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in subjects: "Plates"

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Boundary element formulation for planar time-dependent inelastic deformation of plates with cutouts

A boundary element formulation for planar, time-dependent, inelastic deformation problems for bodies with cutouts is presented in this paper. A stress function description for these nonlinear problems leads to a nonhomogeneous biharmonic equation for the stress function rate. An integral representation of the solution uses modified kernels which guarantee that the cutout boundary is traction free for all time. This incorporation of the effect of the cutout on the stress field into the kernels l… more

Date: February 1, 1980

Creator: Mukherjee, S. & Morjaria, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Optimization of a VISAR for measuring flyer-plate velocities

VISAR (Velocity Interferometer System for Any Reflector) is commonly used for measuring flyer-plate velocities up to 6 km/s. Flyer plates can travel as much as 1 mm, which is large compared to usual depth-of-focus requirements for VISARs. Flyer plates are explosively driven, or driven by some other very energetic means; as such, they must be tested in a chamber, which will contain the explosion. Routing the laser beam to the chamber and the signal beam to the VISAR can be done safely and easily… more

Date: May 6, 1992

Creator: Sweatt, W. C.; Crump, O. B., Jr. & Brigham, W. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Boundary element analysis of time-dependent inelastic deformation of cracked plates loaded in anti-plane shear

A boundary element analysis, for determining stresses in planar cracked bodies undergoing Mode I or Mode II inelastic deformation, has been recently published by the present authors. One primary advantage of this formulation is that the effect of the crack is incorporated in the kernels of the integral equations. Thus, traction free conditions on the crack boundary are satisfied without discretization of this boundary in a numerical calculation procedure. The inelastic deformation of cracked pl… more

Date: July 1, 1980

Creator: Mukherjee, S. & Morjaria, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Progress with small, high-magnetic-field spheromaks in CTX

The current CTX program is directed towards using spheromaks as an energy transfer medium to accelerate metal plates to hypervelocity. In the proposed scheme, the spheromak is first compressed by accelerating a large plate to moderate velocity (3--5 km/s) with high explosives (HE). Another smaller plate is designed such that it experiences little force until the spheromak is compressed to a size comparable to the small plate. Then the force on the small plate rises quickly, accelerating this pl… more

Date: January 1, 1989

Creator: Wysocki, F. J.; Fernandez, J. C.; Henins, I.; Jarboe, T. R.; Marklin, G. J. & Mayo, R. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A numerical study of Rayleigh-Taylor instability in aluminum and steel plates

The SCRAM code is applied to the study of Rayleigh-Taylor instability in metal plates, and comparisons of these computer results are made with experimental data for 1100-O aluminum, 6061-T6 aluminum and 304 stainless steel. Various models for the pressure, temperature, and strain-rate dependencies of the flow stress are compared in the computer calculations. The coefficients that are required in these models to give good agreement with the experimental results are generally close to values that… more

Date: March 1, 1988

Creator: Daly, B.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Weld Penetration and Defect Control

Highly engineered designs increasingly require the use of improved materials and sophisticated manufacturing techniques. To obtain optimal performance from these engineered products, improved weld properties and joint reliability are a necessarily. This requirement for improved weld performance and reliability has led to the development of high-performance welding systems in which pre-programmed parameters are specified before any welding takes place. These automated systems however lack the ab… more

Date: May 15, 1992

Creator: Chin, Bryan A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Present status of the polymeric-materials screening program for the LLL geothermal project

No Description Available.

Date: June 12, 1975

Creator: Lorensen, L.E.; Walkup, C.M. & Mones, E.T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Computational determination of ballistic limits for a simple Whipple bumper shield

A series of numerical simulations has been performed using the multi-dimensional hydrodynamics code CTH to computationally determine a ballistic limit for a Whipple bumper shield. The ballistic limit is generally characterized as a critical diameter such that particle diameters greater than the ballistic limit will generate debris clouds that will penetrate the rear wall and particle diameters less than the ballistic limit will not. The particular shield design used for these analyses is define… more

Date: January 1, 1991

Creator: Hertel, E.S.; Chhabildas, L.C.; Yarrington, L. (Sandia National Labs., Albuquerque, NM (United States)) & Hill, S.A. (National Aeronautics and Space Administration, Huntsville, AL (United States). George C. Marshall Space Flight Center)

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Hypervelocity launch capabilities to over 10 km/s

Very high pressure and acceleration is necessary to launch flier plates to hypervelocities. In addition, the high pressure loading must be uniform, structured, and shockless, i.e., time-dependent to prevent the flier plate from either fracturing or melting. In this paper, a novel technique is described which allows the use of megabar level loading pressures, and 10{sup 9} g acceleration to launch intact flier plates to velocities of 12.2 km/s. 32 refs., 2 figs.

Date: January 1, 1991

Creator: Chhabildas, L.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Some recent observations on the radiation behavior of uranium silicide dispersion fuel

Addition of B{sub 4}C burnable poison results in higher plate swelling in both U{sub 3}Si{sub 2} and U{sub 3}Si-Al dispersion fuel plates and also decreases the blister threshold temperature of these plates. Prolonged annealing of U{sub 3}Si{sub 2}-Al fuel plates produced no blister after 696 hours at 400{degrees}C. Blister formation started between 257 hours and 327 hours at 425{degrees}C and between 115 hours and 210 hours at 450{degrees}C. Operation with breached cladding resulted in pillowi… more

Date: January 1, 1988

Creator: Hofman, G.L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Influence of extrinsic crack deflection and delamination mechanisms on the cryogenic toughness of aluminum-lithium alloy 2090: Behavior in plate (T81) vs sheet (T83) material

Cryogenic strength-toughness relationships are examined in 1.6-mm- thick sheet of commercial 2090-T8 aluminum-lithium alloy, and results compared with behavior in 12.7-mm-thick rolled plate. Unlike the significant increase in L-T fracture toughness exhibited by thick place sections at cryogenic temperatures, the thin sheet (of normally similar composition and microstructure) shows a marked decrease in toughness between 298 and 77 K. Such contrasting observations are attributed primarily to the … more

Date: February 1, 1989

Creator: Venkateswara Rao, K. T. & Ritchie, R. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The effect of surface gas injection on film boiling heat transfer

A database was developed for heat transfer from a horizontal plate with both film boiling and gas jetting occurring simultaneously, in a pool of water maintained at its saturation temperature. The effect of passing nitrogen through established film boiling is to increase the heat transfer from that surface. At the highest superficial gas velocity measured, approximately 8.5 cm/s, and for a constant surface temperature, the heat transfer increases by a factor of two over the heat transfer with n… more

Date: January 1, 1991

Creator: Duignan, M.R. (Westinghouse Savannah River Co., Aiken, SC (United States)); Greene, G.A. (Brookhaven National Lab., Upton, NY (United States)) & Irvine, T.F. Jr. (State Univ. of New York, Stony Brook, NY (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A Mechanism Explaining the Instability of EBR-I, Mark III

Presented at the International Atomic Energy Agencysponsored Seminar on the Physics of Fast and Intermediate Reactors. Vienna, August 3-11, 196l. A feedback model, was developed to account for resonant instabilities in the Mark II core. In this model, the prompt positive power coefficient effect is ascribed to fuel rod bowing and the delayed negative power coefficient effect to thermally lnduced motions in the lower shield plate. Since this model is supported by observations, it is concluded th… more

Date: September 1, 1961

Creator: Smith, R. R.; Matlock, R. G.; McGinnis, F. D.; Novick, M. & Thalgott, F. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Performance of storage walls with highly conductive covering plates and connecting fins

The thermal behavior of a storage wall, constructed of concrete with highly conductive covering plates and connecting vertical fins, is investigated. The results demonstrate that, during the charging mode, the amount of energy released from the front surface is significantly reduced. A portion of the saved energy is stored for future discharge, but a large portion is transferred to the back surface and released. A selective front surface reduces the energy released from the front surface, and t… more

Date: May 1, 1980

Creator: Ortega, J. K. E.; Bingham, C. E. & Connolly, J. M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Development of microstructures with improved cryogenic toughness through local variations in stress state: Aluminum-lithium alloys

Microstructurally-induced changes in the local stress state (triaxial constraint) and their effect on fracture-toughness behavior are examined at ambient and cryogenic temperatures in an Al-Li-Cu-Zr alloy, processed in the form of 12.7 mm-thick naturally laminated'' plate containing aligned-weak interfaces and 1.6 mm-thin unlaminated sheet. It is shown that marked improvements in long-transverse (L-T) toughness can be achieved in the plate material at cryogenic temperatures by promoting through… more

Date: April 1, 1990

Creator: Venkateswara Rao, K. T. & Ritchie, R. O.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Thermal analysis of the TFTR vacuum vessel wall protective plate

The TFTR vacuum vessel is to be protected with tungsten plates from the effects of neutral beam impingement. A thermal analysis is performed to determine the maximum allowable beam intensity (power per unit area) under normal and faulted operating conditions. In order to permit a faulted pulse, or unattenuated injection, to occur after normal pulse series, the maximum neutral beam energy flux should be below 10 kW/cm/sup 2/ depending on the beam design configuration, to prevent the melting of t… more

Date: October 1, 1975

Creator: Lee, A. Y.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Calculation of similarity solutions of partial differential equations

When a partial differential equation in two independent variables is invariant to a group G of stretching transformations, it has similarity solutions that can be found by solving an ordinary differential equation. Under broad conditions, this ordinary differential equation is also invariant to another stretching group G', related to G. The invariance of the ordinary differential equation to G' can be used to simplify its solution, particularly if it is of second order. Then a method of Lie's c… more

Date: August 1, 1980

Creator: Dresner, L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Comparison of multidimensional calculations of long-rod impacts on oblique plates

The justification for three-dimensional versus two-dimensional simulations of non-symmetric armor penetration problems has been a topic of discussion for many years. Two-dimensional plane-strain approximations are generally not quantitatively accurate, especially at later times, but they can be performed efficiently and the results are usually acceptable. Although three-dimensional calculations provide better results, they are very time consuming and expensive to perform. But with the improved … more

Date: January 1, 1989

Creator: Fujita, R.K. & Cort, G.E. (Los Alamos National Lab., NM (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Combustion-turbulence interaction in the turbulent boundary layer over a hot surface

The turbulence-combustion interaction in a reacting turbulent boundary layer over a heated flat plate was studied. Ethylene/air mixture with equivalence ratio of 0.35 was used. The free stream velocity was 10.5 m/s and the wall temperature was 1250/sup 0/K. Combustion structures visualization was provided by high-speed schlieren photographs. Fluid density statistics were deduced from Rayleigh scattering intensity measurements. A single-component laser Doppler velocimetry system was used to obta… more

Date: January 1, 1982

Creator: Ng, T.T.; Cheng, R.K.; Robben, F. & Talbot, L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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X-ray zone plates fabricated using electron-beam and x-ray lithography

Fresnel zone plate patterns, free of spherical abberation, with diameters of up to 0.63 mm and linewidths as small as 1000 A were fabricated on polyimide-membrane x-ray masks using scanning electron beam lithography Distortion of the electron beam scan raster was reduced to < 2500 A over a 2 mm x 2 mm field by applying deflection corrections, while viewing the distortion using a moire method. C/sub k/ x-ray lithography was used to replicate the zone plate pattern in thick PMMA over a 100 A thic… more

Date: May 1979

Creator: Shaver, D. C.; Flanders, D. C.; Ceglio, N. M. & Smith, H. I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Data characterization and compression. [Discussion of Prony's method]

The extraction of information from measured or computed data is all-pervasive; to gain the most value from extracted information, it must often be transformed from one type of data into another, a process that can only preserve or lose information. An information-transformation process based upon Prony's method was found to be increasingly useful for application to electromagnetic-type problems in particular and a growing variety of physical problems in general. This procedure allows the coeffi… more

Date: July 6, 1977

Creator: Miller, E. K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Concerning the generation of very high pressures for EOS studies with ultra-high power laser pulses

The use of basic physical and geometric principles, coupled with current laser technology, seems likely to extend experimental hyperbaric physics investigations from the megabar region into the portions of parameter space in which the ideal (degenerate) Fermi gas approximation is valid for even the highest Z materials. Implosions and speed-multiplying rectilinear stacks of flat plates seem particularly apt techniques for the near-term, transient attainment of pressure of 10/sup 9/ atmospheres i… more

Date: July 1, 1977

Creator: Wood, L. L.; Keeler, R. N. & Nuckolls, J. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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On the micromechanisms of fatigue-crack propagation in aluminum- lithium alloys: Sheet vs. plate material

Micromechanisms influencing the propagation of long (>10 mm) fatigue cracks in aluminum-lithium alloys are examined by specifically comparing crack-growth kinetics in a peak-aged Al-Li-Cu-Zr alloy 2090, processed as 1.6-mm thin (T83) sheet and 12.7-mm thick (T81) plate. It is found that in general crack-growth rates are significantly faster in the sheet material at equivalent stress-intensity levels, due to differences in the role of crack-tip shielding, resulting from crack deflection and cons… more

Date: December 1, 1989

Creator: Rao Venkateswara, K. T.; Ritchie, R. O. & Bucci, R.J. (Aluminum Co. of America, Alcoa Center, PA (United States). Alcoa Labs.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

SEISMIC SOURCE SCALING AND DISCRIMINATION IN DIVERSE TECTONIC ENVIRONMENTS

The objectives of this study are to improve low-magnitude regional seismic discrimination by performing a thorough investigation of earthquake source scaling using diverse, high-quality datasets from varied tectonic regions. Local-to-regional high-frequency discrimination requires an estimate of how earthquakes scale with size. Walter and Taylor (2002) developed the MDAC (Magnitude and Distance Amplitude Corrections) method to empirically account for these effects through regional calibration. … more

Date: July 10, 2007

Creator: Abercrombie, Rachel E.; Mayeda, Kevin; Walter, William R.; Viegas, Gisela M. & Murphy, Katherine

Item Type: Article

Partner: UNT Libraries Government Documents Department