Papers by Keyword: Fretting Wear

Abstract: This study aims to address these challenges by evaluating the displacement and interfacial damage of acetabular components with auxetic inner structures under cyclic loading conditions. Aseptic loosening of the acetabular cup is one of the primary causes of implant failure in hip replacements. However, assessing the damage behavior of implants in vivo remains a significant challenge, particularly when evaluating implant displacement and interfacial damage. A cantilever device for displacement measurements was designed and calibrated using a laser displacement sensor. The cantilever device successfully measured the displacement of the acetabular cup by monotonic and cyclic loading up to-2.3kN. Both AE sensors and cantilever devices could measure the increasing displacement in both the rotational and embedding directions. Finally, the loosening mechanism of the acetabular cup with an auxetic texture was discussed.

Abstract: Fretting wear primarily impacts the bushing of the con-rod, subsequently influencing the con-rod's overall performance. In this investigation, the contact interactions between the con-rod small end, the small end cover, and the bushing under conditions of utmost combustion pressure were investigated. This analysis included examining the contact pressure and friction stress distribution. Subsequently, an orthogonal simulation test was developed to further investigate these interactions. The study took into account the friction coefficient of the interface and the quantity of interference as test factors based on contact mechanics theory. The objective functions were the utmost friction stress and contact pressure, ascertained under conditions of peak combustion pressure. Based on the findings from this study, the contact pressure of the top portion of the bushing is lower than that of the bottom portion. The friction stress of the top portion of the bushing is larger than that of the bottom portion. The optimal values for the interference amount and friction coefficient are 0.11 and 0.15, respectively, which will result in the most favorable conditions for minimizing fretting wear in the bushing.

Abstract: Ti-Nb alloys in deionized water and Hanks' balanced salt solution were investigated at 310K using a ball-on-disc type frictional test machine with a ZrO2 ball counterface. In this study, besides the fretting wear behavior of Ti-Nb alloys was investigated, the relationship between the microstructure and mechanical properties of the Nb-added Ti alloy was investigated, and the relationship between the composition and hardness on the fretting wear of the alloy will be clarified from the results of the wear volume and surface analysis of wear track. The results obtained from the frictional test indicate that the dynamic coefficient of friction converged to a constant value with time variation. Also, wear volume in HBSS was smaller than in water, and wear volume of heat-treated became smaller than As-Rolled. Microstructural observations suggest the scars of adhesive wear were observed. Comparing each morphology, the ratio of the peeling part was more significant in Ti-Nb alloys, which have α+β than in Ti-Nb alloys, which have only β. Moreover, the results of Open circuit potentiometry indicate that the corrosion potential difference increased with wear. This is most likely due to the passive film was damaged. Besides, the corrosion potential difference of β-Ti-Nb alloy heat-treated with HBSS is small. It is assumed that there is an influence of HBSS besides the fine structure.

Abstract: It is well known that damage caused by wear and tear of the mechanical parts always seriously affect the accuracy of machinery. It is very important to improve the material properties of the mechanical elements. Anti-abrasion can improve the durability of machinery and equipment, thereby enhancing industrial competitiveness. Hence, it is important to establish the key technology of wear resistance for the related industries. Since the aluminum-silicon alloys are commonly used on the conditions of severe fretting wear, it is necessary to improve the fretting wear resistance before they are used. Therefore, effects of T6 heat treatment on fretting wear resistance of the aluminum-silicon alloys were investigated in this study. The experimental results of this paper will be very beneficial to the future of precision machinery and vehicle industry to develop more internationally competitive products.

Abstract: Based on the laboratory micro-motion contact resistance test system, fretting characteristics of the two contact pairs of gold-plated probe and tin-plated samples, gold-plated samples and tin-plated probe, is carried out at different plating thickness, contact force and temperatures. The contact pairs after the fretting experiment were subjected to temperature and humidity test and salt spray test to analyze its environmental reliability. 0.76μmAu-Sn has better fretting characteristics than 4μm Sn-Au. When the contact force is greater than or equal to 100 gf, the two kinds of contact pair exhibit good fretting characteristics. Thickness of sample plating is more important than that of probe. The influence of ambient temperature on fretting contact performance is the weakest. The increase of contact resistance of contact pair 4μm Sn-Au is higher than that of 0.76μmAu-Sn after accelerated environmental simulation experiments.

Abstract: Surface defect is the main form of axle failure. In this paper, the cause of surface defect on wheel seat of a certain type of dynamic axle is analyzed systematically. In the test, the macroscopic chemical component of inspection axle was determined using spectrometer. And the chemical composition near the crack was detected by energy disperse spectroscopy and X-ray photoelectron spectroscopy analysis. The microstructure of the crack area was observed by optical microscope, while the crack microscopic characteristic was characterized using scanning electron microscope and confocal laser scanning microscope. The study found that, the defect is transverse crack, which was distributed circumferentially along the wheel seat. Further more, the typical features of wear or friction and iron oxide was observed on the wheel seat near the crack area. It was concluded that, due to surface presure and the existence of stress concentration, which the wheel and axle interference fit resulted in, wear abrasion and fretting fatigue initiated fatigue crack.

Abstract: This work presents a numerical formulation to compute wear in ber-reinforced composite materials that are subjected to fretting wear contact conditions. The formulation is based on authors' previous works [1, 2] and presents contact and wear constitutive laws which consider micromechanical aspects such as the ber orientation relative to the sliding direction, the ber volume fraction or the ber length. The formulation uses the Boundary Element Method (BEM) for computing the elastic in uence coef cients and contact operators over the augmented Lagrangian to enforce contact constraints. The proposed formulation is applied to compute and study wear in different carbon berreinforced bulk and fi lm con gurations.

Abstract: A finite element framework based on dual mortar methods is presented for simulating fretting wear effects in the finite deformation regime. The mortar finite element discretization is realized with Lagrangean shape functions as well as isogeometric elements based on non-uniform rational B-splines (NURBS) in two and three dimensions. Fretting wear effects are modeled in an incremental scheme with the help of Archard’s law and the worn material is considered as additional contribution to the gap function. Numerical examples demonstrate the robustness and accuracy of the presented algorithm.

Abstract: The paper deals with the upper and lower limits estimation of the friction work and fretting wear in the contact of nuclear fuel rods with fuel assembly (FA) spacer grid cells. The friction work is deciding factor for the prediction of the fuel rod cladding abrasion caused by FA vibration. Design and operational parameters of the FA components are understood as random variables defined by mean values and standard deviations. The gradient and three sigma criterion approach is applied to the calculation of the upper and lower limits of the friction work and fretting wear in particular contact surfaces between the fuel rod cladding and some of spacer grid cells. The fuel assembly vibration is excited by pressure pulsations of the cooling liquid generated by main circulation pumps in the coolant loops of the NPP primary circuit. The method is applied for hexagonal type nuclear fuel assembly in the VVER type reactors.

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.