167,319 research outputs found
Measurement of R-values at Intermediate Strain Rates using a Digital Speckle Extensometry
No full text[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Effects of Lewis number, density ratio and gravity on burning velocity and conditional statistics in stagnating turbulent premixed flames
No full textDNS is performed to analyse the effects of Lewis number (Le), density ratio and gravity in stagnating turbulent premixed flames. The results show good agreement with those of Lee and Huh (Combustion and Flame, Vol. 159, 2012, pp. 1576-1591) with respect to the turbulent burning velocity, S-T, in terms of turbulent diffusivity, flamelet thickness, mean curvature and displacement speed at the leading edge. In all four stagnating flames studied, a mean tangential strain rate resulting in a mean flamelet thickness smaller than the unstretched laminar flame thickness leads to an increase in S-T. A flame cusp of positive curvature involves a superadiabatic burned gas temperature due to diffusive-thermal instability for an Le less than unity. Wrinkling tends to be suppressed at a larger density ratio, not enhanced by hydrodynamic instability, in the stagnating flow configuration. Turbulence is produced, resulting in highly anisotropic turbulence with heavier unburned gas accelerating through a flame brush by Rayleigh-Taylor instability. Results are also provided on brush thickness, flame surface density and conditional velocities in burned and unburned gas and on flame surfaces to represent the internal brush structures for all four test flames.X1122sciescopu
A practical design approach for a single-stage sounding rocket to reach a target altitude
No full textA new type of design domain for a sounding rocket is suggested in this study, which is more intuitive, simplified, and conducive to a single-stage sounding rocket development process. Among the various operation parameters, this study identifies several effective variables, which are also among the most practical in a sounding rocket design process. Of the many design variables considered for peak altitude optimisation, arguably the three most effective in shaping the whole system and conferring the most practicality in the design process of a sounding rocket were determined. A simulation-based study was conducted to establish: the effect of the selected parameters on flight performance, and the optimum design conditions of a single-stage sounding rocket in terms of its peak altitude. The simulation result was compared with randomly chosen experimentally tested flight data and validated. With the clear performance curves varying depending on the variables, the combination of the considered design inputs was effective. The new type of design domain and design procedure proposed is expected to constitute a useful reference and deliver practical benefits to the development process for a target-altitude-optimised single-stage sounding rocket.
Experiments on formation of the adiabatic shear band in sheet metal
No full textFormation of the adiabatic shear band in sheet metal is investigated with experiments for high strength steel sheets, 60 C and 60 TRIP. Since the adiabatic shear band is formed as a result of adiabatic shear failure with a narrow band of concentrated shear strain, the adiabatic shear band plays an important role in the analysis of high speed deformation phenomena. For shear band experiments with a tension split Hopkinson bar, specimens are designed to induce large shear strain. The experimental results show that the shear deformation modes of two sheet metals, 60 TRIP and 60 C, are quite different from each other in that the adiabatic shear band is observed only in 60 C. The shear deformation in 60 TRIP is restrained by the abrupt increase of strength due to the plastic strain, which interferes with propagation of the shear crack. Instead, a tensile crack developed at the corner where the shear crack should have been initiated. As a result, the load-displacement curves show that the tensile load of 60 TRIP specimens becomes higher than that of 60 C at the same displacement
Froggy went a-courting, he did ride, uh-huh,
No full textvoiceCollected by Max Hunter (H-5 ) Sung by J. W. Breazeal
For Mary C. Parler Springfield, Missouri
Transcribed by Frances Majors April 27, 1958
Reel 247, Item 13
Froggy Went A-Courting
Froggy went a-courting, he did ride, uh-huh,
Froggy went-a-courting, he did ride,
Sword and pistol by his side, uh-huh.
He rode till he came to the master's hall, uh-huh,
He rode till he came to the master's hall,
There he did both knock and call, uh-huh.
Took Miss Margy on his knee, uh-huh,
Took Miss Margy on his knee,
Says to her, Will you have me? uh-huh.
Old Uncle Rat he's gone from home, uh-huh,
Old Uncle Rat he's gone from home,
And I can't tell you till he's done come, uh-huh.
Uncle Rat laughed and shook his fat sides, uh-huh,
Uncle Rat laughed and shook his fat sides,
To think his niece would be a frog's bride, uh-huh.
Old Uncle Rat he galloped off to town, uh-huh,
Old Uncle Rat he galloped off to town
To buy his niece a wedding gown, uh-huh.
Where shall the wedding supper be? uh-huh,
Where shall the wedding supper be?
Way down yonder in a hallow tree, uh-huh.
What shall the wedding supper be? uh-huh
What shall the wedding supper be?
Two black beans and a blue-eyed pea, uh-huh.
First came in was an old black bug, uh-huh,
First came in was an old black bug,
He had his whiskey in his jug, uh-huh.
The next come in was a little black flea, uh-huh,
The next come in was a little black flea,
Had his fiddle on his knee, uh-huh.
Froggy Went-A-Courting (Cont'd)
Reel 247, Item 13 (Cont'd)
The next came in was an old sly cat, uh-huh,
The next came in was an old sly cat,
She says I'll put a stop to that, uh-huh.
Then Miss Mousy started up the wall, uh-huh,
Then Miss Mousy started up the wall,
Her foot slipped and she did fall, uh-huh.
The frog was left a widder then, uh-huh,
The frog was left a widder then,
Swore he never would marry again, uh-huh.
Started swimming across the brook, uh-huh,
Started swimming across the brook,
And an old black snake took him down his crook, uh-huh.
You may lay this all upon the shelf, uh-huh,
You may lay this all upon the shelf,
And if you want e'er nother one you must sing it yourself, uh-huh.Funding for digitization provided by the Arkansas Humanities Council and the Happy Hollow Foundation
Prediction of fracture initiation in square cup drawing of DP980 using an anisotropic ductile fracture criterion
No full textThis paper deals with the prediction of fracture initiation in square cup drawing of DP980 steel sheet with the thickness of 1.2 mm. In an attempt to consider the influence of material anisotropy on the fracture initiation, an uncoupled anisotropic ductile fracture criterion is developed based on the Lou-Huh ductile fracture criterion. Tensile tests are carried out at different loading directions of 0 degrees, 45 degrees, and 90 degrees to the rolling direction of the sheet using various specimen geometries including pure shear, dog-bone, and flat grooved specimens so as to calibrate the parameters of the proposed fracture criterion. Equivalent plastic strain distribution on the specimen surface is computed using Digital Image Correlation (DIC) method until surface crack initiates. The proposed fracture criterion is implemented into the commercial finite element code ABAQUS/Explicit by developing the Vectorized User-defined MATerial (VUMAT) subroutine which features the non-associated flow rule. Simulation results of the square cup drawing test clearly show that the proposed fracture criterion is capable of predicting the fracture initiation with sufficient accuracy considering the material anisotropy
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