An analysis of fretting-fatigue failure combined with numerical calculations to predict crack nucleation (original) (raw)
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Aspects of Fretting Fatigue Finite Element Modelling
Computers, Materials & Continua, 2020
Fretting fatigue is a type of failure that may affect various mechanical components, such as bolted or dovetail joints, press-fitted shafts, couplings, and ropes. Due to its importance, many researchers have carried out experimental tests and analytical and numerical modelling, so that the phenomena that govern the failure process can be understood or appropriately modelled. Consequently, the performance of systems subjected to fretting fatigue can be predicted and improved. This paper discusses different aspects related to the finite element modelling of fretting fatigue. It presents common experimental configurations and the analytical solutions for cylindrical contact. Then, it discusses aspects of fretting fatigue crack initiation, such as crack location, orientation, and length, as well as stress averaging approaches. Then, it deals with the propagation stage; crack face interaction, orientation criteria, and crack growth rate are discussed. Lastly, additional aspects of recent research on fretting fatigue are reviewed: out-of-phase loading, cohesive zone modelling, wear effects, heterogeneity, and crystal orientation. Fretting fatigue is a phenomenon not well understood, and much more research is needed so that its understanding is increased and proper criteria and laws may be available for different cases.
A fracture mechanics methodology assessment for fretting fatigue
International Journal of Fatigue, 2003
A fracture mechanics methodology was evaluated for a fretting fatigue geometry in which one end of a specimen clamped between fretting pads was loaded in axial fatigue. In previous work, results from experiments on Ti-6Al-4V pads and specimens were evaluated using finite element analyses where stress intensity factors were calculated assuming a single-edge tension, Mode I crack to form. In the present work, mixed-mode behavior was considered and a more realistic crack geometry was incorporated. K I and K II were calculated from stress fields determined from the finite element analysis using a weight function method and assuming a single-edge Mode I/Mode II inclined crack. A correction was then applied based on empirical crack aspect ratio data. K I and K II were analyzed for several experimentally determined combinations of contact pad geometry, specimen thickness, and loading conditions used to obtain a range of normal and shear forces, each corresponding to a fatigue life of 10 7 cycles. The fracture mechanics methodology was used to determine the conditions for propagation or non-propagation of cracks that initiate in the edge of contact region based on a mixed-mode driving force and a short crack corrected threshold. The coefficient of friction was also varied in the analyses. The fracture mechanics approach appears to be a better method for determining the threshold for fretting fatigue than a stress analysis because thresholds for K are better known than criteria for crack initiation in a gradient stress field.
Numerical investigation of contact stresses for fretting fatigue damage initiation
Journal of Physics: Conference Series, 2017
Fretting fatigue phenomena occurs due to interaction between contacting bodies under application of cyclic and normal loads. In addition to environmental conditions and material properties, the response at the contact interface highly depends on the combination of applied loads. High stress concentration is present at the contact interface, which can start the damage nucleation process. At the culmination of nucleation process several micro cracks are initiated, ultimately leading to the structural failure. In this study, effect of ratio of tangential to normal load on contact stresses, slip amplitude and damage initiation is studied using finite element analysis. The results are evaluated for Ruiz parameter as it involves the slip amplitude which in an important factor in fretting fatigue conditions. It is observed that tangential to normal load ratio influences the stick zone size and damage initiation life. Furthermore, it is observed that tensile stress is the most important factor that drives the damage initiation to failure for the cases where failure occurs predominantly in mode I manner.
Tribology International, 2014
A fretting fatigue failure scenario can be explained by accumulation of damage, which leads to formation of initial macro-cracks at the contact interface and propagation of macro-cracks to sudden rupture of bulk material. The main aim of this study is estimating these two portions by means of a numerical modelling approach. For this purpose, an uncoupled damage model based on a thermodynamic potential function is used to model the crack initiation lifetime. In order to model crack propagation part a linearelastic fracture mechanics approach under mixed-mode loading conditions has been considered. The crack propagation direction is defined based on experimental observation and compared with some available criteria in the literature, which are usually used for proportional loading conditions. The estimated results are compared with observed experimental lifetime and show good agreement.
The objective of this work is to study the effects of contact parameters on the cracking parameters of a specimen and a pad assembly. These parameters have been studied and evaluated by the finite element method analysis in two dimensions fretting fatigue model through the Abaqus calculation code. Different values of the coefficient of friction of 0.1, 0.3 and 0.6 were applied on the various lengths in contact for a = 0.1, 0.5 and 1mm. Thus, on the various values of angle of orientation of the crack equal to 15 °, 30 ° and 45 °. In addition, elements of the type (CPE4R) and the criterion of maximum tangential stress were applied. The curves of the crack parameters such as the SIF coefficients and the integral J were obtained and discussed.
Three Dimensional Finite Element Modelling of Cracks Under Fretting Fatigue Conditions
2014
The starting of crack initiation from micro-heterogeneities of the structure is often causes degradation of element’s structure. The industrial metallic materials are generally alloys of complex composition with defects (work hardening, dislocation, segregation of addition elements, grain boundaries, and porosities) which locally create an incompatibility of deformation and/or a stress concentration. Microscopic cracks can then start by accumulation of dislocation on the defect, if local crystallography is favorable there. In fretting fatigue, the application of mechanical under pressure contact during the complex loading of fretting fatigue involves cracks born from crystallographic dislocations. In order to understand and to enrich knowledge of the fretting fatigue phenomenon, a complete study of the parameters of elliptical inclined cracks by three dimensional Finite Element Method under conditions of fretting fatigue with complete contact was carried out. An initial crack was su...
Fretting-contact-induced crack opening/closure behaviour in fretting fatigue
International Journal of Fatigue, 2016
Fretting fatigue experiments and finite element analysis of stainless steel (SUS316L) were performed to investigate the crack opening/closure behaviour of a fretting fatigue crack. The crack nucleated at the location of the maximum shear stress range and then propagated in the maximum tangential stress range direction. The crack path could be successfully predicted based on the criterion of the maximum tangential stress range. A crack opening under compressive bulk stress was found in both the experiment and finite element analysis. The crack opening was induced by the restraint of deformation of one side of the crack surface due to the fretting contact. The predicted fatigue lives without consideration of crack opening were significantly longer than those of the experimental results, while the predicted fatigue lives with consideration of crack opening were in good agreement with the experimental results.
Numerical Estimation of Fretting Fatigue Lifetime Using Damage and Fracture Mechanics
Tribology Letters, 2013
Fretting fatigue is a complex tribological phenomenon that can cause premature failure of connected components that have small relative oscillatory movement. The fraction of fretting fatigue lifetime spent in crack initiation and in crack propagation depends on many factors, e.g., contact stresses, amount of slip, frequency, environmental conditions, etc., and varies from one application to another. Therefore, both crack initiation and propagation phases are important in analysing fretting fatigue. In this investigation, a numerical approach is used to predict these two portions and estimate fretting fatigue failure lifetime under a conformal contact configuration. For this purpose, an uncoupled damage evolution law based on principles of continuum damage mechanics is developed for modelling crack initiation. The extended finite element method approach is used for calculating crack propagation lifetimes. The estimated results are validated with previously reported experimental data and compared with other available methods in the literature.
An investigation of fatigue damage development under complete contact fretting test conditions
2016
In this paper evolution equation based multiaxial fatigue model is applied to the analysis of fretting fatigue of a cantilever test specimen made of EN 10083-1 steel. The adopted high-cycle fatigue model is based on the concept of evolving endurance surface and damage evolution equation. For the endurance surface a simple linear relationship between the hydrostatic stress and the reduced deviatoric stress is used. It is observed that such a simple relationship does not model the fretting fatigue phenomena properly due to the high compressive hydrostatic stress state at the contact region. Also stress gradient effects should be taken into account in a more rigorous manner.
Fretting fatigue crack nucleation: A review
Tribology International, 2018
This study aims to provide an overview of numerical and experimental work, related to crack nucleation under fretting fatigue conditions. In fretting fatigue, multiaxial loads and severe stress gradients are present at the contact interface, which can lead to failure. The damage process, in general, is considered as a two-phase phenomenon, namely, nucleation and propagation. Various damage models and approaches are available in literature to model each phase. In the present work, different criteria, related to nucleation phase, are classified based on the approach used to define failure. These approaches include, critical plane approach, stress invariant approach, fretting specific parameters and continuum damage mechanics. Apart from theoretical background, the work related to the applications of these approaches to fretting fatigue problems is also presented. It is observed that, to analyse various aspects, intricate details near the contact interface and mechanisms involved in fretting fatigue, the strength of finite element method can be employed. In the light of numerical and experimental observations, comparison between different approaches, common sources of errors in prediction and generalized conclusions are presented.