Thermoelastic Distortion of EHD Line Contacts During the Passage of Soft Debris Particles

1999 ◽  
Vol 121 (2) ◽  
pp. 265-271 ◽  
Author(s):  
G. K. Nikas ◽  
R. S. Sayles ◽  
E. Ioannides
Keyword(s):  
Thermal Stresses ◽  
Frictional Heating ◽  
Three Dimensional ◽  
Operational Parameters ◽  
Dimensional Solution ◽  
Debris Particle ◽  
Debris Particles ◽  
Line Contacts ◽  
Contact Mechanical ◽  
Thermoelastic Displacement

During the passage of a debris particle through an EHD contact, mechanical stresses due to particle compression and thermal stresses due to particle frictional heating produce a thermoelastic/plastic stress field, which governs the way a possible damage is generated. In the present paper, the complete three-dimensional solution of the thermoelastic distortion of surfaces due to the compression of a soft, ductile debris particle in an EHD line contact is presented both theoretically and through a realistic example. It is found that thermal stresses increase the likelihood of yielding and produce a characteristic “omega” shaped thermoelastic displacement. The important outcome of this work is the construction of a map which shows the critical particle size to cause damage (plastic deformations) in combination with operational parameters as the lubricant film thickness and relative sliding velocity of the contact.

An Advanced Model to Study the Possible Thermomechanical Damage of Lubricated Sliding-Rolling Line Contacts From Soft Particles

2000 ◽  
Vol 123 (4) ◽  
pp. 828-841 ◽  
Author(s):  
George K. Nikas
Keyword(s):  
Thermal Stresses ◽  
Frictional Heating ◽  
Influential Factors ◽  
Plastic Compression ◽  
Lubricated Contacts ◽  
Debris Particles ◽  
Line Contacts ◽  
Soft Particles ◽  
Thermomechanical Damage ◽  
Advanced Model

A model presented earlier by the author (Nikas et al., 1998, 1999) for the study of the possible risks associated with the entrapment of debris particles in lubricated contacts has been refined to account for additional influential factors that could affect the results obtained from the initial model. The new results showed that soft contaminants could indeed be very destructive and damage a concentrated sliding contact mainly due to the thermal stresses developed from the frictional heating of the contact during the plastic compression and shearing of a particle. This model yielded flash temperatures of the order of 100°C and up to 2000°C (or more, until local yield occurs). It also showed that it is often the thermal stresses which cause the problems, rather than the mechanical stresses from particles’ deformation.

Transient Three-Dimensional Solution for Thermoelastic Displacement Due to Surface Heating and Convective Cooling

2005 ◽  
Vol 127 (4) ◽  
pp. 750-755 ◽  
Author(s):  
Ashlie Martini ◽  
Shuangbiao Liu ◽  
Q. Jane Wang
Keyword(s):  
Frictional Heating ◽  
Three Dimensional ◽  
Surface Displacement ◽  
Elastic Half Space ◽  
Normal Surface ◽  
Dimensional Solution ◽  
Convective Cooling ◽  
Surface Convection ◽  
Tribological Contact ◽  
Thermoelastic Displacement

In tribological contact, frictional heating may lead to temperature rise, which in turn may result in thermal displacement of the contacting bodies. The quantification of these effects is desirable in order to more accurately predict wear and failure of contacting surfaces. The change in temperature at a contact area may be attributed to the combined effects of frictional heating and convective cooling. This paper presents a transient, three-dimensional solution for the normal surface displacement of an elastic half-space due to an arbitrarily distributed, moving heat source and surface convection.

Thermoelastic Effects in Lubricated Rolling/Sliding Line Contacts

1991 ◽  
Vol 113 (1) ◽  
pp. 174-181 ◽  
Author(s):  
P. C. Sui ◽  
F. Sadeghi
Keyword(s):  
Temperature Distribution ◽  
Numerical Model ◽  
Film Thickness ◽  
Thermal Stresses ◽  
Shear Stresses ◽  
Ehd Lubrication ◽  
Line Contacts ◽  
Thermoelastic Effects ◽  
Machine Elements ◽  
Thermoelastic Displacement

A numerical model was developed to investigate the subsurface mechanical and thermal stresses in rolling/sliding machine elements operating under elasto-hydrodynamic (EHD) lubrication of line contacts. A thermal non-Newtonian EHD lubrication model was modified to include the thermoelastic displacement of the solids. The pressure, film thickness, and temperature distribution obtained from the model were used to calculate the subsurface mechanical and thermal stresses within the rolling/sliding machine elements. The thermoelastic effects on the magnitude and location of the maximum shear stresses are presented.

Unsteady thermal stress analysis in three-dimensional problems by means of the thermoelastic displacement potential and the boundary element method

1990 ◽  
Vol 25 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Y Ochiai ◽  
R Ishida ◽  
T Sekiya
Keyword(s):  
Thermal Stress ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Stress Distributions ◽  
Displacement Potential ◽  
Thermal Displacements ◽  
Thermoelastic Displacement ◽  
Element Method

A numerical method to analyse unsteady thermal stresses in three-dimensional problems is proposed. It is shown that three-dimensional unsteady thermal stress problems can be easily solved without the volume integral by means of the thermoelastic displacement potential and the boundary element method. It is also shown that the time integral can be easily carried out analytically. In order to investigate the accuracy of this method, unsteady thermal stress distributions for a sphere and a circular cylinder are obtained. As a numerical example for which it is difficult to obtain the analytical solution, thermal displacements and surface stress distributions for a torus are obtained.

Numerical Conjugate Heat Transfer Study of a Cooled Compressor Rear Cone

2014 ◽  
Author(s):  
Fabian Bleier ◽  
Max Hufnagel ◽  
Tim Pychynski ◽  
Hans-Jörg Bauer ◽  
Christian Eichler
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Frictional Heating ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Parameter Study ◽  
Operational Parameters ◽  
Transfer Coefficients ◽  
Gap Width ◽  
Transfer Study

The paper presents the setup of a conjugate heat transfer study of an annular conical gap, its validation and a parameter study. The main goal of the work is to identify effects of gap width and swirl ratio on the local and global heat transfer in the annular conical gap. The validation of the numerical model is done by a comparison against experimental data from literature. It is shown that the non-axisymmetric flow in the gap can be well reproduced by a three-dimensional axisymmetric model. To identify influences of geometric and operational parameters on the cooling efficiency, a RANS parameter study of the cooling concept is performed. The parameter study includes variations of the gap width and the pre-swirl of the inlet air. The results are used to evaluate the quality of the cooling concept and to identify the effect of geometry on frictional effects and on heat transfer coefficients. In this respect it is important to separate frictional heating and convective heat transfer effects.

A comparative study and combined application of RSM and ANN in adsorptive removal of diuron using biomass ashes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sunil K. Deokar ◽  
Nachiket A. Gokhale ◽  
Sachin A. Mandavgane
Keyword(s):  
Three Dimensional ◽  
Current Approach ◽  
Coefficient Of Determination ◽  
Ann Model ◽  
Operational Parameters ◽  
Initial Concentration ◽  
Combined Application ◽  
Artificial Neural Network Ann ◽  
Relationship Of ◽  
Biomass Ashes

Abstract Biomass ashes like rice husk ash (RHA), bagasse fly ash (BFA), were used for aqueous phase removal of a pesticide, diuron. Response surface methodology (RSM) and artificial neural network (ANN) were successfully applied to estimate and optimize the conditions for the maximum diuron adsorption using biomass ashes. The effect of operational parameters such as initial concentration (10–30 mg/L); contact time (0.93–16.07 h) and adsorbent dosage (20–308 mg) on adsorption were studied using central composite design (CCD) matrix. Same design was also employed to gain a training set for ANN. The maximum diuron removal of 88.95 and 99.78% was obtained at initial concentration of 15 mg/L, time of 12 h, RHA dosage of 250 mg and at initial concentration of 14 mg/L, time of 13 h, BFA dosage of 60 mg respectively. Estimation of coefficient of determination (R 2) and mean errors obtained for ANN and RSM (R 2 RHA = 0.976, R 2 BFA = 0.943) proved ANN (R 2 RHA = 0.997, R 2 BFA = 0.982) fits better. By employing RSM coupled with ANN model, the qualitative and quantitative activity relationship of experimental data was visualized in three dimensional spaces. The current approach will be instrumental in providing quick preliminary estimations in process and product development.

A Three-Dimensional Finite Difference Solution for the Thermal Stresses in Railcar Wheels

1969 ◽  
Vol 91 (3) ◽  
pp. 891-896 ◽  
Author(s):  
G. E. Novak ◽  
B. J. Eck
Keyword(s):  
Computer Program ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Transient Temperature ◽  
Shear Stresses ◽  
Radial Temperature ◽  
Closed Form Solutions ◽  
Brake Application ◽  
History Of ◽  
Thin Disks

A numerical solution is presented for both the transient temperature and three-dimensional stress distribution in a railcar wheel resulting from a simulated emergency brake application. A computer program has been written for generating thermoelastic solutions applicable to wheels of arbitrary contour with temperature variations in both axial and radial directions. The results include the effect of shear stresses caused by the axial-radial temperature gradients and the high degree of boundary irregularity associated with this type of problem. The program has been validated by computing thermoelastic solutions for thin disks and long cylinders; the computed values being in good agreement with the closed form solutions. Currently, the computer program is being extended to general stress solutions corresponding to the transient temperature distributions obtained by simulated drag brake applications. When this work is completed, it will be possible to synthesize the thermal history of a railcar wheel and investigate the effects of wheel geometry in relation to thermal fatigue.

Sign in / Sign up

Export Citation Format

Share Document