Atomistic-level simulation of the vibration spectrum of quantum dot crystals
Quantum dot crystal structures (QDCs) have been recently proposed as the building blocks of novel thermoelectric devices.
phonons↗
SEARCH · Engineering Papers
Results for “VIBRATION SIMULATOR”
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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Application of ground test acoustic simulations of liftoff and transonic vibration to actual Ranger flight vibration data
Ground test acoustic simulation of liftoff and transonic vibration applied to Ranger flight vibration data
RANGER PROJECT↗
Extrapolating Dynamic Transfer Functions from Multiple-Input Multiple-Output Vibration Testing and Simulation (EDTF) [Slides]
Abstract not provided.
42 ENGINEERING↗
Experimental investigation of the longitudinal vibration of a representative launch vehicle with simulated propellants
Longitudinal vibration of full scale representative launch vehicle by means of force controlled vibration techniques
Clary, R. R.↗
Direct simulation with vibration-dissociation coupling
Explore the source record for details and available documents.
Hash, David B.↗
TECHNIQUES FOR SIMULATION AND ANALYSIS OF SHOCK AND VIBRATION ENVIRONMENTS OF SPACE FLIGHT SYSTEMS
Simulation and analysis of shock and vibration environments in space-flight systems
SHOCK SIMULATOR↗
Models for direct Monte Carlo simulation of coupled vibration-dissociation
A new model for reactive collisions is developed within the framework of a particle method, which simulates coupled vibration-dissociation (CVD) behavior in high-temperature gases. The fundamental principles of particle simulation methods are introduced with particular attention given to the probability functions employed to select thermal and reactive collisions. Reaction probability functions are derived which favor vibrationally excited molecules as reaction candidates. The new models derived here are used to simulate CVD behavior during thermochemical relaxation of constant-volume O2 reservoirs, as well as the dissociation incubation behavior of postshock N2 flows for comparisons with previous models and experimental data.
Haas, Brian L.↗
Evaluation of the Barracuda Software Package for Simulating Bubble Motion in Vibrating Liquid-Filled Containers
The commercial software package Barracuda, developed by CPFD Software for simulating particle-laden fluid flows, is evaluated as a means to simulate the motion of bubbles in vibrating liquid-filled containers. Demonstration simulations of bubbles rising due to buoyancy forces in a cylinder filled with silicone oil and angled at 0, 30, 45, and 60 degrees from the vertical were performed by CPFD Software. The results of these simulations are discussed, and the capabilities of Barracuda for simulating bubble motion are assessed. It was determined that at present Barracuda does not meet the needs of the desired application. Further developments that would enable its use for this application are highlighted.
42 ENGINEERING↗
A theoretical basis for mechanical impedance simulation in shock and vibration testing of one-dimensional systems
Feasibility of mechanical impedance control and simulation in shock and vibration testing of one-dimensional structures
VIBRATION TESTING↗
Bubble dynamics in vibrated liquids under normal and simulated low gravity environments
Bubble dynamics in vibrated liquids under normal and simulated low gravity environments
DYNAMICS↗
Laboratory simulation of the combined acoustic-vibration environment of launch vehicle onboard electronic equipment.
Simulation of noise and vibration for testing electronic equipment on launch vehicles
LAUNCH VEHICLE↗
Development of impedance simulation fixtures for spacecraft vibration tests
Vibration test fixture design for mount impedance simulation of aerospace structures
Soharton, T. D.↗
Direct simulation of rotational and vibrational nonequilibrium
The ways in which energy transfer is calculated in the Direct Simulation Monte Carlo method are presented. An energy exchange model that deals with translational and rotational modes is described. A model for simulating the transfer of energy between the translational and vibrational modes is presented as well.
Boyd, Iain D.↗
Three-dimensional random vibration testing definition and simulation
An approach is presented for the definition of 3D random vibration test requirements for multiaxial shaker systems. In particular, it is shown that, by utilizing coherence functions for cross-correlation effects, test requirements can be defined in a simple way and provide a more realistic environmental simulation. The method is applicable to the simulation of all field environments and can be similarly employed to develop laboratory test requirements based on field data. Example problems are presented to demonstrate the approach.
Chang, Kurng Y.↗
Feasibility of the LAMMPS SPH Package for Simulating Bubble Motion in Vibrating Containers
The Smoothed Particle Hydrodynamics (SPH) package within LAMMPS is explored as a possible tool for simulating the motion of bubbles in a vibrating liquid-filled container. As an initial test case, the unphysical but computationally less intense situation of a two-dimensional single bubble rising in a quiescent liquid under the influence of gravity is considered herein. Although physically plausible behavior was obtained under certain conditions, this behavior depends strongly on the system parameters. Moreover, the large density ratio between the liquid and bubble requires extremely small timesteps, which make the simulations undesirably computationally expensive. Ultimately, it was determined that this method is not feasible for providing quantitatively accurate results for the desired application.
42 ENGINEERING↗
TECHNIQUES FOR SIMULATION AND ANALYSIS OF SHOCK AND VIBRATION ENVIRONMENTS OF SPACE FLIGHT SYSTEMS
Simulation & analysis of shock & vibration environments of space flight systems
SHOCK↗
Quasiclassical sampling and Wigner sampling of initial vibrational coordinates and momenta for polyatomic molecules in Monte Carlo molecular dynamics simulations
In a quasiclassical trajectory simulation, the vibrational modes are initialised with quantised vibrational energies, but vibrational phases are sampled by Monte Carlo. This requires an algorithm to assign coordinates and momenta to the various atoms. In this work, we present two methods for implementing this for nonrotating polyatomic molecules, namely, fixed-energy vibrational-state-selected initial conditions and thermal initial conditions. We also present a method for initiating classical trajectories with a ground-state Wigner distribution. These vibrational treatments are sufficient to initialise trajectories for unimolecular processes, and we also show how they can be applied to simulate bimolecular collision processes. The treatments of unimolecular and bimolecular collision processes are available in two Python codes called wigner_state_selected.py and bimolecular_collision.py, respectively, which will generate initial condition files that are recognisable by the SHARC and SHARC-MN computer programs for dynamics calculations. Both codes are available as standalone programs, as well as being included in SHARC-MN, and they will be included in future versions of SHARC. Here, the methods implemented in these codes are mostly also available in the ANT computer program, and those that are not available in ANT will be incorporated in future versions of ANT.
Wigner distribution↗
Modification Of Gear Teeth To Reduce Vibrations
Computer simulations yield data useful in designing for low noise. Effects of modifications in shape of gear teeth upon static transmission error and dynamic loading of gears now analyzed systematically. Design curves generated by conducting numerical simulations of dynamic effects at successive incremental modifications of gear systems operated at various applied loads. Modifications that result in minimum dynamic effect determined from design curves.
Townsend, Dennis P.↗