A Galerkin/hyper-reduction technique to reduce steady-state elastohydrodynamic line contact problems

2021 ◽  
Vol 386 ◽  
pp. 114132
Author(s):  
Leoluca Scurria ◽  
Dieter Fauconnier ◽  
Pavel Jiránek ◽  
Tommaso Tamarozzi
Keyword(s):  
Steady State ◽  
Contact Problems ◽  
Reduction Technique ◽  
Line Contact

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

Fast Solution of Transient Elastohydrodynamic Line Contact Problems Using the Trajectory Piecewise Linear Approach

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Daniel Maier ◽  
Corinna Hager ◽  
Hartmut Hetzler ◽  
Nicolas Fillot ◽  
Philippe Vergne ◽  
...  
Keyword(s):  
Piecewise Linear ◽  
Contact Problems ◽  
Galerkin Projection ◽  
Line Contact ◽  
Reduced Order ◽  
Fast Solution ◽  
Speed Up ◽  
Newton Raphson ◽  
First Time ◽  
Piecewise Linear Approach

In order to obtain a fast solution scheme, the trajectory piecewise linear (TPWL) method is applied to the transient elastohydrodynamic (EHD) line contact problem for the first time. TPWL approximates the nonlinearity of a dynamical system by a weighted superposition of reduced linearized systems along specified trajectories. The method is compared to another reduced order model (ROM), based on Galerkin projection, Newton–Raphson scheme and an approximation of the nonlinear reduced system functions. The TPWL model provides further speed-up compared to the Newton–Raphson based method at a high accuracy.

Steady-State Motion of a Line Mechanical/Heat Source Over a Half-Space: A Thermoelastodynamic Solution

1997 ◽  
Vol 64 (3) ◽  
pp. 562-567 ◽  
Author(s):  
L. M. Brock ◽  
H. G. Georgiadis
Keyword(s):  
Steady State ◽  
Heat Source ◽  
Half Space ◽  
Constant Velocity ◽  
Characteristic Length ◽  
Surface Displacement ◽  
Contact Problems ◽  
Governing Equations ◽  
Asymptotic Expressions ◽  
Thermoelastic Characteristic

An asymptotic solution within the bounds of steady-state coupled thermoelastodynamic theory is given for the surface displacement and temperature due to a line mechanical/heat source that moves at a constant velocity over the surface of a half-space. This problem is of basic interest in the fields of contact mechanics and tribology, and an exact formulation is considered. The results may serve as a Green’s function for more general thermoelastodynamic contact problems. The problem may also be viewed as a generalization of the classical Cole-Huth problem and the associated Georgiadis-Barber correction. Asymptotic expressions are obtained by means of the two-sided Laplace transform, and by performing the inversions exactly. The range of validity of these expressions is actually quite broad, because of the small value of the thermoelastic characteristic length appearing in the governing equations.

Effect of Roughness Orientation on the Elastohydrodynamic Lubrication Film Thickness

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Dong Zhu ◽  
Q. Jane Wang
Keyword(s):  
Film Thickness ◽  
Stochastic Models ◽  
Deterministic Model ◽  
Elastohydrodynamic Lubrication ◽  
Contact Problems ◽  
Operating Conditions ◽  
Orientation Effect ◽  
Line Contact ◽  
Lubrication Film ◽  
Dry Contact

Effect of roughness orientation on lubricant film thickness has been an important issue of surface design, attracting much attention since the 1970 s. A systematical study, however, is still needed for various contact types in an extended range of operating conditions, especially in mixed lubrication cases with film thickness to roughness ratio (λ ratio) smaller than 0.5. The present study employs a deterministic mixed elastohydrodynamic lubrication (EHL) model to investigate the performance of lubricating films in different types of contact geometry, including the line contact, circular contact, and elliptical contacts of various ellipticity ratios. The speed range for analyzed cases covers 11 orders of magnitude so that the entire transition from full-film and mixed EHL down to dry contact (corresponding λ ratio from about 3.5 down to 0.001 or so) is simulated. Three types of machined surfaces are used, representing transverse, longitudinal, and isotropic roughness, respectively. The line contact results are compared with those from the stochastic models by Patir and Cheng (“Effect of Surface Roughness Orientation on the Central Film Thickness in EHD Contacts,” Proc. 5th Leeds-Lyon Symp. on Tribol., 1978, pp. 15–21) and the influence of roughness orientation predicted by the deterministic model is found to be less significant than that by the stochastic models, although the basic trends are about the same when λ > 0.5. The orientation effect for circular or elliptical contact problems appears to be more complicated than that for line contacts due to the existence of significant lateral flows. In circular contacts, or elliptical contacts with the ellipticity ratio smaller than one, the longitudinal roughness may become more favorable than the isotropic and transverse. Overall, the orientation effect is significant in the mixed EHL regime where theλratio is roughly in the range from 0.05 to 1.0. It is relatively insignificant for both the full-film EHL (λ > 1.2 or so) and the boundary lubrication/dry contact (λ < 0.025 ∼ 0.05).

Analysis of Steady-State Rolling Contact Problems in Nonlinear Viscoelastic Materials

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Alaa A. Abdelrahman ◽  
Ahmed G. El-Shafei ◽  
Fatin F. Mahmoud
Keyword(s):  
Steady State ◽  
Contact Problems ◽  
Rolling Contact ◽  
Coulomb’S Friction ◽  
Nonlinear Viscoelastic ◽  
Lagrangian Finite Element ◽  
History Of ◽  
Steady State Rolling ◽  
Incremental Form ◽  
Contact Response

A comprehensive numerical model is developed using Lagrangian finite element (FE) formulation for investigating the steady-state viscoelastic (VE) rolling contact response. Schapery's nonlinear viscoelastic (NVE) model is adopted to simulate the VE behavior. The model accounts for large displacements and rotations. A spatially dependent incremental form of the VE constitutive equations is derived. The dependence on the history of the strain rate is expressed in terms of the spatial variation of the strain. The Lagrange multiplier approach is employed. The classical Coulomb's friction law is used. The developed model is verified and its applicability is demonstrated.

Some Implications of Dundurs' Theorem for Thermoelastic Contact and Crack Problems

1980 ◽  
Vol 22 (5) ◽  
pp. 229-232 ◽  
Author(s):  
J. R. Barber
Keyword(s):  
Steady State ◽  
Thick Plate ◽  
Line Element ◽  
Three Dimensional ◽  
Contact Problems ◽  
Free Boundaries ◽  
Principal Curvatures ◽  
State Heat ◽  
Crack Problems ◽  
Steady State Heat

It is well known that a simply-connected isotropic elastic body in a state of plane strain and with traction-free boundaries remains free of stress if it is subject to steady-state heat conduction. A recent theorem due to Dundurs shows that in this state the curvature of any initially straight line element is proportional to the heat flux across the line element. A closely related three dimensional result is proved for the sum of the principal curvatures of planes parallel to the faces of an infinite thick plate. These results have certain implications for thermoelastic crack and contact problems. For example: (i) thermal distortion has no effect on the contact pressure distribution at an insulated interface or at an interface between two similar materials, (ii) the thermal stress in a cracked solid depends on the temperature field only through the value of a certain constant related to the average temperature difference across the crack, (iii) steady-state heat flow induces no stresses in an axisymmetric thick plate containing an external crack.

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