A New Contact Model of Rough Surface Based on Analytical Method

2018 ◽  
Author(s):  
Yunyun Sun ◽  
Huifang Xiao ◽  
Jinwu Xu
Keyword(s):  
Elastoplastic Deformation ◽  
Polynomial Function ◽  
Contact Stiffness ◽  
Contact Model ◽  
Normal Contact ◽  
Single Asperity ◽  
Proposed Model ◽  
Deformation Regime ◽  
Elliptical Function ◽  
Good Agreement

In this paper, an analytical contact model is proposed to study the contact behavior between two rough surfaces. Elliptical function is employed to describe contact stiffness of a single asperity, and the contact area is characterized by polynomial function in elastoplastic deformation regime. Results show that the proposed model ensures the continuity and smoothness of contact variables across different deformation regimes for a single asperity. The accuracy of the contact model has been demonstrated by the good agreement between the proposed model and the existing statistical model. Influences of material properties on normal contact force and interfacial stiffness have been further studied using the established model.

Elastic Contact Model Accounting for Both Asperity and Substrate Compliance With Application to Patterned Media

2007 ◽  
Author(s):  
Chang-Dong Yeo ◽  
Andreas A. Polycarpou
Keyword(s):  
Bulk Material ◽  
Contact Stiffness ◽  
Contact Model ◽  
Elastic Contact ◽  
Element Analysis ◽  
Patterned Media ◽  
Single Asperity ◽  
Proposed Model ◽  
Stiffness Model ◽  
Bulk Substrate

An improved elastic contact stiffness model for a single asperity system is proposed to account for the effects of both bulk substrate and asperity deformations between two contacting surfaces. Depending upon the applied load, as well as the geometrical and physical properties of the asperity and bulk material, the bulk substrate can have a considerable contribution to the overall contact stiffness. Finite element analysis is performed to verify the proposed analytical model. The single asperity model is extended to rough surfaces in contact. The contact stiffness values from the proposed model are compared to those from the GW model. The proposed contact model can be directly relevant to analyze the contact behavior of modern patterned media.

A Contact Model for Nonlinear Forced Response Prediction of Turbine Blades: Calculation Techniques and Experimental Comparison

2008 ◽  
Author(s):  
Christian M. Firrone ◽  
Marco Allara ◽  
Muzio M. Gola
Keyword(s):  
Normal Load ◽  
Contact Stiffness ◽  
Turbine Blades ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Contact Forces ◽  
Contact Model ◽  
Experimental Comparison ◽  
Normal Contact ◽  
Contact Models

Dry friction damping produced by sliding surfaces is commonly used to reduce vibration amplitude of blade arrays in turbo-machinery. The dynamic behavior of turbine components is significantly affected by the forces acting at their contact interfaces. In order to perform accurate dynamic analysis of these components, contact models must be included in the numerical solvers. This paper presents a novel approach to compute the contact stiffness of cylindrical contacts, analytical and based on the continuous contact mechanics. This is done in order to overcome the known difficulties in simultaneously adjusting the values of both tangential and normal contact stiffness experimentally. Monotonic loading curves and hysteresis cycles of contact forces vs. relative displacement are evaluated as a function of the main contact parameters (i.e. the contact geometry, the material properties and the contact normal load). The new contact model is compared with other contact models already presented in literature in order to show advantages and limitations. The contact model is integrated in a numerical solver, based on the Harmonic Balance Method (HBM), for the calculation of the forced response of turbine components with friction contacts, in particular underplatform dampers. Results from the nonlinear numerical simulations are compared with those from validation experiments.

Study on the Normal Contact Stiffness of Rough Surface in Mixed Lubrication

2018 ◽  
Author(s):  
Huifang Xiao ◽  
Yunyun Sun ◽  
Xiaojun Zhou ◽  
Zaigang Chen
Keyword(s):  
Rough Surface ◽  
Contact Stiffness ◽  
Equivalent Model ◽  
Lubricant Layer ◽  
Asperity Contact ◽  
Normal Contact ◽  
Liquid Lubricant ◽  
Single Asperity ◽  
Rough Surface Contact ◽  
Film Stiffness

In this paper, a general contact stiffness model is proposed to study the mixed lubricated contact between a rough surface and a rigid flat plate, which is the equivalent model for the contact between two rough surfaces and is the general case for engineering contact interfaces. The total interfacial contact stiffness is composed of the dry rough surface contact stiffness and the liquid lubricant contact stiffness. The GW model is used for surface topography description and the contact stiffness of a single asperity is derived from the Hertz contact theory. The whole dry rough contact stiffness is obtained by multiple the single asperity contact stiffness with the number of contact asperities, which is derived based on the statistical model. The liquid film stiffness is derived based on a spring model. The stiffness contributions from the asperity contact part and lubricant layer part are separated and analyzed.

Characteristics extraction and numerical analysis of the rough surface macro-morphology

2019 ◽  
Vol 36 (3) ◽  
pp. 765-780
Author(s):  
Qingchao Sun ◽  
Xiaokai Mu ◽  
Bo Yuan ◽  
Jiawen Xu ◽  
Wei Sun
Keyword(s):  
Surface Morphology ◽  
Contact Pressure ◽  
Contact Area ◽  
Contact Stiffness ◽  
Contact Model ◽  
Normal Contact ◽  
Content Type ◽  
Macro Scale ◽  
Machined Parts ◽  
Morphology Characteristics

PurposeThis paper aims to distinguish the relationship between the morphology characteristics of different scales and the contact performance of the mating surfaces. Also, an integrated method of the spectrum analysis and the wavelet transform is used to separate the morphology characteristics of the actual machined parts.Design/methodology/approachFirst, a three-dimensional (3D) surface profilometer is used to obtain the surface morphology data of the actual machined parts. Second, the morphology characteristics of different scales are realized by the wavelet analysis and the power spectral density. Third, the reverse modeling engineering is used to construct the 3D contact models for the macroscopic characteristics. Finally, the finite element method is used to analyze the contact stiffness and the contact area of the 3D contact model.FindingsThe contact area and the nominal contact pressure Pn have a nonlinear relationship in the whole compression process for the 3D contact model. The percentage of the total contact area of the macro-scale mating surface is about 70 per cent when the contact pressure Pn is in the range of 0-100 MPa, and the elastic contact area accounts for the vast majority. Meanwhile, when the contact pressure Pn is less than 10MPa, the influence factor (the relative error of contact stiffness) is larger than 50 per cent, so the surface macro-scale morphology has a weakening effect on the normal contact stiffness of the mating surfaces.Originality/valueThis paper provides an effective method for the multi-scale separation of the surface morphology and then lays a certain theoretical foundation for improving the surface quality of parts and the morphology design.

scholarly journals Influences of Morphology Parameters on the Contact Behavior of a Steel Interface

2020 ◽  
Vol 12 (01) ◽  
pp. 2050009
Author(s):  
L. F. Fan ◽  
L. Zhao ◽  
X. M. Liu
Keyword(s):  
Contact Stiffness ◽  
Normal Pressure ◽  
Mean Value ◽  
Mechanical Equipment ◽  
Normal Contact ◽  
Contact Behavior ◽  
Proposed Model ◽  
Normal Contact Stiffness ◽  
Rigid Smooth ◽  
Morphology Parameters

The surface roughness induced by geometric irregularities (asperities) has substantial influence on the contact stiffness, which further affects the working performance and service life of mechanical equipment. In this study, an elastic–plastic contact law between a sinusoidal asperity and a rigid smooth flat is first studied, which is then applied on a statistical model to simulate the contact behavior of a pair of 18CrMo4 steel surfaces to investigate the influences of morphology parameters on the contact stiffness. The analysis shows that smaller shape ratios [Formula: see text] and larger wavelengths [Formula: see text] induce larger normal contact stiffness [Formula: see text] for surfaces with identical roughness, wherein the roughness is defined by the mean value of asperity heights [Formula: see text] and the standard deviation of asperity heights [Formula: see text]. The normal contact stiffness increases as [Formula: see text] decreases under the same loading conditions, while the normal contact stiffness increases as [Formula: see text] decreases for surfaces with a fixed [Formula: see text]. Besides, the normal pressure and normal contact stiffness derived from the proposed contact model are validated. The results demonstrate the potential of the proposed model in contact design due to its ability of establishing the relations between the normal contact stiffness and surface morphology parameters.

A MODIFIED COMPLETE NORMAL CONTACT STIFFNESS MODEL OF A FRACTAL SURFACE CONSIDERING CONTACT FRICTION

Fractals ◽  
2020 ◽  
Vol 28 (05) ◽  
pp. 2050081
Author(s):  
CHUNLING WEI ◽  
HUA ZHU ◽  
SHIHUI LANG
Keyword(s):  
Contact Stiffness ◽  
Fractal Dimensions ◽  
Frictional Resistance ◽  
Contact Model ◽  
Contact Friction ◽  
Fractal Surface ◽  
Normal Contact ◽  
Stiffness Model ◽  
Fractal Roughness ◽  
Normal Contact Stiffness

This paper presents a modified complete normal contact stiffness model of a fractal surface considering contact friction. We use this model to study the influence of fractal dimensions and fractal roughness on normal contact stiffness. The fractal micro-contact model of an asperity and the complete length scale contact model of fractal surface (both contrasting classical mechanics) are revised. The influence of frictional resistance at micro-contact interfaces on normal contact stiffness is also considered. Predictions of the new model are found to be in greater agreement with the results of the experiments than the predictions of the original model. The study analyzes the influence of fractal dimensions and fractal roughness on the normal contact stiffness. With the increase of these two fractal parameters, their influences on the normal contact stiffness are opposite and are different under high pressure and low pressure.

Dynamic analysis of vibration-driven systems moving based on frictional locomotion principles

2011 ◽  
Vol 226 (7) ◽  
pp. 1787-1799 ◽  
Author(s):  
A Kamali Eigoli ◽  
GR Vossoughi
Keyword(s):  
Dynamic Analysis ◽  
Longitudinal Vibration ◽  
Equations Of Motion ◽  
Linear Equations ◽  
Normal Contact ◽  
Driven Systems ◽  
Proposed Model ◽  
Linear Equations Of Motion ◽  
And Control ◽  
Good Agreement

In this article, we investigate the dynamic analysis of vibration-driven systems moving based on frictional locomotion principles. Symmetrically actuating particles with longitudinal harmonic forces or with longitudinal vibration of the base does not lead to the net motion, unless the generated slip varies during back and forth motion. Harmonically varying the normal contact force and employing asymmetric friction coefficients are two approaches for obtaining frictional locomotion principles. In order to study the simultaneous effect of these required conditions of generating net displacement, a mathematical model is developed, and the resulting non-linear equations of motion are analytically solved. We have shown that the proposed model can be simply generalized to many other frictional, vibration-induced principles, such as the friction drive and the directional friction concepts. The obtained results are in good agreement with those achieved from numerical integration and experiments, reported in the literature. The presented theoretical findings can be effectively used for the design and control of this type of oscillators.

An Improved Elastic Contact Model Accounting for Asperity Interaction and Bulk Substrate Deformation

2009 ◽  
Author(s):  
Jungkyu Lee ◽  
Chang-Dong Yeo ◽  
Andreas A. Polycarpou
Keyword(s):  
Rough Surface ◽  
Contact Stiffness ◽  
Elastic Half Space ◽  
Contact Model ◽  
Asperity Contact ◽  
Single Asperity ◽  
Surface Contact ◽  
In Series ◽  
Bulk Substrate ◽  
Rough Surface Contact

An improved rough surface contact model is proposed accounting for bulk substrate deformation and asperity interaction. The asperity contact stiffness is based on Hertzian solution for spherical contact, and the bulk substrate stiffness on the solution of Hertzian pressure on a circular region of the elastic half-space. The contact behavior of a single asperity composed of hemi-spherical asperity deformation as well as bulk substrate deformation is calculated by introducing the concept of spring-in-series. Based on the single asperity model, the contact stiffness for the rough surface is calculated including the effect of asperity interaction. Analytical simulation results using the proposed rough surface contact model were compared with the CEB model and experimental measurements.

Normal fractal contact stiffness model among three disks of rod-fastening rotor system with considering friction and the asperities interaction

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nanshan Wang ◽  
Heng Liu ◽  
Yi Liu
Keyword(s):  
Friction Coefficient ◽  
Contact Stiffness ◽  
Fractal Theory ◽  
Rotor System ◽  
Normal Contact ◽  
Content Type ◽  
Elastoplastic Contact ◽  
Proposed Model ◽  
Normal Contact Stiffness ◽  
Rod Fastening Rotor

Purpose The purpose of this study is to develop a normal contact stiffness (NCS) model among three disks of the assembled rotor system, which systematically considers the friction coefficient, the asperities interaction and the elastoplastic contact regime. Design/methodology/approach Based on the revised fractal theory, considering the friction effect, the elastoplastic contact regime and the asperities interaction in a simple way, the total NCS among three disks of the rod-fastening rotor bearing system is established. Effects of fractal dimension and roughness, friction coefficient, asperities interaction and material properties on the normal stiffness are investigated by simulations and the relevant comparisons are given for examining the reasonability of the proposed model. Findings NCS will decrease when asperities interaction and friction are included. As the load increases, the influences of asperities interaction and friction on stiffness become serious. NCS will be enhanced when the elastoplastic regime is considered. Originality/value A comprehensive NCS model is developed. It provides a theoretical basis for the modeling of the NCS for multi-interfaces.

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