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Mild wear in gears is in most cases a smooth process giving initially improved contact conditions followed by a very slow and mild wear process. In some cases the mild wear may cause unfavorable changes of the surface topography, giving non-uniform gear rate, increasing dynamic effects and perhaps more severe forms of tooth failures. The knowledge about the interactions between mild wear, dynamic...
A multidisciplinary approach to wear simulation to investigate rolling-sliding abrasion is described. Wear is a stochastic process where fatigue combines with abrasion, adhesion and corrosion. Statistical methods were found to be highly suitable for conceiving and analysing laboratory simulation of the wear process. A special procedure of so-called two-level complex design of experiments is described...
A computational approach, the so-called Micro-Scale Dynamical Model (MSDM), was developed to simulate wear processes and to predict material performance during wear processes. In this model, a material system is discretized and represented using a discrete lattice. Each lattice site represents a small volume of the material. During a wear process, a lattice site can move under influences of external...
A computer model for simulation of the wear behaviour in helical gears has been developed. The method used can deal with tooth modifications and different profiles. The authors have studied the effects of wear previously but only in a two-dimensional perspective. The objective of the paper is to compare the wear behaviour of gears using different approaches. The gear teeth in this model are regarded...
Owing to the curved contact surfaces in a spherical roller thrust bearing, the rollers will undergo sliding. For an unskewed roller there will be two points along each contact where the sliding velocity is zero. At all other points along the contact, sliding is present. Under boundary lubricated conditions the sliding can give rise to mild wear. Experimental results show that this wear can cause a...
Wear of engineering components is often a critical factor influencing the product life. Prediction and simulation of wear is therefore an important matter in engineering. Numerical simulations of wear of a cylindrical steel roller oscillating against a steel plate are performed with a special version of the finite element program NIKE2D. The simulation was done in steps and the pressure and the sliding...
A simplified model for wear simulation of helical gears is developed. A helical wheel is treated in the model as several thin independent spur gear teeth with a common central axis and gradually turned relative each other a small angle corresponding to the helix angle. The load distribution along a tooth flank varies depending on the stiffness of a tooth. The tooth stiffness is determined with an...
There is currently much interest in the characterisation of wear debris from different types of artificial hip joints. There have been numerous studies on the wear of UHMWPE in hip joint simulators, but relatively few studies on the wear of alternative materials such as metal-on-metal (MOM) and ceramic-on-ceramic (COC). The aim of this study was to compare the wear volumes and wear debris generated...
The mathematical expression of surface geometry and topography is the first step towards modeling the performance of tribological elements with rough surfaces. The recent trend of tribological simulations, as well as failure prediction, demands the description of surface changes in a wear process. Reported in this paper is a method developed to simulate surfaces in a wear process through connecting...
A wheel profile wear prediction tool is developed and applied to a vehicle operating the commuter rail network in Stockholm. The methodology is based on a load collective concept where time-domain simulations are performed based on actual track data, measured rail profiles as well as pertinent operating conditions. The vehicle model is built in the GENSYS MBS software utilising validated suspension...
For a new type of rolling contact fatigue (RCF) (Belgrospi) an explanation has been found by an approach closely combining experimental and theoretical investigations. This new type of RCF has firstly been observed on high speed lines in wide curves. The speed on those locations exceeded 200km/h. Cracks occurred in nests periodically spread along the rail tread. These nests are grouped to the peaks...
Wheel/rail wear simulation based on mathematical models is one of the instruments of study and prognosis of wheel/rail life. Theoretical study of two mutually wearing bodies has shown that their steady-state worn profile depend on their initial profiles. This conclusion enables to suggest the possibility of control over wheel/rail stable-state worn profile, which should be optimal on the selected...
Gears in precision mechanisms, such as industrial robots, are often designed to have no backlash. Deviations from the ideal gear geometries and unfavourable deformations during operation may cause interference between interacting tooth flanks, resulting in high and strongly varying friction. Mild wear of the tooth flanks may improve such conditions. Therefore, this theoretical study has been conducted...
A finite element-based method is presented for simulating both the fretting wear and the evolution of fretting variables with number of wear cycles in a cylinder-on-flat fretting configuration for application to aeroengine transmission components. The method is based on a modified version of Archard's equation and is implemented within a commercial finite element code. Fretting tests are employed...
In this paper, the non-causal 2D AR model was proposed as a new method for generation of reference data of the 3D surface texture. Specification parameters to engender various topographical properties were the correlation distances in the x and y directions, the power index which determined the decaying pattern of the auto-correlation function, the root mean deviation, the skewness and the kurtosis...
In this paper, we propose to create a fractal function defined by an infinite series to model worn surfaces obtained by a grinding process. In this series, each elementary term characterizes a wear process at a given scale. This series is only defined by two parameters: an amplitude parameter and the fractal dimension. This model is tested on worn profiles obtained by using different grinding paper...
Glass-filled polymers are known to produce considerable wear on the screws and barrels of injection-moulding machines and several coatings and surface treatments have been used to combat this ranging from chromium plating to high velocity oxy fuel (HVOF) WC/Co. However, quantification of the benefits of such coatings and treatments has proceeded on an ad hoc basis and there is little data available...
The degradation of the femoral head roughness caused by scratching is known to increase the wear rate of the polyethylene counterface of the Charnley total hip prostheses and therefore to have an impact on osteolysis. The knowledge of the scratching mechanism is hence of paramount importance to improve the long-term clinical performance of these prostheses.The aim of this study is to identify the...
The shape of abrasive particles is an important attribute that can strongly influence wear rate in abrasion and erosion. Particles exhibit great diversity of size and shape due to the complex processes involved during their creation. Moreover, particles are highly anisotropic in that their abrasive potential is dependent on their orientation relative to the wearing surface. In this work, the possibility...
The tractive force transmitted through the contact of rail and wheel is often lower than the limiting friction force and such contacts are not fully slipping. The distribution of traction is no longer proportional to the distribution of normal pressure in the contact patch. The distribution of stress in the rail, and therefore also the shakedown limit and the ratchetting wear rate, is affected as...
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