Wear tests of wheelsets under real working. Therefore, a significant problem in the designing of wheelsets is the aim of the reduction of the excessive wear of wheelsets during operation. Any damage or wear may lead to derailment and cause a crash that may cost lives of hundreds of people. Their task is to guide the vehicle on the track. Wheelsets are among the key components of a rail vehicle. The appropriate hardness of the shaft top layer with coatings caused the mitigation of adhesion thus significantly reducing the development of fretting wear. The application of the coatings under testing produced the expected result. Scientific research indicates that adhesion is the process initiating the development of fretting wear in these tests an attempt was made to eliminate adhesion. The chemical analysis of wear products demonstrated their plastic deformation and oxidation. The microscopic observations of shaft surfaces revealed a similar image of fretting in both sample groups under testing, such an image consisting of wear in the form of material build-up, microgaps, micropits and microcracks. Macroscopic observations demonstrated the occurrence of fretting wear at shaft surfaces in both sample groups under testing, however, the range of wear occurring in samples with the CrN+OX coating was much smaller. Joint dimensions and operation conditions were chosen in such a way that operation conditions of rail vehicle wheel sets could be simulated.Īs part of laboratory tests, the macroscopic and microscopic observations of the shaft top layer wear and the microscopic observations of the sleeve/shaft joint surface were conducted. The analysis of fretting wear consisted in comparing wear images. The first comprised samples without coating, and in the second a CrN+OX multi-layer coating was applied onto shafts. Test samples were divided into two groups. Wear tests were conducted on the example of a sleeve/shaft connection operating in rotational bending conditions, and the negative allowance of 0.02 mm was taken. undertaken of the possibility of the application of PVD coatings to mitigate the development of fretting wear in press-fit joints. The application of PVD coatings may be a way of improving joint durability. Therefore, attempts to eliminate factors enhancing the development of wear should be made. Press-fit joints should be durable and reliable, and this pertains in particular to joints operating in severe conditions or those directly influencing safety, such as rail vehicle wheel sets. Specific driving current profiles Read more Wire conductors as the contact surface deforms and flows in response to Hardness and surface tension are related to materials transfer of the The value of temperature-dependent properties such as Characteristics of material transfer and a descriptive modelĪre presented. On the wear behavior and eventual failure of the armature wireĬonductors. The emphasis is on the effect ofĬurrent/contact under current densities greater than 1 kA/mm2 Of these wires were also tested on molybdenum rail conductors to assess The behavior of wires of silver, copper, aluminum, nickel, molybdenum,Īnd tantalum as armature conductors on ETP copper rail conductors. In simple railgunĮlectromagnetic launchers, the wear behavior of the widely-used aluminumĪlloys as sliding electrical contacts on copper rail conductors leads toĪ progressive change on the rail conductor surface as debris from theĪrmature/rail interaction adheres to the rail. Materials to observed armature performance. The goal of this work is to relate properties of armature It is shown that the proportional wearout model fits these data well but the time-scale model does not. The proportional wearout model is fit to sliding metal wear data, and the results are compared to the fit of the time-scale model used in. A goodness-of-test that may be applied to this model and other degradation models is proposed. A point estimate and a bootstrap confidence interval for the time-to-failure of the mean degradation curve under the usual use condition, t0, are obtained. The mean degradation curve and the acceleration factor for each stress level are estimated non-parametrically. A new model for accelerated degradation data called a proportional wearout model is proposed. This paper focuses on accelerated degradation models in life testing. The time-to-failure is defined as the time when a unit reaches a particular level of degradation. However, many products may degrade before failure, and it is possible to record the actual degradation on units as a function of time. In analyzing the reliability of a product, the quantity of interest is usually the time-to-failure.

Zan autopurge crash