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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 NTRS1985

Impact dynamics research on composite transport structures

The experimental and analytical efforts being undertaken to investigate the response of composite and aluminum structures under crash loading conditions were reviewed. A Boeing 720 airplane was used in the controlled-impact demonstration test. Energy absorption of composite materials, the tearing of fuselage skin panels, the friction and abrasion behavior of composite skins, and the crushing behavior and dynamic response of composite beams were among the topics addressed.

Carden, H. D.↗
NASA NTRS2005

Dynamics Impact Tolerance of Shuttle RCC Leading Edge Panels Using LS-DYNA

This paper describes a research program conducted to enable accurate prediction of the impact tolerance of the shuttle Orbiter leading-edge wing panels using physics-based codes such as LS-DYNA, a nonlinear, explicit transient dynamic finite element code. The shuttle leading-edge panels are constructed of Reinforced-Carbon-Carbon (RCC) composite material, which is used because of its thermal properties to protect the shuttle during reentry into the Earth's atmosphere. Accurate predictions of impact damage from insulating foam and other debris strikes that occur during launch required materials characterization of expected debris, including strain-rate effects. First, analytical models of individual foam and RCC materials were validated. Next, analytical models of foam cylinders impacting 6- in. x 6-in. RCC flat plates were developed and validated. LS-DYNA pre-test models of the RCC flat plate specimens established the impact velocity of the test for three damage levels: no-detectable damage, non-destructive evaluation (NDE) detectable damage, or visible damage such as a through crack or hole. Finally, the threshold of impact damage for RCC on representative Orbiter wing panels was predicted for both a small through crack and for NDE-detectable damage.

Fasanella, Edwin L.↗
NASA NTRS2008

Dynamic Impact Tolerance of Shuttle RCC Leading Edge Panels using LS-DYNA

This paper describes a research program conducted to enable accurate prediction of the impact tolerance of the shuttle Orbiter leading-edge wing panels using 'physics-based- codes such as LS-DYNA, a nonlinear, explicit transient dynamic finite element code. The shuttle leading-edge panels are constructed of Reinforced-Carbon-Carbon (RCC) composite material, which issued because of its thermal properties to protect the shuttle during re-entry into the Earth's atmosphere. Accurate predictions of impact damage from insulating foam and other debris strikes that occur during launch required materials characterization of expected debris, including strain-rate effects. First, analytical models of individual foam and RCC materials were validated. Next, analytical models of individual foam cylinders impacting 6-in. x 6-in. RCC flat plates were developed and validated. LS-DYNA pre-test models of the RCC flat plate specimens established the impact velocity of the test for three damage levels: no-detectable damage, non-destructive evaluation (NDE) detectable damage, or visible damage such as a through crack or hole. Finally, the threshold of impact damage for RCC on representative Orbiter wing panels was predicted for both a small through crack and for NDE-detectable damage.

Fasanella, Edwin↗
DOE OSTI2020

In-situ X-ray Evaluation of Traumatic Brain Injury Dynamic Impacts (Final Report)

The goal of this project was to create an in-situ model of traumatic brain injury that allows for analysis of chronic traumatic encephalopathy (CTE) development. CTE is a neurodegenerative disease that occurs as a result of traumatic brain injuries. The resulting neurodegeneration and atrophying of cortical brain tissue develop as tau proteins build-up around small blood vessels and at the base of cortical sulci. Aggregation of tau proteins results in blood vessel damage and neurological function loss, leading to cortical tissue atrophy. This occurs only at some neuronal junctions in the brain after trauma. It has been conjectured that the geometrical distribution of force along neurons is responsible for initiation of tau deposition. However, to assess the validity of this proposition, it is necessary to analyze the mechanical response under dynamic loading associated with brain trauma in-situ

42 ENGINEERING↗
DOE OSTI2023

Turbulence characteristics and flow dynamics impacts on the H-mode transition in favourable magnetic geometry with lower power threshold

We report the L-H transition power threshold (P LH ) in favourable magnetic geometry (ion ∇B drift pointing towards X-point) is much lower than in the unfavourable magnetic geometry (ion ∇B drift pointing away from X-point) on multiple tokamaks. In a systematic experiment on DIII-D, the ion ∇B drift direction was changed continuously from the unfavourable to favourable configuration during plasma discharges. During such process, the input neutral beam power was kept constant at a value that was above P LH for favourable configuration, but lower than P LH for unfavourable configuration. Toroidal field and plasma current were also kept constant and there was little change in the edge electron density ne and electron temperature T e profiles. The density fluctuation amplitude was reduced approaching the transition, while a large increase of turbulence Reynolds stress and flow shear were simultaneously observed. The turbulence decorrelation rate was found to increase as the ion ∇B drift direction was moving towards the favourable configuration, but the flow shear also increased and exceeded the turbulence decorrelation rate. These measurements demonstrate an important correlation between turbulence and turbulence-driven flow and a lowering of PLH, provide insights into the underlying physics behind the hidden parameters and inform a more complete physics-based model of the L-H transition power threshold.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Explicit Dynamic Impact Analysis of the Building 3525 Packages

This report describes the methodology used for the safety basis analysis of the Building (Bldg.) 3525 casks and presents preliminary results for a selected geometry. The specific problem analyzed is a free fall load case onto an unyielding target at various orientations. The various orientations were analyzed to ensure that the packages were subjected to the orientation that causes the most damage. The analysis approach, material modeling, finite element modeling, and results for the selected case are presented, along with a brief discussion of conservatism and uncertainties. The results for the analyzed load cases show that through selected administrative controls, no breach of the container or loss of shielding will occur in the package.

42 ENGINEERING↗
NASA NTRS1982

Data acquisition system for NASA LaRC impact dynamics research facility

A data system is designed to permit the simultaneous recording of 90 data channels on one 28 track magnetic tape recorder using a constant bandwidth FM multiplexing technique. Dynamic signals from transducers located in the test aircraft are amplified and fed to voltage controlled oscillators where they are converted to discrete FM signals. The signals from each group of five VCO's are fed to a mixer/distribution amplifier where they are combined into one composite signal and recorded, using direct recording techniques, on one magnetic tape recorder track. Millivolt signals from the recorders reproduce heads are amplified to one volt and then electronically switched to an FM demultiplexing system where appropriate frequency discrimination and signal filtering recover the original analog information.

Mccormick, R. F.↗
NASA NTRS1998

Prediction of Dynamical Impact of Changes in Stratospheric Ozone

Under this grant one paper by Lou et al and a second paper by Kindler et al is in journal. These papers both describe N2O simulations using UKMO and Goddard assimilated wind fields and comparisons of the results against CLAES N2O observations. The results of these studies indicate some of the difficulties of using the assimilated wind fields, and the vertical motions in particular, in simulating long term variations in trace gases in the stratosphere. On the other hand, qualitatively the results possess a number of features of the observations even on time scales longer than a month or two. More recently we have started to examine results obtained using NCAR models a 3D version of which also uses the UKMO assimilated wind fields. Calculations have already been made with their 2D model with emphasis on the seasonal cycle in ozone at high latitudes in the upper stratosphere. Simultaneously trends in stratospheric ozone have been studied in detail from SAGE and UARS observations. Moreover, observations of the trends since 1984 do not show a significant interhemispheric asymmetry in upper stratospheric ozone. Therefore any asymmetry in the trends must have occurred prior to the mid-eighties and would most likely have been related to interhemispheric differences in upper stratospheric temperature trends. Another activity has been to compile an ozone climatology from UARS and SAGE observations. This effort has been performed as part of a UARS team activity to assemble a climatology of all the UARS long-lived trace gases for 1992-1993.

Cunnold, Derek M.↗
NASA NTRS2003

Application of Probabilistic Analysis to Aircraft Impact Dynamics

Full-scale aircraft crash simulations performed with nonlinear, transient dynamic, finite element codes can incorporate structural complexities such as: geometrically accurate models; human occupant models; and advanced material models to include nonlinear stressstrain behaviors, laminated composites, and material failure. Validation of these crash simulations is difficult due to a lack of sufficient information to adequately determine the uncertainty in the experimental data and the appropriateness of modeling assumptions. This paper evaluates probabilistic approaches to quantify the uncertainty in the simulated responses. Several criteria are used to determine that a response surface method is the most appropriate probabilistic approach. The work is extended to compare optimization results with and without probabilistic constraints.

Lyle, Karen H.↗
NASA NTRS2009

Developing Soil Models for Dynamic Impact Simulations

This paper describes fundamental soils characterization work performed at NASA Langley Research Center in support of the Subsonic Rotary Wing (SRW) Aeronautics Program and the Orion Landing System (LS) Advanced Development Program (ADP). LS-DYNA(Registered TradeMark)1 soil impact model development and test-analysis correlation results are presented for: (1) a 38-ft/s vertical drop test of a composite fuselage section, outfitted with four blocks of deployable energy absorbers (DEA), onto sand, and (2) a series of impact tests of a 1/2-scale geometric boilerplate Orion capsule onto soil. In addition, the paper will discuss LS-DYNA contact analysis at the soil/structure interface, methods used to estimate frictional forces, and the sensitivity of the model to density, moisture, and compaction.

Fasanella, Edwin L.↗
NASA NTRS2012

Modern Warfare: An M and S Examination of the Dynamic Impact of Warlords and Insurgents on State Stability

9/11 changed the world as we knew it. Part of this change was to redirect the military of the United States away from focusing primarily on conventional conflict to a primary focus on unconventional or irregular conflict. This change required a tremendous learning effort by the military and their supporting research and development community. This learning effort included relearning of old but largely forgotten lessons as well as acquiring newly discovered knowledge. During the process of our immediate 9/11 response, we identified that we were engaged in Iraq and Afghanistan in an insurgency. Subsequently, our focus converged upon the description of insurgencies and the requirements for counterinsurgency. This paper argues that emerging conditions now allow the re-evaluation of the type of conflict occurring today and into the foreseeable future: that we, including the modeling and simulation world, emerge from a singular focus on orthodox insurgencies and start to consider the consequences and opportunities of the complexity of current conflicts. As an example of complexity, this paper will use the relatively common phenomenon of the Warlord or Warlordism. The paper will provide a definition of this phenomenon and then describe the implications for modelers. The paper will conclude by demonstrating the impact of incorporating this one rather prosaic complexity into an insurgency model, using agent based modeling (ABM).

Jones, Phillip N.↗
NASA NTRS2018

NASA ACC High Energy Dynamic Impact Methodology and Outcomes

High fidelity analysis methods known as Progressive Damage Analysis (PDA) methods, capable of reliably predicting the onset and progression of damage in composite materials, are being developed for HEDI event simulation. Four state-of-the-art PDA methods are being investigated: LS-DYNA MAT162, LS-DYNA MAT261, Smooth-Particle Galerkin (SPG), and EMU Peridynamics. Validation of these PDA models aims to follow a building block approach, starting with coupon- and component-level development. As part of the overall effort, material characterization testing was performed to bridge gaps between existing experimental data and the material property inputs required to predict ballistic impact behavior at the component-level. The material models were updated with the results of the coupon-level testing and were then used to predict panel behavior and damage in ballistic impact events. To assess the accuracy of the PDA methods, these pre-test predictions were compared to the results of ballistic impact testing.

Hunziker, Kenneth J.↗
NASA NTRSDate not supplied

On Dynamical Impacts on Stratospheric Water Vapor Trends Above Boulder, Colorado

Long-term stratospheric water vapor (SWV) trends above Boulder, CO, (40°N, 255°E) are generally positive and slightly larger than those for zonal average SWV. This study finds a slight enhancement for SWV at 31.6 hPa above Boulder from middle February through March 1979, as seen in the satellite dataset from the LIMS instrument. That excess of SWV correlates well with air in the polar vortex that underwent an elongation and splitting in middle February following a final stratospheric warming event. Zonal wave-2 events tend to occur in late winter, but not every year. Such aperiodic variations in data time series of SWV may affect the fitting of its linear trend term.

Ellis Remsberg↗
NASA NTRSDate not supplied

On Dynamical Impacts on Stratospheric Water Vapor Trends Above Boulder, Colorado

Long-term stratospheric water vapor (SWV) trends above Boulder, CO, (40°N, 255°E) are generally positive and slightly larger than those for zonal average SWV. This study finds a slight enhancement for SWV at 31.6 hPa above Boulder from middle February through March 1979, as seen in the satellite dataset from the LIMS instrument. That excess of SWV correlates well with air in the polar vortex that underwent an elongation and splitting in middle February following a final stratospheric warming event. Zonal wave-2 events tend to occur in late winter, but not every year. Such aperiodic variations in data time series of SWV may affect the fitting of its linear trend term.

Ellis Remsberg↗