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All sourcesNASA NTRSDOE OSTI
NASA NTRS2019

Pre-Demonstration Development of Controlled-Release Corrosion Inhibitors and Healing Agents as Alternatives to Hexavalent Chromium

This Limited Scope Study was directed to achieve the following objectives: (1) Scale-up of materials that can meet MIL-PRF-23377 (solvent-based primer). (2) Provide evidence of resistance to aircraft alkaline cleaners and de-icing fluids. (3) Provide formulation for initial ecological and toxicity screening. (4) Submit an interim report that will provide the basis for a future ESTCP (the Dept. of Defense's (DoD's) Environmental Security Technology Certification Program) demonstration effort.The encapsulation procedure for two corrosion inhibitors was scaled up from lab scale to 2.0 kilograms. This scale will accommodate high volume production of coatings with encapsulated corrosion inhibitors for large surface areas during a follow-on ESTCP demonstration effort. Test results provided evidence of resistance to alkaline cleaners and aircraft de-icing fluids and compliance with MIL-PRF-23377. All the MIL-PRF-23377 requirements were met with the exception of the adhesion requirement, in top coated panels, and the flexibility requirement. Work on solving these two problems will be done prior to validation and demonstration of the technology. An initial ecological and toxicity screening identified several factors that were not critical to the acceptance of the encapsulated corrosion inhibitor. This new technology will lead to environmentally friendly alternatives to hexavalent chromium that will enable DoD to protect its assets. Field demonstration, licensing, qualification, and commercialization will allow its real world utilization. Abstract for Appendix A. Toxicology Report: Corrosion controls a significant problem for military equipment. Many surface treatment materials currently in use on items of military or aerospace materiel contain chromium (VI) as a component, a source of significant human health and environmental hazard. The formulation under evaluation contains no chromium. Most of the proposed components are low to moderate toxicity and are not a significant concern. Two of the formulation components are associated with some cancer hazard - 2-mercaptobenzothiazole and formaldehyde, but both find widespread use in industry and additional investigation is not required for this project.

Calle, Luz Marina↗
NASA NTRSDate not supplied

The Instrumented Walking and Turning Test to Evaluate Suited Gait Dynamics and Performance in Extravehicular Activity Training Environments

Background and aims: Walking will be required for many exploration tasks on the Moon during the Artemis program. Walking in a straight line on the confined floorspace of a testing area, and repetitive treadmill walking that requires no change in direction may not adequately reflect the balance and coordination required during ambulation. Also, performance of turning maneuvers may be affected differently in different extravehicular activity (EVA) training facilities that simulate partial gravity. For example, the Neutral Buoyancy Lab (NBL) simulates lunar gravity by adding weight to underwater subjects to alter buoyancy and achieve the equivalent ground reaction force of 1/6 of Earth’s gravity (1/6G), whereas the Active Response Gravity Offload System (ARGOS) uses a computer controlled overhead suspension system programmed to continuously offload a percentage of a subject’s weight to simulate 1/6G. The degree to which dynamic movements such as turning are comparable across these EVA training facilities has not yet been evaluated. The instrumented gait test helps NASA scientists and engineers evaluate gait dynamics and performance in suited conditions, and this test demonstrates the unique characteristics and limitations of EVA training facilities. We developed an instrumented walking and turning test using inertial measurement units (IMUs) and conducted the test at NASA’s EVA training facilities. Results were used to compare suited walking and turning characteristics in the ARGOS and the NBL. Methods: Subjects donned the Mark III space suit during offloading with the ARGOS spreader bar gimbal and donned the Z2.5 space suit while underwater in the NBL with weights and floatation added to achieve realistic suit center of gravity. The test team securely attached three Opal (APDM, OR, USA) wireless IMUs on the space suit for each test run: one on the middle of the hard upper torso, and one on the left and on the right ankle bearings. During the NBL tests, the IMUs were encased in a waterproof housing (GoPro) with foam added to create a tighter fit. At both testing facilities, 6.3 m x 1.0 m (LxW) walking lines were marked, and a cone for turning or walking around was located at the end of the walking path with another line on the other side of the cone to indicate the stopping point after walking around the cone. Under simulated 1/6G, subjects began by standing at the marked line with their arms folded across the chest, they then walked at a preferred speed along the straight walking path until they reached the end, turned 180 degrees around the cone, and finally stopped at the marked stopping point. All IMU data recorded during testing were automatically saved to the internal memory. Then, raw IMU signals were processed using custom MATLAB (Mathworks, MA, USA) code to compare gait parameters during both the walking and the turning components of the task. These parameters included time (s), speed (m/s for walking and rad/s for turning), step number (n) and walk:turn time ratio (% time spent straight walking versus turning). Results: Less time, faster gait, fewer steps, and higher walk:turn ratio during both walking and turning components were exhibited during tests performed at the ARGOS versus those performed at the NBL. During the NBL tests, the slower walking speed continued at the same rate throughout a U-shape turn. During the ARGOS tests, the subjects performed shorter and tighter turns at 4 times the speed of the NBL turns because they walked 30% faster and the vertical offloading system gave them more support. Conclusion: Our data show that the differences in walking and turning parameters during the NBL tests may be due to the high viscosity in the water environment where the motion of the lower limbs was slow and did not reach full flexion and extension. These tests improve the current knowledge of testing environments in preparation for EVAs on the lunar surface.

Kyoung Jae Kim↗
DOE OSTI2025

Foaming prediction in pure liquids from dimensionless numbers inspired by the theory of fluid behavior for drops

Foaming prediction is critical for selecting materials and designing processes in industries such as bioprocessing and gas processing. Existing models lack the generality needed for a wide range of materials and overlook the foaming behavior in pure liquids. Here, this work presents a novel method for predicting foaming in pure liquids based on their density, surface tension, and viscosity, using Reynolds ( Re ) and Ohnesorge ( Oh ) numbers. A foaming prediction map, leveraging the theory of fluid drop behavior, was developed by plotting these numbers. This map delineates distinct non-foaming and foaming regions, functioning as a binary classifier for foaming predictions. The map was fitted and validated through shake test experiments on 46 liquids, demonstrating reliable predictions, except for a specific region characterized by small Oh and large Re numbers. This region corresponded to relatively low foam stability and high turbulence, making foaming predictions challenging for liquids in this category.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2014

Investigation of Spiral Bevel Gear Condition Indicator Validation Via AC-29-2C Using Damage Progression Tests

This report documents the results of spiral bevel gear rig tests performed under a NASA Space Act Agreement with the Federal Aviation Administration (FAA) to support validation and demonstration of rotorcraft Health and Usage Monitoring Systems (HUMS) for maintenance credits via FAA Advisory Circular (AC) 29-2C, Section MG-15, Airworthiness Approval of Rotorcraft (HUMS) (Ref. 1). The overarching goal of this work was to determine a method to validate condition indicators in the lab that better represent their response to faults in the field. Using existing in-service helicopter HUMS flight data from faulted spiral bevel gears as a "Case Study," to better understand the differences between both systems, and the availability of the NASA Glenn Spiral Bevel Gear Fatigue Rig, a plan was put in place to design, fabricate and test comparable gear sets with comparable failure modes within the constraints of the test rig. The research objectives of the rig tests were to evaluate the capability of detecting gear surface pitting fatigue and other generated failure modes on spiral bevel gear teeth using gear condition indicators currently used in fielded HUMS. Nineteen final design gear sets were tested. Tables were generated for each test, summarizing the failure modes observed on the gear teeth for each test during each inspection interval and color coded based on damage mode per inspection photos. Gear condition indicators (CI) Figure of Merit 4 (FM4), Root Mean Square (RMS), +/- 1 Sideband Index (SI1) and +/- 3 Sideband Index (SI3) were plotted along with rig operational parameters. Statistical tables of the means and standard deviations were calculated within inspection intervals for each CI. As testing progressed, it became clear that certain condition indicators were more sensitive to a specific component and failure mode. These tests were clustered together for further analysis. Maintenance actions during testing were also documented. Correlation coefficients were calculated between each CI, component, damage state and torque. Results found test rig and gear design, type of fault and data acquisition can affect CI performance. Results found FM4, SI1 and SI3 can be used to detect macro pitting on two more gear or pinion teeth as long as it is detected prior to progressing to other components or transitioning to another failure mode. The sensitivity of RMS to system and operational conditions limit its reliability for systems that are not maintained at steady state. Failure modes that occurred due to scuffing or fretting were challenging to detect with current gear diagnostic tools, since the damage is distributed across all the gear and pinion teeth, smearing the impacting signatures typically used to differentiate between a healthy and damaged tooth contact. This is one of three final reports published on the results of this project. In the second report, damage modes experienced in the field will be mapped to the failure modes created in the test rig. The helicopter CI data will then be re-processed with the same analysis techniques applied to spiral bevel rig test data. In the third report, results from the rig and helicopter data analysis will be correlated. Observations, findings and lessons learned using sub-scale rig failure progression tests to validate helicopter gear condition indicators will be presented.

gears↗
DOE OSTI2021

Hardware-Based Emulator with Deep Learning Model for Building Energy Control and Prediction Based on Occupancy Sensors’ Data

Heating, ventilation, and air conditioning (HVAC) is the largest source of residential energy consumption. Occupancy sensors’ data can be used for HVAC control since it indicates the number of people in the building. HVAC and sensors form a typical cyber-physical system (CPS). In this paper, we aim to build a hardware-based emulation platform to study the occupancy data’s features, which can be further extracted by using machine learning models. In particular, we propose two hardware-based emulators to investigate the use of wired/wireless communication interfaces for occupancy sensor-based building CPS control, and the use of deep learning to predict the building energy consumption with the sensor data. We hypothesize is that the building energy consumption may be predicted by using the occupancy data collected by the sensors, and question what type of prediction model should be used to accurately predict the energy load. Another hypothesis is that an in-lab hardware/software platform could be built to emulate the occupancy sensing process. The machine learning algorithms can then be used to analyze the energy load based on the sensing data. To test the emulator, the occupancy data from the sensors is used to predict energy consumption. The synchronization scheme between sensors and the HVAC server will be discussed. We have built two hardware/software emulation platforms to investigate the sensor/HVAC integration strategies, and used an enhanced deep learning model—which has sequence-to-sequence long short-term memory (Seq2Seq LSTM)—with an attention model to predict the building energy consumption with the preservation of the intrinsic patterns. Because the long-range temporal dependencies are captured, the Seq2Seq models may provide a higher accuracy by using LSTM architectures with encoder and decoder. Meanwhile, LSTMs can capture the temporal and spatial patterns of time series data. The attention model can highlight the most relevant input information in the energy prediction by allocating the attention weights. The communication overhead between the sensors and the HVAC control server can also be alleviated via the attention mechanism, which can automatically ignore the irrelevant information and amplify the relevant information during CNN training. Our experiments and performance analysis show that, compared with the traditional LSTM neural network, the performance of the proposed method has a 30% higher prediction accuracy.

Ye, Zhijing↗
NASA NTRS1990

Historical overview of the Biosphere 2 project

An extensive historical overview is given of the Biosphere 2 project. The overview begins in late 1969, as the moon landings commenced, when work began on ecological projects which laid the conceptual foundation for the current Biosphere 2 project. Continuing through to taking a complete functional suite of microbes together with their associated aquatic elements and an air volume and putting them inside a closed lab flask in which to measure the oxygen and CO2 levels, study energy flows and visually observe the changes therein. The laws of biospherics formulated by the author which can be tested in the Biosphere 2 project are listed.

Allen, John P.↗
NASA NTRS2000

International Space Station: Expedition 2000

Live footage of the International Space Station (ISS) presents an inside look at the groundwork and assembly of the ISS. Footage includes both animation and live shots of a Space Shuttle liftoff. Phil West, Engineer; Dr. Catherine Clark, Chief Scientist ISS; and Joe Edwards, Astronaut, narrate the video. The first topic of discussion is People and Communications. Good communication is a key component in our ISS endeavor. Dr. Catherine Clark uses two soup cans attached by a string to demonstrate communication. Bill Nye the Science Guy talks briefly about science aboard the ISS. Charlie Spencer, Manager of Space Station Simulators, talks about communication aboard the ISS. The second topic of discussion is Engineering. Bonnie Dunbar, Astronaut at Johnson Space Flight Center, gives a tour of the Japanese Experiment Module (JEM). She takes us inside Node 2 and the U.S. Lab Destiny. She also shows where protein crystal growth experiments are performed. Audio terminal units are used for communication in the JEM. A demonstration of solar arrays and how they are tested is shown. Alan Bell, Project Manager MRMDF (Mobile Remote Manipulator Development Facility), describes the robot arm that is used on the ISS and how it maneuvers the Space Station. The third topic of discussion is Science and Technology. Dr. Catherine Clark, using a balloon attached to a weight, drops the apparatus to the ground to demonstrate Microgravity. The bursting of the balloon is observed. Sherri Dunnette, Imaging Technologist, describes the various cameras that are used in space. The types of still cameras used are: 1) 35 mm, 2) medium format cameras, 3) large format cameras, 4) video cameras, and 5) the DV camera. Kumar Krishen, Chief Technologist ISS, explains inframetrics, infrared vision cameras and how they perform. The Short Arm Centrifuge is shown by Dr. Millard Reske, Senior Life Scientist, to subject astronauts to forces greater than 1-g. Reske is interested in the physiological effects of the eyes and the muscular system after their exposure to forces greater than 1-g.

Source record↗
NASA NTRS2013

Robonaut 2 - Preparing for Intra-Vehicular Mobility on the International Space Station

Robonaut 2 (R2) has been undergoing experimental trials on board the International Space Station (ISS) for more than a year. This upper-body anthropomorphic robotic system shown in Figure 1 has been making steady progress after completing its initial checkout. R2 demonstrated free space motion, physically interacted with its human crew mates, manipulated interfaces on its task board and has even used its first tool. This steady growth in capability will lead R2 to its next watershed milestone. Developers are currently testing prototype robotic climbing appendages and a battery backpack in preparation of sending flight versions of both subsystems to the ISS in late 2013. Upon integration of its new components, R2 will be able to go mobile inside the space station with a twofold agenda. First, R2 will learn to maneuver in microgravity in the best possible laboratory for such a task. Second, it will start providing early payback to the ISS program by helping with intra-vehicular (IVA) maintenance tasks. The experience gained inside the ISS will be invaluable in reducing risk when R2 moves to its next stage and is deployed as an extra-vehicular (EVA) tool. Even on its current fixed base stanchion, R2 has already shown its capability of performing several maintenance tasks on the ISS. It has measured the air flow through one of the stations vents and provided previously unavailable real time flow data to ground operators. R2 has cleaned its first handrail, exciting some crew members that perhaps Saturday morning housekeeping on the station may someday become a task they can hand off to their robotic colleague. Other tasks, including using radio frequency identification (RFID) tools for inventory tasks or vacuuming air filters, have also been suggested and will be explored. Once mobile, R2 will take on these tasks and more to free up crew time for more important science and exploration pursuits. In addition to task exploration, research and testing is happening on orbit to prepare for R2 mobility operations. The current vision system in R2 s head is being used to identify and localize IVA handrails throughout the US Lab and ground control software is being updated and integrated in advance of supporting mobility operations.

Badger, Julia↗
NASA NTRS2017

Plans and Preliminary Results of Fundamental Studies of Ice Crystal Icing Physics in the NASA Propulsion Systems Laboratory

This paper describes plans and preliminary results for using the NASA Propulsion Systems Lab (PSL) to experimentally study the fundamental physics of ice-crystal ice accretion. NASA is evaluating whether this facility, in addition to full-engine and motor-driven-rig tests, can be used for more fundamental ice-accretion studies that simulate the different mixed-phase icing conditions along the core flow passage of a turbo-fan engine compressor. The data from such fundamental accretion tests will be used to help develop and validate models of the accretion process. This paper presents data from some preliminary testing performed in May 2015 which examined how a mixed-phase cloud could be generated at PSL using evaporative cooling in a warmer-than-freezing environment.

Ice-Crystal Ice Accretion↗
NASA NTRSDate not supplied

Hybrid Propulsion Emulation Rig (HyPER)

HyPER is a hardware-in-the-loop laboratory that was designed specifically to investigate the dynamic interactions between turbomachinery, the electric power system, and the constantly varying loads of electrified aircraft. It is a small-scale lab capable of rapid reconfiguration through software. This allows the emulation of new engines using simulation models that are easily replaced and then appropriately scaled for power and inertia to the test hardware.

Control↗
NASA NTRSDate not supplied

Manual Crew Override of Vehicle Landings Following G-Transitions

BACKGROUND Manual control during exploration spaceflight consists of both planned automated supervisory control and unplanned crew override. This crew override capability is critical to enable overall mission success during landing contingencies. However, the introduction of manual override capabilities must be implemented to enable crews to mitigate risks introduced by human error. Adaptive changes in the sensorimotor system can manifest during g-transitions as spatial disorientation. While training and landing aids enable successful landing through disorientation, these adaptive changes may increase cognitive demand that needs to be accounted for in the manual control strategy. It is important to characterize these effects as soon as possible following the G-transition to develop appropriate countermeasures. METHODS The following study seeks to inform the risk associated with altered sensorimotor and vestibular function impacting critical mission tasks. We aim to characterize the effects of short and long-duration weightlessness on manual control following G-transitions using simulated lunar landing on a six-degree-of-freedom (6DOF) motion base, a fixed base simulation, and a supervisory control tablet task. The primary goal is to understand the impact of spaceflight on crew ability to perform manual crew override and supervisory control. This aim will be assessed by comparing pre- versus postflight simulation performance in crewmembers assigned to either short duration (< 30 day) or long duration (~6- month) missions to the International Space Station (ISS). We hypothesize there will be postflight increases in the percent time that pilots are outside of the acceptable range for recommended vehicle state parameters and the reaction time for secondary cognitive tasks. Ground-based control subjects, who are demographically matched to the crew considering age (± 5 years) and gender, will undergo the same testing schedule as the crew to examine the effects of flight phase independent of microgravity exposure. The second aim is to examine how adaptive changes in vestibular and cognitive function relate to changes in manual crew override proficiency. Crew performance for a sensorimotor perceptual test battery will evaluate motion perception tracking, roll nulling, and/or vection sensitivity using the 6DOF motion base. We hypothesize that a higher severity of vestibular alterations will be associated with increased percent time outside of guidance limits. Motion sickness severity and sleepiness will also be evaluated. To determine the impact of “just-in-time” training, the third aim seeks to compare performance during on-board lunar landing tasks conducted late in-flight to early postflight. We hypothesize that proficiency on the “just-in-time” laptop trainer late in mission will be positively correlated with early postflight proficiency on the same task. The final aim will establish assessments of performance, training protocols, and the learning progression in a ground-control cohort of first-time users. RESULTS The assessment of the learning progression associated with the piloting task on the motion base system with thirty ground subjects will be reported. Learning curves will be established across four distinct sessions and within session considering trial difficulty. The difficulty of the landing task can be modulated with the landing divert distance and cross or downrange difficulty. Results may include changes in performance across multiple trials of a multi-attribute lunar tablet supervisory control task. Preliminary investigations of eighteen subjects who completed vestibular threshold and motion perception tasks offer expected performance ranges for upcoming preflight crew evaluations. The results yielded an average roll threshold of 0.46 ± 0.30 deg/s and an average roll nulling root mean square error performance of 2.52 ± 0.52 deg/s. RELEVANCE This project will deliver an operational demonstration of crew monitoring capability following spaceflight and identify potential deficits that may require remediation. Comparison of individual vestibular and cognitive changes with crew performance will help better characterize the manual control risks associated with sensorimotor alterations. Ground testing will evaluate learning progression, refine training protocols, and serve as a control cohort for comparisons to crew performance. ACKNOWLEDGEMENTS: The authors acknowledge contributions from Draper, the Dynamic Skills Trainer (DST) Lab, and the Software, Robotics, and Simulation Division toward the development of the lunar landing simulation platforms. This project is funded by the Human Health Countermeasures Element.

Hannah M. Weiss↗
DOE OSTI2020

Deep Exclusive p 0 Electroproduction Measured in Hall A at Jefferson Lab with the Upgraded CEBAF

Our understanding of the proton's structure in terms of its fundamental degrees of freedom, quarks and gluons, is incomplete. Generalized Parton Distributions (GPDs) can enhance our understanding of the partonic structure of the proton as it includes the correlation between the momentum and transverse position of partons. Exclusive electroproduction of the pion (ep→e'p'π 0 ) is one of the potential channels to access the GPDs. GPDs are defined at the Bjorken limit where the total amplitude can be factorized in a hard scattering of the photon off the quark and a soft part described by the GPDs. At sufficiently high Q 2 , a factorization scheme for exclusive meson production processes exists but only for longitudinally polarized virtual photons. As long as the longitudinally polarized virtual photons dominate the cross-section, we can have factorization and extract the GPDs. But the existing data for π 0 production at low Q 2 and low x B show the dominance of transverse part of the cross-section over the longitudinal one. Some transversity GPD models have found that an effective way to factorize the contribution from transversely polarized virtual photons to explain the dominance of σ T over σ L , shown by existing data. The experiment E12-06-114 ran in experimental Hall A during 2014-2016. The primary goal of this experiment was to measure the DVCS cross-section but the experimental configuration also allows the measurement of deep exclusive π 0 production. Taking advantage of the upgraded CEBAF at Jefferson Lab, we explored the high Bjorken-x (0.60) and high Q 2 regime for the first time. The extracted cross-section terms for π 0 production helps us to test the validity of QCD factorization in our kinematic regime. Our π 0 production results can be used to test and improve the existing models of proton structure. Cross-section results will be presented at two different Q 2 values for fixed x B of 0.60.

Karki, Bishnu↗
NASA NTRS1999

ACTS 118x: High Speed TCP Interoperability Testing

With the recent explosion of the Internet and the enormous business opportunities available to communication system providers, great interest has developed in improving the efficiency of data transfer over satellite links using the Transmission Control Protocol (TCP) of the Internet Protocol (IP) suite. The NASA's ACTS experiments program initiated a series of TCP experiments to demonstrate scalability of TCP/IP and determine to what extent the protocol can be optimized over a 622 Mbps satellite link. Through partnerships with the government technology oriented labs, computer, telecommunication, and satellite industries NASA Glenn was able to: (1) promote the development of interoperable, high-performance TCP/IP implementations across multiple computing / operating platforms; (2) work with the satellite industry to answer outstanding questions regarding the use of standard protocols (TCP/IP and ATM) for the delivery of advanced data services, and for use in spacecraft architectures; and (3) conduct a series of TCP/IP interoperability tests over OC12 ATM over a satellite network in a multi-vendor environment using ACTS. The experiments' various network configurations and the results are presented.

Brooks, David E.↗
DOE OSTI2022

Outdoor Test Bed Performance of a Power Line Sensor Using a Real-Time Event Simulator

This report summarizes the design and application of an outdoor power line sensor testbed (OPLST) with a real-time simulator and power meter to compare a potential transformer (PT) and current transformer (CT) versus an advanced line-post sensor. The OPLST was created to validate advanced medium-voltage (20/34.5 kV) outdoor power line sensors used in electrical distribution systems. Electrical utilities have installed metering and relay-protection transformers like PTs and CTs for several decades. The PTs/CTs are iron core measurement transformers based on the electromagnetic induction principle and provide reliable data in normal grid operation. However, new outdoor power line sensors (OPLS) using other technologies like voltage divider, Rogowski coil and optical principles have become available and may have favorable performance and costs compared to PTs/CTs. Therefore, the importance of testing these technologies with the PT/CT, to compare the measured phase voltage/current at different power grid scenarios is crucial to understand the performance of these new OPLS. For this study a G&W Electric Model CVS-36-O power line sensor was chosen as the OPLS to test with voltage/current signals. An OPAL-RT Technologies Model OP4510 real-time simulator and Schweitzer Engineering Laboratories Model SEL-735 power meter were installed with the 20/34.5 kV OPLST to compare the measured transient events collected from an advanced OPLS and the PT/CT. This system is installed at the Distributed Energy Communications and Control (DECC) lab, Oak Ridge National Laboratory (ORNL). The simulator generated different power grid scenarios (electrical faults, capacitor bank operation, service restoration, etc.), and its analog-output signals were connected to the voltage/current amplifiers that feed the 20/34.5 kV aerial cable loop through the PT/CT devices. Additional PT/CT devices were also wired with the medium voltage aerial cable loop to measure the phase current/voltage signals and server as references. After each test, common format for transient data exchange (COMTRADE) files were collected from the SEL-735 power meter and used to compare the performance of the OPLS with the PT/CT. The behavior of analog signals, harmonic components, total harmonic distortion and crest factors were assessed and found favorable for the G&W sensor as compared to the reference PT/CT.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1998

A Specimen Size Effect on the Fatigue Crack Growth Rate Threshold of IN 718

Fatigue crack growth rate (FCGR) tests were conducted on IN 718 in the solution annealed and aged condition at room temperature in accordance with E647-87. As part of each test, the FCGR threshold was measured using the decreasing Delta K method. A new heat of material was being tested and some of this material was sent to a different laboratory which wanted to use a specimen with a 127 mm width. Threshold data previously had been established on specimens with a width of 50.8 mm. As a check of the laboratory, tests were conducted at room temperature and R equal to 0.1 for comparison with the earlier data. The results were a threshold significantly higher than previously observed. Interchanging of specimen sizes and laboratories showed that the results were not due to a heat-to-heat or lab-to-lab variation. The results to be presented here are those obtained at the original laboratory. Growth rates were measured using the electric potential drop technique at R values of 0.1, 0.7, and 0.9. Compact tension specimen sizes with planer dimensions of 25.4 mm, 50.8 mm, and 127 mm were used. Crack growth rates at threshold were generally below 2.5 X 10(exp -8) mm / cycle. Closure measurements were made on some of the specimens by a manual procedure using a clip gage. When the crack growth rate data for the specimens tested at R equal to 0.1 were plotted as a function of applied Delta K, the thresholds varied with specimen width. The larger the width, the higher the threshold. The thresholds varied from 6.5 MPa-m(exp 1/2) for the 25.4 mm specimen to 15.4 MPa-m(exp 1/2) for the 127 mm specimen. At R equal to 0.7, the 25.4 mm and 50.8 mm specimens had essentially the same threshold, about 2.9 MPa-m(exp 1/2)while the 127 mm specimen had a threshold of 4.5 MPa-m(exp 1/2). When plotted as a function of effective Delta K, the R equal to 0.1 data are essentially normalized. Various aspects of the test procedure will be discussed as well as the results of analysis of the data using some different closure models.

Garr, K. R.↗
NASA NTRS2006

USDC based rapid penetrator of packed soil

Environment protection requires more testing and analysis tools. To detect buried chemical containers or other objects embedded in soil and avoid possible damages of them, a penetrator of packed soil operated using low pushing force was developed. The design was based on a novel driving mechanism of the ultrasonic/sonic driller/corer (USDC) device developed in the NDEAA lab at JPL [Bar-Cohen et al 2001, Bao et al 2003]. In the penetrator, a small free-flying mass is energized by a piezoelectric transducer and impacts a rod probe on its shoulder at frequencies of hundreds times per second. The impacts help the probe to penetrate the packed soil rapidly. A great reduction of the needed pushing force for penetration was achieved. The details of the design of the prototype penetrator and the results of performance tests are presented.

sampling↗
DOE OSTI2023

Perspectives for self-driving labs in synthetic biology

Self-driving labs (SDLs) combine fully automated experiments and data collection with artificial intelligence (AI) and control algorithms that decide not only the set of parameters for the next experiment, but also potentially which scientific hypotheses to test. Taken to their ultimate expression, SDLs could usher a new paradigm of scientific research, where the world is probed, interpreted, and explained by machines for human benefit. Whereas there are functioning SDLs in the fields of chemistry and materials science, we contend that synthetic biology provides a unique opportunity since the genome provides a single, easily accessible, target for affecting the incredibly wide repertoire of biological cell behavior. Since they can provide large amounts of high-quality data, SDLs can be a platform for AI to develop approaches to systematically convert data into scientific knowledge systems. These knowledge systems can be used both to understand the biological world and to design bioengineered systems to fit a desired specification (inverse design). However, the level of investment required for the creation of biological SDLs is only warranted if directed towards solving difficult and enabling biological questions. Here, we discuss challenges and opportunities in creating SDLs for synthetic biology.

59 BASIC BIOLOGICAL SCIENCES↗