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Abstract
Wear modeling is essential to predict and improve wear resistance of machine parts. This article presents a fatigue wear model of plane sliding pairs under dry friction. The wear model is constructed through developing a dynamic contact model of surfaces and proposing a mean fatigue damage constant of asperities. It is simpler and more practical than existing fatigue wear models because it describes the quantitative relationship between the wear behaviors of the plane sliding pairs and the main factors including the load and sliding speed, material property, friction property, and surface topography of the pairs. Furthermore, the wear model can predict the wear of each component of the sliding pairs. Reasonability and applicability of the wear model are validated via pin-on-disc wear tests. The wear model is applicable to predict the wear of the plane sliding pairs, which is characterized by friction fatigue of contact surfaces. The wear model can also be used to guide the tribological design of sliding pairs in machinery.
Nomenclature
| A | = | Real contact area of two rough surfaces |
| A0 | = | Geometry normal contact area of two asperities |
| A1 | = | Real normal contact area of two asperities |
| D | = | Surface density of asperities |
| E | = | Elasticity modulus |
| E′ | = | Composite elasticity modulus of material of the two contact surfaces |
| F | = | Friction force |
| f | = | Friction coefficient |
| h | = | Distance between the two reference planes in the contact rough surfaces |
| k | = | Friction fatigue exponent |
| l | = | One cycle length for sliding contacts (length of sliding surface) |
| m | = | Number of contact asperities on contact surface (number of contact spots) |
| n | = | Number of asperities on rough surface; Number of contact interactions that cause fatigue fracture of an asperity |
| N1 | = | Number of contact interactions between asperities in one sliding cycle |
| Nc | = | Number of sliding cycles |
| R | = | Mean radius of asperities |
| R′ | = | Composite mean radius of asperities of the two contact surfaces |
| S | = | Nominal contact area of sliding pairs |
| Sa | = | Arithmetical mean height of asperities |
| Sq | = | Root mean square height of asperities |
| t | = | Sliding time |
| V1 | = | Material removal volume of contact surface in one sliding cycle |
| V | = | Macroscopic wear volume |
| ΔV | = | Volume of fatigue fracture of an asperity |
| Vc | = | Theoretical wear loss |
| Ve | = | Experimental wear loss |
| w | = | Width of sliding surface |
| z | = | Height of asperities |
| δ | = | Normal deformation of asperity |
| ϵ | = | Mean volume of material removal of an asperity in one contact interaction |
| ν | = | Poisson ratio |
| σ | = | Standard deviation of asperity height distribution |
| σ′ | = | Composite standard deviation of asperity height distribution of the two contact surfaces |
| σb | = | Tensile strength |
| τ | = | Mean shear stress (unit friction force) |
| υ | = | Sliding speed |
| ψ (z) | = | Distribution function of asperity height |