Wear damage mechanisms

Wear is the surface damage or removal of material from one or both of two solid surfaces in a sliding, rolling, or impact motion relative to one another. 

Wear damage precedes actual loss of material and may also occur independently. Wear as in the context of friction is not an inherent material property. It depends on the operating conditions and surface conditions. Wear rate does not relate to friction. Wear occurs by mechanical and/or chemical means and is generally accelerated by frictional heating. 

The principal wear mechanisms are (i) adhesive (ii) abrasive (iii) fatigue (iv) impact by erosion and percussion (v) chemical and (vi) electrical arc-induced. 

There are other mechanisms such as fretting, fretting corrosion, and fretting CF, which is a combination of adhesive, corrosive, and abrasive forms of wear. Wear by all mechanisms except fatigue mechanism, occurs by gradual removal of material. One or more of these mechanisms may be operating in a particular machine. In many cases, wear may be initiated by one mechanism but may proceed by other mechanisms and thereby complicate failure analysis (60). 

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Use of synthetic ropes on a Koepe hoist should be more predictable compared with drum hoists, as the external rope-to-rope contact and resulting wear/damage mechanisms do not... 

By examining the dispersion properties of surface acoustic waves, the layer thickness and mechanical properties of layered solids can be obtained using the SAM. It can be used to analyze the wear damage progress [104], and detect the defects of thermally sprayed coatings [105]. 

The most important step in failure analysis is to identify the damage mechanism involved in the failure. In the broad sense damage mechanisms are classified as distortion, fracture, corrosion and wear. That this classification is simplistic is... 

An alternate method of classification of damage mechanisms in terms of environmental conditions such as stress, temperature, corrosion, wear, radiation is known as the failure wheel. In this representation secondary mechanisms are underlined as opposed to primary damage mechanisms. The boiler tube failure discussed can be represented in terms of failure wheel, as shown in Figure 2.31. The aim in any case is to identify definitively the underlying mechanism of failure to enable one to undertake remedial action such that future failures do not occur. 

If one considers that wear damage also results in energy dissipation, this approach can tentatively be applied to wear. Accordingly, wear processes can be classified as cohesive or interfacial depending on the length scales associated with particles detachment mechanisms (Fig. 1). 

Mining Corrosion in this sector is not as significant a problem as in other sectors. The primary life-limiting factors for mining equipment are wear and mechanical damage. Maintenance painting, however, is heavily relied on to prevent corrosion, with an estimated annual expenditure of 0.1 billion. 

Ceramics can often be damaged under low contact loads and, thus, it is important to understand these damage mechanisms. These processes not only give rise to strength degradation but are linked to wear and erosion. Indentation fracture mechanics has been found to be a very useful approach in understanding these contact-damage processes (see Section 8.8). 

In addition to the four main types of wear, related mechanisms can occur in certain design applications. Erosion by a stream of sharp particles is analogous to abrasive wear. Cavitation involves damage to a surface caused by the collapse of a bubble in an adjacent liquid. The surface damage results from the mechanical shock associated with the bubble s sudden collapse. 

According to the definition, corrosion is not a part of wear, since it is not caused by mechanical action, but by chemical reactions, and can therefore also occur in completely stationary systems. Since corrosion increases wear or even makes it possible. It Is considered as the fifth wear mechanism [3]. The main types of corrosion are summarized in Figure 5.28. Corrosion is largely the dominant damage mechanism in molds and is therefore discussed in fuller detail below. 

Disks, plates, basins according to fracture, wear and damage mechanics,... 

McKellop HA. Wear modes, mechanisms, damage, and debris. Separating cause from effect in the wear of total hip replacements. In Galante JO, Rosenberg AG, Callaghan JJ, editors Total hip revision surgery. New York Rave Press, Ltd. 1995. 

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