Pyrotechnic shock analysis and testing methods
Statistical analysis of pyrotechnic shock data from Ranger and Mariner test programs
MARINER PROGRAM↗
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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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Digital vibration control techniques
Analog vibration control techniques are reviewed and are compared with digital techniques. The advantages of the digital methods over the analog methods are demonstrated. The following topics are covered: (1) methods of computer-controlled random vibration and reverberation acoustic testing; (2) methods of computer-controlled sinewave vibration testing; and (3) methods of computer-controlled shock testing. Basic concepts are stressed rather than specific techniques or equipment. General algorithms are described in the form of block diagrams and flow diagrams. Specific problems and potential problems are discussed. The material is computer sciences oriented but is kept at a level that facilitates an understanding of the basic concepts of computer-controlled induced environmental test systems.
Chapman, P.↗
Seminar on Understanding Digital Control and Analysis in Vibration Test Systems
The advantages of the digital methods over the analog vibration methods are demonstrated. The following topics are covered: (1) methods of computer-controlled random vibration and reverberation acoustic testing, (2) methods of computer-controlled sinewave vibration testing, and (3) methods of computer-controlled shock testing. General algorithms are described in the form of block diagrams and flow diagrams.
Source record↗
Assessing Uncertainties in Boundary Layer Transition Predictions for HIFiRE-1 at Non-zero Angles of Attack
Boundary layer stability was analyzed for the HIFiRE-1 flight vehicle geometry for ground tests conducted at the CUBRC LENS I hypersonic shock test facility and the Langley Research Center (LaRC) 20- inch Mach 6 Tunnel. Boundary layer stability results were compared to transition onset location obtained from discrete heat transfer measurements from thin film gauges during the CUBRC test and spatially continuous heat transfer measurements from thermal phosphor paint data during the LaRC test. The focus of this analysis was on conditions at non-zero angles of attack as stability analysis has already been performed at zero degrees angle of attack. Also, the transition onset data obtained during flight testing was at nonzero angles of attack, so this analysis could be expanded in the future to include the results of the flight test data. Stability analysis was performed using the 2D parabolized stability software suite STABL (Stability and Transition Analysis for Hypersonic Boundary Layers) developed at the University of Minnesota and the mean flow solutions were computed using the DPLR finite volume Navier-Stokes computational fluid dynamics (CFD) solver. A center line slice of the 3D mean flow solution was used for the stability analysis to incorporate the angle of attack effects while still taking advantage of the 2D STABL software suite. The N-factors at transition onset and the value of Re(sub theta)/M(sub e), commonly used to predict boundary layer transition onset, were compared for all conditions analyzed. Ground test data was analyzed at Mach 7.2 and Mach 6.0 and angles of attack of 1deg, 3deg and 5deg. At these conditions, the flow was found to be second mode dominant for the HIFiRE-1 slender cone geometry. On the leeward side of the vehicle, a strong trend of transition onset location with angle of attack was observed as the boundary layer on the leeward side of the vehicle developed inflection points at streamwise positions on the vehicle that correlated to angle of attack. Inflection points are a strong instability mechanism that lead to rapid breakdown and transition to turbulence. The transition onset location on the windward side of the vehicle displayed no trend with angle of attack or freestream Reynolds number and transition was observed farther down the vehicle than observed on the leeward side of the vehicle. In analysis of both windward and leeward sides of the vehicle, use of the N factor methodology to develop trends to predict boundary layer transition onset showed improvements over the Re(sub theta)/M(sub e) empirical correlation methodology. Stronger correlations and less scatter in the data were observed when using the N factor method for these cases.
Marek, Lindsay C.↗
Shock and vibration tests of a SNAP 8 mercury pump
Shock and vibration tests of SNAP 8 centrifugal mercury pump
Foley, R. S.↗
Evaluation of Conservatism in Low Frequency Vibration Test Control
Aerospace structures are typically qualified for low frequency flight environments by using a swept-sine vibration test method. However, this ground testing has a tendency to produce substantial overtesting at certain frequencies. This paper presents an evaluation of the response conservatism present with a typical swept-sine and two transient vibration tests when applied to a typical spacecraft component. The absolute conservatism between a typical launch transient response and the test environment responses is measured using alternative characterizations of transient vibrations previously used in shock testing. The characterizations used include the Shock Intensity Spectrum, Shock Response Spectrum, Acceleration Root Mean Square in both frequency and time domains, and Ranked Peaks. Control of the test/flight conservatism is shown to be possible through the overtest factor (OTF) parameter.
Conservatism↗
Combustion of LOX with H2(sub g) under subcritical, critical, and supercritical conditions (Task 1) and experimental observation of dense spray and mixing of impinging jets (Task 2)
The objective was to achieve a better understanding of the combustion processes of liquid oxygen and gaseous hydrogen under broad range of pressure covering subcritical, critical, and supercritical conditions. The scope of the experimental work falls into the following areas: (1) design of the overall experimental setup; (2) modification of an existing windowed high pressure chamber; (3) design of the LOX feeding system; (4) provision of the safety features in the test rig design; (5) LOX cleanliness requirements; (6) cold shock testing; (7) implementation of data acquisition systems; (8) preliminary tests for system checkout; (9) modification of LOX feeding system; and (10) evaporation tests. Progress in each area is discussed.
Kuo, K. K.↗
Cathode & Electromagnet Qualification Status and Power Processing Unit Development Update for the Ascendant Sub-kW Transcelestial Electric Propulsion System
A review of the component-level flight qualification efforts and power processing unit development status of the Ascendant Sub-kW Transcelestial Electric Propulsion System (ASTRAEUS) program is presented. Component-level qualification efforts were undertaken for the system’s ultra-compact heaterless LaB6 hollow cathode and electromagnets, both of which employ designs bespoke to ASTRAEUS, as they represent the highest failure risks for the thruster. Through parallel long-duration wear and ignition tests, the ASTRAEUS cathode demonstrated invariant discharge performance over more than 5000 h of operation at its maximum operating current of 4 A and demonstrated more than 25,000 ignition cycles. The ASTRAEUS electromagnets completed their environmental qualification through a demonstration of more than 1200 deep thermal cycles with no indication of coil degradation (the test articles previously completed qualification-level vibration and shock testing). ASTRAEUS’s prototype power processing unit has demonstrated more than 92% total power conversion efficiency and class-leading power density & specific power density of 4.5 W/cm3 & 1670 W/kg, respectively. The various power converters found in the ASTRAEUS power processing unit are reviewed with a focus on the methods by which such high performance was achieved.
Conversano, Ryan W.↗
Pyrotechnic shock measurement and data analysis requirements
A study of laboratory measurement and analysis of pyrotechnic shock prompted by a discrepancy in preliminary Mariner Jupiter/Saturn shock test data is reported. It is shown that before generating shock response plots from any recorded pyrotechnic event, a complete review of each instrumentation and analysis system must be made. In addition, the frequency response capability of the tape recorder used should be as high as possible; the discrepancies in the above data were due to inadequate frequency response in the FM tape recorders. The slew rate of all conditioning amplifiers and input converters must be high enough to prevent signal distortion at maximum input voltage; amplifier ranges should be selected so that the input pulse is approximately 50% of full scale; the Bessel response type should be chosen for digital shock analysis if antialiasing filters are employed; and transducer selection must consider maximum acceleration limit, mounted resonance frequency, flat clean mounting surfaces, base bending sensitivity, and proper torque.
Albers, L.↗
Incident shock-wave characteristics in air, argon, carbon dioxide, and helium in a shock tube with unheated helium driver
Incident shock-wave velocities were measured in the Langley 6-inch expansion tube, operated as a shock tube, with air, argon, carbon dioxide, and helium as test gases. Unheated helium was used as the driver gas and most data were obtained at pressures of approximately 34 and 54 MN/sq m. A range of pressure ratio across the diaphragm was obtained by varying the quiescent test-gas pressure, for a given driver pressure, from 0.0276 to 34.5 kN/sq m. Single- and double-diaphragm modes of operation were employed and diaphragms of various materials tested. Shock velocity was determined from microwave interferometer measurements, response of pressure transducers positioned along interferometer measurements, response of pressure transducers positioned along the driven section (time-of-arrival gages), and to a lesser extent, measured tube-wall pressure. Velocities obtained from these methods are compared and limitations of the methods discussed. The present results are compared with theory and the effects of diaphragm mode (single or double diaphragm), diaphragm material, heating of the driver gas upon pressurization of the driver section, diaphragm opening time, interface mixing, and two-dimensional (nonplanar) flow are discussed.
Miller, C. G., III↗
De-Trending Techniques: Methods for Cleaning Questionable Shock Data
Not all zero shifted acceleration data can De-trended using this technique. DC shifts, improper AC coupling, Circuit noise/EMI/EMR, Equivalent RC circuit gain response/Circuit saturation(Slew Rate Limited), fixture grounding and wiring losses can all contribute to bad shock data being recorded. Some data that is zero-shifted or exhibit large instantaneous velocity shifts is inherently bad and a retest is warranted. Clean Acceleration-Time history data can be bad upon examining the Velocity & Displacement profiles. Laser Vibrometers provide a high level of accuracy for pyrotechnic shock testing. Engineering judgment and experience will determine the validity of Shock data.
Grillo, Vincent J.↗
Summary of NASA Progress on the Development and Qualification of a 12-kW Hall-Effect, Solar Electric Propulsion Thruster
Beginning in 2014, the National Aeronautics and Space Administration (NASA) Space Technology Mission Directorate (STMD) began a project to increase the state of the art for the Hall-Effect Solar Electric Propulsion (SEP) technology. The Technology Demonstration Missions (TDM) Program Office provides programmatic oversight of SEP with the project being led by Glenn Research Center, supported by the Jet Propulsion Laboratory and development, qualification & flight hardware all provided by Aerojet Rocketdyne (AR). This technology was pursued as the propulsion system for the Asteroid Redirect and Robotic Mission (ARRM). While the concept was originally slated for ARRM, it was realigned to Gateway to support future Moon to Mars objectives. The Gateway lunar station was established and will play a key role in NASA’s Artemis Program which utilizes collaboration with the Canadian Space Agency (CSA), the European Space Agency (ESA) and the Japanese Space Agency (JAXA). The 12-kW hardware will be the primary propulsion for the Gateway element, Power & Propulsion Element (PPE), from Low Earth Orbit to a Near Rectilinear Halo Orbit around the Moon. Initial efforts began with utilizing Technology Development Units (TDU) built by NASA as the predecessor to the contract activity with AR. Over the past few years, AR has built Engineering Test Units (ETU), Engineering Development Units (EDU) and qualification & flight models (QM and FM, respectively). With requirement changes from the AARM mission to PPE, the joint team has modified the design and has started qualification activities for environment testing (shock, vibe) at multiple facilities in the US leading to eventual life testing. This paper will explore the various design changes, system modeling and the latest status for qualification testing.
Joel Robinson↗
Summary of NASA Progress on the Development and Qualification of a 12 kW Hall Effect, Solar Electric Propulsion Thruster
Beginning in 2014, the National Aeronautics and Space Administration (NASA) Space Technology Mission Directorate (STMD) began a project to increase the state of the art for the Hall-Effect Solar Electric Propulsion (SEP) technology. The Technology Demonstration Missions (TDM) Program Office provides programmatic oversight of SEP with the project being led by Glenn Research Center, supported by the Jet Propulsion Laboratory and development, qualification & flight hardware all provided by Aerojet Rocketdyne (AR). This technology was pursued as the propulsion system for the Asteroid Redirect and Robotic Mission (ARRM). While the concept was originally slated for ARRM, it was realigned to Gateway to support future Moon to Mars objectives. The Gateway lunar station was established and will play a key role in NASA’s Artemis Program which utilizes collaboration with the Canadian Space Agency (CSA), the European Space Agency (ESA) and the Japanese Space Agency (JAXA). The 12-kW hardware will be the primary propulsion for the Gateway element, Power & Propulsion Element (PPE), from Low Earth Orbit to a Near Rectilinear Halo Orbit around the Moon. Initial efforts began with utilizing Technology Development Units (TDU) built by NASA as the predecessor to the contract activity with AR. Over the past few years, AR has built Engineering Test Units (ETU), Engineering Development Units (EDU) and qualification & flight models (QM and FM, respectively). With requirement changes from the AARM mission to PPE, the joint team has modified the design and has started qualification activities for environment testing (shock, vibe) at multiple facilities in the US leading to eventual life testing. This paper will explore the various design changes, system modeling and the latest status for qualification testing.
Joel W Robinson↗
Altus small button cell performance
Results of testing performed on Altus lithium thionyl chloride cells are presented. The test plan followed simulates the mine environment. It involves nondestructive testing, ruggedness testing and destructive testing. The nondestructive testing involves open circuit voltage measurements initially on all the cells, alternating current resistance measurements initially on all the cells and closed circuit voltage pulses, 20s on and 20s through 1000, 100, 10 and 1 ohms at temperatures of -54 to 71 C. The ruggedness testing involves low frequency vibration, high frequency vibration, and two-phase water entry shock at temperatures of -54, 25 and 71 C. It also involves thermal shock tests.
Freeman, C.↗
12.5kW Advanced Electric Propulsion System Thruster Development Testing
Since 2012, NASA has been developing the12.5kW Hall Effect Rocket with Magnetic Shielding (HERMeS)thruster to serve the need for deep space propulsion. Aerojet Rocketdyne (AR)is developing the HERMeS Hall Current Thruster (HCT)into a flight capable design through the Advanced Electric Propulsion System (AEPS) program. In execution of this program, Aerojet Rocketdyne has designed, built and begun test of two Engineering Test Unit (ETU)HCTs, designated ETU-1 and ETU-2. This paper presents some of the preliminary results from theETU-1 thruster and draws comparisons to previous HERMeS Technology Demonstration Units (TDUs)and theETU-2 characterization unit. The ETU-1 thruster serves to evaluate the ETU design against dynamic and thermal environments while ETU-2 undergoes operational characterization and wear testing. The thruster has been exposed to acceptance and qualification-level vibration and shock testing and has undergone acceptance and characterization hot-firing to evaluate thruster performance after exposure to dynamic environments. The results have demonstrated that the dynamic environments have not had an adverse effect on performance and demonstrated that stability and operating characteristics remain unaffected. Together, ETU-1 and ETU-2 HCTs have demonstrated operating performance and characteristics in-family with each other and with the NASA HERMeS Technology Demonstration Units.
AEPS↗
Accelerated stress testing of terrestrial solar cells
The development of an accelerated test schedule for terrestrial solar cells is described. This schedule, based on anticipated failure modes deduced from a consideration of IC failure mechanisms, involves bias-temperature testing, humidity testing (including both 85-85 and pressure cooker stress), and thermal-cycle thermal-shock testing. Results are described for 12 different unencapsulated cell types. Both gradual electrical degradation and sudden catastrophic mechanical change were observed. These effects can be used to discriminate between cell types and technologies relative to their reliability attributes. Consideration is given to identifying laboratory failure modes which might lead to severe degradation in the field through second quadrant operation. Test results indicate that the ability of most cell types to withstand accelerated stress testing depends more on the manufacturer's design, processing, and worksmanship than on the particular metallization system. Preliminary tests comparing accelerated test results on encapsulated and unencapsulated cells are described.
Lathrop, J. W.↗
Computer-controlled vibration testing
System features quickly achieved steady state, increased accuracy of spectrum definition, and true Gaussian amplitude distribution of resulting signals. Controlled shock-tests might also be tried with this system.
Chapman, C. P.↗
Composite wall concept for high temperature turbine shrouds: Survey of low modulus strain isolator materials
Plasma sprayed yttria stabilized zirconium oxide turbine seal specimens, incorporating various low modulus porous metal strain isolator pads between the zirconium oxide and a dense metal substrate, were subjected to cyclic thermal shock testing. Specimens that had a low modulus pad composed of sintered FeNiCrAlY fibermetal survived 1000 thermal shock cycles without spalling of the ceramic. A figure of merit for the low modulus pad materials taking into consideration the elastic modulus, thermal conductivity, strength, and oxidation resistance of the pad was proposed, and showed reasonable agreement with the thermal shock results. A potential surface distress problem on the zirconium oxide, associated with nonuniform temperature distribution and rapid stress relaxation was identified. One approach to solving the surface distress problem through application of laser surface fusion of the zirconium oxide layer showed some promise, but improvements in the laser surface fusion process are necessary to prevent process associated damage to the ceramic.
Bill, R. C.↗