Numerical Contact Model of a Smooth Ball on an Anisotropic Rough Surface

1994 ◽  
Vol 116 (2) ◽  
pp. 194-201 ◽  
Author(s):  
C. Y. Poon ◽  
R. S. Sayles
Keyword(s):  
Rough Surface ◽  
Contact Pressure ◽  
Smooth Surface ◽  
Contact Model ◽  
The Real ◽  
Numerical Result ◽  
Realistic Situation ◽  
Surface Contact ◽  
Rough Surface Contact ◽  
Sinusoidal Surface

A numerical elastic-plastic contact model of a smooth ball on a directionally structured anisotropic rough surface is presented. The contact model is tested on three types of surface contact of a smooth ball on (i) a smooth surface, (ii) a sinusoidal surface, and (iii) a real rough surface. The validity of the model is proven by good agreement of the numerical result for the smooth surface with the Hertz analytical result. The contact of the sinusoidal surface shows that by the introduction of surface undulation in a regular pattern, the real pressure distribution follows the expected behavior where the contact pressure at the peak is maximum and the contact pressure at the valley is zero and the peak pressure decreases away from the ball center. The contact of the real rough surface shows the ability of the model to cope with the more practically realistic situation where the asperity heights are distributed randomly. The results of the rough surface contact analysis for different surface roughness are presented in a separate paper.

Rough Surface Contact of Curved Conformal Surfaces: An Application to Rotor–Stator Rub

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Philip Varney ◽  
Itzhak Green
Keyword(s):  
Rough Surface ◽  
Contact Force ◽  
Contact Stiffness ◽  
Point Contact ◽  
Contact Model ◽  
Industrial Society ◽  
Real Surface ◽  
Linear Elastic ◽  
Surface Contact ◽  
Rough Surface Contact

Rotating machines and associated triboelements are ubiquitous in industrial society, playing a central role in power generation, transportation, and manufacturing. Unfortunately, these systems are susceptible to undesirable contact (i.e., rub) between the rotor and stator, which is both costly and dangerous. These adverse effects can be alleviated by properly applying accurate real-time diagnostics. The first step toward accurate diagnostics is developing rotor–stator rub models which appropriately emulate reality. Previous rotor–stator rub models disavow the contact physics by reducing the problem to a single esoteric linear contact stiffness occurring only at the point of maximum rotor radial deflection. Further, the contact stiffness is typically chosen arbitrarily, and as such provides no additional insight into the contacting surfaces. Here, a novel rotor–stator rub model is developed by treating the strongly conformal curved surfaces according to their actual nature: a collection of stochastically distributed asperities. Such an approach is advantageous in that it relies on real surface measurements to quantify the contact force rather than a heuristic choice of linear contact stiffness. Specifically, the elastoplastic Jackson–Green (JG) rough surface contact model is used to obtain the quasistatic contact force versus rotor radial deflection; differences and similarities in contact force between the linear elastic contact model (LECM) and JG model are discussed. Furthermore, the linear elastic model's point contact assumption is assessed and found to be inaccurate for systems with small clearances. Finally, to aid in computational efficiency in future rotordynamic simulation, a simple exponential curve fit is proposed to approximate the JG force–displacement relationship.

A Rough Surface Contact Model for General Anisotropic Materials

2004 ◽  
Vol 126 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Yuan Lin ◽  
Timothy C. Ovaert
Keyword(s):  
Rough Surface ◽  
Half Space ◽  
Contact Pressure ◽  
Surface Displacement ◽  
Anisotropic Materials ◽  
Elastic Half Space ◽  
Iteration Scheme ◽  
Real Contact Area ◽  
Surface Contact ◽  
Rough Surface Contact

A method for solving the two-dimensional (2-D) isothermal rough surface contact problem of general anisotropic materials with friction is presented. By using Stroh’s formalism, the surface displacements of an elastic half-space due to uniform distributions of traction over a strip are derived from the surface Green’s function. The surface displacement and subsurface stresses of the anisotropic half-space due to the distributed contact pressure may then be calculated by superposition. The real contact area and the contact pressure are determined via an iteration scheme using the conjugate gradient method.

scholarly journals Elastic Rough Surface Contact and the Root Mean Square Slope of Measured Surfaces over Multiple Scales

2021 ◽  
Vol 5 (2) ◽  
pp. 44
Author(s):  
Robert Jackson ◽  
Yang Xu ◽  
Swarna Saha ◽  
Kyle Schulze
Keyword(s):  
Rough Surface ◽  
Root Mean Square ◽  
Contact Area ◽  
Multiple Scales ◽  
Real Contact Area ◽  
Mean Square ◽  
The Real ◽  
Real Contact ◽  
Surface Contact ◽  
Rough Surface Contact

This study investigates the predictions of the real contact area for perfectly elastic rough surfaces using a boundary element method (BEM). Sample surface measurements were used in the BEM to predict the real contact area as a function of load. The surfaces were normalized by the root-mean-square (RMS) slope to evaluate if contact area measurements would collapse onto one master curve. If so, this would confirm that the contact areas of manufactured, real measured surfaces are directly proportional to the root mean square slope and the applied load, which is predicted by fractal diffusion-based rough surface contact theory. The data predicts a complex response that deviates from this behavior. The variation in the RMS slope and the spectrum of the system related to the features in contact are further evaluated to illuminate why this property is seen in some types of surfaces and not others.

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