Nonlinear Thermoelastic Behavior of Structural Joints—Solution to a Missing Link for Prediction of Thermal Deformation of Machine Tools

1979 ◽  
Vol 101 (3) ◽  
pp. 348-354 ◽  
Author(s):  
M. H. Attia ◽  
L. Kops
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Contact Pressure ◽  
Thermal Deformation ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Structural Elements ◽  
Nonlinear Load ◽  
Missing Link ◽  
Dependent Form

The analysis of the process of heat transfer across the joints in machine tool structures reveals their non-linear thermoelastic behavior. Nonlinearity basically results from two distinctive causes. First, it is the material nonlinearity due to the fact, that the stiffness of the surface asperities takes a nonlinear, load-dependent form. The second cause is the nonlinearity resulting from the thermoelastic behavior of contacting elements, which experience a closed-loop interaction between the thermal field and the thermal deformation of structural elements in contact. This interaction affects the distribution of the contact pressure along the joint and causes a consequent redistribution of the thermal contact resistance. As a result, the final pattern of deformation depends on the final contact pressure distribution which is unknown in advance. The nonlinear thermoelastic behavior of the joint is inherent to the process of heat transfer across the interface. By considering this behavior of the joint, characterized by the time-dependent distribution of the thermal contact resistance along the interface, thermal deformation of the whole structure can be treated with thermally interacting structural elements taken into account. This was a missing link in predicting the thermal deformation. As a solution, a consecutive-iteration technique is proposed, which, with introduction of contact elements representing equivalent properties of the joint, allows us to portray the thermal deformation of the structure under transient and steady state conditions.

scholarly journals Test Rig for Applied Experimental Investigations of the Thermal Contact Resistance at the Blade-Rotor-Connection in a Steam Turbine

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Dennis Toebben ◽  
Xavier E. R. de Graaf ◽  
Piotr Luczynski ◽  
Manfred Wirsum ◽  
Wolfgang F. D. Mohr ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Steam Turbine ◽  
Contact Pressure ◽  
Rotational Speed ◽  
Thermal Contact Resistance ◽  
Thermal Stresses ◽  
Thermal Contact ◽  
Experimental Investigations ◽  
Molybdenum Steel ◽  
Bottle Neck

Recent studies have shown that in a prewarming, respectively, warm-keeping operation of a steam turbine, the blades and vanes transport most of the heat to the thick-walled casing and rotor. Thereby, a thermal bottle-neck arises at the connection between the blade root and the rotor. The thermal contact resistance (TCR) at these interfaces affects the temperature distribution and thus the thermal stresses in the rotor. The present paper introduces an experimental setup, which is designed to quantify the TCR at the blade-rotor-connection of a steam turbine. An uncertainty analysis is presented, which proves that the average measurement uncertainties are less than one percent. The experiments especially focus on the investigation of the contact pressure, which is a function of the rotational speed. Therefore, the results of several steady-state measurements under atmospheric and evacuated atmosphere using a high temperature-resistant chromium-molybdenum steel are presented. For the evaluation of the TCR, a numerical model of the specimen is developed in addition to a simplified 1D approach. The results show a significantly increasing TCR with decreasing contact pressure, respectively, rotational speed.

scholarly journals Contribution to the Study of Solid-Solid Thermal Contact Resistances--A Comparative Study

2021 ◽  
Vol 45 (4) ◽  
pp. 267-272
Author(s):  
Rahmouna Cheriet ◽  
Bourassia Bensaad ◽  
Fatiha Bouhadjela ◽  
Soufyane Belhenini ◽  
Mohammed Belharizi
Keyword(s):  
Contact Resistance ◽  
Contact Pressure ◽  
Mixed Method ◽  
Thermal Contact Resistance ◽  
Low Cost ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Empirical Models ◽  
Three Dimensional Finite Element ◽  
Semi Empirical

This study presents a mixed numerical / semi-empirical approach that primarily aimed to estimate the thermal contact resistance between two solids. The results obtained by this mixed method were compared and validated by experimental measurements of this resistance. Three semi-empirical models were used, namely the Mikic model, the Yovanovich model and the Antonetti model. The three-dimensional finite element numerical simulation was used to estimate the contact pressure between the two solids. Then this contact pressure obtained numerically was compared to the hardness of the solids in contact. The findings indicated that the numerically obtained contact pressures were close to hardness. Therefore, the hardness, which is usually used as an input variable in semi-empirical models, was replaced by the contact pressure. The thermal contact resistance obtained by this mixed method was then compared with the experimental one. The outcomes obtained from this comparison turned out to be very conclusive and can therefore be used to reinforce our approach which can actually be viewed as a reliable and low-cost method for estimating the thermal contact resistance between solids in contact.

scholarly journals Study of an inclined interface of contact using lattice Boltzmann method

2019 ◽  
Vol 23 (3 Part B) ◽  
pp. 1837-1846
Author(s):  
Mhamdi El ◽  
Elalami Semma
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Thermal Contact Resistance ◽  
Transfer Problem ◽  
Thermal Contact ◽  
Image Model ◽  
Steady Regime ◽  
Boltzmann Method

The lattice Boltzmann method and the particle image model are adopted to study a heat transfer problem with thermal contact resistance. In this paper, a new study involving an inclined interface of contact between two media is introduced in order to evaluate a 2-D heat transfer in the steady regime. A case of study and numerical results are provided to support this configuration. The obtained results show the effect of the thermal contact resistance on the heat transfer, as well as the temperature distribution on the two contacting media.

The Steady-State Thermal Characteristics Analysis of Precise Composite Grinding Machine

2011 ◽  
Vol 338 ◽  
pp. 241-244
Author(s):  
Hong Lin Zhao ◽  
Rui Chen ◽  
Yu Mei Huang ◽  
Guang Peng Zhang ◽  
Bo Wang ◽  
...  
Keyword(s):  
Contact Resistance ◽  
Thermal Deformation ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Thermal Characteristics ◽  
Numerical Control ◽  
Deformation Analysis ◽  
Characteristics Analysis ◽  
Grinding Machine ◽  
The Impact

It is commonly used method to analyze the overall thermal characteristics of mechanical structure without considering the thermal contact resistance of components. But in terms of precision composite grinding machine, the impact of thermal contact resistance can not be ignored. On the basic of thermal contact resistance characteristics, this article gives the concept and empirical value of the equivalent area factor. By calculating the equivalent contact coefficient, the thermal contact resistance characteristics were integrated into the grinder simulation. According to the structure and processing characteristics of grinder, grinding machine was analyzed in two parts respectively to get the pattern of temperature rise and thermal deformation. Analysis shows the impact that thermal deformation has on working accuracy, so as to provide basis to the compensation of numerical control system to improve the working accuracy.

The problem of thermal contact resistance during heat transfer to liquid metals

Atomic Energy ◽  
1962 ◽  
Vol 11 (3) ◽  
pp. 910-913
Author(s):  
O. P. Astakhov ◽  
V. I. Petrov ◽  
O. S. Fedynskii
Keyword(s):  
Heat Transfer ◽  
Contact Resistance ◽  
Thermal Contact Resistance ◽  
Liquid Metals ◽  
Thermal Contact
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