scholarly journals Revisiting Y junctions for strings with currents: Transonic elastic case

2020 ◽  
Vol 102 (8) ◽  
Author(s):  
I. Yu. Rybak
Keyword(s):  
Elastic Case

scholarly journals Theoretical study of the generation of soap films: role of interfacial visco-elasticity

2013 ◽  
Vol 739 ◽  
pp. 124-142 ◽  
Author(s):  
Jacopo Seiwert ◽  
Benjamin Dollet ◽  
Isabelle Cantat
Keyword(s):  
Steady State ◽  
Liquid Film ◽  
Capillary Number ◽  
Theoretical Study ◽  
Surfactant Solution ◽  
Constant Thickness ◽  
Interfacial Rheology ◽  
Soap Films ◽  
Elastic Case

AbstractIn this work, we study theoretically the thickness of a liquid film (typically made of a surfactant solution) pulled out of a bath at constant speed in the absence of gravity, when it features a viscous or an elastic interfacial rheology. We show that a purely viscous rheology does not lead to the extraction of a steady state film of constant thickness. In contrast, the thickness of the film is well defined in the elastic case, which allows us to compute it. This thickness depends on the capillary number of the experiment, and on the elasticity of the interface. It is always lower than or equal to that obtained for an incompressible interface predicted by Frankel (Mysels, Shinoda and Frankel, Soap Films: Studies of their Thinning and a Bibliography, 1959), which is recovered in the limit of an arbitrary large elasticity.

Dispersion analysis of an optimally accurate 3-D finite difference scheme for the elastic case

2013 ◽  
Author(s):  
Kei Hasegawa ◽  
Hiromitsu Mizutani ◽  
Robert J. Geller ◽  
Nobuyasu Hirabayashi
Keyword(s):  
Finite Difference ◽  
Difference Scheme ◽  
Finite Difference Scheme ◽  
Dispersion Analysis ◽  
Elastic Case

Nonlinear Behaviors of Three Dimensional Sloshing in the LNG Elastic Tank

2021 ◽  
Author(s):  
Zhongchang Wang ◽  
Meirong Jiang ◽  
Yang Yu
Keyword(s):  
Natural Frequency ◽  
High Frequency ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Surface Elevation ◽  
Fluid Structure ◽  
Elastic Case ◽  
Structure Interaction ◽  
Elastic Tank ◽  
Sloshing Pressure

Abstract Aiming at the nonlinear sloshing in the LNG tank, a three-dimensional elastic model is established to investigate the fluid structure interaction effect. For the transient flow and the tank motion, the direct coupling method is employed to calculate the interaction between the sloshing and the bulkhead. The finite element software ADINA is adopted to do the computation. The sloshing natural frequency is verified with the results of the theoretical formula. Different wall thicknesses, filling ratios and external excitations are considered and the structure natural frequency, surface elevation and sloshing pressure are obtained. The results of the elastic case are further compared with the rigid results and the nonlinear characteristics are extracted to see the hydro-elastic effect. The sloshing natural frequencies are agreed well with the theoretical results. Due to the influence of the fluid structure interaction, the couple frequencies are obviously less than those of the empty tank. With the increase of the wall thickness, the frequencies of the empty tank and the couple frequencies all increase gradually. For the surface elevation, the thinner the bulkhead thickness is, the more the high frequency component is. The free surface is relatively flat and stable in the rigid tank but tend to be chaotic for the elastic one. Due to the fluid structure interaction, the sloshing pressure of the elastic case presents obvious high-frequency fluctuation and the sloshing pressure in the elastic tank is smaller than that in the rigid tank. This model clearly shows the valuable ability to solve the three dimensional sloshing in the elastic tank.

The seismic pulse in materials possessing solid friction, II: Lamb's problem

1959 ◽  
Vol 49 (4) ◽  
pp. 403-413
Author(s):  
L. Knopoff
Keyword(s):  
Seismic Waves ◽  
Elastic Case ◽  
Pulse Input ◽  
Lamb’S Problem ◽  
High Q ◽  
Solid Friction

Abstract The study of the propagation of seismic waves through a medium having attenuation factors varying as the first power of the frequency has been extended to the geometry used by Lamb for the perfectly elastic case. The results show three pulse groups corresponding to P, S, and R events. For high Q, all three pulses are very sharp; these pulses broaden at rates proportional to the product of the distance and 1/Q. For symmetric pulse input and high Q, the R pulse is noticeably asymmetric, the P pulse only weakly so.

Added Mass in Ship Collisions with Structures in Shallow Water

1990 ◽  
Vol 34 (03) ◽  
pp. 194-198
Author(s):  
David J. Ball ◽  
Jean-Philippe Roisin
Keyword(s):  
Shallow Water ◽  
Current Velocity ◽  
Added Mass ◽  
Elastic Case ◽  
Mass Coefficient ◽  
Added Mass Coefficient ◽  
Energy And Momentum ◽  
Plastic Case ◽  
Sway Motion ◽  
Ship Speed

The added-mass coefficients for a tanker ship in sway motion are examined experimentally for plastic impact in very shallow water. Marked differences between the elastic and plastic cases are found. Al-though energy and momentum coefficients have similar values in elastic impacts, they differ increasingly in plastic impacts as the duration of impact increases. Unexpectedly, the energy added-mass coefficient does not appear to be sensitive to underkeel clearance, which has a significant effect on the coefficient in elastic condition. There is no difference between current-driven and wind-driven tests for the plastic case. However, in the elastic case there is an increase in the energy added-mass coefficient as the ratio of current velocity to ship speed increases, suggesting added care is needed in designing elastic fendering systems against impact from a drifting ship.

Torsion Instability of Offshore Cables During Installation

2017 ◽  
Author(s):  
Svein Sævik ◽  
Evgenii Koloshkin
Keyword(s):  
Analytical Solution ◽  
Cross Section ◽  
Design Criteria ◽  
Instability Analysis ◽  
Elastic Case ◽  
Linear Elastic ◽  
Beam Elements ◽  
Flexible Pipes ◽  
Vessel Motion

The present paper addresses torsion instability at the touch down point during installation of offshore cables and flexible pipes. A model for installation instability analysis is established on the basis of standard co-rotated beam elements. The model is validated with respect to the Greenhill analytical solution as well as results obtained for the linear elastic case reported in literature. A case study is then carried out to investigate the effects of cross-section friction moment, inherent torque and vessel motion. This is then used as basis for a proposed design criteria and recommended analysis procedures for evaluating kink formation of offshore flexibles during installation.

Static and dynamic effective moduli of elastic-perfectly plastic granular aggregates under normal compression

Geophysics ◽  
2019 ◽  
Vol 84 (5) ◽  
pp. MR185-MR194 ◽  
Author(s):  
Abdulla Kerimov ◽  
Gary Mavko ◽  
Tapan Mukerji ◽  
Jack Dvorkin
Keyword(s):  
Contact Area ◽  
Spherical Particles ◽  
Effective Moduli ◽  
Normal Loading ◽  
Normal Contact ◽  
Elastic Case ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Unloading Stiffness ◽  
Explicit Expressions

Based on an existing simplified theoretical model for the normal contact interaction between two elastic-perfectly plastic spherical particles, we derived explicit expressions for the static and dynamic normal and dynamic tangential contact stiffnesses of elastic-perfectly plastic two-particle combination at pre-yield, yield, and post-yield conditions of normal loading. We used “static stiffness” or “loading stiffness” to refer to the slope of the force-displacement curve during monotonically increasing load. The “dynamic stiffness” or “unloading stiffness” refers to the stiffness that controls the speed of infinitesimal strain elastic waves propagating through the contacts. The static and dynamic contact stiffnesses are compared with numerical modeling of a two-sphere combination using the finite-element method. Furthermore, we used the explicit expressions for contact stiffnesses with the commonly used statistical averaging scheme to derive the static and dynamic effective bulk and shear moduli of a dry, random packing of identical elastic-perfectly plastic spherical particles. Elastic contact/mechanics-based effective medium models are unable to model the growth of contact area between inelastic (e.g., plastic) particles under normal force, which results in inaccurate predictions of contact stiffnesses and effective moduli. Once the particle reaches the limit of elasticity with onset of plastic deformation (yielding), further loading of two elastic-perfectly plastic spherical particles leads to a larger contact area than for two elastic particles under the same normal loading. As a result, after yielding, the dynamic effective moduli become stiffer than the corresponding moduli in the elastic case, whereas the static effective moduli remain constant, rather than increasing as in the elastic case.

scholarly journals On the Interaction of Viscoelasticity and Waviness in Enhancing the Pull-Off Force in Sphere/Flat Contacts

2021 ◽  
Vol 69 (4) ◽  
Author(s):  
Michele Ciavarella ◽  
Antonio Papangelo
Keyword(s):  
Qualitative Agreement ◽  
Elastic Case ◽  
Viscoelastic Effect ◽  
Elastic Instabilities ◽  
Low Modulus ◽  
The Cross ◽  
Smooth Sphere

AbstractMotivated by roughness-induced adhesion enhancement (toughening and strengthening) in low modulus materials, we study the detachment of a sphere from a substrate in the presence of both viscoelastic dissipation at the contact edge, and roughness in the form of a single axisymmetric waviness. We show that the roughness-induced enhancement found by Guduru and coworkers for the elastic case (i.e. at very small detachment speeds) tends to disappear with increasing speeds, where the viscoelastic effect dominates and the problem approaches that of a smooth sphere. This is in qualitative agreement with the original experiments of Guduru’s group with gelatin. The cross-over velocity is where the two separate effects are comparable. Viscoelasticity effectively damps roughness-induced elastic instabilities and makes their effects much less important. Graphical Abstract

Elastoplastohydrodynamic Lubrication with Dent Effects

1996 ◽  
Vol 210 (4) ◽  
pp. 233-245 ◽  
Author(s):  
G Xu ◽  
D A Nickel ◽  
F Sadeghi ◽  
X Ai
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Line Contact ◽  
Sliding Contacts ◽  
Element Analysis ◽  
Elastic Case ◽  
Local Material

A line contact elastoplastohydrodynamic lubrication (EPHL) model has been developed to investigate the effect of a dent on heavily loaded rolling/sliding contacts. The Jinite element analysis (FEA) was used to obtain the plastic deformation of the surfaces caused by the high-pressure spikes that occur in the contact due to the presence of a dent. The effects of various dent sizes on the pressure and film thickness were studied. The results indicate that by including the plastic deformation of the surfaces in the analysis, the pressure spikes that occur due to a dent in the contact are smaller than those of the purely elastic case, and local material yielding occurs, resulting in bumps at the edges of the dent. Effects of diflerent bump shapes at the dent edges were then studied in elastohydrodynamic lubrication (EHL) contacts and the results indicated that these bumps can reduce the magnitude of pressure spikes.

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