Fretting Fatigue Behavior Research Articles

Fretting Fatigue Behavior under Tension–Bending Mixed-Mode Loading

Fretting Fatigue Behavior under Tension–Bending Mixed-Mode Loading

Investigation of pad radius effects on multiaxial fretting fatigue behavior of al2024 alloy

Fretting fatigue, a critical phenomenon prevalent in engineering applications, occurs at the interface of contacting surfaces under cyclic loading, presenting significant challenges. The advent of Finite Element Analysis (FEA) has transformed the investigation of fretting fatigue by offering detailed insights into stress distributions and fatigue damage mechanisms. This study delves into the impact of pad radius on the fretting fatigue behavior of Al2024 alloy using FEA, with a focus on hot spot analysis and the Smith-Watson-Topper (SWT) criterion. The analysis aims to validate numerical results against analytical findings and explore the role of pad radius in determining contact behavior, fatigue life, and hot spot locations. By incorporating "fe-safe" software, computations are streamlined, facilitating efficient comparison of different fatigue initiation criteria. The results demonstrate that variations in pad radius significantly influence fretting fatigue behavior. Larger pad radii tend to distribute stresses more uniformly across the contact interface, resulting in reduced fatigue damage and longer fatigue life compared to smaller pad radii. Hot spot analysis reveals that smaller pad radii concentrate stresses at specific regions, accelerating fatigue damage initiation. The findings contribute to a deeper understanding of fretting fatigue mechanisms, shedding light on the importance of pad radius in designing more durable engineering components. Through professional scientific methodology, this study provides valuable insights into optimizing pad design to mitigate fretting fatigue and enhance the reliability of mechanical systems.

Fretting fatigue behavior of helical-torsional contact steel wire in wire rope

Fretting wear and torsional deformation of steel wire can reduce the performance of wire rope and threaten the safety of mine hoisting system. In this study, to explore the influence of different torsional deformation on the fretting fatigue wear behavior under multi-wire spiral contact, an experimental study was conducted on a self-made test apparatus. The results show that the increase of torsional deformation can reduce the breaking force of steel wire by about 2.6%, and reduce the bending fatigue performance by about 36.4%. In addition, the maximum wear depth, wear amount and coefficient of wear increase with the increase of torsional deformation. The torsion and deformation of the pearlite lamellae parallel to the tensile stress direction are the main reasons for the decrease of the wear resistance of the main steel wires. More torsional deformation makes the steel wire produce less furrow morphology in fretting fatigue wear. The main wear mechanism of steel wire with small torsional deformation is abrasive and tribochemical reactions, and the main wear mechanism of steel wire with large torsional deformation is surface fatigue and tribochemical reactions.

Modelling of microscopic crack initiation behaviour of fretting fatigue based on X-ray micro-computed tomography scan

Fretting fatigue is a particularly destructive form of fatigue failure that has drawn significant attention from researchers. This paper proposes a numerical modelling method based on tomography scan to investigate the impact of inclusions on fretting fatigue crack initiation behaviour. The results reveal that inclusions can affect the crack initiation direction and reduce the initiation lifetime. The difference between the properties of inclusions and matrix leads to local mechanical response mismatch, resulting in local stress, strain, and damage concentration. The mismatch in strain and damage follows a gradient distribution along the thickness as the distribution in these mechanical responses. These could explain why particles closer to the surface are more likely to cause damage. Additionally, the aggregation distribution of inclusions results in merging and connecting local regions with high stress, strain, and damage concentration, ultimately promoting fracture behaviour. Finally, the numerical models are validated with experimental data from fretting fatigue tests. Compared to the homogeneous model, the numerical model that considers inclusions from topography data can more accurately analyse the material damage and provide a more comprehensive understanding of fretting fatigue behaviour.

Enhanced fretting fatigue strength of TC11 titanium alloy using laser-assisted ultrasonic surface rolling process

In this paper, ultrasonic surface rolling (USRP) and laser heating-assisted USRP (Laser-USRP) techniques are employed to enhance the fretting fatigue strength of TC11 titanium alloy. Furthermore, the surface deformation mechanism and fretting fatigue behavior are investigated. The properties of the reinforced surfaces were observed using transmission electron microscope (TEM), microhardness test, residual stress test and fretting fatigue experiments. The results showed that laser-USRP led to a remarkable enhancement in the fretting fatigue life of TC11 titanium alloy compared to traditional USRP. This was mainly due to the fact that laser heating improved the plasticity of TC11 titanium alloy, contributed to the formation of a smoother surface and increased the degree of surface oxidation, which could improve surface lubrication. Under high temperature, more slip systems were activated and more stable dislocations were formed, which resulted in larger compressive residual stress (CRS) with higher stability. The superposition of the elevated temperature field and the kinetic energy of the ultrasonic vibration produced an annealing effect in localized regions, resulting in the formation of more stable gradient nanograins. This study demonstrated the immense potential of laser-assisted plastic deformation in improving the surface properties of titanium alloys.

Effect of interference magnitude on fretting wear and fatigue strength of scaled press-fitted railway axles

Railway axles represent a typical example of interference fit structures that are vulnerable to fretting fatigue induced by rotational bending loads. This study investigated the influence of interference magnitude on the fretting wear and fatigue of scaled press-fitted railway axles. In this study, the fretting fatigue strength was tested at three interference magnitudes within the standard range, and the fretting wear and fretting cracks were analyzed. The results indicate a trend where the fretting fatigue strength initially rises and then declines with increasing interference magnitude. 3D finite element models, with and without considering the fretting wear, were developed to investigate the variation in contact parameters in the press-fitted region, and the Smith-Watson-Topper multiaxial fatigue model was employed to evaluate the fretting fatigue behavior. The results demonstrate that the competition between contact pressure and axial slip produces relatively slight fretting wear when the interference magnitude takes the middle value, thereby causing a minor stress concentration and ultimately leading to higher fretting fatigue strength.

Study on bending fretting fatigue behaviour of 15-5PH stainless steel with different fretting regimes

The failure of the aircraft spline shaft was attributed to overstressing, cyclic bending loads, and other complex conditions. This study investigates the bending fretting fatigue behaviours and failure mechanisms of 15–5PH stainless steel. The study analysed the residual stress, microstructure, morphology, and chemical state of the worn surface and the fatigue failure mechanisms. The results showed that fretting wear significantly reduces the bending fatigue life. The surface residual stress transitions from compressive to tensile stress states. The value of residual stress increased, and the oxygen content of the worn surface was higher in the mixed fretting regime. Fatigue fractures occur at a depth of 50–100 µm below the surface in the present experiment.

Plain and fretting fatigue characteristics of 16MnCr5 steel under cyclic bending loading with the application of engine piston pin

The current study examined the plain fatigue and the fretting fatigue behaviors of the piston pin alloy (16MnCr5 steel) under fully-reversed rotating bending loading. The standard fatigue testing sample was cut out from the piston pin used in internal combustion engines. Furthermore, the failure mechanisms of samples were studied using field emission scanning electron microscopy. The obtained result indicated that the fatigue lifetime of 16MnCr5 steel was significantly affected by the fretting damage. The investigation of the failure mechanisms determined that the fracture behavior of the specimens under the plain fatigue and fretting fatigue conditions was brittle; however, it was considerably influenced by the casting defects in the samples. The test results can merely be used to compare the fatigue performance of the studied material under different conditions. More naturalistic experiments are required for further optimization in designing components made from this material to improve their reliability and service life, especially in contacting surfaces under rotating bending conditions.

Fretting fatigue behavior of metal injection molded stainless steel MIM 316L with small pores and low porosity

The fretting fatigue of metal injection molded stainless steel (MIM 316L) with a mean pore diameter of 3 μm and porosity of 5.1% was investigated both experimentally and numerically. The granular-like wear debris accumulated in pores on the fretted surface of the MIM 316L specimen was the cause of the reduction in the tangential force coefficient, potentially improving fretting fatigue strength. These pores did not significantly influence the location of fretting crack nucleation and crack path due to high stress concentration at the fretting contact edge. Under the large-scale yielding at the crack tip and fretting-contact-induced crack opening/closure, a continuum body finite element model can be applied to estimate crack nucleation and propagation behavior, as well as fretting fatigue life.

Development of a Graph-GPT Model for Predicting (Fretting) Fatigue Behavior, Accounting for Experimentally Observed Scatter Phenomena Influenced by Microstructure Inhomogeneity

Development of a Graph-GPT Model for Predicting (Fretting) Fatigue Behavior, Accounting for Experimentally Observed Scatter Phenomena Influenced by Microstructure Inhomogeneity

Effect of contact stress and slip amplitude on fretting fatigue behaviour of ultrasonic surface nanocrystallized TC11 titanium alloy

In this paper, combined experimental and numerical methods are applied to investigate the effect of different contact stress and slip amplitude on the fretting fatigue (FF) behaviour of TC11 titanium alloy with gradient nanostructure introduced by ultrasonic surface rolling process (USRP). The properties of gradient nanostructure are characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray residual stress tester, microhardness tester. As evidenced by the FF experimental results, USRP can significantly improve the FF life of TC11 by introducing large compressive residual stress and work hardening layer. The dominant parameters in improving the FF resistance under different loading conditions are investigated. In addition, the simulated results from Abaqus show that contact stress plays a more important role in influencing FF life compared to fretting bridge span, which is attributed to the change in slip amplitude and stress concentration. Fretting fatigue life initially increases and then decreases with contact stress and there is a contact stress threshold that leads to minimum lifetime. This threshold of USRP specimens is greater than that of untreated specimens. The transition of fretting mode along with contact stress is observed and discussed.

Prediction of the effect of shot peening residual stress on fretting fatigue behaviour

Fretting occurs at two contact bodies, which sustain oscillation loading. The fretting phenomenon decreases the fatigue lifetime dramatically. Shot peening is a commonly used surface treatment to enhance the resistance to damage because the residual stress is introduced to the surface of the material. Some studies showed that residual stress was helpful to improve fatigue lifetime. Under fretting fatigue condition, there are two main stages: crack initiation stage and the crack propagation stage. In this paper, the authors apply the Critical Plane (CP) method combined with the Theory of Critical Distance (TCD) to study the fretting fatigue crack initiation behaviour under the influence of shot peening residual stress, including the crack initiation position, orientation and the crack initiation lifetime. Meanwhile, the Linear Elastic Fracture Mechanics (LEFM) theory and the Extension Maximum Tangential Stress (EMTS) criterion are adopted to study crack propagation behaviour considering shot peening residual stress effect. The results show that the methods applied in this paper can make good predictions of fretting fatigue behaviour, including both initiation and propagation stages. Meanwhile, the influence of residual stress in these two stages are studied as well.

Very high cycle fretting fatigue behavior of IN718 reinforced by IN625/20 % WC laser cladding

The objective of this study is to evaluate the very high cycle fretting fatigue (VHCFF) behavior of laser cladding (LC) Inconel 718 (IN718) metal matrix composites reinforced with IN625/20 % WC. Experiments and simulations were conducted to analyze the fretting fatigue behavior of the cladding layer. The wear and fracture morphologies were obtained by using a confocal laser scanning microscope (CLSM) and a scanning electron microscope (SEM). The multiaxial fatigue damage parameters of the FS and SWT models were used to predict fatigue life through the fitting curve, and the critical plane method was adopted to predict the crack initiation and propagation path. Results indicate that the predicted crack corresponds well with the real crack of the specimen. WC particles can improve the anti-fatigue performance of the contact surface, which is proportional to the contact area between the WC and fretting pad.

Fretting fatigue behavior and damage mechanism of cast Al-Si-Cu-T6 alloy under two surface roughness conditions

This paper experimentally evaluates the fretting fatigue properties of cast Al-Si-Cu-T6 alloys against nodular cast irons with two surface roughnesses. A softening phenomenon contrary to the cyclic response behavior of plain cyclic loading is pointed out and discovered to be affected by persistent damage and cumulative plastic deformation. Two considerably different roughness conditions produce two entirely distinct damage mechanisms, and a schematic diagram is drawn to illustrate the discrepancy. The initiation and propagation of cracks are not only affected by fretting wear damage but also significantly depend on the microstructure, especially the α-Fe and (β + ω) phases play key roles. The realization of this research comprehensively reveals the fretting damage mechanism of Al-Si cast alloys under two characteristic contact surface states, which serves the fretting failure analysis of aluminum castings in the automotive industry.

Fretting fatigue tests and microstructure analysis of bridge stay cable wires

AbstractSaddle systems are a popular method for supporting the cables at the pylons of cable‐stayed bridges. Fretting fatigue failure of bridge stay cables is a major design consideration for saddle systems. Current design provisions require large‐scale tests of these anchoring systems. However, such tests are costly and time‐consuming. With this in mind, the current paper presents a small‐scale fretting fatigue setup to evaluate the fretting fatigue behavior of bridge stay cable wires at saddle supports. In this paper, fretting tests are conducted on bare and galvanized wires. Hourglass samples are then used to evaluate the material properties and plain fatigue performance of the studied wires. Finally, the microstructure of the wires is evaluated, and the influence of defects on the fretting fatigue life of the wires is discussed.

Effect of friction stir processing on plain fatigue and fretting fatigue behaviour of the AA6063 alloys

The present work investigated the effect of friction stir processing (FSP) on the plain fatigue and fretting fatigue of the AA6063 alloys. The FSP had noticeably smaller grains than the base material. The ultimate tensile strength of the FSP increased by 31.6 %. The fatigue life of the FSP specimen was improved by approximately 10 % in plain fatigue and 28.3 % in fretting fatigue. Increment in life is caused by grain refinement and increased compressive stress. The fretting wear damage and value of the coefficient of friction were observed to be more significant in the case of base material instead of FSP. For base and FSP materials, the life was reduced by 1.6 and 1.18 times, respectively, due to fretting fatigue over plain fatigue.

Experimental study on the fretting fatigue of Inconel 718 superalloy

Fretting fatigue is a surface damage phenomenon appearing in mechanical assemblies subjected to time-varying contact forces. This type of failure is a very frequent problem in many engineering components, with special relevance in the blade-disc connections in aircraft gas turbines. In this study, different plain and fretting fatigue tests were done using different load levels and also under two different temperatures, at room temperature and high temperature (650 °C), in order to obtain the fretting fatigue behaviour in both conditions and compare them with that of plain fatigue test. The contact pair used to carry out these tests is the frequently used cylindrical pad pressed against a dog-bone test specimen with a rectangular cross-section. The material used to manufacture both elements is the often used Nickel alloy Inconel 718, which is widely used in the manufacture of gas turbine parts. Moreover, and because the material was received in annealed condition, this material was heat treated to improve its mechanical properties. Results of tests under different conditions are analysed and compared. Subsequently, the fracture surfaces for different specimens are analysed and fatigue crack growth rate under different testing conditions are presented and compared with data from the literature.

The effect of geometry on fretting fatigue test results in Al7075-t651 specimens with cylindrical contact

Fretting fatigue is a material damage phenomenon that produces damage on the contact surface, such as wear and surface cracks that can grow through the specimen. It is possible to reproduce the phenomenon in a laboratory using different geometries. In the absence of a common guide, this work studies the effect of different geometries of specimens and contact pairs on the fretting fatigue behaviour. This paper compares the results of a fretting fatigue test campaign made with cylindrical contact pairs made of AL7075-T651 alloy. In addition, 3D numerical models are developed to analyse the stress/strain fields and asses the total life. According to the experimental and numerical results, the differences of total life obtained between the geometries considered are negligible.

Fretting-fatigue of shrink fit lug-bush assemblies: Interference-fit effect

The fretting-fatigue behaviour of shrink fit lug-bush assemblies is investigated. In this paper, experimental fatigue tests are carried out on lug-bush specimens with three different levels of interference fit. It is observed that the relative movements of fretting induce tribo-oxidation phenomena at the shrink-fit interface and that the crack initiation sites correspond well to the oxides formation spots. The increase in the fatigue life with interference fit is consistent with stress analysis considering the SWT multiaxial fatigue criterion, but the predicted fatigue life is not conservative relative to material reference data. In order to account for fretting surface damage, different approaches are investigated considering homogeneous and heterogeneous distributions of the coefficient of friction.

Fretting fatigue of Inconel 718 at room and elevated temperatures considering both constant and cyclic normal contact loads

This work investigates the influence of cyclic normal contact load on the fretting fatigue behavior of the Inconel 718 alloy at room and elevated temperatures. Fretting fatigue and friction tests with constant and cyclic contact load were conducted at 20 °C and 540 °C. Moreover, to estimate fretting fatigue life, numerical models (including and neglecting wear) were used in conjunction with the SWT parameter and a non-local stress approach. Experiments showed that the cyclic normal contact load has a beneficial effect on fatigue life. Additionally, no significant difference was observed for the measured friction coefficient whether considering constant or cyclic contact load. However, friction coefficient was significantly reduced at 540 °C. Generally, the life estimate approaches here considered yielded satisfactory results.