scholarly journals Viscoelastic rate type fluids with temperature dependent material parameters – stability of the rest state

2017 ◽  
Author(s):  
Judith Stein ◽  
Vít Průša
Keyword(s):  
Temperature Dependent ◽  
Material Parameters ◽  
Rest State ◽  
Rate Type

Rheological Equations for Synovial Fluids

1978 ◽  
Vol 100 (4) ◽  
pp. 169-186 ◽  
Author(s):  
W. M. Lai ◽  
S. C. Kuei ◽  
V. C. Mow
Keyword(s):  
Constitutive Equations ◽  
Synovial Joint ◽  
Integral Type ◽  
Material Parameters ◽  
Material Functions ◽  
Synovial Fluids ◽  
Joint Biomechanics ◽  
Differential Type ◽  
The Many ◽  
Rate Type

This review examines a number of theoretical constitutive equations which are applicable to the description of rheological behaviors of synovial fluids. These equations include the integral type, the rate type, the differential type and the generalized new-tonian fluid. Explicit values of the material parameters and/or material functions appearing in these equations are obtained from the many rheological measurements on synovial fluids of the literature. Many of the values of these parameters are taken from the literature, but some are newly computed values obtained by the present authors to make the list of available constitutive equations more extensive, using the existing experimental data. It is hoped that the diversity of the constitutive equations presented here and their appropriate material constants and/or functions will afford researchers in the field of synovial joint biomechanics the choice of a particular constitutive model for synovial fluid to meet their specific purpose.

Transmission Coefficients for Tunneling of Electrons and Holes in Biased Ga1−xAlxAs–GaAs–Ga1−xAlxAs Triple Barriers Semiconductor Heterostructures

2008 ◽  
Author(s):  
A. M. Elabsy ◽  
H. G. Abdelwahed
Keyword(s):  
Applied Voltage ◽  
Low Temperatures ◽  
Semiconductor Heterostructures ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Material Parameters ◽  
Transmission Coefficients ◽  
Effective Masses ◽  
Resonant Transmission ◽  
Double Wells

In this work we calculate the transmission coefficients for tunneling of electrons and holes through biased triple barriers (double-wells) semiconductor heterostructures (TBSH’s), composed of Ga1−xAlxAs–GaAs–Ga1−xAlxAs with x = 0.45. The calculations are based on the effective mass theory that employs the spatial effective masses and the temperature dependent of the material parameters that constitute the heterostructure. The transverse motions of carriers are also considered. In the analysis the Airy’s function formalism is taken into account. It is found that, the resonant transmission energies for both electrons and holes are decreased by enhancing the applied voltage. Also, the total resonant transmission energies for the tunneling carriers are deviated toward higher energies, as the temperature is increased. Therefore, these devices should be operated at low temperatures. Furthermore, the present work shows a discrepancy in resonant transmission energies with those reported ones, due to ignoring the effect of temperature.

Using Nonlinear Kinematic Hardening Material Models for Elastic-Plastic Ratcheting Analysis

2015 ◽  
Author(s):  
Tim Gilman ◽  
Bill Weitze ◽  
Jürgen Rudolph ◽  
Adrian Willuweit ◽  
Arturs Kalnins
Keyword(s):  
Material Model ◽  
Pressure Vessels ◽  
Growth Strain ◽  
Temperature Dependent ◽  
Material Models ◽  
Hardening Material ◽  
Material Parameters ◽  
Elastic Plastic ◽  
Material Data ◽  
Inelastic Analysis

Applicable design codes for power plant components and pressure vessels demand for a design check against progressive plastic deformation. In the simplest case, this demand is satisfied by compliance with shakedown rules in connection with elastic analyses. The possible non-compliance implicates the requirement of ratcheting analyses on elastic-plastic basis. In this case, criteria are specified on maximum allowable accumulated growth strain without clear guidance on what material models for cyclic plasticity are to be used. This is a considerable gap and a challenge for the practicing CAE (Computer Aided Engineering) engineer. As a follow-up to two independent previous papers PVP2013-98150 ASME [1] and PVP2014-28772 [2] it is the aim of this paper to close this gap by giving further detailed recommendation on the appropriate application of the nonlinear kinematic material model of Chaboche on an engineering scale and based on implementations already available within commercial finite element codes such as ANSYS® and ABAQUS®. Consistency of temperature-dependent runs in ANSYS® and ABAQUS® is to be checked. All three papers together constitute a comprehensive guideline for elasto-plastic ratcheting analysis. The following issues are examined and/or referenced: • Application of monotonic or cyclic material data for ratcheting analysis based on the Chaboche material model • Discussion of using monotonic and cyclic data for assessment of the (non-stabilized) cyclic deformation behavior • Number of backstress terms to be applied for consistent ratcheting results • Consideration of the temperature dependency of the relevant material parameters • Consistency of temperature-dependent runs in ANSYS® and ABAQUS® • Identification of material parameters dependent on the number of backstress terms • Identification of material data for different types of material (carbon steel, austenitic stainless steel) including the appropriate determination of the elastic limit • Quantification of conservatism of simple elastic-perfectly plastic behavior • Application of engineering versus true stress-strain data • Visual checks of data input consistency • Appropriate type of allowable accumulated growth strain. This way, a more accurate inelastic analysis methodology for direct practical application to real world examples in the framework of the design code conforming elasto-plastic ratcheting check is proposed.

scholarly journals Modeling of Dielectric Heating within Lyophilization Process

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Jan Kyncl ◽  
Jiří Doubek ◽  
Lubomír Musálek
Keyword(s):  
Mathematical Model ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Heating System ◽  
Temperature Fields ◽  
Dielectric Heating ◽  
Temperature Dependent ◽  
Partial Differential ◽  
Material Parameters ◽  
Coupled Problem

A process of lyophilization of paper books is modeled. The process of drying is controlled by a dielectric heating system. From the physical viewpoint, the task represents a 2D coupled problem described by two partial differential equations for the electric and temperature fields. The material parameters are supposed to be temperature-dependent functions. The continuous mathematical model is solved numerically. The methodology is illustrated with some examples whose results are discussed.

First Exact Solutions for Flows of Rate Type Fluids in a Circular Duct that Applies a Constant Couple to the Fluid

2014 ◽  
Vol 69 (5-6) ◽  
pp. 232-238 ◽  
Author(s):  
Corina Fetecau ◽  
Mehwish Rana ◽  
Niat Nigar ◽  
Constantin Fetecau
Keyword(s):  
Shear Stress ◽  
Circular Cylinder ◽  
Integral Transforms ◽  
Second Grade ◽  
Rotational Flow ◽  
Stress Distributions ◽  
Circular Duct ◽  
Material Parameters ◽  
Similar Solutions ◽  
Rate Type

Rotational flow of an Oldroyd-B fluid induced by an infinite circular cylinder that applies a constant couple to the fluid is studied by means of integral transforms. Such a problem is not solved in the existing literature for rate type fluids and the present solutions are based on a simple but important remark regarding the governing equation for the non-trivial shear stress. The solutions that have been obtained satisfy all imposed initial and boundary conditions and can easy be reduced to the similar solutions corresponding to Maxwell, second-grade, and Newtonian fluids performing the same motion. Finally, the influence of material parameters on the velocity and shear stress distributions is graphically underlined.

scholarly journals On thermodynamics of incompressible viscoelastic rate type fluids with temperature dependent material coefficients

2017 ◽  
Vol 95 ◽  
pp. 193-208 ◽  
Author(s):  
Jaroslav Hron ◽  
Vojtěch Miloš ◽  
Vít Průša ◽  
Ondřej Souček ◽  
Karel Tůma
Keyword(s):  
Temperature Dependent ◽  
Rate Type
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