Stability of Thermoelastic Contact for the Aldo Model

1981 ◽  
Vol 48 (3) ◽  
pp. 555-558 ◽  
Author(s):  
J. R. Barber
Keyword(s):  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Multiple Steady State ◽  
Imperfect Contact ◽  
One Dimensional ◽  
Thermoelastic Contact ◽  
The Stability ◽  
Contact Pressures ◽  
Steady State Solutions ◽  
Small Separation

A perturbation method is used to investigate the stability of a simple one-dimensional rod model of thermoelastic contact which exhibits multiple steady-state solutions. A thermal contact resistance is postulated which is a continuous function of the contact pressure or separation. It is found that solutions involving substantial separation and/or contact pressures are always stable, but these are separated by unstable “imperfect contact” solutions in which one of the rods is very lightly loaded or has a very small separation. The results can be expressed in terms of the minimization of a certain energy function.

Stability Considerations in Thermoelastic Contact

1980 ◽  
Vol 47 (4) ◽  
pp. 871-874 ◽  
Author(s):  
J. R. Barber ◽  
J. Dundurs ◽  
M. Comninou
Keyword(s):  
Steady State ◽  
Perturbation Method ◽  
Energy Function ◽  
First Principles ◽  
Dimensional Model ◽  
Contact Conditions ◽  
One Dimensional ◽  
Thermoelastic Contact ◽  
The Stability ◽  
Steady State Solutions

A simple one-dimensional model is described in which thermoelastic contact conditions give rise to nonuniqueness of solution. The stability of the various steady-state solutions discovered is investigated using a perturbation method. The results can be expressed in terms of the minimization of a certain energy function, but the authors have so far been unable to justify the use of such a function from first principles in view of the nonconservative nature of the system.

The Effect of Thermal Contact Resistance on Heat Management in a Shuttling PCR System

2013 ◽  
Vol 284-287 ◽  
pp. 1941-1945
Author(s):  
Jyh Jian Chen ◽  
Wei Hua Chen ◽  
Yi Shiang Shie
Keyword(s):  
Pid Controller ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Computer Code ◽  
Reaction Chamber ◽  
Operational Parameters ◽  
Heat Management ◽  
Dna Templates ◽  
Polymerase Chain ◽  
The Stability

A novel shuttling polymerase chain reaction (PCR) system is assembled to make temperature uniform in the reaction chamber. The chamber is oscillated by a servo motor and contacted with three different isothermal zones to complete several thermal cycles. The home-made computer code is utilized to investigate the influences of operational parameters on the temperature inside the chamber. Numerical results show that the contact resistances between the heating blocks and the reaction chamber dominate the temperatures inside the PCR chamber. In this work a PCR system that is composed of the PID controller, the moving stage, three aluminum blocks for three different isothermal zones and a reaction chamber is also developed. Experimental results demonstrated that the stability of this shuttling PCR system is confirmed. And results show that DNA templates provided with the yT&A® cloning vector are amplified successfully in this PCR system.

Morphological Instability in Early Stages of Solidification of Pure Metals Part I: A Theoretical Model

2012 ◽  
Vol 445 ◽  
pp. 337-342 ◽  
Author(s):  
Faruk Yigit
Keyword(s):  
Thermal Conductivity ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Shell Growth ◽  
Mold Material ◽  
Morphological Instability ◽  
Dimensional Model ◽  
One Dimensional ◽  
Solidification Processes ◽  
Irregular Growth

A simple one dimensional model has been introduced to investigate the morphological instability observed in many solidification processes. It is shown that the solidified shell material with higher thermal conductivity might result in planar shell growth, whereas the mold material with higher thermal conductivity may cause irregular growth of the shell which, generally, causes cracking near the surface, and the thicker mold causes faster growth of the shell, and the higher thermal contact resistance leads to faster growth of the shell.

The Emergence of Multiple Equilibria in Electromechanical Systems

1994 ◽  
Vol 116 (4) ◽  
pp. 735-744 ◽  
Author(s):  
Neyram Hemati
Keyword(s):  
Multiple Equilibria ◽  
Chaotic Behavior ◽  
Multiple Equilibrium ◽  
Equilibrium Solutions ◽  
Multiple Steady State ◽  
Brushless Dc ◽  
Variable Reluctance ◽  
Stable Operating ◽  
The Stability ◽  
Steady State Solutions

The dynamic characteristics of brushless dc machines are considered. It is demonstrated that due to the inherent nonlinear dynamics of these systems, multiple steady-state solutions can exist. The presence of multiple equilibrium solutions is in turn used to provide an explanation for the loss of stability associated with a locally stable operating state. Numerical simulations are used to help verify the presence of multiple equilibria and their effect on the stability of the systems under investigation. Finally, an example is presented which demonstrates that the presence of multiple equilibria can lead to chaotic behavior in bldcm systems with variable reluctance.

scholarly journals Bistabilities and domain walls in weakly open quantum systems

2020 ◽  
Vol 9 (4) ◽  
Author(s):  
Florian Lange ◽  
Achim Rosch
Keyword(s):  
Steady State ◽  
Conservation Laws ◽  
Weak Coupling ◽  
Domain Walls ◽  
Hydrodynamic Equation ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Multiple Steady State ◽  
One Dimensional ◽  
Steady State Solutions

Weakly pumped systems with approximate conservation laws can be efficiently described by (generalized) Gibbs ensembles if the steady state of the system is unique. However, such a description can fail if there are multiple steady state solutions, for example, a bistability. In this case domains and domain walls may form. In one-dimensional (1D) systems any type of noise (thermal or non-thermal) will in general lead to a proliferation of such domains. We study this physics in a 1D spin chain with two approximate conservation laws, energy and the zz-component of the total magnetization. A bistability in the magnetization is induced by the coupling to suitably chosen Lindblad operators. We analyze the theory for a weak coupling strength \epsilonϵ to the non-equilibrium bath. In this limit, we argue that one can use hydrodynamic approximations which describe the system locally in terms of space- and time-dependent Lagrange parameters. Here noise terms enforce the creation of domains, where the typical width of a domain wall goes as \sim 1/\sqrt{\epsilon}∼1/ϵ while the density of domain walls is exponentially small in 1/\sqrt{\epsilon}1/ϵ. This is shown by numerical simulations of a simplified hydrodynamic equation in the presence of noise.

Effect of Material Properties on the Stability of Static Thermoelastic Contact

1990 ◽  
Vol 57 (2) ◽  
pp. 365-369 ◽  
Author(s):  
Ronggang Zhang ◽  
J. R. Barber
Keyword(s):  
Heat Flow ◽  
Stability Criterion ◽  
Material Properties ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Steady State Solution ◽  
The Other ◽  
Pressure Perturbation ◽  
Stability Behavior ◽  
The Stability

When heat is conducted across an interface between two different materials, the interaction between thermoelastic distortion and thermal contact resistance can cause the system to be unstable. This paper investigates the influence of material properties on the stability criterion for an interface between two half planes. It is found that most material combinations exhibit one or other of two kinds of stability behavior. In one of these, the stability criterion is closely related to that for uniqueness of the steady-state solution and instability is only possible for one direction of heat flow. In the other, instability can occur for either direction of heat flow and in one case is characterized by the oscillatory growth of a pressure perturbation.

scholarly journals The Variations of Thermal Contact Resistance and Heat Transfer Rate of the AlN Film Compositing with PCM

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Huann-Ming Chou ◽  
Jin-Chi Wang ◽  
Yuh-Ping Chang
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Phase Change Materials ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Melting Process ◽  
High Heat ◽  
Green Technology ◽  
Aln Film ◽  
Contact Pressures

The electrical industries have been fast developing over the past decades. Moreover, the trend of microelements and packed division multiplex is obviously for the electrical industry. Hence, the high heat dissipative and the electrical insulating device have been popular and necessary. The thermal conduct coefficient of aluminum nitride (i.e., AlN) is many times larger than the other materials. Moreover, the green technology of composite with phase change materials (i.e., PCMs) is worked as a constant temperature cooler. Therefore, PCMs have been used frequently for saving energy and the green environment. Based on the above statements, it does show great potential in heat dissipative for the AlN film compositing with PCM. Therefore, this paper is focused on the research of thermal contact resistance and heat transfer between the AlN/PCM pairs. According to the experimental results, the heat transfer decreases and the thermal contact resistance increases under the melting process of PCM. However, the suitable parameters such as contact pressures can be used to improve the above defects.

Influence of Thermal Contact Resistance on Frictionally Excited Thermoelastic Instability (TEI)

2004 ◽  
Author(s):  
J. R. Barber ◽  
M. Ciavarella ◽  
L. Afferante
Keyword(s):  
Steady State ◽  
Contact Problem ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Frictional Heating ◽  
Thermal Contact ◽  
Contact Problems ◽  
General Stability ◽  
Static Contact ◽  
Steady State Solutions

Thermoelastic contact problems can posess non-unique and/or unstable steady-state solutions if there is frictional heating or if there is a pressure-dependent thermal contact resistance at the interface. These two effects have been extensively studied in isolation, but their possible interaction has not been investigated until recently. We shall discuss some idealized geometries in which the two effects are seen to form limiting cases of a more general stability and existence behavior. In most cases, frictional heating has a destabilizing effect relative to the static contact problem, but if the thermal contact resistance is very sensitive to pressure, cases of stabilization can be obtained. Also, the critical sliding speed depends on the contact pressure in contrast to results obtained in the absence of thermal contact resistance.

The Effect of Thermal Contact Resistance on Heat Transfer Between Periodically Contacting Surfaces

1973 ◽  
Vol 95 (3) ◽  
pp. 411-412 ◽  
Author(s):  
J. R. Howard ◽  
A. E. Sutton
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Analog Computer ◽  
Contact Interface ◽  
Computer Study ◽  
One Dimensional

An analog-computer study is made of one-dimensional heat conduction through two bars whose axes are in line and whose adjacent ends make and break contact periodically. The work extends a previous study to take account of imperfect thermal contact at the contact interface. The effect of frequency and duration of contact are also discussed.

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