Fretting Fatigue Lifetime Research Articles

Improvement mechanism of fretting fatigue lifetime of turbine dovetail tenon by shot peening combined with CuNiIn coating at 500 °C

Improvement mechanism of fretting fatigue lifetime of turbine dovetail tenon by shot peening combined with CuNiIn coating at 500 °C

A data‐assisted physics‐informed neural network (DA‐PINN) for fretting fatigue lifetime prediction

AbstractIn this study, we present for the first time the application of physics‐informed neural network (PINN) to fretting fatigue problems. Although PINN has recently been applied to pure fatigue lifetime prediction, it has not yet been explored in the case of fretting fatigue. We propose a data‐assisted PINN (DA‐PINN) for predicting fretting fatigue crack initiation lifetime. Unlike traditional PINN that solves partial differential equations for specific problems, DA‐PINN combines experimental or numerical data with physics equations as part of the loss function to enhance prediction accuracy. The DA‐PINN method, employed in this study, consists of two main steps. First, damage parameters are obtained from the finite element method by using critical plane method, which generates a data set used to train an artificial neural network (ANN) for predicting damage parameters in other cases. Second, the predicted damage parameters are combined with the experimental parameters to form the input data set for the DA‐PINN models, which predict fretting fatigue lifetime. The results demonstrate that DA‐PINN outperforms ANN in terms of prediction accuracy and eliminates the need for high computational costs once the damage parameter data set is constructed. Additionally, the choice of loss‐function methods in DA‐PINN models plays a crucial role in determining its performance.

Prediction of fretting fatigue lifetime of aluminium alloy treated with Friction Stir Processing using continuum damage mechanics

In the aviation industry, fretting fatigue represents a significantly hazardous form of fatigue failure, thus warranting substantial research attention. A key area of focus lies in enhancing the fretting fatigue resistance of aluminium alloys. This study investigates the feasibility of using Friction Stir Processing (FSP) to enhance fretting fatigue lifetime. After FSP, large-size inclusions in the Base Material (BM) are shattered, clustered inclusions are dispersed, and the preferred orientation of inclusions is disrupted. Consequently, areas of stress concentration, damage concentration and merging of hazardous zones become less, and the peak values of stress, stress triaxiality, and damage are decreased with 6–10 %. Compared to BM, the results show that the fretting fatigue lifetime of Friction Stir Processed (FSPed) material is increased by 50.1 %. Hence, FSP could emerges as a highly promising surface treatment technique for enhancing fretting fatigue performance.

The influence of 3D-printed PLA coatings on pure and fretting fatigue properties of AM60 magnesium alloys under cyclic bending loads

A study was conducted to compare the pure fatigue and fretting fatigue properties of AM60 magnesium alloys, with and without 3D-printed PLA coatings. The PLA coating layers led to an increase in the fatigue lifetime in both pure and fretting conditions. They delayed the crack initiation time compared to uncoated samples, thereby increasing fatigue lifetime. Additionally, in the case of fretting fatigue, PLA coating caused the fretting pads to reach the magnesium alloy later, which also contributed to the longer lifetime of coated samples, compared to uncoated specimens. Using field emission scanning electron microscopy, all specimens exhibited the brittle fracture behavior, with the presence of both cleavage and quasi-cleavage marks. By the fractography, it was found that the number of cracks in coated samples decreased in both pure and fretting fatigue conditions. Remarkably, PLA coating during fretting fatigue resulted in a significant enhancement of the fretting fatigue lifetime, within 56%–2182 %.

Critical Plane Methodology for Intelligent Prediction of Fretting Fatigue Lifetime Based on Shear Strain Dynamics

Critical Plane Methodology for Intelligent Prediction of Fretting Fatigue Lifetime Based on Shear Strain Dynamics

Numerical prediction of fretting fatigue life for cold-drawn eutectoid carbon steel wire using continuum damage mechanics and effective slip amplitude

The effective and safe use of wire ropes in various applications relies on a comprehensive understanding of the fretting fatigue phenomena that occur between internal wires. Estimating the fatigue life of steel wires subjected to fretting loading through numerical simulation techniques requires significant computational capacity and time, especially when considering wear process. In this study, a more straightforward and practical approach for predicting fretting fatigue life is developed using Continuum Damage Mechanics (CDM). This involves introducing damage stresses that account for relative slip amplitude and modified maximum principal stresses into the CDM framework. Additionally, the Effective Slip Amplitude (ESA) approach is utilized, incorporating relative slip amplitude and Walker effective stress, to evaluate fretting fatigue lifetime. A finite element model is replicated to obtain the relative slippages and stresses at the contact region. The accuracy of the CDM approach and the ESA approach is individually validated and verified by comparing them to experimental data and simulation results including the wear process from published literature. The results indicate that the CDM and ESA approaches, which combine relative slip amplitude and Walker effective stress, effectively predict the fretting fatigue lifetime of cold-drawn eutectoid carbon steel wires.

Estimation of fretting fatigue lifetime in heterogeneous material based on microstructure characterization and multi-scale homogenization

Fretting fatigue is a complex phenomenon that is affected by multiaxial stress and contact problems. In the contact surface, due to the cyclic load, a relatively small displacement is generated, and the stress concentration is established as well. To assess the fretting fatigue endurance complimentary to experimental efforts, the Finite Element Method (FEM) has become a useful tool combined with theoretical approaches. Meanwhile, most (if not all) of commercially available structural materials can be regarded as heterogeneous materials due to the existence of secondary phases and some fabrication defects and porosity. Therefore, to further understand the mechanism of fretting fatigue, knowledge of the material’s microstructure is important. In this study, several microstructure characterization techniques are applied to characterize precipitates and micro-voids in aluminium alloy AA2024-T3. These techniques are Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). To account for the precipitates, the homogenization method is adopted in this study. Additionally, a 3D structure non-destructive reconstruction technique is applied to obtain accurate information on micro-voids. The fretting fatigue lifetime is estimated by using the critical plane approach combined with the theory of critical distance. The numerical results are compared with experimental data showing a good agreement. The influence of micro-voids on the fretting fatigue endurance is studied and discussed as well.

Numerical modelling of microstructure inhomogeneity to reproduce experimentally observed scatter in fretting fatigue lifetimes

Experimental fretting fatigue lives exhibit large degree of scatter. One of the aspects behind this is the microstructural inhomogeneity which affects the stresses in the material. Variance in stress values can greatly impact crack initiation speed, leading to changes in fretting fatigue lifetimes, as well as the crack propagation behaviour. This research aims to study this issue in more detail and recreate the experimentally observed scatter using numerical modelling. In this work, Voronoi tessellation is used to simulate microstructural topologies of low carbon steel, where each grain is assigned elasto-plastic properties at random, from a predetermined range. In total, 60 finite element models are created and the effect of microstructural inhomogeneity on fretting fatigue lifetime dispersion is evaluated using a Continuum Damage Mechanics approach. Additionally, crack propagation is studied with XFEM combined with Smith-Watson-Topper fatigue parameter to determine crack path under multiaxial, non-proportional loading conditions. For both crack initiation and propagation investigation, the Theory of Critical Distances is applied to overcome the effect of high stress gradients. Simulation results show that microstructural inhomogeneity has significant impact on the contact stress distributions and subsurface stress and strain fields. Scatter observed in the predicted lifetimes matches well with that observed in practical experiments and is used to propose a design curve for the studied material. The applied crack path prediction approach captures the variance in crack paths originating from microstructural inhomogeneity and shows good correlation with reference experimental results at low bulk stress levels.

Two-Scale analysis of fretting fatigue crack initiation in heterogeneous materials using Continuum Damage Mechanics

The phenomenon of fretting fatigue damage is related to tribological behaviour and commonly occurs at the contact interface between two bodies that sustain oscillation loads. Based on the complicated mechanical situation, several methods have been developed to predict the crack initiation location and life. The Continuum Damage Mechanics (CDM) approach in conjunction with Finite Element Method (FEM) is used in this paper. The fretting fatigue lifetime includes two parts, crack initiation lifetime and crack propagation lifetime, and this paper focuses on the crack initiation phase. Homogeneous materials are usually studied in fretting fatigue problems, and the influence of defects is necessary to be considered. In this study, the authors proposed several models to consider the effect of heterogeneity on crack initiation location and lifetime. The numerical model is a 2D one with plane strain assumption. To get more accurate numerical results with low computational cost, a Two-Scale Analysis approach is developed in this paper. Two macroscopic models and three microscopic models are proposed, including a Macroscopic homogeneous model (Macro-HOMO), a Multiscale Homogenization model with Direct Numerical Simulation (MH-DNS), a Microscopic homogeneous model (Micro-HOMO), a Microscopic Model with equivalent material properties by using Mean Field Homogenization method (Micro-MFH), and a microscopic model with Direct Numerical Simulation (Micro-DNS). The results obtained by using the CDM approach with different microscopic models are compared, and show that the prediction accuracy of the Micro-DNS is the best. In addition, in terms of computational cost, the Micro-DNS model shows great advantages as well comparing to the Macro-DNS model.

Fretting fatigue lifetime estimation for heterogeneous material using critical distance with mesh control

Fretting fatigue has a wide range of applications in many fields, which have high requirements for accurate prediction of their lifetime. In this paper, the theory of critical distance using volume method and mesh control approach are applied to predict the fretting fatigue lifetime. Considering the existence of heterogeneity and defects in the material, the homogenization method and sub-model technique is used to directly investigate the influence of defects on stress, strain and fatigue lifetime. It is found that the computational cost can be reduced dramatically due to the use of mesh control approach. The prediction accuracy is improved through the implementation of the Unit Cell (UC) models based on a sub-modelling technique. Meanwhile, the Representative Volume Element (RVE) is applied for the estimations of fretting fatigue lifetimes using homogenization method taking into account the heterogeneity of material.

Heat-treating and nano-reinforcing improvements on fretting fatigue properties and fracture behaviors of cylinder head aluminum alloys

The presence of cyclic loading alongside the wear increases the probability of fretting fatigue phenomenon in the cylinder head of automobiles. In the current study, the nano-reinforcing and the T6 heat-treating impact on the fretting fatigue behavior of the cylinder head aluminum alloy were studied. Fretting fatigue tests were performed in the high-cycle fatigue regime, under 15 N contact load and four different stress levels (75, 100, 125, and 150 MPa). According to the test results, the fretting fatigue lifetime of heat-treated nano-composites under the lowest stress level increased by about 621%. Furthermore, the fracture surface of the studied aluminum alloys, the worn surface of the cast-iron ring used as fretting pads, and the derbies obtained during the fretting test were investigated with the help of field emission scanning electron microscopy. The failure behavior of the cylinder head materials concerning the presence of the quasi-cleavage and cleavage marks were brittle in all cases. In addition, as it is observed the wear mechanism of fretting pads was adhesive.

Artificial neural network combined with damage parameters to predict fretting fatigue crack initiation lifetime

The fretting problem occurs at two contact surfaces sustaining small relative displacement, and it reduces the fatigue lifetime dramatically. Estimating accurate fretting fatigue lifetime plays an important role in engineering applications. Due to the complicated stress state, and high-stress gradient in the contact surface, the average methods are necessary to obtain the precise lifetime, but the critical distance for the average zone is difficult to estimate. In this work, Artificial Neural Network (ANN) tool combined with damage parameters is proposed to determine the optimal critical distance for different fretting conditions. This tool can also be used to accurately predict the crack initiation lifetime. The fretting fatigue lifetimes calculated by using this approach have shown good agreement with experimental results from literatures. In addition, rough estimates of critical distance for different cases are made based on the numerical results.

A Perspective on Metamaterials for the Biomechanics Application: Multi-Material Metamaterial (4M) Structures

Designers are still seeking novel, smart and advanced materials. Moreover, a designed geometry for special purposes is also required for structures. In this regard, metamaterials are artificial structures with optimized topology. Furthermore, the multi-material metamaterial (4M) structure could be a frontier technology in different industries, especially in biomechanics, which provides various functions. In this short perspective, 4M structures have been introduced by emphasizing the application of bones and implants. Under cyclic loading, such a smart material should be topology-optimized with the objective of fatigue properties, the fretting fatigue lifetime, reliability, and weight. In addition, the constraint in this finite element modeling-based multi-objective optimization is the strength or the deformation of the structure.

An applied approach for estimating fretting fatigue lifetime of dovetail joints using coupon scale test data

Fretting fatigue is a complex phenomenon responsible for decrease in lifetime of many industrial components, such as a dovetail joint between blade and disk in a typical turbine or compressor configuration. In order to mitigate this issue numerous techniques of estimating the lifetime of elements affected by fretting fatigue have been developed over the years. In this research, for the first time, an applied approach is proposed to predict fretting fatigue lifetime of a dovetail joint using experimental results from standard coupon scale tests. To this end, a finite element model of a dovetail joint configuration is created to evaluate the forces and stresses at contact interface. The numerically extracted data, along with experimental results collected from literature, are used to estimate the fretting fatigue lifetime of the dovetail joint by using a simplified approach based on the combination of fretting fatigue damaging stress concept and continuum damage mechanics. The accuracy of this approach is validated by comparing the predicted lives to the experimental data from literature. Based on the obtained results, it can be concluded that proposed methodology can correctly estimate the lifetime of a dovetail joint, provided that the experimental results from coupon scale tests are matched with the dovetail joint configuration based on value of fretting fatigue stress normalized with peak shear traction.

A coupled 3D wear and fatigue numerical procedure: Application to fretting problems in ultra-high strength steel wires

This work presents a coupled 3D wear and fatigue numerical procedure for fretting problems in ultra-high strength steel wires that combines Archard’s wear equation with the Smith–Watson–Topper parameter to predict crack nucleation. For total life prediction, a mode I crack propagation based on the weight function method was used. To assess fretting fatigue lifetime, several experimental campaigns were run. The numerical results were in good agreement with the fretting fatigue experimental results. Thus, this study provides a 3D numerical methodology to study the combined effects of wear and fatigue in fretting with a case study in ultra-high strength steel wires.

A debris layer evolution-based model for predicting both fretting wear and fretting fatigue lifetime

A continuum damage mechanics (CDM)-based approach is proposed to investigate fretting wear and fretting fatigue behavior of Ti-6Al-4V with the consideration of debris layer evolution. An elastic-plastic-damage model is developed to calculate the stress, strain, and fatigue damage fields. The debris layer and its thickness evolution are considered in a friction energy-based wear model. Both models are implemented in a finite element package to predict the fretting wear profile and fatigue lifetime. It is found that the numerical approach with the consideration of debris layer provides more accurate predictions than that without debris layer. The effects of debris layer evolution on the fretting fatigue lifetime, wear profile, contact pressure and subsurface stress are evaluated.

Numerical estimation of fretting fatigue life of bolted joints using continuum damage mechanics and SEAM Tool

For fretting fatigue, micro-slipping often causes initial micro-cracks in the contact surfaces, which gradually propagate and eventually result in fracture failure. However, it is difficult to directly observe and measure the crack initiation and propagation processes of single-lap bolted joints due to the obstacle of testing technique. Therefore, this article presents an elastic analysis–based method, in which the total fretting fatigue lifetime is divided into initiation life predicted by continuum damage mechanics and propagation life calculated by SEAM Tool in combination with Paris’s law. Since the initiation life model implicitly reflects the result of damage process, one can directly calculate the initiation life based on the elastic stress analysis. The predicted fretting fatigue life, initial crack location, and propagation path are in reasonable agreement with the fretting fatigue test and scanning electron microscope observation results. In addition, it is found that among the main factors affecting fretting fatigue of steel single-lap bolted joints, the initial life is affected by cyclic stress, friction coefficient, and tightening torque, and the propagation path is mainly influenced by tightening torque.

A numerical study on effects of randomly distributed subsurface hydrogen pores on fretting fatigue behaviour of aluminium AlSi10Mg

Abstract The successful construction of additively manufactured metallic components for safety-critical applications requires a thorough understanding of the associated tribo-mechanical properties such as fretting fatigue phenomenon. Various porosity formations mechanisms occur in selective laser melting of aluminium alloys. The internal porosity is forming because of the powder and printing process itself. These pores, which act as internal micro defects, result in premature fatigue crack initiation and subsequent fatigue failure. In this study, numerical simulation technique is used to investigate the effects of randomly distributed hydrogen pores on the fretting fatigue response of additively manufactured aluminium AlSi10Mg part. From the simulation results it has been found that at the high-stress levels the fretting fatigue primary variables such as tangential and frictional shear stresses along with slip amplitude are slightly affected by the distribution of porosity close to the contact interface. 60% of the fatigue crack initiation locations are detected at the pore sites (killer defects) underneath the contact interface near the contact edge. The killer defect size varies between 32 μm and 60 μm in diameter. Eventually, the fretting fatigue lifetime decreases for 92% of simulated case studies and higher scatter results are observed at the high-stress levels compared to the low stresses.

On the use of the theory of critical distances with mesh control for fretting fatigue lifetime assessment

Abstract This work analyses the viability of the theory of critical distances (TCD) using mesh control for fretting fatigue lifetime assessment. More than seven hundred sets of simulations were performed by taking seventy different experimental tests reported previously in the literature. The outcome of the present study suggests that the TCD mesh control method can be extended to fretting fatigue problems by the reasonable assumption of setting the right element size proportional to critical distance. In this study, a significant computational time reduction of up to 97% was obtained. Thus, this study provides a simple method to design complex 3D industrial components subjected to fretting fatigue phenomena using finite element analysis efficiently without requiring complex remeshing techniques.

A coupled crack initiation and propagation numerical procedure for combined fretting wear and fretting fatigue lifetime assessment

This work presents a numerical procedure for combined fretting wear and fretting fatigue problems. It combines the Archard wear model and the Smith-Watson-Topper fatigue indicator parameter with the Miner damage rule for crack nucleation estimation. The eXtended Finite Element Method (XFEM) is then used in combination with the Archard wear model for crack propagation prediction. This procedure was validated in 12 experimental tests taken from the literature, and a good correlation was found. The procedure allows a detailed study of the interaction between the crack and fretting contact in combination with wear. The results show that the relative slip decreases and changes its distribution unevenly when the crack grows, and highlight the key importance of accounting for wear in order to obtain non-conservative predictions.