Results for “penetration testing” — Page 20

NASA NTRS2002

Numerical Simulation of a Convective Turbulence Encounter

A numerical simulation of a convective turbulence event is investigated and compared with observational data. The numerical results show severe turbulence of similar scale and intensity to that encountered during the test flight. This turbulence is associated with buoyant plumes that penetrate the upper-level thunderstorm outflow. The simulated radar reflectivity compares well with that obtained from the aircraft's onboard radar. Resolved scales of motion as small as 50 m are needed in order to accurately diagnose aircraft normal load accelerations. Given this requirement, realistic turbulence fields may be created by merging subgrid-scales of turbulence to a convective-cloud simulation. A hazard algorithm for use with model data sets is demonstrated. The algorithm diagnoses the RMS normal loads from second moments of the vertical velocity field and is independent of aircraft motion.

Proctor, Fred H.↗

NASA NTRS1999

Design and Development of a Composite Dome for Experimental Characterization of Material Permeability

This paper presents the design and development of a carbon fiber reinforced plastic dome, including a description of the dome fabrication, method for sealing penetrations in the dome, and a summary of the planned test series. This dome will be used for the experimental permeability characterization and leakage validation of composite vessels pressurized using liquid hydrogen and liquid nitrogen at the Cryostat Test Facility at the NASA Marshall Space Flight Center (MSFC). The preliminary design of the dome was completed using membrane shell analysis. Due to the configuration of the test setup, the dome will experience some flexural stresses and stress concentrations in addition to membrane stresses. Also, a potential buckling condition exists for the dome due to external pressure during the leak testing of the cryostat facility lines. Thus, a finite element analysis was conducted to assess the overall strength and stability of the dome for each required test condition. Based on these results, additional plies of composite reinforcement material were applied to local regions on the dome to alleviate stress concentrations and limit deflections. The dome design includes a circular opening in the center for the installation of a polar boss, which introduces a geometric discontinuity that causes high stresses in the region near the hole. To attenuate these high stresses, a reinforcement system was designed using analytical and finite element analyses. The development of a low leakage polar boss system is also investigated.

Estrada, Hector↗

NASA NTRS2012

NASA's Evolutionary Xenon Thruster (NEXT) Long-Duration Test as of 736 kg of Propellant Throughput

The NASA s Evolutionary Xenon Thruster (NEXT) program is developing the next-generation solar-electric ion propulsion system with significant enhancements beyond the state-of-the-art NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) ion propulsion system to provide future NASA science missions with enhanced mission capabilities. A Long-Duration Test (LDT) was initiated in June 2005 to validate the thruster service life modeling and to qualify the thruster propellant throughput capability. The thruster has set electric propulsion records for the longest operating duration, highest propellant throughput, and most total impulse demonstrated. At the time of this publication, the NEXT LDT has surpassed 42,100 h of operation, processed more than 736 kg of xenon propellant, and demonstrated greater than 28.1 MN s total impulse. Thruster performance has been steady with negligible degradation. The NEXT thruster design has mitigated several lifetime limiting mechanisms encountered in the NSTAR design, including the NSTAR first failure mode, thereby drastically improving thruster capabilities. Component erosion rates and the progression of the predicted life-limiting erosion mechanism for the thruster compare favorably to pretest predictions based upon semi-empirical ion thruster models used in the thruster service life assessment. Service life model validation has been accomplished by the NEXT LDT. Assuming full-power operation until test article failure, the models and extrapolated erosion data predict penetration of the accelerator grid grooves after more than 45,000 hours of operation while processing over 800 kg of xenon propellant. Thruster failure due to degradation of the accelerator grid structural integrity is expected after

Shastry, Rohit↗

NASA NTRS2012

NASA's Evolutionary Xenon Thruster (NEXT) Long-Duration Test as of 736 kg of Propellant Throughput

The NASA s Evolutionary Xenon Thruster (NEXT) program is developing the next-generation solar-electric ion propulsion system with significant enhancements beyond the state-of-the-art NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) ion propulsion system to provide future NASA science missions with enhanced mission capabilities. A Long-Duration Test (LDT) was initiated in June 2005 to validate the thruster service life modeling and to qualify the thruster propellant throughput capability. The thruster has set electric propulsion records for the longest operating duration, highest propellant throughput, and most total impulse demonstrated. At the time of this publication, the NEXT LDT has surpassed 42,100 h of operation, processed more than 736 kg of xenon propellant, and demonstrated greater than 28.1 MN s total impulse. Thruster performance has been steady with negligible degradation. The NEXT thruster design has mitigated several lifetime limiting mechanisms encountered in the NSTAR design, including the NSTAR first failure mode, thereby drastically improving thruster capabilities. Component erosion rates and the progression of the predicted life-limiting erosion mechanism for the thruster compare favorably to pretest predictions based upon semi-empirical ion thruster models used in the thruster service life assessment. Service life model validation has been accomplished by the NEXT LDT. Assuming full-power operation until test article failure, the models and extrapolated erosion data predict penetration of the accelerator grid grooves after more than 45,000 hours of operation while processing over 800 kg of xenon propellant. Thruster failure due to degradation of the accelerator grid structural integrity is expected after groove penetration.

Shastry, Rohit↗

NASA NTRSDate not supplied

Smooth Particle Hydrodynamic Code Predictions for Meteoroid Damage to Thermal Protection Systems Shielded By Composite Structures

Interplanetary spacecraft are exposed to meteoroid fluxes with characteristics far exceeding the physical simulation capabilities of test facilities for predicting the likelihood that a meteoroid will penetrate a spacecraft’s critical systems. Accurate risk predictions are crucial to ensuring that important interplanetary missions, such as sample returns, can survive years of exposure to the meteoroid environment and safely reenter the Earth’s atmosphere with their scientific cargo. In this paper, we summarize a series of meteoroid impact damage computational simulations into two types of spacecraft composite protective structures using the Smooth Particle Hydrodynamics Code. We consider the effects of both meteoric materials and non-meteoric materials on a shielded forebody thermal protection system (TPS) for an extreme entry environment and on an unshielded aftbody TPS that is similar to the material covering the space shuttle’s external tank.

Brooke Corbett↗

DOE OSTI2020

Machine Learning-Based PV Reserve Determination Strategy for Frequency Control on the WECC System

This paper proposes a machine learning based strategy, that is suitable for real-time operation, to determine the optimal photovoltaic (PV) power plants reserve for frequency control. The proposed machine learning algorithm is trained and tested on 1,987 offline simulations of a 60% renewable penetration Western Electricity Coordinating Council (WECC) system. On a realistic 1-day operation profile of the WECC system, the ML model demonstrates a savings of more than 40% PV headroom compared to a conservative approach.

14 SOLAR ENERGY↗

NASA NTRS2000

Lack of Penetration in Friction Stir Welds: Effects on Mechanical Properties and NDE Feasibility

This presentation reviews the issue of lack of penetration (LOP) in Friction Stir Welding and the feasibility of using non-destructive tests to detect . Friction Stir Welding takes place in the solid phase below the melting point of the materials to be joined. It thus gives the ability to join materials which are difficult to fusion weld, for example 2000 and 7000 aluminium alloys. This process though can result in a lack of penetration, due to an incomplete penetration of the DXZ. This is frequently referred to as a "kissing bond", which requires micro examination to detect. The presentation then discusses the surface crack tension tests. It then reviews the simulated service test and results. It then discusses the feasibility of using non-destructive examination to detect LOP, the forms of test which can be used, and the results the tests.

Kinchen, David G.↗

DOE OSTI2023

Dual-Purpose Canister Filling Demonstration Project Progress Report at ORNL, 2023

The US DOE Office of Nuclear Energy is investigating the feasibility of direct disposal of dual-purpose canisters (DPCs) in a hypothetical geological repository to offset the potential requirement to repackage spent nuclear fuel (SNF) from existing DPCs into smaller, disposal-ready canisters. Oak Ridge National Laboratory (ORNL) is currently evaluating the feasibility of filling void space in loaded DPCs with an engineered material to prevent a criticality event caused by groundwater/moderator intrusion. Metal alloys are being investigated as a filler material because of their relatively low viscosities when molten, which may facilitate their injection via an existing drainpipe that runs almost the full length of the DPC. ORNL’s strategy for evaluating filler viability includes simulations and physical demonstrations of filling and casting behavior, as well as evaluations of materials for compatibility in the repository environment. Filling of DPCs in this manner is expected to mitigate the risk associated with a post-closure criticality event during the repository performance assessment time frame (10,000 years or greater). Efforts in this fiscal year focused on (1) destructive analysis of experimental filler castings made in FY 2022, (2) a report outlining a conceptual design of a DPC filling facility (Fortner et al., 2023, M3SF 23OR010305044/ ORNL/SPR-2023/2921, May 31, 2023), (3) a report on affected features, events, and processes (FEPs) due to DPC filling (Price et al., 2023, M3SF-23SN010305093, issuance pending), (4) developing and testing a more practical alloy filler based upon a Sn-Al eutectic, and (5) modeling the heating and cooling dynamics of a DPC subjected to molten metal filling. The preliminary results from each of these tasks support the feasibility of filling DPCs with metal as a strategy against the possibility of criticality in the repository. The FY 2022 casting was found to penetrate even very small orifices in the mold and internal structures. Preliminary testing of the Sn-Al eutectic indicate little interaction of the melt with Zircaloy cladding. Thermal modelling shows that a filled DPC will cool to manageable temperatures within 2-3 days, which is likely manageable in a facility.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS2009

Hatch Integration Testing of a NASA TransHab Derivative Woven Inflatable Module

Current options for Lunar habitat architecture include inflatable habitats and airlocks. Inflatable structures can have mass and volume advantages over conventional structures. However, inflatable structures are also perceived to carry additional risk because they are at a lower Technical Readiness Level (TRL) than more conventional metallic structures. The use of inflatable structures for habitation will require large penetrations in the inflatable structure to accommodate hatches and/or windows The Hatch Integration Test is designed to study the structural integrity of an expandable structure with an integrated hatch, and to verify mathematical models of the structure. The TransHab project developed an experimental inflatable module at Johnson Space Center in the 1990's. The TransHab design was originally envisioned for use in Mars Transits but was also studied as a potential habitat for the International Space Station (ISS).

Edgecombe, John↗

NASA NTRS1995

Use of the quartz crystal microbalance to determine the monomeric friction coefficient of polyimides

When a thin film of polymer is coated on to a quartz crystal microbalance (QCM), the QCM can be used to detect the rate of increase in weight of the polymer film as the volatile penetrant diffuses into the polymer. From this rate information the diffusion coefficient of the penetrant into the polymer can be computed. Calculations requiring this diffusion coefficient lead to values which approximate the monomeric friction coefficient of the polymer. This project has been concerned with the trial of crystal oscillating circuits suitable for driving polymer coated crystals in an atmosphere of penetrant. For these studies done at room temperature, natural rubber was used as an easily applied polymer that is readily penetrated by toluene vapors, qualities anticipated with polyimides when they are tested at T(g) in the presence of toluene. Three quartz crystal oscillator circuits were tested. The simplest circuit used +/- 5 volt dc and had a transistor to transistor logic (TTL) inverter chip that provides a 180 deg phase shift via a feed back loop. This oscillator circuit was stable but would not drive the crystal when the crystal was coated with polymer and subjected to toluene vapors. Removal of a variable resistor from this circuit increased stability but did not otherwise increase performance. Another driver circuit tested contained a two stage differential input, differential output, wide band video amplifier and also contain a feed back loop. The circuit voltage could not be varied and operated at +/- 5 volts dc; this circuit was also stable but failed to oscillate the polymer coated crystal in an atmosphere saturated with toluene vapors. The third oscillator circuit was of similar construction and relied on the same video amplifier but allowed operation with variable voltage. This circuit would drive the crystal when the crystal was submerged in liquid toluene and when the crystal was coated with polymer and immersed in toluene vapors. The frequency readings obtained when using this oscillating circuit are highly variable. This circuit requires further modification to stabilize frequency readings before its use in studies to determine the diffusion coefficient of penetrant molecules into a polymer film coated on a QCM.

Bechtold, Mary M.↗

NASA NTRS1987

Structural frequency functions for an impulsive, distributed forcing function

The response of a penetrator structure to a spatially distributed mechanical impulse with a magnitude approaching field test force levels (1-2 Mlb) were measured. The frequency response function calculated from the response to this unique forcing function is compared to frequency response functions calculated from response to point forces of about 2000 pounds. The results show that the strain gages installed on the penetrator case respond similiarly to a point, axial force and to a spatially distributed, axial force. This result suggests that the distributed axial force generated in a penetration event may be reconstructed as a point axial force when the penetrator behaves in linear manner.

Bateman, Vesta I.↗

DOE OSTI2020

Experimental Test Bed to Enable Realistic Evaluations for Direct Transfer Trip Relaying via Private Wireless LTE Communications

Increasing penetration levels of inverter-based distributed energy resources (DERs) in distribution systems are creating challenges in system operation. Currently, wired or proprietary wireless communications are used by advanced distribution management systems (ADMS) to detect the state of the system and control the DERs for optimal operation. Wireless communications are an alternative solution that can enable connectivity between the dispersed assets used in distribution system applications. This paper demonstrates an experimental test bed to enable the realistic evaluation of communications system characteristics for direct transfer trip (DTT) relaying of a photovoltaic inverter system using a private 900-MHz spectrum wireless LTE network. Private LTE network communications can be deployed to many remote DERs and other grid-edge devices to prevent costly infrastructure upgrades across distribution systems. In addition, this paper provides a framework for evaluating the impact of signal strength and network traffic in communications systems. The results shown develop a better understanding of the best practices for using LTE communications systems across multiple utility applications, such as protective relaying, voltage regulation, and supervisory control and data acquisition system messages.

900-MHz LTE network↗

DOE OSTI2021

Experimental Test Bed to Enable Realistic Evaluations for Direct Transfer Trip Relaying via Private Wireless LTE Communications

Increasing penetration levels of inverter-based distributed energy resources (DERs) in distribution systems are creating challenges in system operation. Currently, wired or proprietary wireless communications are used by advanced distribution management systems (ADMS) to detect the state of the system and control the DERs for optimal operation. Wireless communications are an alternative solution that can enable connectivity between the dispersed assets used in distribution system applications. This paper demonstrates an experimental test bed to enable the realistic evaluation of communications system characteristics for direct transfer trip (DTT) relaying of a photovoltaic inverter system using a private 900-MHz spectrum wireless LTE network. Private LTE network communications can be deployed to many remote DERs and other grid-edge devices to prevent costly infrastructure upgrades across distribution systems. In addition, this paper provides a framework for evaluating the impact of signal strength and network traffic in communications systems. The results shown develop a better understanding of the best practices for using LTE communications systems across multiple utility applications, such as protective relaying, voltage regulation, and supervisory control and data acquisition system messages.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS2024

Exploration Extravehicular Mobility Unit (xEMU) Chamber B Thermal Vacuum “Suit 2” Pressure Garment System Hardware and Test Design

NASA’s Exploration Extravehicular Mobility Unit (xEMU) is the government reference next-generation space suit design and is engineered to protect astronauts from extreme lunar environmental temperatures. To evaluate the xEMU hardware thermal requirements, the xEMU Testing Team invented, designed, and executed a dual-suit, uncrewed thermal vacuum (TVAC) test at Johnson Space Center’s (JSC) Chamber B. This paper details the test hardware design and test methodology for the “Suit 2” Pressure Garment System (PGS) test article. The uncrewed “Suit 2” PGS test article consisted of a full PGS assembly with simulated Portable Life Support System (PLSS) functionality provided by test equipment, including a ventilation loop and two distinct thermal control loops. This paper will discuss in depth the test hardware design, including internal suit thermal boundary simulation, sensor quantity and placement, test support equipment rigs for gas flow, water flow, and power. Custom hardware designed to add additional penetrations to the suit or provide additional interfaces for sensors will also be discussed. This paper will also address the assembly and integration sequence for the test article. In addition to test hardware design, this paper will provide insights into the test methodology for this test article, including a discussion of thermal steady-state testing, simultaneous dual suit thermal vacuum testing, and hazard mitigation and controls.

xEMU↗

DOE OSTI2021

Sensors with Intelligent Measurement Platform and Low-cost Equipment (SIMPLE) for Monitoring and Control of Medium Voltage Distribution Systems with High Penetration of Intermittent Distributed Energy Resources

The primary focus of the SIMPLE project was to develop, commission, test and introduce intelligent voltage and current sensor platform with enhanced characteristics (accuracy, bandwidth and harmonic range) and high measurement granularity for medium voltage distribution system monitoring, protection and control. The enhancements incorporated existing (commercially available) sensors and made them suitable for applications such as voltage regulation, frequency support, fault detection and location, distribution system state estimation, power quality measurements and electrical distribution network topology processing. The development of the intelligent sensor platform was driven by the need for high-fidelity monitoring and control of medium voltage distribution feeder to enable higher penetration of renewable resources and microgrid operation.

14 SOLAR ENERGY↗

NASA NTRS1980

Turbid water measurements of remote sensing penetration depth at visible and near-infrared wavelength

Remote sensing of water quality is dicussed. Remote sensing penetration depth is a function both of water type and wavelength. Results of three tests to help demonstrate the magnitude of this dependence are presented. The water depth to which the remote-sensor data was valid was always less than that of the Secchi disk depth, although not always the same fraction of that depth. The penetration depths were wavelength dependent and showed the greatest variation for the water type with largest Secchi depth. The presence of a reflective plate, simulating a reflective subsurface, increased the apparent depth of light penetration from that calculated for water of infinite depth.

Morris, W. D.↗

DOE OSTI2021

Experimental Study of Microgel Conformance-Control Treatment for a Polymer-Flooding Reservoir Containing Superpermeable Channels

Summary Polymer flooding has been widely used to improve oil recovery. However, its effectiveness would be diminished when channels (e.g., fractures, fracture-like channels, void-space conduits) are present in a reservoir. In this study, we designed a series of particular sandwich-like channel models and tested the effectiveness and applicable conditions of micrometer-sized preformed particle gels (PPGs, or microgels) in improving the polymer-flooding efficiency. We studied the selective penetration and placement of the microgel particles, and their abilities for fluid diversion and oil-recovery improvement. The results suggest that polymer flooding alone would be inefficient to achieve a satisfactory oil recovery as the heterogeneity of the reservoir becomes more serious (e.g., permeability contrast kc/km > 50). The polymer solution would vainly flow through the channels and leave the majority of oil in the matrices behind. Additional conformance-treatment efforts are required. We tried to inject microgels in an attempt to shut off the channels. After the microgel treatment, impressive improvement of the polymer-flooding performance was observed in some of our experiments. The water cut could be reduced significantly by as high as nearly 40%, and the sweep efficiency and overall oil recovery of the polymer flood were improved. The conditions under which the microgel-treatment strategy was effective were further explored. We observed that the microgels form an external impermeable cake at the very beginning of microgel injection and prevent the gel particles from entering the matrices. Instead, the microgel particles could selectively penetrate and shut off the superpermeable channels under proper conditions. Our results suggest that the 260-µm microgel particles tested in this study are effective to attack the excessive-water-production problem and improve the oil recovery when the channel has a high permeability (>50 darcies). The gels are unlikely to be effective for channels that are less than 30 darcies because of the penetration/transport difficulties. After the gels effectively penetrate and shut off the superpermeable channel, the subsequent polymer solution is diverted to the matrices (i.e., the unswept oil zones) to displace the bypassed oil. Overall, this study provides important insights to help achieve successful polymer-flooding applications in reservoirs with superpermeable channels.

Engineering↗

NASA NTRS2016

Technical Capability Upgrades to the NASA Langley Research Center 8 ft. by 15 ft. Thermal Vacuum Chamber

The 8 ft. by 15 ft. thermal vacuum chamber (TVAC), housed in Building 1250 at the NASA Langley Research Center (LaRC), and managed by the Systems Integration and Test Branch within the Engineering Directorate, has undergone several significant modifications to increase testing capability, safety, and quality of measurements of articles under environmental test. Significant modifications include: a new nitrogen distribution manifold for supplying the shroud and other cold surfaces to liquid nitrogen temperatures; a new power supply and distribution system for accurately controlling a quartz IR lamp suite; a suite of contamination monitoring sensors for outgassing measurements and species identification; a new test article support system; signal and power feed-throughs; elimination of unnecessary penetrations; and a new data acquisition and control commanding system including safety interlocks. This paper will provide a general overview of the LaRC 8 ft. by 15 ft. TVAC chamber, an overview of the new technical capabilities, and will illustrate each upgrade in detail, in terms of mechanical design and predicted performance. Additionally, an overview of the scope of tests currently being performed in the chamber will be documented, and sensor plots from tests will be provided to show chamber temperature and pressure performance with actual flight hardware under test.

Thornblom, Mark N.↗