According to relative motion directions for a ball-on-flat contact, there are four fundamental fretting wear modes,
e.g., tangential, radial, torsional and rotational modes. In this paper, the ...mechanisms of these four fundamental fretting wear modes, particularly for the later three modes, have been reviewed from results obtained by the authors in combination with results from literature. Some general features have been reported. Differences both in running and degradation behavior have been discussed in detail. Results showed that some similar laws for three fretting regimes (partial slip regime, mixed regime and slip regime), fretting maps (running condition fretting map and material response fretting map), wear and cracking mechanisms obtained from the classic mode (
i.e. tangential fretting) were also identified and useful to characterize the other modes. Nevertheless, the occurrence of relative slip for the radial fretting, the formation of mixed regime for the torsional fretting, the evolution of surface morphology for the rotational fretting were quite different compared to that of the classical fretting mode.
► Review the running behavior and wear mechanism of tangential/classical fretting wear. ► Outline the common characters for tangential, radial, torsional and rotational fretting. ► Outline the particularities for varied fretting modes.
– This article presents the design, production and testing of an experimental device that seeks to evaluate fretting fatigue of wires taken from conductors used in energy transmission lines. The ...fretting device has three independent actuators that allow tests to be carried out under controlled load (or displacement). Thus, the effect of relevant parameters to the fretting fatigue process (such as normal, tangential and bulk forces, wear level, and wear surface morphology) can be studied. To evaluate the device performance, tests were carried out on 6201 aluminum alloy wires, considering two different contact normal forces, P. Results showed that, for lives greater than 106 cycles, the increase of P from 250 to 500 N produced a substantial reduction on fatigue strength when compared to tests of smooth wire specimens. The SEM images and EDS analyses after the fretting fatigue test demonstrate that the wire-wire marks generated by the device show all the characteristics found in wires of internal layers of overhead conductors fractured by fatigue under fretting conditions.
•The device is able to reproduce a fretting fatigue test in wires of energy conductor cables.•The between device was designed to enable fretting tests at several possible angles formed by the wires.•Small variations in force in the tested wires perceived by the load cell are sent to controllers that readjust the loads.•The EDS images and analyses at the wire-wire marks generated by the device show fretting characteristics.•The device developed is able to precisely control and/or record the normal and bulk fatigue loads/displacements.
The effect of displacement amplitude on fretting wear behavior and damage mechanisms of alloy 690 in air and nitrogen atmospheres was investigated in detail. The results showed that in air, the ...friction coefficient gradually increased with the increase in displacement amplitude which conformed to the universal law. In nitrogen, however, it had the highest point at the displacement amplitude of 60 μm due to very strong adhesion. Whether in air or nitrogen, the wear volume gradually increased with the increase in displacement amplitude. The wear volume in air was larger than that in nitrogen except at 30 μm. At 30 μm, the wear volume in air was slightly smaller. With an increase in displacement amplitude, a transformation of fretting running status between partial slip, mixed stick-slip, and final gross slip occurred along with the change of Ft-D curves from linear, to elliptic, to, finally, parallelogrammical. Correspondingly, the fretting regime changed from a partial slip regime to a mixed regime to a gross slip regime. With the increase in displacement amplitude, the transition from partial slip to gross slip in nitrogen was delayed as compared with in air due to the strong adhesion actuated by low oxygen content in a reducing environment. Whether in air or nitrogen, the competitive relation between fretting-induced fatigue and fretting-induced wear was prominent. The cracking velocity was more rapid than the wear. Fretting-induced fatigue dominated at 30 μm in air but at 30–60 μm in nitrogen. Fretting-induced wear won the competition at 45–90 μm in air but at 75–90 μm in nitrogen.
A dual motion combined by radial and tangential fretting was achieved on a modified hydraulic fretting wear test rig. The dual motion fretting tests of medical pure titanium (TA2) and Ti6Al7Nb alloy ...in artificial saliva were carried out under varied contact inclined angles (45° and 60°), and the maximum imposed load varied from 200 to 400 N at a constant loading speed of 6 mm/min. The effects of the cyclic vertical force and the inclined angle were investigated in detail. Dynamic analysis in combination with microscopic examinations shows that the wear scar and plastic deformation accumulation present a strong asymmetry. The Ti6Al7Nb has better wear resistance than TA2 in artificial saliva at the same test parameters, and with the increase of inclined angle and decrease of imposed load, the wear reduces accordingly. The wear mechanisms of pure titanium TA2 and Ti6Al7Nb alloy under the condition of dual motion fretting in artificial saliva are abrasive wear, oxidative wear and delamination.
This paper proposes a new methodology for fretting fatigue life assessment. It uses a combination of multiaxial fatigue criteria, the theory of critical distances and a node-displacement wear ...algorithm to account for the initiation life under fretting. Further, the extended finite element method is considered to compute the propagation life. A new method is also introduced to predict the crack propagation path under nonproportional loading conditions. To validate the analysis, available fretting fatigue data using an Al 2024-T3 alloy was considered. All the total lives estimated by the proposed approach fell within a scatter band 2, with an error between 11% and −39%. An analysis of the energy dissipated on the contact surface was performed and showed that for certain cases the inclusion of wear in the modeling of the problem is indeed essential to obtain more accurate fretting fatigue life assessments.
•Fretting fatigue in partial slip regime life assessment is carried out for Al2024-T3.•The numerical method proposed including wear effects and crack propagation life.•A new method based on the critical plane to predict the crack propagation angle.•The methodology proposed obtained more accurate predictions than simple methods.•The maximum energy dissipated has shown to be a parameter capable to identify when is necessary to compute wear or not.
Fretting maps of Zr alloy tube under grid-to-rod configuration in high temperature pressurised water were established. Running condition fretting map shows three fretting regimes, namely, partial ...slip regime, mixed fretting regime and gross slip regime. According to material response fretting map, the wear mechanism under partial slip regime is adhesive wear with the character of delamination of local regions, both adhesive wear and cracking are found for mixed fretting regime, while abrasive wear and severe delamination for gross slip regime. Compared with the results at room temperature, the mixed fretting regime range increases obviously at high temperature, while friction coefficient at high temperature is lower. In addition, fretting wear behaviour of Zr alloy tube under different fretting regimes is discussed.
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•RCFM and MRFM of Zr alloy cladding tube in HTP water was established.•Compared with RT condition, the range of MFR increases obviously in HTP water.•The main wear mechanism under PSR and MFR is adhesive wear.•The main wear mechanisms under GSR are abrasive wear and delamination.
In recent years, much progress has been made on the development of aerospace materials for structural and engine applications. Alloys, such as Al-based alloys, Mg-based alloys, Ti-based alloys, and ...Ni-based alloys, are developed for aerospace industry with outstanding advantages. Composite materials, the innovative materials, are taking more and more important roles in aircrafts. However, recent aerospace materials still face some major challenges, such as insufficient mechanical properties, fretting wear, stress corrosion cracking, and corrosion. Consequently, extensive studies have been conducted to develop the next generation aerospace materials with superior mechanical performance and corrosion resistance to achieve improvements in both performance and life cycle cost. This review focuses on the following topics: (1) materials requirements in design of aircraft structures and engines, (2) recent advances in the development of aerospace materials, (3) challenges faced by recent aerospace materials, and (4) future trends in aerospace materials.
The error incurred in the representation of the contact pressure at the edges of incomplete contacts by first order asymptotes is treated, and the maximum value of the relative error found for a ...range of geometries, both symmetric and non-symmetric. For a symmetric power-law geometry, we identify when the first-order asymptote achieves maximum fidelity. Shear tractions are excited by both the application of a shear force and the application of bulk tension in one body. An asymptotic representation of the shear traction distribution under conditions of full stick is presented.
This paper presents a combined experimental and computational methodology for fretting wear-fatigue prediction of pressure armour wire in flexible marine risers. Fretting wear, friction and fatigue ...parameters of pressure armour material have been characterised experimentally. A combined fretting wear-fatigue finite element model has been developed using an adaptive meshing technique and the effect of bending-induced tangential slip has been characterised. It has been shown that a surface damage parameter combined with a multiaxial fatigue parameter can accurately predict the beneficial effect of fretting wear on fatigue predictions. This provides a computationally efficient design tool for fretting in the pressure armour layer of flexible marine risers.
•Fretting wear-fatigue model predict effect of tangential slip on crack initiation.•Experimental testing on representative pressure armour steel.•Identification of fatigue, friction and wear parameters.•Fretting surface damage parameter combined with multiaxial fatigue parameter.•Prediction of beneficial effect of wear-induced stress re-distribution on fatigue.
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