scholarly journals Characteristic Time and Length Scales in Melts of Kremer–Grest Bead–Spring Polymers with Wormlike Bending Stiffness

2020 ◽  
Vol 53 (6) ◽  
pp. 1917-1941 ◽  
Author(s):  
Carsten Svaneborg ◽  
Ralf Everaers
Keyword(s):  
Characteristic Time ◽  
Bending Stiffness ◽  
Length Scales

DNA Bending Stiffness on Small Length Scales

2008 ◽  
Vol 100 (1) ◽  
Author(s):  
Chongli Yuan ◽  
Huimin Chen ◽  
Xiong Wen Lou ◽  
Lynden A. Archer
Keyword(s):  
Dna Bending ◽  
Bending Stiffness ◽  
Small Length ◽  
Length Scales

Modelling Changes to Submarine Pipeline Embedment and Stability due to Pipeline Scour

2018 ◽  
Author(s):  
Scott Draper ◽  
Terry Griffiths ◽  
Liang Cheng ◽  
David White ◽  
Hongwei An
Keyword(s):  
Bending Stiffness ◽  
Probabilistic Framework ◽  
Submarine Pipeline ◽  
Length Scales ◽  
Sediment Mobility ◽  
Beam Bending ◽  
Predictive Formulas ◽  
Seabed Roughness

In this paper a beam bending model is combined with existing predictive formulas for pipeline scour to study changes to pipeline stability during scour and lowering. The model is introduced and demonstrated for a range of simplified conditions, including scour-induced lowering of a pipeline resulting from multiple uniformly spaced scour initiation points. The model is then used with a synthetic seabed generated with a variety of length scales. In this simulation the pipeline is ‘laid’ onto the seabed, leading to the formation of ‘natural’ initiation points for scour. The distribution and spacing of the initiation points (which are a function of the pipeline bending stiffness, tension and seabed roughness) lead to different rates of pipeline lowering and stability. The resulting model may be used within a probabilistic framework to estimate changes to pipeline stability resulting from sediment mobility and scour.

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

CALCULATION-EXPERIMENTAL METHOD FOR DEFINITION OF LOWEST FREQUENCY IN BENDING VIBRATIONS OF COACH CAR BODY IN VERTICAL PLANE BASED ON IDENTIFICATION OF ITS BENDING STIFFNESS

2020 ◽  
Vol 2020 (9) ◽  
pp. 35-46
Author(s):  
Aleksandr Skachkov ◽  
Viktor Vasilevskiy ◽  
Aleksey Yuhnevskiy
Keyword(s):  
Least Squares Method ◽  
Vertical Plane ◽  
Bending Stiffness ◽  
Dimensional Problem ◽  
Euler Beam ◽  
Bending Vibrations ◽  
Car Body ◽  
Variable Function ◽  
Experimental Values ◽  
Definition Of

The consideration of existing methods for a modal analysis has shown a possibility for the lowest frequency definition of bending vibrations in a coach car body in a vertical plane based on an indirect method reduced to the assessment of the bending stiffness of the one-dimensional model as a Bernoulli-Euler beam with fragment-constant parameters. The assessment mentioned can be obtained by means of the comparison of model deflections (rated) and a prototype (measured experimentally upon a natural body) with the use of the least-squares method that results in the necessity of the solution of the multi-dimensional problem with the reverse coefficient. The introduction of the hypothesis on ratability of real bending stiffness of the prototype and easily calculated geometrical stiffness of a model reduces a multi-dimensional problem incorrect according to Adamar to the simplest search of the extremum of one variable function. The procedure offered for the indirect assessment of bending stiffness was checked through the solution of model problems. The values obtained are offered to use for the assessment of the lowest frequency of bending vibrations with the aid of Ritz and Grammel methods. In case of rigid poles it results in formulae for frequencies into which there are included directly the experimental values of deflections.

Lossless Photon management – Optical design for manufacture at different length scales - NOLOSS - H2020

Impact ◽  
2018 ◽  
Vol 2018 (1) ◽  
pp. 48-50
Author(s):  
Toralf Scharf ◽  
Paul Urbach ◽  
Carsten Rockstuhl ◽  
Frank Setzpfand
Keyword(s):  
Optical Design ◽  
Length Scales ◽  
Design For Manufacture ◽  
Photon Management
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