Modeling Sliding Wear: From Dry to Wet Environments - Gaseous Environment
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Model Parameters
Name Description Parameter Type Value Units View Sub-Model
V(t)Wear volume of the speciment at sliding time tVariablemillimeter cube 
tsliding timeConstant (Dimensions Req.)minutes 
Ce(t)Equivalent protective coverage of the wear surfaceSubModel/EquationView
N(t)Quantity of wear debris particles generated per unit time on a unit area of the wear surfaceVariableNot Specified 
Aa(t)Fraction of the total apparent area of contactVariableNot Specified 
DWear debris particle sizeSubModel/EquationView
f(D)Function for the size of the newly generated wear debris particlesVariableNot Specified 
Pr(D)Probability of a wear debris particle being removed from the wear trackVariableNot Specified 

Failure Mechanism
Name
Wear

Component / Technology Types

Characteristics
Title Description
Fatigue Approach to WearModel considers low cycle fatigue to be the mechanism responsible for the generation of wear debris.
Retained Wear DebrisThis model considers the effects of wear debris particles that are retained between the contacting surfaces. This includes both the generation of additional wear debris as well as the cold-welding of hardened, wear-protective layers on the sliding surface.
Oxygen and Other Reactive SpeciesThis model considers the effects of oxygen partial pressure and other reactive species in the determination of wear debris particle size (D) and surface energy (gamma) of the contacting surfaces).
Surface EnergyThe surface energy is related to the partial pressure of the reactive species by the Gibbs' adsorption isotherm and the classical Langmuir gas adsorption isotherm.
Max Vertical StrainThe maximum vertical strain in the wear surface due to the frictional action (Emax) is approximately equal to the strain limit of the material at the formation of the wear debris.
Wear-Protective LayerThe model accounts for compact layers as well as glaze layers on the wear surface generated from debris particles, the latter being the most effective.
Vret(t) ParameterThe volume of wear debris retained between the sliding surfaces [Vret(t)] is a sub-model of this model. However, as it's value is required to solve one of it's own sub-models, it's described as a Constant(Testing Req'd) for that sub-model.

Assumptions
Title Description
Wear Rate of Protective LayersThe wear rate of the protective layers formed by debris particles on the sliding surface is assumed to be negligible compared to other areas uncovered by such wear-protective layers.
Retained ParticlesIt's assumed that all retained particles are compacted eventually to form wear-protective layers of an average thickness ranging from 2-15 micrometers. This assumption is to establish the equation to determine the coverage of the wear surface by compact layers (Cc).

Limitations
Title Description
N/AN/A

Constraints
Title Description
N/AN/A

Uncertainty Limits
Type Uncertainty
N/AN/A

Data or Information Needed from Outside Sources
Category Source Description
Material PropertiesUserPartial pressure of the reactive species (pA)
Scaling FactorUserConstant in the Langmuir isotherm representing the ratio between the rate constants for adsorption and desorption of a gas on a solid (b), testing required
Material PropertiesUserNumber of bonds per unit area along the crack-plane (NA)
Material PropertiesUserSurface energy of a solid in a vacuum (γ0)
Material PropertiesUserMaximum vertical strain in the wear surface due to frictional action (εmax)
Material PropertiesManufacturerElastic modulus (E)
Mechanical PropertiesManufacturerPoisson's Ratio (ν)
Material PropertiesUserCritical glaze oxide thickness for effective wear protection (δc)
Physical Dimension(s)UserAn area of the compact layer that develops into a glaze layers after a period of tcg [dAc(τ)]
Physical Dimension(s)UserFraction of the total apparent area of contact [Aa(t)]
Physical Dimension(s)UserAverage thickness of wear protective layers (δ)
Physical Dimension(s)UserQuantity of wear debris particles generated per unit time on a unit area of the wear surface [N(t)]
Physical Dimension(s)UserFunction for the size of the newly generated wear debris particles [f(t)]
Material PropertiesUserProbability of a wear debris particle being removed from the wear track [Pr(t)]

Bibliographic Citation
Published Status Source Type Title Authors
PublishedArticle/PaperModelling Sliding Wear: From Dry to Wet EnvironmentsJiaren Jang,
M. M Stack
Abstract/Summary
Corrosive species in various forms exist widely in the environment and can significantly affect wear behaviour of materials, usually accelerating wear. Under conditions where the environments are seemingly non-deleterious in terms of corrosivity, some species from the environment can still affect the tribological behaviour of materials. It is thus extremely important to recognise the roles of reactive species in affecting the tribological processes and to understand the processes of tribo-corrosion interactions. In this paper, the mechanisms of wear debris generation and the roles of reactive species in the generation of wear debris during sliding wear in gaseous or aqueous environments are discussed. The effect of environment on the development of wear-protective layers is described. Based on the proposed mechanisms, mathematical models for sliding wear in both dry and aqueous environments are outlined, and the validity of the models is assessed against experimental data in sliding conditions.
Report # Publication Name Volume # Publisher Name
N/AWear2612006N/A
Publication Date Pages Source URL Copyright Info
2006-05-02954-965http://www.sciencedirect.com2006 Elsevier B.V. All rights reserved

Technical Point of Contact (PoC)
Jiaren Jiang
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WARP-ADMIN
Apr 30 at 11:52 pm
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