modeling

The future of materials design is rapidly advancing through the combination of quantum mechanics and data-driven modeling. These approaches integrate quantum principles with advanced data analysis, enabling precise insights into material behavior. This talk will highlight recent progress in using these methods for computational design, particularly in high-entropy alloy catalysts, emphasizing the role of hierarchical machine-learning architectures for accurate predictions. Additionally, I will discuss our work on developing machine learning interatomic potentials (MLPs) for single-element metals, metal oxides, and alloys under extreme conditions, focusing on melting behavior and phase properties at high temperatures and pressures. We have also refined our MLP models to capture dynamic surface interactions, such as CO2 and CO adsorption on MgO, using both static and molecular dynamics simulations. These models maintain high accuracy while significantly reducing computational costs compared to first-principles calculations. By enabling efficient and accurate simulations, this work supports broader community adoption, optimizes datasets for materials discovery, and extends the accessible time, size, and environmental conditions beyond the limits of experiments and traditional simulations.

machine learning↗

Effect on fan flow characteristics of length and axial location of a cascade thrust reverser

A series of static tests were conducted on a model fan with a diameter of 14.0 cm to determine the fan operating characteristics, the inlet static pressure contours, the fan-exit total and static pressure contours, and the fan-exit pressure distortion parameters associated with the installation of a partial-circumferential-emission cascade thrust reverser. The tests variables included the cascade axial length, the axial location of the reverser, and the type of fan inlet. It was shown that significant total and static pressure distortions were produced in the fan aft duct, and that some configurations induced a static pressure distortion at the fan face. The amount of flow passed by the fan and the level of the flow distortions were dependent upon all the variables tested.

Dietrich, D. A.↗

Explicit Finite Element Modeling of Multilayer Composite Fabric for Gas Turbine Engine Containment Systems, Phase II: Material Model Development and Simulation of Experiments - Part 3

A team consisting of Arizona State University, Honeywell Engines, Systems & Services, the National Aeronautics and Space Administration Glenn Research Center, and SRI International collaborated to develop computational models and verification testing for designing and evaluating turbine engine fan blade fabric containment structures. This research was conducted under the Federal Aviation Administration Airworthiness Assurance Center of Excellence and was sponsored by the Aircraft Catastrophic Failure Prevention Program. The research was directed toward improving the modeling of a turbine engine fabric containment structure for an engine blade-out containment demonstration test required for certification of aircraft engines. The research conducted in Phase II began a new level of capability to design and develop fan blade containment systems for turbine engines. Significant progress was made in three areas: (1) further development of the ballistic fabric model to increase confidence and robustness in the material models for the Kevlar(TradeName) and Zylon(TradeName) material models developed in Phase I, (2) the capability was improved for finite element modeling of multiple layers of fabric using multiple layers of shell elements, and (3) large-scale simulations were performed. This report concentrates on the material model development and simulations of the impact tests.

Zylon↗

Results of transonic/supersonic static stability wind tunnel tests of an 0.004-scale space shuttle orbiter model (0A49)

Experimental aerodynamic investigations of the configuration 4 space shuttle orbiter were conducted in the 14-inch trisonic wind tunnel during November and December 1973. Elevon, aileron, bodyflap, speedbrake, rudder effectiveness, and effects of ventral fins were investigated at angles of attack from -10 deg to 40 deg, angles of sideslip from -10 deg to +10 deg, and Mach numbers from 0.6 to 4.96. Resulting six-component static stability data and associated test information are presented.

Allen, E.↗

Verification of RSRM Nozzle Thermal Models With ETM-3 Aft Exit Cone In-depth Temperature Measurements

One of the goals of the Engineering Test Motor (ETM-3) static test was to verify analytical models through the use of instrumentation that provide real-time transient temperature response of ablating phenolic liners. Accurate measurement of in-depth temperature is critical for validating the analytical models and assessing design safety margins for nozzle insulation materials. Recent developments of in-depth thermocouple plugs have been made to more accurately measure temperature response of nozzle Liners. Thermocouple plugs were installed at two axial stations (four plugs circumferentially at each station) near the end of the ETM-3 nozzle aft exit cone to gather temperature histories during and after motor operation. The thermocouple plugs were placed at depths that bounded the reusable solid rocket motor nominal measured char depth in order to portray the carbon phenolic temperature response during the charring process. The data were used to verify the analytical models during motor operation and to better define char penetration during heat soak after motor burn out.

Maw, Joel F.↗

Investigation of the influence of frictional viscosity regularization on quasi-static gas-solid flow predictions in a conical spouted bed with non-porous draft tube

The stress in the quasi-static particle flow is often modeled through the Mohr-Coulomb failure criterion. In the extension to complex three-dimensional flows, a granular viscosity is introduced through a tensorial rheology and the deviatoric frictional stress tensor is assumed aligned with the strain rate tensor. This granular viscosity is singular as the shear rate approaches zero, regardless of the local rheology. We discuss the influence of regularizing such a frictional viscosity on the particle circulation rate and other measured characteristics in a laboratory scale draft tube spouted bed. Here, the friction between particles is modeled either with a constant Coulomb rheology or using a local particle pressure and strain-rate based friction known as μ ( I )-rheology. The predictions appear very dependent on the regularization parameter introduced by the method. The mean properties of the flow (e.g. circulation and pressure drop) monotonically converge towards the measurements when the regularization parameter tends to zero. In other respects, the two regularization models regarded in this study induced similar hydrodynamics within the spouted bed of interest. But the analysis of the conditional averages of the inertial number and the fraction of the solids in the quasi-static regime shows that the extent and staticity of the quasi-static region is sensitive to changes to the regularization parameter or regularization function.

36 MATERIALS SCIENCE↗

Dense granular flows with MFIX-Exa

This report extends the linear spring dashpot collision model the discrete element method available in MFIX-Exa to include static a static tangential friction force. Additionally, two rolling friction models frequently used in the literature are also implemented. The governing equations are provided with an emphasis on the new terms. The new model is validated by comparison to existing experimental data of single particle oblique collisions. The model is then tested on three dense granular flow problems: the formation of static piles, the discharge from a flat-bottom hopper and the self-induced granular Rayleigh-Taylor instability.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Static and dynamical magnetic properties of the extended Kitaev-Heisenberg model with spin vacancies

Motivated by the potential to suppress antiferromagnetic long-range order in favor of the long-sought-after Kitaev quantum spin liquid state, we study the effect of spin vacancies in the extended Kitaev-Heisenberg model. In particular, we focus on a realistic model obtained from fitting inelastic neutron scattering on α–RuCl 3 . We observe that the long-range zigzag magnetic ordered state only survives when the doping concentration is smaller than 5%. Upon further increasing the spin vacancy concentration, the ground state becomes a short-range ordered state at low temperatures. Compared with experiments, our classical solution overstabilizes the zigzag correlation in the presence of spin vacancies. Here, our theoretical results provide guidance toward interpreting inelastic neutron scattering experiments on magnetically diluted Kitaev candidate materials

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Static force tests of a sharp leading edge delta-wing model at ambient and cryogenic temperatures with a description of the apparatus employed

A sharp leading edge delta-wing model was tested through an angle-of-attack range at Mach numbers of 0.75, 0.80, and 0.85 at both ambient and cryogenic temperatures in the Langley 1/3-meter transonic cryogenic tunnel. Total pressure was varied with total temperature in order to hold test Reynolds number constant at a given Mach number. Agreement between the aerodynamic data obtained at ambient and cryogenic temperatures indicates that flows with leading-edge vortex effects are duplicated properly at cryogenic temperatures. The test results demonstrate that accurate aerodynamic data can be obtained by using conventional force-testing techniques if suitable measures are taken to minimize temperature gradients across the balance and to keep the balance at ambient (warm) temperatures during cryogenic operation of the tunnel.

Kilgore, R. A.↗

Subsonic longitudinal and lateral-directional static aerodynamic characteristics for a close-coupled wing-canard model in both swept back and swept forward configurations

A general research fighter model was tested in the Langley 7 by 10-foot high speed tunnel at a Mach number of 0.3. The close-coupled wing-canard combination was tested with both lifting surfaces in a 60 deg swept back configuration and in a 32 deg swept forward configuration. The angle-of-attack range was from approximately -4 deg to 48 deg at sideslip angles of zero deg, -5 deg. The data is presented without analysis in order to expedite publication.

Huffman, J. K.↗