Papers by Keyword: Fretting Fatigue

Abstract: Reliable fretting fatigue prediction requires rigorous evaluation of analytical methods under realistic loading conditions. This study builds upon previous research on the fretting fatigue behavior of 42CrMo4+QT steel by incorporating new experimental data from square cross-section specimens tested under axial loading with various pad geometries. The application of a non-zero tensile mean bulk load promoted localized crack initiation near the specimen edges, leading to more asymmetric crack growth in the majority of cases unlike the more symmetric behavior observed under fully reversed loading (R = –1). Finite element analysis (FEA), along with the Dang Van and Papuga QCP methods, was employed to evaluate whether this behavior could be accurately modeled. In addition, a linear-elastic fracture mechanics approach was used to model and explain these observations. Furthermore, fretting fatigue tests on 34CrNiMo6+QT steel revealed that tribological effects governed crack initiation, in contrast to the stress-driven failure observed in 42CrMo4+QT. These findings enhance understanding of fretting fatigue mechanisms and improve predictive modeling approaches.

Abstract: The FEM analysis evaluated how varying tightening loads affect diaphragm fatigue life at the position where fretting fatigue is most critical. Increasing body-side tightening load significantly shortened fatigue life, while increasing piece-side load slightly extended it. Under high body-side load, the beneficial effect of greater piece-side load became more noticeable. These findings indicate differing impacts from each side, with the body-side load having a stronger influence. An optimal tightening load balance may exist to maximize fatigue life.

Abstract: 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.

Abstract: The critical plane-based multiaxial criterion originally proposed by the authors for plain fatigue is here applied to estimate the crack initiation life of fretting high-cycle fatigued structural components. Although fretting fatigue can be regarded as a case of multiaxial fatigue, the common multiaxial fatigue criteria have to be modified to account for the severe stress gradients in the contact zone. Therefore, the above criterion is used in conjunction with the Taylor’s point method to numerically estimate the fatigue life of Ti-6Al-4V and Al-4Cu specimens under cylindrical contacts.

Abstract: The fretting is responsible for many failures of components in the industry. It is present in assemblies like rivet and screw fixture, dovetailjoint, shaft and hub with key, and all connections of two bodies with a contact force and a small induced relative displacement. Topic of studies for decades, the researchers perform experimental tests with some simplification in order to accelerate the phenomenon, some times using standard devices or creating dedicated machines for better representing the behavior of the desired components. There are a few studies with thin sheets, in which the fretting fatigue has more impact because a small reduction of the cross section due to the wear of crack results in a significant increase of stress and rate of crack propatation, decresing the number of cycles until failure. In this work, it wasbuild a device to generate the fretting fatigue with two different shape of contact pad. The specimen is a stainless steel sheet thickness 0.152mm, which fractures and surfaces were analyzed using the SEM and white light interferometer to understand the fractures.

Abstract: Fretting fatigue denotes the detrimental effect on a material arising from the cyclic sliding of two contacting surfaces with small relative displacements between them. One or both of the components in contact may be subject to bulk stresses caused by cyclic loads. The assessment of the fretting fatigue strength and life of any component is a complicated issue due to the many parameters affecting it, the complexity of the stress fields cyclic variation during fretting and the uncertainties associated to the contact conditions. This paper describes some singular aspects of fretting fatigue related to strength analysis and testing, presents a procedure developed by the authors during the last years to estimate the fretting fatigue strength and life and compares the assessment outcomes with the results of tests carried out by different authors.

Abstract: In the present study fretting fatigue behaviour of 12-Cr steels at 300°C has been investigated under three different contact pressures. For comparisons fretting fatigue behaviour of 12-Cr steels at room temperature has also been investigated. The result showed that with an increase in contact pressure and temperature, the fretting fatigue significantly reduces. Finite element analyses were carried out to evaluate the stress distribution (tangential stress and compressive stress) at the contact during fretting fatigue. Tangential stress range – compressive stress range diagram (TSR-CSR diagram) were constructed for 12-Cr steel at room temperature and at 300°C. Then, a generalized TSR-CSR diagram to predict fretting fatigue strength of 12-Cr steel regardless of contact pressure and temperature was constructed.

Abstract: Fretting fatigue is an important failure mode of dovetail attachments in gas turbine engines. One of the most difficult challenges in carrying out experiments of components with actual geometry is the design of fixtures for the dovetail attachments since it can change the stress distribution under a given load. A circular arc dovetail attachment specimen with a tenon at each end respectively was designed and machined to simulate the fatigue damage that occurs in wide-chord fan blade attachments, so it can perform two dovetail attachment simulations at each time, and its related fixture was connected with the testing machine by two pins which were orthogonal to each other so as to eliminate additional bending moment. An Instron 8802 servo-hydraulic fatigue testing system was used to provide fatigue loads. Furthermore, Finite Element (FE) analysis based on the experimental configuration was carried out to obtain the stress distribution on the contact surface, crack initiation location and number of cycles to the fretting fatigue failure were predicted based on the FE results. The results show a good agreement with the experimental counterparts.

Abstract: Recently, high-strength alloy steels have been developed and used for various products. It is well known that fretting fatigue does not show fatigue limit. In other words, fretting fatigue failure may occur in very high cycle regime more than 10⁷ cycles. However, it is difficult to investigate fretting fatigue property in very high cycle regime by using conventional fatigue testing machines because it is time-consuming. In this study, a fretting fatigue testing method for carburized alloy steels in very high cycle regime is explored by using an ultrasonic torsional fatigue testing machine. Carburized SCM420H was used for investigation. The experimental results showed that it is possible to conduct fretting fatigue testing of carburized alloy steels by using an ultrasonic torsional fatigue testing machine.

Abstract: The influence of functionally graded TiN coating on fretting fatigue behavior of titanium alloy was investigated. The coating was deposited using an ion beam assisted deposition technique. TiN film was fabricated by an electron beam evaporation of titanium and simultaneous nitrogen ion bombardment. An acceleration voltage of ion beam was set at 0.2 or 2.0 keV. The functionally graded layer was fabricated by varying the mixing ratio of nitrogen/argon ion beam. The mixed layer became thicker by an increase in acceleration voltage. The adhesive strength and wear resistance were improved with an increase in the acceleration voltage. Moreover, they were significantly improved by inserting the functionally graded layer. The fretting fatigue tests were conducted using a four-point bending fatigue testing machine. The fretting fatigue life of specimen coated with monolayer TiN film was longer than that of uncoated specimen. The TiN coating with functionally graded layer was the most effective to improve the fretting fatigue life.