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Results for “Shock sensitivity”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Shock Sensitivity of energetic materials

Viscoplastic deformation is examined as the principal source of hot energy. Some shock sensitivity data on a proposed model is explained. A hollow sphere model is used to approximate complex porous matrix of energetic materials. Two pieces of shock sensitivity data are qualitatively compared with results of the proposed model. The first is the p2 tau law. The second is the desensitization of energetic materials by a ramp wave applied stress. An approach to improve the model based on experimental observations is outlined.

Kim, K.↗
NASA NTRS1980

The NOL Gap Test: Past, present, and future

A brief history of the development of the gap test is presented with emphasis on accumulated knowledge of how best to use it as a tool to assess relative shock sensitivity of explosives and propellants. Present information about the detonation process in build-up, steady state, and failure is used to show that failure diameter cannot give the desired shock sensitivity assessment. Suggestions are made for improving the test to an experiment. The use of spherical donors, water as attenuator, and camera instrumentation are briefly discussed.

Jacobs, S. J.↗
NASA NTRS2016

Development of Multi-Physics Dynamics Models for High-Frequency Large-Amplitude Structural Response Simulation

An analytic approach is demonstrated to reveal potential pyroshock-driven dynamic effects causing power losses in the Thermo-Electric (TE) module bars of the Mars Science Laboratory (MSL) Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). This study utilizes high-fidelity finite element analysis with SIERRA/PRESTO codes to estimate wave propagation effects due to large-amplitude suddenly-applied pyro shock loads in the MMRTG. A high fidelity model of the TE module bar was created with approximately 30 million degrees-of-freedom (DOF). First, a quasi-static preload was applied on top of the TE module bar, then transient tri-axial acceleration inputs were simultaneously applied on the preloaded module. The applied input acceleration signals were measured during MMRTG shock qualification tests performed at the Jet Propulsion Laboratory. An explicit finite element solver in the SIERRA/PRESTO computational environment, along with a 3000 processor parallel super -computing framework at NASA AMES, was used for the simulation. The simulation results were investigated both qualitatively and quantitatively. The predicted shock wave propagation results provide detailed structural responses throughout the TE module bar, and key insights into the dynamic response (i.e., loads, displacements, accelerations) of critical internal spring/piston compression systems, TE materials, and internal component interfaces in the MMRTG TE module bar. They also provide confidence on the viability of this high-fidelity modeling scheme to accurately predict shock wave propagation patterns within complex structures. This analytic approach is envisioned for modeling shock sensitive hardware susceptible to intense shock environments positioned near shock separation devices in modern space vehicles and systems.

Shock Waves↗
NASA NTRS2010

Ignition-and-Growth Modeling of NASA Standard Detonator and a Linear Shaped Charge

The main objective of this study is to quantitatively investigate the ignition and shock sensitivity of NASA Standard Detonator (NSD) and the shock wave propagation of a linear shaped charge (LSC) after being shocked by NSD flyer plate. This combined explosive train was modeled as a coupled Arbitrary Lagrangian-Eulerian (ALE) model with LS-DYNA hydro code. An ignition-and-growth (I&G) reactive model based on unreacted and reacted Jones-Wilkins-Lee (JWL) equations of state was used to simulate the shock initiation. Various NSD-to-LSC stand-off distances were analyzed to calculate the shock initiation (or failure to initiate) and detonation wave propagation along the shaped charge. Simulation results were verified by experimental data which included VISAR tests for NSD flyer plate velocity measurement and an aluminum target severance test for LSC performance verification. Parameters used for the analysis were obtained from various published data or by using CHEETAH thermo-chemical code.

Oguz, Sirri↗
NASA NTRS1986

JPL pyro shock test approaches and results

This paper presents the overall approach at JPL in performing spacecraft pyrotechnic shock qualification testing. Initially, the assembly shock requirements are developed early in the program based on previous spacecraft test experience and data. Pyrotechnic device development testing firings and spacecraft Development Test Model (DTM) pyro firings are then conducted to verify the adequacy of the assembly shock requirements and to determine the subsystem test firing and the subsequent system level test firing requirements. The electro-dynamic shaker, through shock synthesis techniques, is utilized to qualify the shock sensitive flight equipment with margins applied. Actual pyrotechnic device firings on spacecraft equipment or science instruments are performed when the influence of the pyros is localized and can be ignored at the system level. Full spacecraft system level shock tests, which include multiple firings of certain critical pyro devices, are conducted to verify the spacecraft design structural integrity and functions as well as to qualify hardware items which have not been previously qualified. These tests also provide a source of data from which assembly level requirements can be evaluated and compared. For example, during the Galileo program, the results demonstrated that good agreement between predicted and measured shock environments and adequate qualification of the flight spacecraft was achieved.

Chang, Kurng Y.↗
NASA NTRS1980

What's wrong with the NOL card gap test?

The card gap test, originally developed for explosives, was adopted for determining the shock sensitivity of propellants. Testing solid propellants resulted in the discovery of several deficiencies in the test. The effects of critical diameter, donor pulse duration, and initiator variability are discussed. Reproducibility of results is shown to be worse for solid propellants than is reported for explosives. The calibration to express test results as shock pressure is of questionable accuracy. Use of the test in its present form leads to erroneous conclusions.

Brown, B.↗
NASA NTRS1962

STABILITY TESTS OF MONOPROPELLANTS EXPOSED TO FLAMES AND RIFLE FIRE

Tests of the stability of several monopropellants under the effects of impact and heat were conducted in order to assess the potential hazard in a propellant storage area from major fires and enemy attack. Hydrazine, hydrazine nitrate solution, n-propyl nitrate, and ethylene oxide were all tested in one-gallon aluminum containers (half of them filled to 25% and half to 95% capacity) by being subjected to oil bonfires and wood bonfires, and 20-mm incendiary, 20mm high explosive incendiary, and .30-caliber rifle fire. Aviation gasoline was tested in the same manner, for comparison. In the bonfire tests, all four monopropellants generally gave explosion intensities equivalent to one another regardless of the type of bonfire (oil or wood) or the amount of liquid in the test container. Occasionally, however, with hydrazine, hydrazine nitrate solution, and n-propyl nitrate, anomalous results occurred: there was either (a) no explosion or (b) an explosion of above average intensity. Ethylene oxide more nearly approximated the behavior of aviation gasoline than did the other monopropellants. In the rifle-fire tests, n-propyl nitrate appeared to be most shock- sensitive since it was exploded by all three types of ammunition. Hydrazine and hydrazine nitrate solution were exploded by the high-explosive ammunition, but not by the incendiary or .30-dber ammunition. Ethylene oxide was not exploded by any of the gunfire, but the liquid was ignited by both incendiary and high-explosive incendiary ammunition.

FIRING↗
NASA NTRS1983

forced overdischarge related safety aspects of Li/SO2 and Li/SOCl2 cells

Results of an experiment investigating overdischarge behavior of two types of Li/SO2 cells are presented. Forced overdischarges of the Li/LiBr, CH3CN/SO2 cell can result in unsafe behavior such as venting with fire and release of toxic gases. The hazards may be minimized or eliminated by careful cell design considerations and practice of high standards of quality contol in cell manufacture. Seemingly safe cells at 25 C when forced overdischarged at -25 C, even at low currents, exhibited incipient signs of hazards. Their cathodes indicated signs of shock sensitivity. Cathode limited Li/SOCl2 cells were safe during forced overdischarge for long periods of time. Lithium limited Li/SOCl2 cells in which practically all Li had been used up before cell reversal did not exhibit hazardous behavior. Anode limited Li/SOCl2 cells, but not Li limited, exhibited detonations, all during overdischarges at relatively low current densities of or = 1 mA/sq cm 2. Anode potentials 4v with large oscillations preceeded the events. The events were confined to the anode and the temperature rose high enough to melt Ni grids.

Abraham, K. M.↗
NASA NTRS1996

Guide for Oxygen Component Qualification Tests

Although oxygen is a chemically stable element, it is not shock sensitive, will not decompose, and is not flammable. Oxygen use therefore carries a risk that should never be overlooked, because oxygen is a strong oxidizer that vigorously supports combustion. Safety is of primary concern in oxygen service. To promote safety in oxygen systems, the flammability of materials used in them should be analyzed. At the NASA White Sands Test Facility (WSTF), we have performed configurational tests of components specifically engineered for oxygen service. These tests follow a detailed WSTF oxygen hazards analysis. The stated objective of the tests was to provide performance test data for customer use as part of a qualification plan for a particular component in a particular configuration, and under worst-case conditions. In this document - the 'Guide for Oxygen Component Qualification Tests' - we outline recommended test systems, and cleaning, handling, and test procedures that address worst-case conditions. It should be noted that test results apply specifically to: manual valves, remotely operated valves, check valves, relief valves, filters, regulators, flexible hoses, and intensifiers. Component systems are not covered.

Bamford, Larry J.↗
NASA NTRS2006

Explosive Event in MON-3 Oxidizer System Resulting from Pressure Transducer Failure

In 2003, a Druck(Registered Trademark) pressure transducer failed catastrophically in a test system circulating nitrogen tetroxide at NASA Johnson Space Center White Sands Test Facility. The cause of the explosion was not immediately obvious since the wetted areas of the pressure transducer were constructed of materials compatible with nitrogen tetroxide. Chemical analysis of the resulting residue and a materials analysis of the diaphragm and its weld zones were used to determine the chain of events that led to the catastrophic failure. Due to excessive dynamic pressure loading in the test system, the diaphragm in the pressure transducer suffered cyclic failure and allowed the silicon oil located behind the isolation diaphragm to mix with the nitrogen tetroxide. The reaction between these two chemicals formed a combination of 2,4-di and 2,4,6-trinitrophenol, which are shock sensitive explosives that caused the failure of the pressure transducer. Further research indicated numerous manufacturers offer similar pressure transducers with silicone oil separated from the test fluid by a thin stainless steel isolation diaphragm. Caution must be exercised when purchasing a pressure transducer for a particular system to avoid costly failures and test system contamination.

Baker, David L.↗
NASA NTRS1986

Shock-tube pyrolysis of acetylene - Sensitivity analysis of the reaction mechanism for soot formation

The impact of thermodynamic parameters on the sensitivity of model predictions of soot formation by shock-tube pyrolysis of acetylene were assessed analytically. The pyrolysis process was treated as having three components: initiation, the initial pyrolysis stages; cyclization, formation of larger molecules and radicals and small aromatic molecules; and polymerization, further growth of aromatic rings. Rate equations are reviewed for each component. Thermodynamic effects were assessed by varying the C2H-H and C2H3-H bond energies and the Ct-(Ct) group additivity value. Any change in the C2H-H bond energy had a significant impact on the temperature and the maximum amount of the soot yield. The findings underscore the necessity of using accurate thermodynamic data for modeling high-temperature chemical kinetics.

Frenklach, M.↗
NASA NTRS2001

Use of Pressure Sensitive Paint for Diagnostics in Turbomachinery Flows With Shocks

The technology of pressure sensitive paint (PSP) is well established in external aerodynamics. In internal flows in narrow channels and in turbomachinery cascades, however, there are still unresolved problems. In particular, the internal flows with complex shock structures inside highly curved channels present a challenge. It is not always easy and straightforward to distinguish between true signals and "ghost" images due to multiple internal reflections in narrow channels. To address some of the problems, investigations were first carried out in a narrow supersonic channel of Mach number 2.5. A single wedge or a combination of two wedges were used to generate a complex shock wave structure in the flow. The experience gained in a small supersonic channel was used for surface pressure measurements on the stator vane of a supersonic throughflow fan. The experimental results for several fan operating conditions are shown in a concise form, including performance map points, midspan static tap pressure distributions, and vane suction side pressure fields. Finally, the PSP technique was used in the NASA transonic flutter cascade to compliment flow visualization data and to acquire backwall pressure fields to assess the cascade flow periodicity. A summary of shortcomings of the pressure sensitive paint technology for internal flow application and lessons learned are presented in the conclusion of the paper.

Lepicovsky, Jan↗
NASA NTRS1999

DSMC Simulation of Shock/Shock Interactions: Emphasis on Type IV Interactions

This paper presents the results of a numerical study of shock/shock interactions that include both the Edney type IV and type III interactions, with emphasis on the type IV interactions. Computations are made using the direct simulation Monte Carlo (DSMC) method of Bird for Mach 10 air flow, as produced in the ONERA R5Ch low-density wind tunnel. The simulations include the flow about a shock generator which creates a relatively weak oblique shock that impinges on a much stronger cylinder bow shock. The sensitivity and characteristics of the interactions are examined by varying the horizontal distance separating the shock generator leading edge and cylinder. Results of the simulation for one separation distance are compared with wind tunnel measurements. Comparisons are made for surface heating and pressure and for flow-field values of density and rotational temperatures, as obtained with the Dual-line Coherent Anti-Stokes Scattering (DL-CARS) technique. The comparisons between experiment and calculation yield a consistent description of the shock interaction features and a consistent description of the surface heating and pressure distributions, with the exception of the peak values-the computed values being greater than the measured values.

Moss, J. N.↗
NASA NTRS1984

A sensitive optical pyrometer for shock-temperature measurements

A new optical system was used to determine temperatures above 2400 K in shocked materials by measuring the spectral radiance of sub-microsecond pulses of light emitted from initially transparent solid samples in the visible and near infrared (450 to 900 nm). The high sensitivity of this optical pyrometer is attributed to the small number of channels, large aperture (0.03 steradian), the large bandwidth per channel (40 nm), and large photodiode detection area (0.2 sq cm). Improved calibration techniques reduce systematic errors encountered in previous shock-temperature experiments.

Boslough, M. B.↗
NASA NTRS1991

Thermoluminescence survey of 12 meteorites collected by the European 1988 Antarctic meteorite expedition to Allan Hills and the importance of acid washing for thermoluminescence sensitivity measurements

Natural and induced thermoluminescence (TL) data are reported for 12 meteorites recovered from the Allan Hills region of Antarctica by the European field party during the 1988/1989 field season. The samples include one with extremely high natural TL, ALH88035, suggestive of exposure to unusually high radiation doses (i.e., low degrees of shielding), and one, ALH88034, whose low natural TL suggests reheating within the last 100,000 years. The remainder have natural TL values suggestive of terrestrial ages similar to those of other meteorites from Allan Hills. ALH88015 (L6) has induced TL data suggestive of intense shock. TL sensitivities of these meteorites are generally lower than observed falls of their petrologic types, as is also observed for Antarctic meteorites in general. Acid-washing experiments indicate that this is solely the result of terrestrial weathering rather than a nonterrestrial Antarctic-non-Antarctic difference. However, other TL parameters, such as natural TL and induced peak temperature-width, are unchanged by acid washing and are sensitive indicators of a meteorite's metamorphic and recent radiation history.

Benoit, P. H.↗