查看更多>>摘要：This special issue of the Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology contains selected papers from the 10th International Conference on Tribology - BALKANTRIB '20, which was held on May 20-22, 2021. The International Conference on Tribology - BALKANTRIB is supported by the Balkan Tribological Association and is organised every three years since 1993, each time in a different Balkan country. The previous conferences were held in Bulgaria (1993 and 2008), Greece (1996 and 2011), Romania (1999 and 2014), Turkey (2002 and 2017) and Serbia (2005). The 10th jubilee BALKANTRIB conference was organised in Belgrade, by the Serbian Tribology Society and the University of Belgrade, Faculty of Mechanical Engineering.
查看更多>>摘要：Metal glass fibre reinforced composites which are considered as advanced composite materials play a significant role in aerospace, marine and automotive industries. In the current study, an attempt has been made to examine the tribological characteristics of glass fibre reinforced plastic (GFRP) composite filled with aluminium oxide (Al_2O_3) and silicon carbide (SiC) powder particles. Experiments were performed on pin-on-disc tribometer to evaluate the friction and wear rate as a function of normal load and sliding velocity under different conditions. For each composition of glass-epoxy composite filled with and without fillers, sliding tests were performed with normal load (20 N, 40 N, 60 N, 80 N 100 N) and sliding velocity (2.62 m/s, 4.18 m/s, 5.23 m/s, 6.85 m/s, 7.85 m/s) respectively. The metal GFRP composites were fabricated using hand-lay-up technique. The filler content (SiC & Al_2O_3) in epoxy-glass composite were varied. SiC was varied from 0 to 10% while Al_2O_3 was kept constant at 5%. To study the worn surface of glass-epoxy composite material scanning electronic microscopy is used. Before and after the experiment, weights of the composites (pin specimens) were studied on digital balance for wear loss. The present studies reported that the fabricated metal epoxy-fibre composite has performed excellent wear resistance when compared with epoxy-fibre composite without metal powders. The present work findings offer new insights into reinforcement in epoxy-glass composites with metal powders.
Igor MukhortovIgor LevanovKseniya YakuninaElena Zadorozhnaya...
6页
查看更多>>摘要：The study aim is to develop methods of efficiency enhancement for the antiwear additives in the lubricants based on hydrocarbon oils. The tribological properties of triaryl and trialkyl phosphorothionates with similar hydrocarbyl groups have been compared. The testing has been carried out in the contact unit of combined rolling and sliding friction. It has been shown that trioctyl phosphorothionate is considerably superior to tribenzyl phosphorothionate and triphenyl phosphorothionate in antifriction and antiwear properties. The obtained results validate the suggestion that for a given polar group contained in an antiwear additive molecule the maximal efficiency can be achieved with sufficiently great hydrocarbonyl groups, when their structures are similar to the prevailing structure of the lubricant hydrocarbon molecules.
Ivan StebakovAlexey KornaevSergey PopovLeonid Savin...
15页
查看更多>>摘要：The paper deals with the application of deep learning methods to rotating machines fault diagnosis. The main challenge is to design a fault diagnosis system connected with multisensory measurement system that will be sensitive and accurate enough in detecting weak changes in rotating machines. The experimental part of the research presents the test rig and results of high-speed multisensory measurements. Six states of a rotating machine, including a normal one and five states with loosened mounting bolts and small unbalancing of the shaft, are under study. The application of deep network architectures including multilayer perceptron, convolutional neural networks, residual networks, autoencoders and their combination was estimated. The deep learning methods allowed to identify the most informative sensors, then solve the anomaly detection and the multiclass classification problems. An autoencoder based on ResNet architecture demonstrated the best result in anomaly detection. The accuracy of the proposed network is up to 100% while the accuracy of an expert is up to 65%. A one-dimensional convolutional neural network combined with a multilayer perceptron that contains a pretrained encoder demonstrated the best result in multiclass classification. The detailed fault detection accuracy with the determination of the specific fault is 83.3%. The combinations of known deep network architectures and application of the proposed approach of pretraining of the encoders together with using a block of inputs for one prediction demonstrated high efficiency.
查看更多>>摘要：Wear of a friction pair of brake (brake disc and pads), in addition to reducing the active safety of vehicles, leads to the formation of particles that can affect the environment and human health. In addition to the technologies that are being developed for the collection of particles created by the wear of brakes during braking process, today new materials are being introduced, as well as various technologies for processing friction pairs with the aim of reducing brake wear and thus the formation of particles. Furthermore, today, technologies for coating (cladding) the friction surfaces of disc brakes with some materials are increasingly applied and researched, in order to reduce the wear intensity (wear rate) of disc brakes, i.e. the emission of particles created by wear of friction pairs. The aim of this paper is to analyse and review different deposition techniques and materials used for brake discs coatings, as well as the effect it has on the wear rate of friction pair. There are many coating deposition techniques, and special attention is paid to the technology of laser hardfacing of brake rotors.
查看更多>>摘要：A hardening of high velocity oxy-fuel sprayed Inconel 625 coating systems was performed by pulsed plasma nitriding treatment. After deposition of an Inconel 625 coating, samples were pulsed plasma nitrided at 520℃ for 12 h in a gas ratio of 3:1 N_2 and H_2 under a constant pressure of 2.5 × 10~2 Pa. Pulsed plasma nitriding improved the microhardness of the high velocity oxy-fuel sprayed Inconel 625 coating from 355 to 401 HV_(0.05). The high velocity oxy-fuel-sprayed Inconel 625 coating after pulsed plasma nitriding process showed excellent corrosion resistance as well as a reduction of both the friction coefficient and wear rate during the sliding phase in a 3.5 wt.% NaCl solution against sliding action of Al_2O_3 ball.
查看更多>>摘要：The report presents the positron annihilation studies of subsurface zone generated in pure titanium exposed to a long period dry sliding test. The total depth of the subsurface zone induced is detected at about 250 μm. Only dislocations and vacancy clusters which consist of two or three vacancies are observed in this zone. Their concentration decreases with the depth, especially at the depth above 100 μm. Despite the long duration of the sliding test, no clear signs indicating the presence of a tribolayer were observed. This was confirmed also by observation of annealing of defects in this zone at different depths. The lack of the tribolayer is in contrast to the research done so far for other metals.
Erick Martinez-MendezDaniel Antonio-AguirreManuel Vite-TorresJose F Marquez-Santiago...
7页
查看更多>>摘要：In the automotive industry, galling is a huge problem either for the tool life or the quality of the stamping metal component. Galling is a severe form of scuffing associated with gross damage to the surface or failure. This work aims to carry out a series of experiments of galling tests at different loads and similar roughness with 6061 aluminum and D2 steel, common materials used in automotive components and tools respectively. A tribometer was employed to generate Galling wear, the button-on-button configuration, according to the ASTM G-196-08 standard. The results show the threshold of minimum load without galling wear. Post-test-surface analysis of the specimens was conducted by confocal microscopy to identify the damage generated during the wear tests. Additionally, a couple of friction tests were carried only to illustrate the friction coefficient behavior under galling conditions.
Nikolaos A FountasKonstantinos KitsakisKyriaki-Evangelia AslaniJohn D Kechagias...
6页
查看更多>>摘要：This work investigates the effect of 3D-printing parameters on surface roughness in polylactic acid printed material by adopting Taguchi's design of experiments approach. The control parameters under study were: number of shells, printing temperature, infill rate, and printing pattern. As the response, mean surface roughness (Ra) was selected. The control parameters were assigned to an L9 orthogonal array to organize the experiments and obtain the mean surface roughness results. It is concluded that printing temperature is the dominant parameter that affects surface roughness when it comes to 3D printing of polylactic acid material followed by printing pattern, infill rate, and the number of shells.
查看更多>>摘要：Agricultural equipment is working in very high-stress conditions. However, it has a significant influence on the wear losses of soil processing parts. Chisel is operating at 30 cm working depth at a maximum of 12 km·h~(-1) working speed. Due to unpredictable soil conditions, chisel tines suffer high wear losses. It leads to time consumption and cost expenses during the soil preparation period. Wear resistance, and agronomical requirements (working depth, loosening of soil) are the main criteria of agricultural equipment producers. The discrete element method is a solution that simulates soil as sphere shape particles with soil properties. Wear results reveal the change of parts shape, acting forces, and stresses during the simulation in the virtual soil bin. The used Rocky DEM software uses a parameter C (volume/shear work ratio) to describe wear intensity, which varies for different geometry. Chisel tine geometry should be divided into sections with varied parameter C according to stress acting on the surface. The test conditions can be used for future wear analysis of varied tool geometry and protection (sintered tungsten carbide plates, hard-faced surface, etc.) agricultural tools to compare its durability in different soil conditions.
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