Fretting Fatigue Life Prediction Research Articles

Study of the Point Method for fretting fatigue life prediction

With the improvement and success of the Theory of Critical Distances (TCD) in notch fatigue problems, the TCD, especially the Point Method (PM), combined with multiaxial fatigue criteria, has been used over the last few years to predict the fretting fatigue life. However, little attention is paid to the effect of different damage mechanisms, especially stress distribution, between the two conditions on the application of the PM. This paper aims to select a suitable path for the PM, considering various stress distributions, for the fretting fatigue life prediction of complete contacts. A new method is developed to select the suitable path of the PM for fretting fatigue life prediction. To validate the analysis, corresponding tests were carried out using an improved proving ring-like rig in a Ti-6Al-4V alloy. Predicted lives on all paths were calculated using the PM combined with different multiaxial fatigue criteria, without incorporating wear effects, and compared with experimental lives using an error bar graph. Results indicate that when the fretting wear is not considered, the minimum predicted life path is more suitable for the PM than the perpendicular and maximum predicted life paths. This suitable path is compared to the path selection in the uniaxial symmetric V-notch fatigue condition. Analysis shows that the conventional path (the notch bisector) of the PM produces the maximum predicted life for the notch fatigue condition. The cause of this different path selection of the PM in the two fatigue conditions is assumed to be the effect of the asymmetric stress distribution and fretting wear damage in the fretting fatigue condition.

Fretting Fatigue Life Prediction for Aluminum Alloy Based on Particle-Swarm-Optimized Back Propagation Neural Network

Fretting fatigue is a specific fatigue phenomenon. Due to the complex mechanisms and multitude of influencing factors, it is still hard to predict fretting fatigue life accurately, despite there being many works on this topic. This paper developed a particle-swarm-optimized back propagation neural network to predict the fretting fatigue life of aluminum alloys using the test data gathered from the published literature. A commonly used critical plane model, the Smith, Watson, and Topper criterion, was used as a contrast. The analysis result shows that the proposed fretting fatigue life prediction neural network model achieves a higher prediction accuracy compared to the traditional SWT model. Experimental validation demonstrates the effectiveness of the model in improving the accuracy of fretting fatigue life prediction. This research provides a new data-driven methodology for fretting fatigue life prediction.

Finite element analysis of fretting fatigue properties of GH4169 superalloy considering the surface treatments

In the present work, the fretting fatigue properties of GH4169 superalloy at 650℃ were investigated through numerical simulation considering the influences of the surface treatments. As a detrimental phenomenon, fretting fatigue involves fatigue and wear simultaneously, where the coefficient of friction and residual stress fields induced by the surface coating or modification techniques may affect the fretting fatigue lifetimes by changing the complex stress state between the two contacting surfaces. The numerical solutions were implemented to compare the crack initiation angles and paths under different surface conditions. The simulation results indicated that fretting fatigue cracks in residual stress fields were tendentiously parallel to the surface resulting in crack retardation and debris peeling, as verified by experimental observations. Additionally, three propagation models were compared to study the effect of compressive loading on the driving force of crack propagation rates, especially where compressive residual stresses was present. The combination of the linear superposition model with the Harter-T method was proven to be more accurate in the fretting fatigue life prediction, which may provide a modeling basis for service life prediction of engineering components in many practical applications.

Fretting Fatigue Life Prediction of Dovetail Structure Based on Plastic Effect and Sensitivity Analysis of Influencing Factors.

Micro relative sliding exists on the contact surface of the main primary equipment's surface structures, resulting in serious fretting fatigue. The plastic effect causes serious fatigue to the structure under alternating loads. Existing fatigue life prediction models fail to fully consider the shortcomings of fretting and plastic effects, which causes the prediction results to be significantly different to real-lifeworld in engineering situations. Therefore, it is urgent to establish a fretting damage fatigue life prediction model of contact structures which considers plastic effects. In this study, a plastic fretting fatigue life prediction model was established according to the standard structural contact theory. The location of dangerous points was evaluated according to a finite element simulation. The cyclic load maximum stress value was compared with the fretting fatigue test data to confirm the error value, and the error between the proposed fretting fatigue life model and the test value was within 15%. Concurrently, we combined this with mass data analysis and research, as it is known that the contact zone parameters have an impact on fretting fatigue and affect the structural lifespan. With the help of ABAQUS, the fretting numerical calculation of the dovetail tenon model was carried out to analyze the sensitive factors affecting the fretting fatigue life of the dovetail tenon structure. By keeping the fretting load unchanged, the contact area parameters such as contact surface form, contact area width and friction coefficient were changed in order to calculate the fretting stress value, σfretting and the dovetail structure was improved to extend its fretting fatigue life. Finally, it was concluded that fretting fatigue was most sensitive to the width and contact form of the contact area. In actual engineering design, multiple factors should be considered comprehensively to determine a more accurate and suitable width and form of the contact area. For the selection of friction coefficient, on the premise of saving costs and meeting the structural strength requirements, the friction coefficient should be as small as possible, and the problem can also be solved through lubrication during processing.

Experimental study and fretting fatigue life prediction in dovetail assembly considering stress–temperature nonlinear coupling effect

AbstractAs a paramount failure form of dovetail assembly, high‐temperature fretting fatigue seriously restricts the actual service life. Aiming at the problem of fretting fatigue life prediction of dovetail assembly of the aero‐engine compressor under the coexistence of stress and high temperature, based on D‐M contact theory and continuum damage mechanics theory, a fretting fatigue life prediction model considering stress–temperature nonlinear coupling effect is proposed in this paper by, respectively, introducing the fretting fatigue stress σfretting and the high‐temperature influence factor λ. Meanwhile, the judgment criterion of fretting fatigue crack initiation and failure is raised based on the strain–displacement method, and the fretting fatigue test is designed and carried out for experimental verification. The results show that the proposed fretting fatigue life prediction model has high life prediction ability, whose life prediction results are within ±1.7 times the error band, which can provide a theoretical reference for the structural design optimization and damage tolerance design of dovetail assembly.

A Review of Research Progress on the Fretting Fatigue Mechanism and Protection Measures of Metal Matrix Composites

The performance characteristics of metal matrix composites (MMCs) and the need to study their fretting fatigue and wear during service are discussed. Four main elements of the study of fretting fatigue wear of MMCs (aluminum, copper, titanium, iron, magnesium, nickel, etc.) are discussed. These are factors influencing fretting fatigue, mechanism research, life prediction, and the development process of protection methods, respectively. Factors such as internal crack nucleation and development, loading conditions, and working environment are analyzed and discussed. The development trend of fretting fatigue research is outlined from several perspectives such as the fretting fatigue mechanism, research methods, and protection methods. In particular, the current state of research and the results achieved are highlighted, and some of the issues that remain to be studied are illustrated. The combined effects of fretting, fatigue and wear, the accuracy and applicability of fretting fatigue life prediction, the dispersion of the strengthening phase, and interface problems of MMCs themselves, etc., are all issues that need further research. The review summarizes some of the existing results and provides some reference help for subsequent developments.

Research on High Temperature Fretting Fatigue Life Prediction Based on Surface-to-surface Contact Structure

Research on High Temperature Fretting Fatigue Life Prediction Based on Surface-to-surface Contact Structure

A New Model for Predicting Fretting Fatigue Crack Initiation Life Based on Effective Slip Amplitude

In this study, a new model has been developed for fretting fatigue crack initiation life prediction based on the slip amplitude as a macroscopic feature of the contact interfaces. The main difference between the presented model and many other fretting fatigue life prediction models is the focus on the fretting specific characteristics. In this model, a damage parameter is combined with a damage severity factor to obtain a new fretting fatigue crack initiation life prediction parameter. To investigate the accuracy of this new parameter, a series of fretting fatigue tests have been conducted. Also, crack initiation life data from the literature were added to enhance parameter accuracy investigation. It is shown that the effective slip amplitude is an unbiased geometric-independent parameter in fretting fatigue crack initiation life prediction. Also, comparing prediction results from the effective slip amplitude with those of Smith-Watson-Topper and Ruiz parameters showed that the new parameter can outperform available fretting fatigue life prediction parameters.

On the use of the theory of critical distances with mesh control for fretting fatigue life assessment in complete and nearly complete contacts

In this work, the theory of critical distances using point method and mesh control approach for fretting fatigue life prediction in complete and nearly complete contacts is analysed. The approach is applied to thirty experimental tests found in the literature, where almost nine hundred simulations are carried out. The work concludes that the theory of critical distances using mesh control is able to predict the fretting fatigue strength of components using an optimum mesh size of 1.6 times the critical distance for all contact configurations analysed. Due to the use of an element size of around the critical distance length, the computational cost can be reduced up to 98% in comparison with the traditional theory of critical distances.

Research on factors affecting fretting fatigue life of high‐temperature dovetail tenon

AbstractThis paper takes the dovetail structure of an aero‐engine compressor as the research object, designs a high‐temperature dovetail fretting fatigue test, and discusses the effect of high temperature on fretting fatigue damage. Based on the fretting fatigue continuous damage accumulation model, a high‐temperature fretting fatigue life prediction model of dovetail tenon considering the temperature effect is proposed and verified by experiments. The results show that the experimental data prove that the model has good prediction accuracy and its prediction error is less than 19.24%. Finally, the relative sliding distance, contact stress, Ruiz parameters, and friction work of the dovetail structure are selected, and the dovetail structure under different actual use conditions is calculated through simulation. The influence of friction coefficient, load, temperature, arc size, and other factors on the evaluation index is analyzed. The internal law of high‐temperature fretting fatigue life of dovetail structure under multi‐factor coupling conditions is studied.

A fretting fatigue model based on self-steered cracks

In this article a new fretting fatigue life prediction model is presented. The model can be classified as a variable crack initiation length: the crack initiation and crack propagation phases are calculated as a function of the crack initiation length, and among all the feasible crack initiation lengths and orientations, that producing the minimum fatigue life is considered. In this new proposal the crack direction is automatically determined as a function of fatigue parameters in both phases: initiation and propagation. The model is applied to a wide experimental campaign of fretting fatigue tests, and excellent correlation is obtained between experimental and predicted fretting fatigue lives and crack paths.

Experimental study of fretting fatigue in dovetail assembly considering temperature effect based on damage mechanics method

Fretting fatigue of dovetail structure of aero-engine compressor is a very complex phenomenon, which is affected by different factors such as temperature, load, friction coefficient, and arc radius, etc. Aiming at the problem of the high-temperature fretting fatigue life prediction of dovetail structure, the high-temperature effect on fretting fatigue life is analyzed, and then the fretting fatigue life prediction model is established considering the temperature effect by introducing temperature equivalent factor based on the circular flat contact theory and continuous damage mechanics theory. Besides, the criterion of fretting fatigue cracks initiation failure is proposed based on the displacement–strain joint monitoring method in the fretting fatigue tests. The experiment results show that the proposed fretting fatigue life prediction model has a high life prediction ability within ± 2.0 times error band. It is found that the traditional damage mechanics accumulation model cannot reflect the change of fretting fatigue damage only by changing the material performance parameters in a high-temperature environment, needing temperature correction and the proposed fretting fatigue life prediction model considering temperature effect in the exponential form of temperature ratio is feasible.

RA-based fretting fatigue life prediction method of Ni-based single crystal superalloys

Abstract Fretting fatigue damage can significantly reduce the service life of Ni-based single crystal (NBSX) superalloys turbine blades. In this work, we proposed a fretting fatigue life prediction method by considering cracking, wear and their mutual interaction. Specifically, a parameter, denoted as RA, is developed with combination of Resolved shear stress based damage factor and Accumulated dissipated energy based damage factor, by which the contribution from cracking and wear are described respectively. The proposed method is validated with experimental data in the literature. Finite element analyses are performed to study the distribution of stresses and strains. Results show that the predicted crack initiation site, failure plane and life cycles are consistent with the experimental results.

An experimental study on the key fretting variables for flexible marine risers

This paper presents an experimental investigation into the effects of contact conformity, contact pressure and displacement amplitude on gross-slip fretting behaviour for grease-lubricated cylinder-on-flat contacts in the context of flexible marine riser pressure armour wire, and compares behaviour with that observed in unlubricated conditions. Characterisation of friction and wear is critical to fretting fatigue life prediction in flexible risers since friction directly controls trailing-edge fretting stresses and hence fatigue crack initiation, on the one hand, and on the other hand, directly affects wear via relative tangential slip (displacement). Wear can have a beneficial or detrimental effect on fatigue crack initiation and propagation, depending on relative slip and slip regime. For the grease-lubricated conditions, the behaviour is determined by whether grease can be retained in the contact (as opposed to being extruded out). Retention (or replenishment) of grease in the contact results in low rates of wear and low coefficients of friction; these conditions are favoured by fretting displacements above a critical value, by low contact conformity, and by low applied loads.

Numerical measures of non-proportionality degree in incomplete contact subjected to fretting fatigue loading

Fretting fatigue failure is a fatigue fracture that initiates at a surface area where fretting has occurred. Fretting fatigue life assessment under multiaxial loading is a rather complex task, as the stresses at contact interface are multiaxial. A phase-shift between stress components leads to lower equivalent stress values calculated by most of available multiaxial fatigue criteria and therefore to an increased estimated fretting fatigue life. In this study a correlation based non-proportionality factor is introduced to predict the fretting fatigue lifetime under non-proportional stressing. The proposed factor is based on a statistical correlation of normal and shear stress components and does not depend on the choice of the coordinate system. A two dimensional finite element model is used to extract the stress components at crack initiation site. Moreover, to enhance the fretting fatigue lifetime assessment, stress-based Findley multiaxial fatigue criterion is modified by introducing the non-proportionality factor. A series of experimental data of high strength CrNi steel, taken from literature, are used to investigate the effect of non-proportional stressing on fretting fatigue life prediction.

Fatigue and fretting fatigue life prediction of double-lap bolted joints using continuum damage mechanics-based approach

Fatigue and fretting fatigue are the main failure mode in bolted joints when subjected to cyclic load. Based on continuum damage mechanics, an elastic–plastic fatigue damage model and a fretting fatigue damage model are combined to evaluate the fatigue property of bolted joints to cover the two different failure modes arisen at two possible critical sites. The predicted fatigue lives agree well with the experimental results available in the literature. The beneficial effects of clamping force on fatigue life improvement of the bolted joint are revealed: part of the load is transmitted by friction force in the contact interface, and the stress amplitude at the critical position is decreased due to the reduction in the force transmitted by the bolt. The negative effect of fretting damage on the bolted joint is also captured in the simulation.

New approach based on continuum damage mechanics with simple parameter identification to fretting fatigue life prediction

A new continuum damage mechanics model for fretting fatigue life prediction is established. In this model, the damage evolution rate is described by two kinds of quantities. One is associated with the cyclic stress characteristics obtained by the finite element (FE) analysis, and the other is associated with the material fatigue property identified from the fatigue test data of standard specimens. The wear is modeled by the energy wear law to simulate the contact geometry evolution. A two-dimensional (2D) plane strain FE implementation of the damage mechanics model and the energy wear model is presented in the platform of ABAQUS to simulate the evolutions of the fatigue damage and the wear scar. The effect of the specimen thickness is also investigated. The predicted results of the crack initiation site and the fretting fatigue life agree well with available experimental data. Comparisons are made with the critical plane Smith-Watson-Topper (SWT) method.

Two dimensional versus three dimensional modelling in fretting fatigue life prediction

This work analyses the influence that the type of geometry used to model a cylindrical contact has on fretting fatigue life predictions. It also studies the effect that the assumed fatigue crack shape has on fretting fatigue life predictions. The strain–stress fields are obtained using different finite elements models. These models consider the following three types of behaviour: plane stress, plane strain (2D geometries) and 3D. Each of these models produces a different crack-initiation life, a different evolution of the stress intensity factor (SIF), and therefore a different crack-propagation life. As a consequence, different fretting fatigue life predictions are obtained with each model. Regarding the SIF evaluation, the weight function method is employed in all the models. Finally, the lives obtained using the three numerical models are compared with experimental lives.

Effects of fatigue damage and wear on fretting fatigue under partial slip condition

The continuum damage mechanics model incorporating wear was developed in the previous paper by the authors [27] to predict the fretting fatigue crack initiation life for both cases of partial slip and gross sliding. In the present study, the effects of external parameters on the fretting fatigue crack initiation behaviour under partial slip condition are investigated systematically. Firstly, a different fatigue damage accumulation rule is used, which can predict a more reasonable damage process. Secondly, the effects of the relative slip amplitude and wear coefficient are evaluated based on the improved approach. It is significant to note that the impact of wear coefficient on the fretting fatigue life is non-monotonic, and the action mechanism of that is analysed in detail in this work. Finally, the combination and competition between fatigue damage and wear are presented. The results indicate that none of the fatigue damage and wear can be neglected in the fretting fatigue life prediction.

Stability of critical distance approach to predict fretting fatigue cracking: a “ℓopt–bopt” concept

Fretting fatigue life prediction is a strategic issue for modern industry. Accurate prediction of total lifetime depends on crack nucleation time prediction. However, fretting fatigue is characterized by a high stress gradient which overestimates cracking risk at the hotspot. Hence non-local analyses are required. The present study focused on the critical distance method. However, no defined method is currently established to obtain this value, which has been shown to depend on microstructure or stress gradient. The present study investigated the influence of incipient crack length on critical distance crack nucleation prediction. An optimal ℓopt–bopt condition was introduced enabling accurate prediction of the crack nucleation condition whatever the loading condition. This approach was then applied to fretting endurance experiments, allowing to correlate fretting cracking endurance with shear fatigue data. Finally it was used on fretting fatigue lifetime experiments, showing good endurance prediction.