Some aspects of the deformation of a Neo- Hookean material in compression Interim report
Deformation of neo-Hookean material during uniaxial compression
DEFORMATION↗
SEARCH · Engineering Papers
Results for “compressing”
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.
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Bending strength of large thin-walled pressure- stabilized cylinder beyond onset of compressive skin wrinkling.
Ultimate bending moment capability of thin walled pressure stabilized cylinder with typical axial loads demonstrated to be 50 percent greater than bending moment at which compressive wrinkling occurs
THIN WALLED SHELL↗
Normal shock waves in a compressible fluid.
Fundamental relations for normal shock wave behavior in compressible fluid for classical and hydromagnetic cases
NORMAL SHOCK WAVE↗
Magnetic-compression waves in collisionless plasma - Oblique ambient magnetic field.
Numerical analysis of structure of one-dimensional unsteady magnetic compression waves propagating into collisionless plasma, using motion equations
MOTION EQUATION↗
Radiation of an antenna in a compressible magnetoplasma.
Radiation of monofrequency antenna in compressible magnetoplasma expressing far field as sum of modal plane waves
PLANE WAVE↗
On the one-dimensional theory of steady compressible fluid flow in ducts with friction and heat addition
Steady, diabatic (nonadiabatic), frictional, variable-area flow of a compressible fluid is treated in differential form on the basis of the one-dimensional approximation. The basic equations are first stated in terms of pressure, temperature, density, and velocity of the fluid. Considerable simplification and unification of the equations are then achieved by choosing the square of the local Mach number as one of the variables to describe the flow. The transformed system of equations thus obtained is first examined with regard to the existence of a solution. It is shown that, in general, a solution exists whose calculation requires knowledge only of the variation with position of any three of the dependent variables of the system. The direction of change of the flow variables can be obtained directly from the transformed equations without integration. As examples of this application of the equations, the direction of change of the flow variables is determined for two special flows. In the particular case when the local Mach number m = 1, a special condition must be satisfied by the flow if a solution is to exist. This condition restricts the joint rate of variation of heating, friction, and area at m = 1. Further analysis indicates that when a solution exists at this point it is not necessarily unique. Finally it is shown that the physical phenomenon of choking, which is known to occur in certain simple flow situations, is related to restrictions imposed on the variables by the form of the transformed equations. The phenomenon of choking is thus given a more general significance in that the transformed equations apply to a more general type of flow than has hitherto been treated. (author)
HIGH-SPEED↗
Requirements for Auxiliary Stiffeners Attached to Panels Under Combined Compression and Shear
Panels of aluminum alloy sheets, framed by side and end stiffeners, were subjected to combined loading by means of offset knife edges applying loads to top and bottom end plates with reacting forces against the end plates supplied by laterally acting rollers. The test specimens were 17S-T aluminum alloy shoots 0.040 inch thick in panels of 10-inch width and three different lengths (approximately 10, 26, and 30 inch). Data were obtained for the bowing of transverse and longitudinal ribs of rectangular cross section and varying depths mounted on one side of the sheet only, for several ratios of compression to shear loads. Limiting values of the moments of inertia were calculated from these measurements. The experimental values exceed the theoretical values given by Timoshenko for the case of simply supported sheets with uniformly distributed boundary stresses. The work reported includes measurements of the effective shear moduli of the nine test panels with and without ribs. These data are compared with values published by Lahdo and Wagner.
ALUMINUM ALLOYS, SHEET - ALCOA 17ST - STRENGTH↗
The "limiting line" in mixed subsonic and supersonic flow of compressible fluids
It is well known that the vorticity for any fluid element is constant if the fluid is non-viscous and the change of state of the fluid is isentropic. When a solid body is placed in a uniform stream, the flow far ahead of the body is irrotational. Then if the flow is further assumed to be isentropic, the vorticity will be zero over the whole filed of flow. In other words, the flow is irrotational. For such flow over a solid body, it is shown by Theodorsen that the solid body experiences no resistance. If the fluid has a small viscosity, its effect will be limited in the boundary layer over the solid body and the body will have a drag due to the skin friction. This type of essentially isentropic irrotational flow is generally observed for a streamlined body placed in a uniform stream, if the velocity of the stream is kept below the so-called "critical speed." At the critical speed or rather at a certain value of the ratio of the velocity of the undisturbed flow and the corresponding velocity of sound, shock waves appear. This phenomenon is called the "compressibility bubble." Along a shock wave, the change of state of the fluid is no longer isentropic, although still adiabatic. This results in an increase in entropy of the fluid and generally introduces vorticity in an originally irrotational flow. The increase in entropy of the fluid is, of course, the consequence of changing part of the mechanical energy into heat energy. In other words, the part of fluid affected by the shock wave has a reduced mechanical energy. Therefore, with the appearance of shock waves, the wake of the streamline body is very much widened, and the drag increases drastically. Furthermore, the accompanying change in the pressure distribution over the body changes the aerodynamic moment acting on it and in the case of an airfoil decreases the lift force. All these consequences of the breakdown of isentropic irrotational flow are generally undesirable in applied aerodynamics. Its occurrence should be delayed as much as possible by modifying the shape or contour of the body. However, such endeavor will be very much facilitated if the cause or the criterion for the breakdown can be found first.
MACH NUMBER↗
Compressive buckling of flat rectangular plates supported by rigid posts
Results of a theoretical investigation of the compressive buckling of flat, rectangular, simply supported plates supported in the interior by equally spaced rows of rigid posts are presented. It is found that the plates buckle as if simply supported along all of the transverse lines or else all of the longitudinal lines passing through the rigid posts, the occurrence of the one buckling mode or the other depending on the number and spacing of the posts.
LOADS AND STRESSES, STRUCTURAL - COMPRESSION↗
Generalization of Joukowski formula to an airfoil of a cascade in compressible gas stream with subsonic velocities
It is shown that the ordinary Joukowski formula for lift force of cascade blades in incompressible flow can be applied to the case of subsonic compressible flow with sufficient accuracy, provided that the density in the formula is taken as the arithmetic mean of the densities far ahead of and behind the cascade.
CASCADES, THEORY↗
Behavior of fast moving flow of compressible gas in cylindrical pipe in presence of cooling
For compressible flow with friction in a cylindrical pipe the momentum, continuity, and heat-transfer equations are examined to determine whether an increase in Mach number ("thermal" Laval nozzle) is obtainable through heat conduction from the gas through the pipe walls. The analysis is based on the assumption that the wall temperature is negligibly small in comparison with the stagnation temperature of the gas. The analysis leads to a negative result. When the gas cooling is increased by also considering radiation to the wall, a limited region at high temperatures is obtained where Mach number increases were theoretically possible. Obtaining this condition practically is considered impossible.
FLOW, SUPERSONIC↗
A VLSI Processor Design of Real-Time Data Compression for High-Resolution Imaging Radar
For the high-resolution imaging radar systems, real-time data compression of raw imaging data is required to accomplish the science requirements and satisfy the given communication and storage constraints. The Block Adaptive Quantizer (BAQ) algorithm and its associated VLSI processor design have been developed to provide a real-time data compressor for high-resolution imaging radar systems.
data compression VLSI processor design imaging rad↗
Wavelet Compression of Seismic Data
While wavelet transforms have been used in the analysis of seismic signals, the methods used for the compression of seismic signals have been limited to Linear Predictive Coding and Transform Coding.
wavelet compression seismic data linear predictive↗
Learning Nonlinear Predictive Models for Lossless Image Compression
We describe a genetic programming system which learns nonlinear predictive models for lossless image compression.
genome-complier↗
Real-Time Adaptive Lossless Hyperspectral Image Compression using CCSDS on Parallel GPGPU and Multicore Processor Systems
The proposed CCSDS (Consultative Committee for Space Data Systems) Lossless Hyperspectral Image Compression Algorithm was designed to facilitate a fast hardware implementation. This paper analyses that algorithm with regard to available parallelism and describes fast parallel implementations in software for GPGPU and Multicore CPU architectures. We show that careful software implementation, using hardware acceleration in the form of GPGPUs or even just multicore processors, can exceed the performance of existing hardware and software implementations by up to 11x and break the real-time barrier for the first time for a typical test application.
realtime↗
Design of a Variational Multiscale Method for Turbulent Compressible Flows
A spectral-element framework is presented for the simulation of subsonic compressible high-Reynolds-number flows. The focus of the work is maximizing the efficiency of the computational schemes to enable unsteady simulations with a large number of spatial and temporal degrees of freedom. A collocation scheme is combined with optimized computational kernels to provide a residual evaluation with computational cost independent of order of accuracy up to 16th order. The optimized residual routines are used to develop a low-memory implicit scheme based on a matrix-free Newton-Krylov method. A preconditioner based on the finite-difference diagonalized ADI scheme is developed which maintains the low memory of the matrix-free implicit solver, while providing improved convergence properties. Emphasis on low memory usage throughout the solver development is leveraged to implement a coupled space-time DG solver which may offer further efficiency gains through adaptivity in both space and time.
Design↗
Recent High Resolution Measurements of the Specific Heat and Isothermal Compressibility Near the He***sup3*** Liquid-Gas Critical Point
A new electrostriction technique was developed to measure the isothermal compressibility along isochores and isotherms near the critical point. Initial measurements that validate this new technique will also be presented.
specific↗
Bit-Wise Arithmetic Coding for Data Compression
Consider the problem of compressing a uniformly quantized source. A traditional approach is to assign variable length codewords to the quantizer output symbols or groups of symbols. Here an alternate solution is proposed: assign a fixed length binary codeword to each output symbol in such a way that a zero is more likely than a one in every codeword bit position. The encoding procedure is described.
Arithmetic↗