scholarly journals Differential Sea-Ice Drift. II. Comparison of Mesoscale Strain Measurements to Linear Drift Theory Predictions

1974 ◽  
Vol 13 (69) ◽  
pp. 457-471 ◽  
Author(s):  
W. D. Hibler
Keyword(s):  
High Pressures ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Local Pressure ◽  
Strain Measurements ◽  
Linear Drift ◽  
Special Cases ◽  
Drift Theory ◽  
Sea Ice Drift ◽  
Frequency Behavior

A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicate that the ice divergence rate and vorticity follow the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds the divergence rate was found to be negative with the vorticity being counter-clockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior was shown to agree with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen (1970) for pack ice. The best least-squares values of the constitutive law parametersηandζwere found to be ≈ 1012kg/s. Using typical divergence rates these values yield compressive stresses of the magnitude of 105N/m which are similar to values suggested by the Parmerter and Coon (1972) ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low-pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer).Calculations were also carried out using a more general linear visco-elastic constitutive law that includes memory effects and which includes a generalized Hooke’s law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates overall a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated “viscosities” similar to the Glen law behavior at temporal frequencies less than ≈ 0.01 h−1.

scholarly journals Differential Sea-Ice Drift. II. Comparison of Mesoscale Strain Measurements to Linear Drift Theory Predictions

1974 ◽  
Vol 13 (69) ◽  
pp. 457-471 ◽  
Author(s):  
W. D. Hibler
Keyword(s):  
High Pressures ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Local Pressure ◽  
Strain Measurements ◽  
Linear Drift ◽  
Special Cases ◽  
Drift Theory ◽  
Sea Ice Drift ◽  
Frequency Behavior

A comparison of mesoscale strain measurements with the atmospheric pressure field and the wind velocity field indicate that the ice divergence rate and vorticity follow the local pressure and wind divergence with significant correlation. For low atmospheric pressures and converging winds the divergence rate was found to be negative with the vorticity being counter-clockwise. The inverse behavior was observed for high pressures and diverging winds. This behavior was shown to agree with predictions based upon the infinite boundary solution of a linearized drift theory in the absence of gradient current effects and using the constitutive law proposed by Glen (1970) for pack ice. The best least-squares values of the constitutive law parameters η and ζ were found to be ≈ 1012 kg/s. Using typical divergence rates these values yield compressive stresses of the magnitude of 105 N/m which are similar to values suggested by the Parmerter and Coon (1972) ridge model. In general, the infinite boundary solution of the linear drift equation indicates that in a low-pressure region that is reasonably localized in space, the ice would be expected to converge for high compactness (winter) and diverge for low compactness (summer).Calculations were also carried out using a more general linear visco-elastic constitutive law that includes memory effects and which includes a generalized Hooke’s law as well as the Glen law as special cases. A best fit of this more general calculation with strain measurements indicates overall a better agreement with viscous behavior than with elastic behavior, with the frequency behavior of the estimated “viscosities” similar to the Glen law behavior at temporal frequencies less than ≈ 0.01 h−1.

Design of a centralized regional water distribution system: a case study in the County of Paintearth No. 18, Alberta, Canada

2012 ◽  
Vol 39 (7) ◽  
pp. 801-811 ◽  
Author(s):  
Mathew Langford ◽  
Jean-Luc Daviau ◽  
David Z. Zhu
Keyword(s):  
Rural Communities ◽  
Rural Areas ◽  
Distribution System ◽  
Water Distribution ◽  
High Pressures ◽  
Population Distribution ◽  
Pressure Control ◽  
Local Pressure ◽  
Head Losses ◽  
Sparse Population

Water supply to rural communities has historically been difficult. The sparse population distribution results in large infrastructure cost per capita compared to larger urban municipalities. The challenge is to deliver this water efficiently and minimize the corresponding increase in wastewater. Urban water systems supply both fire flow and drinking water at high pressures in large pipes. One solution for rural areas is supplying only potable water using small pipes that are supplied in long spools and that can be ploughed-in, a novel method of direct-bury. This water is delivered to private cisterns at low pressure, extending the range of the system for the same input energy level. Pressure control valves are used to keep pressure positive at high points to safeguard water quality. Modelling is particularly important in rural systems, where extensive pipeline distances and elevation difference result in significant head losses and areas of high local pressure.

Transport Phenomena in the Shock Initiation Problem

1971 ◽  
Vol 49 (20) ◽  
pp. 2532-2539
Author(s):  
James Parker Elliott
Keyword(s):  
Heat Flux ◽  
Transverse Energy ◽  
Constitutive Law ◽  
Navier Stokes ◽  
Axial Flux ◽  
Shock Initiation ◽  
Transverse Pressure ◽  
Special Cases ◽  
Small Times ◽  
Structure Problem

The collisionless solution of the shock initiation problem is considered. Expressions for the fluid mechanical variables are given for arbitrary initial equilibrium states on either side of the diaphragm. Whereas, in certain special cases, a constitutive law in Navier–Stokes form can be obtained for the stress, no such relationship exists in general. Departure from the Navier–Stokes law is found to be related to gradients in the transverse pressure that come about as a result of the mixing of molecules with different thermal energies. The heat flux is broken down as the sum of a flux of axial energy and a flux of transverse energy. The ratio of the axial flux to the total flux is examined in several cases. Comparison is made with the Chapman–Enskog value, and with the values assumed by other authors in studying the shock structure problem. Departure of this ratio from its near-equilibrium value of 1/3 is suggested as a means of assessing the validity of the collisionless solution. The possibility of extending the Navier–Stokes solution down to small times is discussed.

A New Constitutive Model for the Compressibility of Elastomers at Finite Deformations

2001 ◽  
Vol 74 (4) ◽  
pp. 541-559 ◽  
Author(s):  
Jeffrey E. Bischoff ◽  
Ellen M. Arruda ◽  
Karl Grosh
Keyword(s):  
Uniaxial Tension ◽  
Volume Change ◽  
Constitutive Models ◽  
Hydrostatic Compression ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Compression Tests ◽  
Volume Response ◽  
Using Data ◽  
Nonlinear Elastic

Abstract Although traditional constitutive models for rubbery elastic materials are incompressible, many materials that demonstrate nonlinear elastic behavior are somewhat compressible. Clearly important in hydrostatic deformations, compressibility can also significantly affect the response of elastomers in applications for which several boundaries are rigidly fixed, such as bushings, or triaxial states of stress are realized. Compressibility is also important for convergence of finite element simulations in which a rubbery elastic constitutive law is in use. Volume changes that reflect compressibility have been observed historically in both uniaxial tension and hydrostatic compression tests; however, there appear to be no data obtained from both types of tests on the same material by which to validate a compressible hyperelastic law. In this paper, we propose a new compressible hyperelastic constitutive law for elastomers and other rubbery materials in which entropy and internal energy changes contribute to the volume change. Using data from the literature, we show that this law is capable of reproducing both the pressure—volume response of elastomers in hydrostatic compression, as well as the stress—stretch and volume change—stretch data of elastomers in uniaxial tension.

On the Dynamics of Fractional Visco-Elastic Beams

2012 ◽  
Author(s):  
Salvatore Di Lorenzo ◽  
Francesco P. Pinnola ◽  
Antonina Pirrotta
Keyword(s):  
Elastic Beam ◽  
Constitutive Law ◽  
Dynamic Loads ◽  
Elastic Behavior ◽  
Advanced Manufacturing ◽  
Suitable Model ◽  
Bernoulli Beam ◽  
Static Behavior ◽  
Creep Tests ◽  
Euler Bernoulli Beam

With increasing advanced manufacturing process, visco-elastic materials are very attractive for mitigation of vibrations, provided that you may have advanced studies for capturing the realistic behavior of such materials. Experimental verification of the visco-elastic behavior is limited to some well-known low order models as the Maxwell or Kelvin models. However, both models are not sufficient to model the visco-elastic behavior of real materials, since only the Maxwell type can capture the relaxation tests and the Kelvin the creep tests, respectively. Very recently, it has been stressed that the most suitable model for capturing the visco-elastic behavior is the spring-pot, characterized by a fractional constitutive law. Based on this assumption, the quasi-static behavior has been investigated very recently, however for noise control there is a need of exploiting the dynamic behavior of such a fractional visco-elastic beam. The present paper introduces the dynamic response of fractional visco-elastic Euler-Bernoulli beam under dynamic loads.

Thermo-elastic behavior of grossular garnet at high pressures and temperatures

2017 ◽  
Vol 102 (4) ◽  
pp. 851-859 ◽  
Author(s):  
Sula Milani ◽  
Ross J. Angel ◽  
Lorenzo Scandolo ◽  
Mattia L. Mazzucchelli ◽  
Tiziana Boffa Ballaran ◽  
...  
Keyword(s):  
High Pressures ◽  
Elastic Behavior ◽  
High Pressures And Temperatures ◽  
Grossular Garnet

Elastic Instabilities of Inflated Rubber Shells

1999 ◽  
Vol 72 (2) ◽  
pp. 263-268 ◽  
Author(s):  
A. N. Gent
Keyword(s):  
Spherical Cavity ◽  
Cylindrical Tube ◽  
Constitutive Law ◽  
Elastic Behavior ◽  
Inflation Pressure ◽  
Elastic Instabilities ◽  
Thin Walled ◽  
Uniform Expansion ◽  
Modest Degree ◽  
Rubber Block

Abstract Using a simple constitutive law for elastic behavior that includes the feature of a maximum allowable strain, equations are derived for inflation pressure as a function of the amount of inflation for three rubber shells: a thin-walled spherical balloon, a small spherical cavity in a large rubber block, and a thin-walled cylindrical tube. The results are compared with those obtained using the neo-Hookean constitutive law. Uniform expansion is generally predicted to become unstable at a modest degree of inflation but the new relations give a second stable inflation state, in accord with experience.

scholarly journals Nickel-titanium pseudo-elastic behavior under equi-biaxial dynamic loading conditions

2018 ◽  
Vol 183 ◽  
pp. 02054
Author(s):  
Pierre Quillery ◽  
Bastien Durand ◽  
Olivier Hubert ◽  
Han Zhao
Keyword(s):  
Thermal Emission ◽  
Solid Phase ◽  
Dynamic Compression ◽  
Nickel Titanium ◽  
Impact Testing ◽  
Constitutive Law ◽  
Scale Model ◽  
Elastic Behavior ◽  
Temperature Phase ◽  
Stress Strain

Shape memory alloys (SMA) undergo a solid-solid phase transformation called martensitic transformation, involving a "high temperature" phase (austenite) and a "low temperature" phase (martensite). The stress-strain pseudo-elastic behavior of a nickel-titanium under equi-biaxial dynamic compression is measured thanks to a new home-made impact testing set-up using split Hopkinson bars. The use of thermal and optical cameras allows strain and heating sources fields to be identified. The stress field is estimated by the combination of the strain gauges information placed on bars, and a finite element analysis of the specimen. Experimental average stress-strain behavior and thermal emission are finally compared to the results of a finite difference axisymmetric model where the constitutive law is given by a fully coupled stochastic multi scale model.

Elastohydrodynamic Analysis of Reverse Pumping in Rotary Lip Seals With Microasperities

1995 ◽  
Vol 117 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Richard F. Salant ◽  
Andrew L. Flaherty
Keyword(s):  
Fluid Mechanics ◽  
High Pressures ◽  
Elastic Behavior ◽  
Lip Seal ◽  
Lubricating Film ◽  
Lip Seals ◽  
Reverse Pumping

An elastohydrodynamic analysis of a rotary lip seal containing microasperities, incorporating both the fluid mechanics of the lubricating film and the elastic behavior of the lip, has been performed numerically. The results indicate that some asperity patterns generate reverse pumping that prevents leakage through the seal. Other asperity patterns are found to generate negative reverse pumping that enhances leakage. In all cases considered, the asperities also hydrodynamically generate sufficiently high pressures to provide load support and maintain the integrity of the film.

Elastohydrodynamic Analysis of Reverse Pumping in Rotary Lip Seals With Microundulations

1994 ◽  
Vol 116 (1) ◽  
pp. 56-62 ◽  
Author(s):  
R. F. Salant ◽  
A. L. Flaherty
Keyword(s):  
Fluid Mechanics ◽  
High Pressures ◽  
Elastic Behavior ◽  
Pumping Rate ◽  
Dynamic Conditions ◽  
Lip Seal ◽  
Lubricating Film ◽  
Lip Seals ◽  
Reverse Pumping

An elastohydrodynamic analysis of a rotary lip seal containing microundulations, incorporating both the fluid mechanics of the lubricating film and the elastic behavior of the lip, has been performed numerically. The results indicate that, under dynamic conditions, the undulation pattern deforms such that it produces reverse pumping. The reverse pumping rate is substantial, and overwhelms the natural leakage induced by the sealed pressure, thereby preventing leakage through the seal. The results also show that the undulations hydrodynamically generate sufficiently high pressures, within the film, to provide load support and maintain the integrity of the film.

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