Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “LOAD RING”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Community Data Contribution to M.E.T.A. with ATF-relevant Hydrided Zr cladding (Coated and Uncoated)

Since the aftermath of the Fukushima Daiichi loss-of-coolant accident, accident-tolerant fuel (ATF) claddings have been developed to improve the coping times in such events. However, the mechanical performance of ATF cladding is crucial in ensuring that it does not negatively impact the mechanical integrity during all other stages of the nuclear fuel cycle, and the validity of the existing safe operating margins must be verified. However, due to the cladding’s tube geometry and textured anisotropy, determination of apparent mechanical properties under certain deformation paths is challenging. In the uniaxial hoop direction, for instance, the measured mechanical stresses include frictional forces caused by loading mandrels or varying deformation paths in the sample during traditional ring tensile testing. This experimental difficulty is exacerbated by the specimen size. However, addressing these challenges enables irradiation separate-effects investigations in which the materials can be inserted in reactors like the High Flux Isotope Reactor, and reducing the material consumption of commercially irradiated material allows for further post-irradiation examinations. Despite the advantages of reduced-scale mechanical testing, any drawbacks from new specimen geometries must be evaluated, and uncertainties from specimen preparation, setup, and analysis methodologies must be understood.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1984

Stress-derivative control of keystoning deformation in finite element codes

The stress derivative technique for control of keystoning deformation in under-integrated finte elements is based on expansion of the stress in a Taylor series about the element center and retention of additional terms beyond the constant stress term. It has the advantage over other control techniques that keystoning resistance is provided by actual rather than artificial material properties. Application of this technique to the quadrilateral ring elements used for modelling solids of revolution subjected to axisymmetric loads is described. In a cylindrical coordinate system additional terms appear in the formulation which must be dealt with in arriving at a workable keystoning control scheme.

Schulz, J. C.↗
NASA NTRS1985

Design of traction drives

Traction drives are among the simplest of all speed-changing mechanisms. Because of their simplicity and their ability to smoothly and continuously adjust speed, they are excellent choices for many drive system applications. They have been used in industrial service for more than 100 years. Today's traction drives have power capacities which rival the best gear and belt drives due to modern traction fluids and highly fatigue-resistant bearing steels. This report summarizes methods to analyze and size traction drives. Lubrication principles, contact kinematics, stress, fatigue life, and performance prediction methods are presented. The effects of the lubricant's traction characteristics on life and power loss are discussed. An example problem is given which illustrates the effects of spin on power loss. Loading mechanism design and the design of nonlubricated friction wheels and rings are also treated.

Loewenthal, S. H.↗
NASA NTRS1994

Influence of an asymmetric ring on the modeling of an orthogonally stiffened cylindrical shell

Structural models are examined for the influence of a ring with an asymmetrical cross section on the linear elastic response of an orthogonally stiffened cylindrical shell subjected to internal pressure. The first structural model employs classical theory for the shell and stiffeners. The second model employs transverse shear deformation theories for the shell and stringer and classical theory for the ring. Closed-end pressure vessel effects are included. Interacting line load intensities are computed in the stiffener-to-skin joints for an example problem having the dimensions of the fuselage of a large transport aircraft. Classical structural theory is found to exaggerate the asymmetric response compared to the transverse shear deformation theory.

Rastogi, Naveen↗
NASA NTRS1980

Effect of cage design on characteristics of high-speed-jet-lubricated 35-millimeter-bore ball bearing

Parametric tests were conducted with a 35 mm bore angular contact ball bearing with a double outer land guided cage. Provisions were made for jet lubrication and outer-ring cooling of the bearing. Test conditions included a combined thrust and radial load at nominal shaft speeds of 48,000 rpm, and an oil-in temperature of 394 K (250 F). Successful operation of the test bearing was accomplished up to 2.5 million DN. Test results were compared with those obtained with similar bearing having a single outer land guided cage. Higher temperatures were generated with the double outer land guided cage bearing, and bearing power loss and cage slip were greater. Cooling the outer ring resulted in a decrease in overall bearing operating temperature.

Schuller, F. T.↗
DOE OSTI2015

Analysis of ringing effects due to magnetic core materials in pulsed nuclear magnetic resonance circuits

This work presents investigations and detailed analysis of ringing in a non-resonant pulsed nuclear magnetic resonance (NMR) circuit. Ringing is a commonly observed phenomenon in high power switching circuits. The oscillations described as ringing impede measurements in pulsed NMR systems. It is therefore desirable that those oscillations decay fast. It is often assumed that one of the causes behind ringing is the role of the magnetic core used in the antenna (acting as an inductive load). We will demonstrate that an LRC subcircuit is also set-up due to the inductive load and needs to be considered due to its parasitic effects. It is observed that the parasitics associated with the inductive load become important at certain frequencies. The output response can be related to the response of an under-damped circuit and to the magnetic core material. This research work demonstrates and discusses ways of controlling ringing by considering interrelationships between different contributing factors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1972

Computer controlled performance mapping of thermionic converters: effect of collector, guard-ring potential imbalances on the observed collector current-density, voltage characteristics and limited range performance map of an etched-rhenium, niobium planar converter

The effect of collector, guard-ring potential imbalance on the observed collector-current-density J, collector-to-emitter voltage V characteristic was evaluated in a planar, fixed-space, guard-ringed thermionic converter. The J,V characteristic was swept in a period of 15 msec by a variable load. A computerized data acquisition system recorded test parameters. The results indicate minimal distortion of the J,V curve in the power output quadrant for the nominal guard-ring circuit configuration. Considerable distortion, along with a lowering of the ignited-mode striking voltage, was observed for the configuration with the emitter shorted to the guard ring. A limited-range performance map of an etched-rhenium, niobium, planar converter was obtained by using an improved computer program for the data acquisition system.

Manista, E. J.↗
DOE OSTI2013

Analysis of dose rates to O-ring and membrane for SAVY-4000 container

New generation standard nuclear material containers (NG SNMC aka SAVY 4000) have been designed for storage of various actinide materials whose specific activity is less than or equal to that of heat source plutonium (13.4 Ci/g). The containers also have a limiting decay heat of 25 W. The objective of this analysis is to determine the maximum absorbed dose rate delivered to the Viton o-ring and to the Teflon filter membrane located in the container’s lid under these activity and decay heat constraints. Previous analysis conducted in 2011 showed that the dose rate to the o-ring is higher for the 1-Quart container as compared to the 3-Quart container for the maximum material loading at the density of 3 g cm -3 for all material compositions studied given the size constraints of each container. Ratios of dose rates to the o-ring for the 1-Quart container as compared to the 3-Quart container are summarized in Table 1. In addition, the dose rate to the Teflon filter membrane is 3.4 times higher for the 1-Quart container with MT52+Am as compared to the 3-Quart container with MT52+Am. Thus only the 1-Quart container is analyzed in this report.

61 RADIATION PROTECTION AND DOSIMETRY↗
NASA NTRS1942

The stresses in stiffener openings

The present study treats as a typical example a ring the center line of which is produced by the intersection of two circular cylinders of different diameter. Three load cases are analyzed: (1) Axial and circumferential stresses in both cylinders, the cylinder stresses themselves to be in the ratio conformal to the cylinders loaded under internal pressure. (2) Pure longitudinal tension in the large cylinder. (3) Pure shear (torsion) in the large cylinder. To simplify the calculation, it is assumed that the ring, compared to the shell, is very strong, so that its deformations have no perceptible effect on the stress condition in the shell. This provides an upper limit for the ring stresses actually produced in a shell design, for, according to the theory of stressed skin statics the shells, by elastic flexibility of the ring, regroup the forces deposited on it in such a manner that the ring is relieved.

Marguerre, K↗
DOE OSTI2024

Defining Reactivity–Deconstructability Relationships for Copolymerizations Involving Cleavable Comonomer Additives

The incorporation of cleavable comonomers as additives into polymers can imbue traditional polymers with controlled deconstructability and expanded end-of-life options. The efficiency with which cleavable comonomer additives (CCAs) can enable deconstruction is sensitive to their local distribution within a copolymer backbone, which is dictated by their copolymerization behavior. While qualitative heuristics exist that describe deconstructability, comprehensive quantitative connections between CCA loadings, reactivity ratios, polymerization mechanisms, and deconstruction reactions on the deconstruction efficiency of copolymers containing CCAs have not been established. Here, in this work, we broadly define these relationships using stochastic simulations characterizing various polymerization mechanisms (e.g., controlled/living, free-radical, and reversible ring-opening polymerizations), reactivity ratio pairs (spanning 2 orders of magnitude between 0.01 and 100), CCA loadings (2.5% to 20%), and deconstruction reactions (e.g., comonomer sequence-dependent deconstruction behavior). We show general agreement between simulated and experimentally observed deconstruction fragment sizes from the literature, demonstrating the predictive power of the methods used herein. These results will guide the development of more efficient CCAs and inform the formulation of deconstructable materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2008

Saturn Magnetospheric Impact on Surface Molecular Chemistry and Astrobiological Potential of Enceladus

The active south polar surface of Enceladus is exposed to strong chemical processing by direct interaction with charged plasma and energetic particles in the local magnetospheric environment of this icy moon. Chemical oxidation activity is suggested by detection of H202 at the surface in this region and less directly by substantial presence of C02, CO, and N2 in the plume gases. Molecular composition of the uppermost surface, including ejecta from plume activity, is radiolytically transformed mostly by penetrating energetic electrons with lesser effects from more depleted populations of energetic protons. The main sources of molecular plasma ions and E-ring dust grains in the magnetospheric environment are the cryovolcanic plume emissions from Enceladus. These molecular ions and the dust grains are chemically processed by magnetospheric interactions that further impact surface chemistry on return to Enceladus. For example, H20 neutrals dominating the emitted plume gas return to the surface mostly as H30+ ions after magnetospheric processing. Surface oxidant loading is further increased by return of radiolytically processed ice grains from the E-ring. Plume frost deposition and micrometeoroid gardening protect some fraction of newly produced molecular species from destruction by further irradiation. The evident horizontal and vertical mobility of surface ices in the south polar region drive mixing of these processed materials into the moon interior with potential impacts on deep ice molecular chemistry and plume gas production. Similarly as suggested previously for Europa, the externally driven source of radiolytic oxidants could affect evolution of life in any subsurface liquid water environments of Enceladus.

Cooper, Paul D.↗
NASA NTRS1975

Bifurcation and collapse analysis of stringer and ring-stringer stiffened cylindrical shells with cutouts

Results for cylindrical configurations using the STAGS computer program were presented. Discontinuities were imposed upon the shell's skin by incorporating symmetrical cutout openings. In addition, the surface is stiffened with both stringer and ring-stringer arrangements. The cutout problem has been shown to be highly nonlinear for smooth surface shells, but it was found that bifurcation and collapse loads are close when one is considering stiffened skin configurations. In order to arrive at this conclusion, it was necessary to evaluate the following: (1) comparison between smeared and discrete stiffener theory for linear solutions, (2) numerical finite difference convergence as directed toward buckling determination, (3) collapse load results with the various skin stiffeners. A linear bifurcation study relating to stiffening effects around cutout areas present within stringer and ring-stringer shell surfaces was included. Comparisons were made between a variety of geometric positions considering cutout frame and thickened skin additions.

Palazotto, A. N.↗
DOE OSTI2019

Recommendations for DOT 7A Type A Drum Closure and Drop Testing with Additional 49 CFR 173.465(c)(2) Testing and Analysis

The Savannah River National Laboratory (SRNL) is in the process of developing recommendation for the U S. Department of Energy contractors and vendors who want to qualify drums as U S. Department of Transportation (DOT) 7A Type A to meet 49 CFR 173.465 drop testing requirements for fissile and non-ftssile material to maintain containment. Based on the finite element analysis (FEA) models, the safety features suffering the maximum damage that result in loss of containment are identified as the closure ring mechanism (in entirety), the top (mouth area) of the drum, and the lid (including the gasket). The maximum damage is measured in terms of the collective ability of these combined three safety features to maintain containment. As such, both drop testing and FEA were performed to determine the sensitivities of these safety features to drop variations. As part of this effort, a series of physical drop tests and FEAs were conducted at SRNL. These tests used Skolnik drums, CQ5508L (see Attachment 1), which are open DOT 7A Type A open- head carbon steel 208-liter (55-gallon) drums with 12-gauge bolted closure rings. Variables studied were (1) stress relief methods during closure ring installation, (2) content configurations, and (3) drum orientations during a 4-foot free fall. It should be noted that the Skolnik CQ5508L drums have a closure ring with a "V shaped" cross section. (1) The closure testing with analysis confirmed that closure stress relief by rapping is necessary to distribute the closure ring tension around the perimeter and to maintain sufficient closure pre-load for lid retention during 4-foot drops of the heavier packages (500 to 1,000 lbs). It was concluded that no specific style of stress relief is preferred (e g., multi-step rapping/torqueing process, heavy hits vs. light hits, hitting near closure vs. away), as long as no additional change in bolt torque occurs with additional rapping. (2) (3) Modeling indicated that maximum damage is a result of both: (2) content configuration and (3) drop orientation. The worst-case content configuration is one with an eccentrically loaded concentrated content mass. FEA modeling showed that the center- of-gravity over top (CGoT) with the eccentric content on the high side was the orientation of maximum damage relative to drum lid retention. In this content configuration (i.e., CGoT), FEA modeling showed payloads over 500 lbs were required to contain a load distribution plate between content and lid. Both analysis and testing showed the drum with distribution plate can pass the 4-foot CGoT drop.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1977

Displacement coefficients along the inner boundaries of radially cracked ring segments subject to forces and couples

Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius R sub o/R sub i in the range of 1.1 to 2.5, and ratios a/W in the range 0.1 to 0.8 where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient delta or the corresponding influence coefficient, can be obtained for any practical load line location of a pin loaded specimen.

Gross, B.↗
NASA NTRS1977

Lunar gravity determinations and their implications

Mass distributions inferred from lunar gravity data are studied, with emphasis on mascons as mass excesses in topographic lows in all the near-side ringed basins, with best representation as near-surface disks with excess loads of 800 kg per sq cm. The gravity data are derived from earth-based radiometric data on speed variations of orbiting Apollo spacecraft observed from the earth. Mass deficits are found in the case of large 100 km craters (Langrenus, Theophilus, Copernicus), and are consistent with crater volume. Earlier states of the moon are hypothesized on the basis of the small gravitational anomaly associated with the Apennine mountains, and on the basis of lunar isostasy, plasticity, and maria flooding and filling.

Sjogren, W. L.↗
NASA NTRS1978

Displacement coefficients along the inner boundaries of radially cracked ring segments subject to forces and couples

Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius in the range of 1.1 to 2.5 and ratios a/W in the range 0.1 to 0.8, where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient or the corresponding influence coefficient can be obtained for any practical load line location of a pin-loaded specimen.

Gross, B.↗
NASA NTRS1999

Deflections of a Uniformly Loaded Circular Plate with Multiple Support Points: Introduction - 1

This technical memorandum describes a method for determining the transverse deflections of a uniformly loaded, thin circular plate of constant thickness supported by single or multiple rings of equally spaced discreet points. The rotations are assumed free at each point. This could have application in the design of telescope mirror supports that must minimize structural gravitational deformations. It could also be of general use to the structural analyst.

Craig, L. D.↗