Applied Engineering Letters

45-51

Authors: Alexander Pastukhov, Evgeny Timashov, Damjan Stanojević

The purpose of this work is to prove the effectiveness of a practical study of the temperature regime for diagnosing bearing assemblies of mechanical transmissions. Using the example of a two-row roller bearing of the rear support of the intermediate shaft of the vehicle transmission, the temperature in the friction zone under different transmission operating modes on a KAMAZ-5320 was calculated. Finite element analysis of temperature fields made it possible to determine the relationship between the temperature on the outer surface of the bearing assembly and the temperature in the friction zone through the coefficient k=0.327. The zone for temperature measurement – the bearing cover is determined and the maximum temperature of its heating is set. Thermal imaging observations confirmed the effectiveness of the developed method of technical diagnostics of bearings.

60-69

Authors: Hammad T. Elmetwally, Mostafa A. Abdelhafiz, M. N. El-Sheikh, Mahmoud E. Abdullah

Friction stir welding (FSW) is considered to be a solid-state welding technique that is suitable well for joining copper and aluminium sheets. The current experimental study focused on the influence of pin geometry on the micro-structural and mechanical characteristics of such joints. An aluminium sheet was welded to a copper sheet at a constant rotational speed of 1280 rpm and a traverse speed of 16 mm/min. The welding tool was made from W302 steel with four different pin profiles: straight cylindrical, tapered, triangular, and squared. When the squared pin was utilized, the optimum joint was produced as the specimen prepared from this joint had a defect- free structure and a tensile strength of 107.2 MPa (80% of the aluminium strength). On the other hand, the pin with a triangular profile was utilized to determine the minimum characteristics, and the specimens’ structures revealed dislocations, separations, and cracking in copper particles inside the aluminium matrix. The microhardness trend is consistent across all specimens. Moreover, specimens welded using squared and cylindrical pin tools have the maximum hardness values obtained at the stir zone of the copper side. The inspection of fractured surfaces showed well mixing between aluminium and copper as well as ductile fracture when a squared pin tool was used while it showed a combination of ductile fracture and brittle fracture for the specimen welded with a triangular pin tool. Based on this study, the use of the squared pin tool gives the most favourable results compared with other pin profiles.

80-90

Authors: Damir Nozica, Damir Blazevic, Tomislav Keser

Exponential progress in integrated circuits, best described by Moore’s Law, has enabled tremendous advances in applied computing. Today, more than ever, there are palm-sized embedded devices with computational capabilities millions of times greater than those of what was once the lead computer on the Apollo 11 mission. Such levels of integration enable the fusion of functionalities that were once unimaginable, or at least impractical. Furthermore, today’s existing technologies rely mostly on one or two communication technologies to organize UAVs for efficient search and rescue missions that largely do not utilize the communication convergence principle, thus omitting the potential for better search yield and rescue success. This paper recognizes that niche where communication convergence lacks its potential and presents a concept for the convergence of Wi-Fi, Bluetooth, LoRa and/or satellite IoT communication technologies to serve as an airborne communication infrastructure, a backbone generally, and enables a swarm of unmanned aerial vehicles (UAV) to communicate efficiently wherever there is no local terrestrial communication infrastructure (such as GSM, Wi-Fi, digital radio, etc.). The concept was elaborated and applied to a use-case localization application scenario (of Wi-Fi enabled devices) for the purpose of search during rescue operations.