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Many aspects of wear are still far from understanding. The paper proposes theoretical approach exploring the mechanisms of friction and wear on the basis of combining micro- and macro-modelling. In a macroscopic phenomenological model processes of wear are considered as stochastic processes in the surface layers of contacting bodies, including spalling of wear microparticles, local stochastic transport...
Most recent numerical works on fractal surfaces have simply compared the low load limit of the coefficient of proportionality κ of the relationship between real contact area and load. In particular, that provided by Persson's theory, and that obtained from the Bush, Gibson and Thomas (BGT-A) asperity contact theory, which is a generalized form of the Greenwood and Williamson (GW) one. The two theories...
This study investigates the room temperature sliding wear behaviors of Al 2 O 3f and SiC p reinforced aluminum matrix hybrid composites under both the dry and lubricant conditions. The effects of fiber orientation of Al 2 O 3f and hybrid ratio of Al 2 O 3f volume fraction to SiC p volume fraction on the wear behaviors are discussed in...
The mechanism of stick-slip associated with Schallamach waves was investigated using a sliding point contact between a glass hemisphere and a transparent soft-material plate that was driven via tangentially compliant support. The measurement of the tangential deflection and the observation of the contact zone were performed simultaneously. Schallamach waves synchronized with stick-slip were observed...
The tribological behaviour of thin films for tribological applications is commonly tested for failure using a variety of model tests and destructive characterisation methods. Typically, these tests are based on strongly simplified mechanical test conditions compared to the complex load situation occurring in most real applications. Thus, slip-rolling, fretting, and cyclic indentation behaviour may...
The relationship between initial coefficient of friction, μ i and surface energy (or attractive force) for ultra-high molecular weight polyethylene (UHMWPE) film is modeled and experimentally measured at low normal loads (15–75mN). The results show that the initial coefficient of friction increases exponentially with increasing attractive force between a silicon nitride ball and visco-elastic...
Wear processes occurring in synovial joints, mainly known as osteoarthritis (OA), affect many people worldwide. One of the symptoms of OA is wear of articular cartilage; it is thought that among other factors this may be due to failure of lubrication. Injections of biolubricants into human joints can be used in order to maintain the proper functioning of the joint. Phosphatidylcholines, being major...
The chemical reaction of tricresyl phosphate (TCP) during friction motion has been investigated by using our newly developed in situ observation system of the two-dimensional fast imaging FTIR-ATR spectrometer combined with the temperature-controlled friction equipment (Sasaki et al. (2008) [18]). The time-dependent 2D distribution of chemical reaction on the friction surface was obtained for the...
The paper presents a numerical model of the edge rounding of brittle materials during vibratory finishing. The material removal in this process is dominated by small-scale edge chipping where the abrasive particles protruding from the impacting media indent the surface asperities of the wear zone producing chips of the order of 10μm in length. The model predicts the evolution of the edge profile by...
This paper studied the anti-scuffing property of lubricating oil dispersed with diamond nano-particles as an oil additive. The lubricating oil which contains nano-diamond additive with various volumetric concentrations was used to evaluate the tribological performances and scuffing resistance demonstrated in the blocks-on-ring adapter operating at different speed and load conditions. The number of...
The authors previously found that the change in volume loss rate with the exposure time can be expressed by a logistic curve. In this study, the validity of this model is examined for various materials such as pure aluminum, carbon steels, stainless steels, cobalt alloys, and so on. The MDE (mean depth of erosion) d as a function of the exposure time can be expressed by three parameters α, β and c...
We briefly review the most important contact mechanic theories regarding the average separation between an elastic solid with a nominal flat surface and a hard solid with a randomly rough surface, as a function of the squeezing pressure. We present experimental results for a silicon rubber (PDMS) block, squeezed against two different road surfaces. Finally we compare the theoretical predictions of...
Tribologically loaded polymer parts such as gears, bearings and other machine elements are exposed to a load spectrum, which is composed, amongst others, of a relative movement, causing heat and wear, and a surface pressure in an application dependent environment. This is especially true for systems without external lubrication, where melting, material fatigue and wear are the lifetime-limiting factors...
This paper presents a PTFE/serpentine solid lubricant composite that exhibits low friction coefficient and low wear rate. It is postulated that synergistic effect alters the dominant wear mechanism of PTFE matrix. In order to examine the influence of serpentine content on tribological properties of PTFE/serpentine composite, six blends of PTFE with serpentine (in the range of 0–30wt.%) were evaluated...
A contact with a flat region and a rounded corner will have adhered and slipping regions and a locally non-singular contact traction distribution. When wear occurs in the slipping region, the geometry and thus the pressure distributions change. An analytical asymptotic analysis of the edge of this “almost complete” contact shows that wear will leave a complete contact with the same extent as the original...
The tribological properties of the nano-eutectic Fe 1.87 C 0.13 alloy are investigated under dry-sliding against AISI52100 steel ball in ambient environment with varying applied load and sliding speed. As comparison, the tribological properties of the same alloy after annealing treatment, which is with coarse-grained microstructure, also are examined at the same testing condition....
The abrasive wear behaviour of many materials is closely related to their hardness. However, classical wear models do not take into consideration the contact scale dependence of hardness, an effect commonly known as indentation size effect (ISE). In this work is carried out an evaluation of the abrasive wear behaviour of ductile metallic materials at the nanometric contact scale, by performing AFM-based...
A system consisting of a two-degree-of-freedom oscillator with sliding interfaces to two surfaces subjected to wear is investigated with respect to surface evolution and wear pattern dynamics. The system shows the usual possibility of wear pattern generation due to instabilities of the surface evolution equations. As a novel phenomenon in the context of wear pattern dynamics it is shown that, depending...
In this paper, 316L stainless steel micro-mixers were fabricated by micro powder injection molding. The tribological behavior of the stainless steel micro-mixer sliding against AISI 52100 steel at low loads was investigated using a ball-on-disk tribometer. The morphologies and compositions of the worn surfaces were analyzed by SEM, Raman and XPS. The results showed that the wear mechanism of stainless...
In the present work, the effects of fiber orientation on the tribological behavior of a short carbon fiber (SCF)/PTFE/graphite (10vol.% for each) filled PEEK composite was studied under different nominal pressures ranging from 1MPa to 5MPa. The fiber orientations were parallel, anti-parallel and normal relative to the sliding direction. The results indicate that the effect of fiber orientation shows...
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