Dynamic model investigation of water pressures and accelerations encountered during landings of the Apollo spacecraft
Apollo spacecraft landing simulation to determine impact water pressures, accelerations, and landing dynamics
SPACECRAFT LANDING↗
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Results for “Impact testing”
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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Engineering Mechanics Division
Screening methods for metal oxide semiconductor field effect transistors and resistors, impact survival testing of spacecraft electronic parts, and parachute jettisoning from planetary capsules
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ITOS/space shuttle study
The results are reported of a study to explore the potential cost reductions in the operational ITOS weather satellite program as a consequence of shuttle/bug availability for satellite placement and retrieval, and satellite servicing and maintenance. The study program was divided into shuttle impact on equipment and testing costs, and shuttle impact on overall future ITOS operational program costs, and shuttle impact on configuration. It is concluded that savings in recurring spacecraft costs can be realized in the 1978 ITOS program, if a space shuttle is utilized.
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Simulated meteoroid penetration of reusable surface insulation
Meteoroid impact simulation test results on insulation tiles were used to determine penetration resistance of reusable surface insulation attached to simulated shuttle structures. The probability of no meteoroid damage to a typical shuttle orbiter was determined. Specimens were plasma jet tested to determine effects of various size meteoroid cavities on their thermal performance. None of the tiles failed catastrophically, but large, egg-shaped craters did result from meteoroid penetration. The metallic side of a specimen that was completely penetrated showed a petalled hole typical for thin gage shielded structures.
Lehman, J. K.↗
Pin puller impact shock attenuation
Design of a pin arresting mechanism for a pyrotechnically actuated pin puller is reviewed. The investigative approach is discussed and the impact shock test results for various candidate designs are presented. The selected pin arresting design reduced the peak value of the shock response spectrum by five to one.
Auclair, G. F.↗
The impact of CFD on development test facilities - A National Research Council projection
The results of a National Research Council study on the effect that advances in computational fluid dynamics (CFD) will have on conventional aeronautical ground testing are reported. Current CFD capabilities include the depiction of linearized inviscid flows and a boundary layer, initial use of Euler coordinates using supercomputers to automatically generate a grid, research and development on Reynolds-averaged Navier-Stokes (N-S) equations, and preliminary research on solutions to the full N-S equations. Improvements in the range of CFD usage is dependent on the development of more powerful supercomputers, exceeding even the projected abilities of the NASA Numerical Aerodynamic Simulator (1 BFLOP/sec). Full representation of the Re-averaged N-S equations will require over one million grid points, a computing level predicted to be available in 15 yr. Present capabilities allow identification of data anomalies, confirmation of data accuracy, and adequateness of model design in wind tunnel trials. Account can be taken of the wall effects and the Re in any flight regime during simulation. CFD can actually be more accurate than instrumented tests, since all points in a flow can be modeled with CFD, while they cannot all be monitored with instrumentation in a wind tunnel.
Korkegi, R. H.↗
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.↗
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.↗
Utilization of satellite data in mesoscale modeling of severe weather
The Visible Infrared Spin Scan Radiometer Atmospheric Sounder (VAS) data were used to model the 36 hour cyclogenesis period over the Pacific Ocean. Various combinations of VAS data, conventional radiosonde data, and gridded data from the National Weather Service global analysis were used in successive-correction and variational objective-analysis procedures. The Penn State/NCAR mesoscale model was used to test the impact of the VAS data on a 12 hour forecast of convective precipitation in the midweastern U.S.
Warner, Thomas T.↗
APSA - A new generation of photovoltaic solar arrays
This paper provides details on the Advanced Photovoltaic Solar Array (APSA) wing design, fabrication, and testing. The impact of array size change on performance and mechanical characteristics is discussed. Projections for future performance enhancements that may be expected through the use of advanced solar cells presently under development are examined.
Stella, P. M.↗
Radar observations of orbital debris at NASA Johnson Space Center
This paper describes the original Debris Environment Characterization Radar concept and the design verification experiments developed and carried out with the purpose of establishing methods for assessing the hazards to the Space Station Freedom from radar measurements. Three design verification experiments, utilizing the Arecibo, the Goldstone, and the ALCOR radars were performed. Data obtained from RCS measurements of a representative sample of debris from ground-test hypervelocity impacts and from explosions of simulated satellites will be used to establish a relationship between the physical size of a randomly shaped debris object and its RCS.
Stansbery, E. G.↗
Notch sensitivity of hydrogenated oxygen-strengthened titanium
While earlier studies have shown that the tensile properties and fracture test intensity factors of oxygen-strengthened Ti remain nearly unaffected by the presence of about 70 ppm (weight) hydrogen, the Charpy V-notch test-determined impact properties of oxygen-bearing Ti are strongly affected by the presence of hydrogen. The present study establishes that, concurrently with the strengthening effect of oxygen, there is a substantial lowering of ductility. The presence of hydrogen has virtually no effect on the notch strength of Ti alloys of either low or high oxygen content, where hydrogen contents lie in the 25-80 range.
Wasz, M. L.↗
Whipple shield sizing equations
Wipple shield sizing equations are given for use in current Space Station Freedom (SSF) Work Package 2 (WP-2) trade study activities. These equations are modifications of the 1969 Cour-Palais predictor equations which were used by McDonnell Douglas to size WP-2 meteoroid and debris shielding for the SSF preliminary design review. Recent hypervelocity impact (HVI) test results have shown that the original 1969 Cour-Palais predictor improperly scales to the particle sizes that the WP-2 shields must be designed to protect against. The original equations have been redesigned to correct this scaling deficiency. Substantial increases to WP-2 shielding weight estimates are indicated by the modified equations. Several possibilities exist, however, to reduce the weight of WP-2 shielding. These equations will be updated in the future as warranted by the results of ultra-high speed (greater than 19 km/sec) HVI tests and further analysis.
Christiansen, Eric L.↗
A multi-shock concept for spacecraft shielding
A spacecraft-shielding technique is investigated in which the geometrical configuration and material used are emphasized. Ultrathin spaced shield elements are employed to repeatedly shock the impacting projectile to a high energy state that causes melting and vaporization. The ratio of the thickness of the elements to projectile diameter corresponds to a relatively small percentage of debris-plume mass that can be withstood by the backsheet. The strength of the backsheet is thereby reduced and employed in a specific configuration that prevents the debris plume from destroying successive sheets before the particulates reach the sheet. The primary benefit is weight reduction of 30 percent when compared to a 'Whipple shield' fabricated with the same material. The concept is shown to be effective against all impact types tested and produces minimal secondary debris.
Cour-Palais, Burton G.↗
Compression response of thick layer composite laminates with through-the-thickness reinforcement
Compression and compression-after-impact (CAI) tests were conducted on seven different AS4-3501-6 (0/90) 0.64-cm thick composite laminates. Four of the seven laminates had through-the-thickness (TTT) reinforcement fibers. Two TTT reinforcement methods, stitching and integral weaving, and two reinforcement fibers, Kevlar and carbon, were used. The remaining three laminates were made without TTT reinforcements and were tested to establish a baseline for comparison with the laminates having TTT reinforcement. Six of the seven laminates consisted of nine thick layers whereas the seventh material was composed of 46 thin plies. The use of thick-layer material has the potential for reducing structural part cost because of the reduced part count (layers of material). The compression strengths of the TTT reinforced laminates were approximately one half those of the materials without TTT reinforcements. However, the CAI strengths of the TTT reinforced materials were approximately twice those of materials without TTT reinforcements. The improvement in CAI strength is due to an increase in interlaminar strength produced by the TTT reinforcement. Stitched laminates had slightly higher compression and CAI strengths than the integrally woven laminates.
Farley, Gary L.↗
Predicting ground level impacts of solid rocket motor testing
Beginning in August of 1988 and continuing until the present, NASA at Stennis Space Center, Mississippi has conducted environmental monitoring of selected static test firings of the solid rocket motor used on the Space Shuttle. The purpose of the study was to assess the modeling protocol adapted for use in predicting plume behavior for the Advanced Solid Rocket Motor that is to be tested in Mississippi beginning in the mid-1990's. Both motors use an aluminum/ammonium perchlorate fuel that produces HCl and Al2O3 particulates as the major combustion products of concern. A combination of COMBUS.sr and PRISE.sr subroutines and the INPUFF model are used to predict the centerline stabilization height, the maximum concentration of HCl and Al2O3 at ground level, and distance to maximum concentration. Ground studies were conducted to evaluate the ability of the model to make these predictions. The modeling protocol was found to be conservative in the prediction of plume stabilization height and in the concentrations of the two emission products predicted.
Douglas, Willard L.↗
Structural Damage Prediction and Analysis for Hypervelocity Impact. UDRI Light Gas Gun Test Data Summaries
The HEX bumper was originally developed for use with the Defensive Shields Demonstration (DSD) Program. The University of Dayton Research Institute was a subcontractor to the Martin Marietta Astronautics Group in Denver Colorado at the time the HEX bumper was designed for use on the DSD Program. The design originated at the University and was essentially made available to interested parties. All HEX bumpers used in the DSD Program were fabricated at the University by rolling sheet stock through a special set of rollers. Two pieces of 3003-H14 aluminum sheet were rolled to produce the bumpers evaluated in Shots 4-1302 and 4-1304. A brief summary of the results of these tests is given in below. Contact prints of the multiple-exposure, orthogonal view radiographs of the debris clouds produced by the tests are attached. A sketch of the HEX bumper design is also attached.
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Numerical Simulation of the Water Cycle Change Over the 20th Century
We have used numerical models to test the impact of the change in Sea Surface Temperatures (SSTs) and carbon dioxide (CO2) concentration on the global circulation, particularly focusing on the hydrologic cycle, namely the global cycling of water and continental recycling of water. We have run four numerical simulations using mean annual SST from the early part of the 20th century (1900-1920) and the later part (1980-2000). In addition, we vary the CO2 concentrations for these periods as well. The duration of the simulations is 15 years, and the spatial resolution is 2 degrees. We use passive tracers to study the geographical sources of water. Surface evaporation from predetermined continental and oceanic regions provides the source of water for each passive tracer. In this way, we compute the percent of precipitation of each region over the globe. This can also be used to estimate precipitation recycling. In addition, we are using the passive tracers to independently compute the global cycling of water (compared to the traditional, Q/P calculation).
Bosilovich, Michael G.↗