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The determination of the sliding transition is of primary importance in describing the loading conditions in a contact. Various damages have been observed depending on the sliding regime. Assuming Mindlin hypotheses, an analysis for an elastic ball on flat contact submitted to a constant normal force and a varying tangential force is made. Both the energy and the sliding ratio are studied in order...
The development of wear maps has enhanced a new approach to the wear behaviour of materials as it is a precise description of the mechanical loading (local stress and strain fields).This paper studies crack nucleation using fatigue criteria in the case of an elastically loaded dry contact. Fretting behaviour is analysed for partial slip conditions which have been identified experimentally and theoretically...
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...
The effect of insulated rail joint (IRJ) on the wheel–rail normal and tangential contact stress distribution is studied using the finite element method. In this investigation, contact elements are used to simulate the interaction between wheel and rail. Numerical simulations are used to explore the effects of contact distances and materials of IRJ on the contact stress and the maximum shear stress...
In partial slip fretting contact, the coefficient of friction (CoF) is often assumed to be constant along the contact surface. The literature shows that the CoF is related to the relative slip, which varies in the slip region of a partial slip contact. This study develops a methodology to consider the effects of non-uniform CoF distribution in the slip region. Two cases were investigated. In the first...
This paper presents a numerical model that maps the evolution of fretting fatigue life of Hertzian rough contacting bodies in fretting wear. Effect of surface roughness parameters (i.e. root mean square, skewness and orientation) on fretting fatigue life is reported. Fretting fatigue life is calculated as the crack initiation period predicted by the Smith Watson Topper multiaxial fatigue theory. Fretting...
This paper addresses the influence of the partial slip phenomenon on the dynamic motion of a spherical workpiece held in a fixture with application to machining fixture design. The model considers the effect of interfacial slip damping arising from partial slip at a spherical–planar frictional contact subjected to a constant normal load and oscillating tangential load. The model can be used in both...
The aim of this study is to characterize the baseline fretting behavior of Ti–6Al–4V on Ti–6Al–4V in point contact at relatively high pressure. The effect of the displacement amplitude on fretting damage is investigated. Two normal forces of 586 and 1485N corresponding to 1.4 and 3.5, respectively, of the force for subsurface yield based on von Mises criterion are considered. Experiments are conducted...
Tangential traction caused by friction in contacting surfaces is a major factor in fretting fatigue that increases stress levels and leads to a reduction in fatigue life. Friction in fretting contact was studied in partial, mixed and gross slip conditions on quenched and tempered steel. Measurements were made with sphere-on-plane contact geometry for polished and ground surfaces. Friction was evaluated...
A novel method for measuring the interfacial coefficient of friction between two solids which avoids sliding is described, and sample results are given. The technique makes use of the fact that a carefully controlled sequence of partial slip states between contacting bodies may be used to produce relative motion whose extent is a strong function of the coefficient of friction. It is argued that this...
Bronze–steel contacts are common in machinery where the loading might give rise to fretting conditions. The flat surfaces of the quenched and tempered steel (QT) specimens were fretted with aluminum bronze spheres in partial slip and gross sliding conditions. The dry friction coefficient was around unity in gross sliding. Material transfer occurred from bronze pad to the QT-specimen and cracks initiated...
The material response of a railway wheel subjected to thermomechanical rolling contact is evaluated. Thermal and mechanical loads are combined in a three-dimensional sequentially coupled analysis where nodal temperatures from a transient thermal analysis are applied as predefined fields in a structural analysis featuring an elastic–plastic material model. The mechanical contact load is prescribed...
Traditional analyses of slip at corners of contacts, based on linear elasticity and a Coulomb friction law, are very sensitive to the details of local geometries, owing to the effects of elastic singularities. Following the use of cohesive-zone models to address such issues in mode-II fracture, we present analyses of slip and wear at corners of contacts when a finite interfacial shear strength is...
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