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NASA NTRS2003

Multifunction Sensor Algorithm Development

A multifunction sensor has been developed in the Sensors and Electronics Technology Branch. It is capable of measuring heat flux, surface temperature, and, in principle, strain magnitude & direction, while compensating for the apparent strain due to changes in operating temperature. In order to achieve this strain measuring capability, Mr. Zeller will work on improving the signal processing algorithm to include several special cases, such as when the principal strain axis lies either parallel to or perpendicular to one of the arms of the sensor. In addition, he will implement a GUI to make the sensor more user friendly.

Zeller, Donald F.↗

NASA NTRS2017

Building Better Biosensors for Exploration into Deep-Space, Using Humanized Yeast

1.BioSentinel is 1 of 13 secondary payloads hitching a ride beyond Low Earth Orbit on Exploration Mission 1 (EM-1), set to launch from NASAs Space Launch System in 2019. EM-1 is our first opportunity to investigate the effects of the deep space environment on a eukaryotic biological system, the budding yeast S. cerevisiae. Though separated by a billion years of evolution we share hundreds of genes important for basic cell function, including responses to DNA damage. Thus, yeast is an ideal biosensor for detecting typesextent of damage induced by deep-space radiation.We will fly desiccated cells, then rehydrate to wake them up when the automated payload is ready to initiate the experiment. Rehydration solution contains SC (Synthetic Complete) media and alamarBlue, an indicator for changes in growth and metabolism. Telemetry of LED readings will then allow us to detect how cells respond throughout the mission. The desiccation-rehydration process can be extremely damaging to cells, and can severely diminish our ability to accurately measure and model cellular responses to deep-space radiation. The aim of this study is to develop a better biosensor: yeast strains that are more resistant to desiccation stress. We will over-express known cellular protectants, including hydrophilin Sip18, the protein disaggregase Hsp104, and thioredoxin Trx2, a responder to oxidative stress, then measure cell viability after desiccation to determine which factors improve stress tolerance. Over-expression of SIP18 in wine yeast starter cultures was previously reported to increase viability following desiccation stress by up to 70. Thus, we expect similar improvements in our space-yeast strains. By designing better yeast biosensors we can better prepare for and mitigate the potential dangers of deep-space radiation for future missions.This work is funded by NASAs AES program.

biosensor↗

NASA NTRS1999

Rate Dependent Deformation and Strength Analysis of Polymer Matrix Composites

A research program is being undertaken to develop rate dependent deformation and failure models for the analysis of polymer matrix composite materials. In previous work in this program, strain-rate dependent inelastic constitutive equations used to analyze polymers have been implemented into a mechanics of materials based composite micromechanics method. In the current work, modifications to the micromechanics model have been implemented to improve the calculation of the effective inelastic strain. Additionally, modifications to the polymer constitutive model are discussed in which pressure dependence is incorporated into the equations in order to improve the calculation of constituent and composite shear stresses. The Hashin failure criterion is implemented into the analysis method to allow for the calculation of ply level failure stresses. The deformation response and failure stresses for two representative uniaxial polymer matrix composites, IM7/977-2 and AS4-PEEK, are predicted for varying strain rates and fiber orientations. The predicted results compare favorably to experimentally obtained values.

Goldberg, Robert K.↗

NASA NTRS1986

Summary of laser speckle photogrammetry for HOST

High temperature static strain measurement capability is important for the success of the HOST program. As part of the NASA Lewis effort to develop the technology for improved hot-section durability, the HOST instrumentation program has, as a major goal, the development of methods for measuring strain at high temperature. Development work includes both improvements in resistance strain-gauge technology and, as an alternative approach, the development of optical techniques for high temperature strain measurement.

Pollack, Frank G.↗

NASA NTRS2019

Fatigue Behavior of Coated Titanium Alloys

Advanced multi-component TiAlCrTaSiN-based multilayered coatings were developed and processed onto Ti-6Al-4V (Ti-6-4) and GammaMet PX (GMPX or TiAl) alloys by a magnetron-enhanced physical vapor deposition technique. The coatings have recently been in development with the goal of improving advanced titanium alloy, turbine engine component durability and oxidation-erosion resistance. In this work, the performance of the multi-component coating system (including the outer layer nitride based coating and inner TiAlCrSi oxidation barrier bond coat) was studied, and the coating's influence on the fatigue behavior of the titanium-based alloys were compared. Although the multi-component coating was initially optimized to improve the coating's high temperature oxidation and erosion resistance, the lower ductility nitride-based coating needs further work on microstructure or composition to improve its mechanical stress resistance and strain tolerance for use in cyclically loaded, turbine blade operating conditions. This is particularly true for GMPX and other γ-TiAl alloys because these intermetallic titanium alloys have limited ductility and are very sensitive to defects such as coating cracks. However, the inner layer TiAlCrSi-coating had better adhesion and ductility, and may be a suitable choice to improve the oxidation resistance of titanium alloys.

Oxidation Barrier Coatings↗

NASA NTRSDate not supplied

Use of Tardigrade Proteins for Enhancing Cellular Stress Tolerance on the Moon

With sights set on returning a human presence to the Moon and plans to explore even farther beyond, it is imperative we understand the impact of deep space radiation, partial gravity, and the lunar surface on biology. The need for countermeasures to protect future astronauts from the unique conditions of space is ever-pressing and an assessment of bioproduction capabilities in space is a crucial step for sustaining long-term missions. The Lunar Explorer Instrument for space biology Applications (LEIA) aims to investigate the cell’s response to the lunar environment and test strategies for enhancing cellular tolerance on the Moon, utilizing the budding yeast Saccharomyces cerevisiae as a biosensor. S. cerevisiae serves as an excellent model organism due to its widespread use as an analog for human cells, well-characterized set of genetic tools, and ability to survive desiccation. However, these cells must remain desiccated for up to one year prior to launch and the radiation-sensitive strains designed for LEIA will likely be more vulnerable to desiccation effects. In this work, we introduce tardigrade proteins known for their protective mechanisms into potential LEIA strains to test genetic strategies for improving desiccation and radiation tolerance. Tardigrades are extremotolerant animals well-known for their ability to survive in harsh environments. Notably, they can survive extreme desiccation and radiation due to the upregulation of intrinsically disordered proteins (IDPs). It has been shown that integration of these tardigrade IDPs, such as cytosolic abundant heat-soluble (CAHS) proteins, into yeast can confer increased desiccation tolerance in synergy with trehalose. Our ongoing testing and assessment of bioengineered radiation and desiccation tolerance will help us gain insight into optimizing strain design and selection for protecting LEIA’s biological payload as well as genetic engineering strategies for enhancing bioproduction potential for future missions beyond low Earth orbit.

Genetics↗

NASA NTRSDate not supplied

Use of Tardigrade Proteins for Enhancing Cellular Stress Tolerance on the Moon

Genetics↗

NASA NTRS1982

A practical ultrasonic plethysmograph

An ultrasonic plethysmograph, which gives improved performance over the standard Whitney Strain Gauge, is described. This instrument monitors dimension changes in human limbs by measuring the transit times of acoustic pulses across two chords of the limb. In the case of a small uniform expansion, the percentage change in limb volume is shown to be proportional to twice the percentage change in either of the measured chords. Measurement of two chords allows correction for possible non-uniform expansion. In addition, measurement of two chords allows an estimate of the absolute cross-sectional area of the limb. The developed instrument incorporates a microprocessor, which performs necessary calculation and control functions. Use of the microprocessor allows the instrument to be self-calibrating. In addition, the device can be easily reprogrammed to incorporate improvements in operating features or computational schemes.

Wu, V. C.↗

NASA NTRSDate not supplied

BioNutrients-2: Improvements to the BioNutrients-1 Nutrient Production System

The BioNutrients (BN) project aims to develop an on-demand biological production system capable of rapid and safe delivery of multiple nutrients in single-use production packs for long-duration missions. The general concept of this system is to develop edible engineered microorganisms that produce nutrients for human consumption following long-term storage, revival, and growth. BN-1 is a five-year flight project currently on the International Space Station (ISS). It is testing the long-term storage of various microorganisms for the biomanufacturing of space-relevant compounds and validating the performance of the first generation of production packs. The BN-2 project expands the BN-1 flight project scope by introducing novel products, broadening the range of microbial food sources, and improving upon production pack hardware. We are optimizing the biomanufacturing platform for in situ production of yogurt and kefir on the ISS. BN-2 also will test engineered microorganisms, including a probiotic strain, to produce carotenoids or follistatin. To improve the feasibility of this technology for mission use, we transitioned from a hard-shell pack to a second-generation fluorinated ethylene propylene (FEP) bag. The single-use FEP bioreactor facilitates growth of target organisms in a contaminant free environment, while reducing mass and volume compared to the BN-1 hardware. These bioreactors will be employed for production of additional space-relevant products in the BN-2 project. On-orbit testing of FEP production packs will enable optimization of the platform for eventual flight use by the crew.

Natalie Ball↗

NASA NTRS1979

Mechanisms of boron fiber strengthening by thermal treatment

The fracture strain for boron on tungsten fibers can be improved by heat treatment under vacuum or argon environments. The mechanical basis for this improvement is thermally-induced axial contraction of the entire fiber, whereby strength-controlling core flaws are compressed and fiber fracture strain increased by the value of the contraction strain. By highly sensitive measurements of fiber density and volume, the physical mechanisms responsible for contraction under both environments was identified as boron atom diffusion out of the fiber sheath. The fiber contracts because the average volume of the resulting microvoid was determined to be only 0.26 + or - 0.09 the average atomic volume of the removed atom. The basic and practical implications of these results are discussed with particular emphasis on the theory, use, and limitations of heat-induced contraction as a simple cost-effective secondary processing method.

Dicarlo, J. A.↗

NASA NTRS1979

Studies for improved high temperature coatings for Space Shuttle application

Improvement of the current Class 2 Space Shuttle Orbiter RCG coating was experimentally investigated.Coatings, which are applied to LI-900 or LI-2200 tiles, were prepared to provide increased performance in thermal expansion, impact, residual strain and increased viscosity. Turbulent duct arc-plasma tests at NASA/Ames Research Center are continuing on two candidates that show improved low residual strain and increased high temperature viscosity. A coating system with lower fusion-temperature (1950 F) was identified which has the potential of improving tile yield through reduced LI-900 shrinkage and distortion since it can be fused at 250 F lower than the present Class 2 coating.

Creedon, J.↗

NASA NTRS1982

A time-dependent ice sheet model - Preliminary results

A numerical model of ice sheet flow is developed, and preliminary results are described. This model includes vertical resolution of temperature, stress, and strain rate which represents a considerable improvement over previous vertically averaged ice sheet models. The model follows the flow of ice along a flow line within an ice sheet drainage basin. Longitudinal stresses and basal sliding are included. Basal sliding is dependent on the base shear stress and a specified distribution of basal water pressure. The numerical methods used to solve the coupled set of stress and velocity equations for the static and time-evolutionary cases are discussed. A steady state profile simulating an ice stream is calculated for a particular set of input parameters, and changes in the profile are examined for different choices of parameters. Preliminary studies of response behavior are completed using a simplified ice sheet geometry with a fixed terminus or grounding line. The results of these studies illustrate ice sheet thinning in response to a lowered sea level or to a reduction in the extent of ice rises (or pinning points) within ice shelves.

Bindschadler, R. A.↗

NASA NTRS1984

Low-cost single-crystal turbine blades, volume 2

The overall objectives of Project 3 were to develop the exothermic casting process to produce uncooled single-crystal (SC) HP turbine blades in MAR-M 247 and higher strength derivative alloys and to validate the materials process and components through extensive mechanical property testing, rig testing, and 200 hours of endurance engine testing. These Program objectives were achieved. The exothermic casting process was successfully developed into a low-cost nonproperietary method for producing single-crystal castings. Single-crystal MAR-M 247 and two derivatives DS alloys developed during this project, NASAIR 100 and SC Alloy 3, were fully characterized through mechanical property testing. SC MAR-M 247 shows no significant improvement in strength over directionally solidified (DS) MAR-M 247, but the derivative alloys, NASAIR 100 and Alloy 3, show significant tensile and fatigue improvements. Firtree testing, holography, and strain-gauge rig testing were used to determine the effects of the anisotropic characteristics of single-crystal materials. No undesirable characteristics were found. In general, the single-crystal material behaved similarly to DS MAR-M 247. Two complete engine sets of SC HP turbine blades were cast using the exothermic casting process and fully machined. These blades were successfully engine-tested.

Strangman, T. E.↗

NASA NTRS1986

Dynamic response and stability of a composite prop-fan model

Results are presented for blade response and stability during wind tunnel tests of a 62.2 cm diameter model of a prop-fan, advanced turboprop, with swept graphite/epoxy composite blades. Measurements of dynamic response were made with the rotor mounted on an isolated nacelle, with varying tilt for nonuniform inflow, at flow speeds from 0.36 to 0.9 Mach number. The blade displayed no instabilities over the operating range tested, up to 0.9 Mach number and 10,000 RPM. Measurements are compared with those for other prop-fan models of both solid metal and graphite composite construction. The swept composite blade had less response than an unswept composite blade. Composite blades had more response than metal blades. Measurements are compared with theoretically based predictions. The 1-P blade response was significantly overpredicted using unimproved methods and somewhat overpredicted using improved methods. Unexpectedly high 2-P strain levels were measured and suggest the presence of nonlinear effects on blade response.

Smith, A. F.↗

NASA NTRS1988

Properties of silicon carbide fiber-reinforced silicon nitride matrix composites

The mechanical properties of NASA Lewis developed SiC/RBSN composites and their thermal and environmental stability havd been studied. The composites consist of nearly 30 vol pct of aligned 142 micron diameter chemically vapor-deposited SiC fibers in a relatively porous silicon nitride matrix. In the as-fabricated condition, the unidirectional and 2-D composites exhibited metal-like stress-strain behavior, graceful failure, and showed improved properties when compared with unreinforced matrix of comparable density. Furthermore, the measured room temperature tensile properties were relativley independent of tested volume and were unaffected by artifical notches normal to the loading direction or by thermal shocking from temperatures up to 800 C. The four-point bend strength data measured as a function of temperature to 1400 C in air showed that as-fabricated strength was maintained to 1200 C. At 1400 C, however, nearly 15 pct loss in strength was observed. Measurement of room temperature tensile strength after 100 hr exposure at temperatures to 1400 C in a nitrogen environment indicated no loss from the as-fabricated composite strength. On the other hand, after 100 hr exposure in flowing oxygen at 1200 and 1400 C, the composites showed approximately 40 pct loss from their as-fabricated ultimate tensile strength. Those exposed between 400 to 1200 C showed nearly 60 pct strength loss. Oxidation of the fiber/matrix interface as well as internal oxidation of the porous Si3N4 matrix are likely mechanisms for strength degradation. The excellent strength reproducibility, notch insensitivity, and high temperature strength of the composite makes it an ideal candidate for advanced heat engine applications provided coating or densification methods are developed to avoid internal oxidation attack.

Bhatt, Ramakrishna T.↗

NASA NTRS2014

Temporal Changes in Left Ventricular Mechanics: Impact of Bed Rest and Exercise

The use of more sensitive and specific echocardiographic techniques such as speckle tracking imaging may address the current limitations of conventional cardiac imaging techniques to provide insight into the extent and time course of cardiac deconditioning following spaceflight or headdown tilt bed rest (HDTBR). METHODS Speckle tracking assessment of longitudinal, radial, and circumferential strain and twist was used to evaluate the impact of 70 days of HDTBR (n=7) and HDTBR + exercise (n=11) on temporal changes in LV mechanics. Echocardiograms were performed pre (BR‐2), during (BR31, 70), and following (BR+4hr) HDTBR. Repeated measures ANOVA was used to evaluate the effect of HDTBR on cardiac variables in control and exercise subjects. RESULTS After sedentary HDTBR, longitudinal (‐19.0 +/- 1.8% vs. ‐14.9 +/- 2.4%) and radial (15.0 +/- 1.9% vs. 11.3 +/- 2.2%) strain and twist (18.0 +/- 4.0deg vs. 17.0 +/- 3.6deg) were significantly impaired. In contrast, exercise preserved LV mechanics, and there were non‐significant improvements from BR‐2 to BR70 in longitudinal strain (‐18.7 +/- 1.5% vs. ‐20.4 +/- 2.7%), radial strain (13.2 +/- 2.4% vs. 14.2 +/- 1.6%), and twist (16.3 +/- 3.6deg vs. 18.6 +/- 5.9deg). CONCLUSIONS Using speckle tracking echocardiography provides important new insights into temporal changes in LV mechanics during disuse and exercise training.

Scott, J. M.↗

NASA NTRS2020

Use of an Internal Mercury-Argon Lamp for the Calibration of Raman Frequency in Large Raman Images of Astromaterials

Raman imaging is an emerging tool for the analysis of meteorites, as it is capable of describing mineralogy, carbon composition/speciation, and crystal orientation all within a petrographic context. Adequately examining the heterogeneous composition of a meteorite, while maintaining low laser powers needed to prevent damage to meteorite mineralogy and organics, often requires the collection of large Raman images with long collection times on the timescale of days. However, the frequency calibration of the Raman instrument/spectrometer drifts on long timescales resulting in low frequency precision for the Raman spectra comprising a large Raman image. This decrease in frequency precision can compromise the analysis of geological markers that can provide important information on a meteorite sample. We examine, in detail, the change in bandwidth and frequency of the Raman bands and Hg-Ar emission lines in our Raman images as a function of time and laboratory temperature. To overcome the drift in calibration, we utilize a commercial WITec Raman instrument with an internal Hg-Ar calibration lamp to individually calibrate each spectrum in the Raman image. Our instrument, known as “Ratatoskr”, uses a beam splitter in place of the customary mirror to facilitate collection of Hg-Ar calibration lines concurrent with Raman spectra. We show that using the internal calibration we can improve the frequency precision for the spectra in our Raman images from ~±0.15 cm(exp -1) to ~±0.05 cm(exp -1) for Raman spectra collected over multiple days. This is important as it improves measurements of mineral chemistry, latent strain, and other features that are dependent upon accurate peak position determination. We also examine the spectral signal-to-noise ratio needed to minimize the frequency error when fitting bands to Gaussian/Lorentzian profiles. We then use our results to suggest a general method for calibrating the frequency of Raman spectra in large Raman images.

Jakubek, Ryan S.↗

NASA NTRS1992

ANS shell elements with improved transverse shear accuracy

A method of forming assumed natural coordinate strain (ANS) plate and shell elements is presented. The ANS method uses equilibrium based constraints and kinematic constraints to eliminate hierarchical degrees of freedom which results in lower order elements with improved stress recovery and displacement convergence. These techniques make it possible to easily implement the element into the standard finite element software structure, and a modified shape function matrix can be used to create consistent nodal loads.

Jensen, Daniel D.↗