Journal of Modern Mechanical Engineering and Technology

Wear Resistance of Amorphous-Crystalline Coatings Under Boundary Friction

2025-03-13T19:19:41+00:00

The results of tests under boundary friction conditions are present detonation coatings Zr-Al-B in a wide range of changes in friction conditions.

The obtained results were compared with the parallel tested coatings based on tungsten carbide type WK-15, also with samples of 30HGSNA steel and BrOCS6-6-3 bronze.

The qualitative and quantitative composition of surface layers participating in boundary friction conditions was assessed using modern physical methods of analysis. Profilograms and microphotographs of friction surfaces of amorphous-crystalline coatings are presented, showing that under boundary friction conditions, coating samples are smoothed, which leads to a decrease in roughness.

Installed the presence of the formation of solid solutions of oxygen interstitialization in zirconium, which corresponds to the formation of secondary structures of the first type on friction surfaces, the characteristic feature of which is their surface localization, ultra-dispersed structure, the ability to minimize destruction and screen unacceptable adhesive phenomena. Using Auger electron microscopy, it was confirmed that oxygen completely replaces sulfur in surface structures.

It is shown that the studied detonation coatings Zr-Al-B, developed for practice, have high tribotechnical characteristics in the entire range of tests under boundary friction conditions. At the same time, as a result of studies of the mechanism of tribochemical transformations of hydrocarbons and the properties of transformed surface films, it was established that they retain lubricating properties and provide high antifriction characteristics of the friction system in the entire wide range of changes in boundary friction conditions.

Application of Wave Technologies for the Preparation of Fuels Containing Organic Waste Pyrolysis Products

2025-05-20T15:34:22+00:00

Products of fast pyrolysis of organic materials (bio-oil) have such advantages as ease of storage and transportation, production from renewable raw materials, but have not yet found wide application as motor and boiler fuels. The article describes the results of research aimed at obtaining such fuel containing petroleum fuel oil and bio-oil as the main components. Direct mixing of these components is a difficult task due to their chemical incompatibility. Its solution required the development of technology and devices, which was the purpose of the presented research results. The research methodology was based on mathematical modeling of the processes of mixing fuel components, analysis of its results, their transfer to natural samples and their experimental study. As a result, a technology and design of mixers were developed that made it possible to obtain a stable mixed fuel containing fuel oil and bio-oil in the following proportions of the mass ratio up to 50:50. The obtained results confirmed the correctness of the chosen approach, which made it possible to develop new technology and equipment to achieve the stated research goal.

Single-Layer 79 GHz Microstrip Patch Array for All-Weather Automotive Radar

2025-06-23T09:11:44+00:00

Advanced driver-assistance systems (ADAS) demand radar sensors that combine centimetre-level resolution, wide angular coverage, and all-weather reliability, yet must fit behind a plastic bumper at automotive cost. This study meets that challenge with a fully self-contained 79 GHz front-end fabricated on a single-layer RO3003 printed-circuit board.

Closed-form cavity models, applied from first principles, yield patch dimensions without iterative tuning. Sixteen patches arranged in a 4 × 4 half-wavelength array deliver 16 dBi broadside gain, 3.2 GHz (−10 dB) impedance bandwidth, and a 33° half-power beam-width, thereby covering the entire 76–81 GHz allocation.

Solving the radar-range equation shows that even under 8 dB km⁻¹ heavy-rain attenuation the sedan detection limit contracts by only 2 m (51 m → 49 m), while motorcycle and pedestrian ranges are virtually unaffected. To our knowledge, this is the first single-layer PCB radar front-end to achieve such performance without empirical tuning, and it offers a clear upgrade path toward imaging radar and highway ACC.

A Statistical Methodology of Cyclic Plasticity Inhomogeneity at Grain Scale

2025-07-16T16:06:27+00:00

The inhomogeneous plastic deformation has important effects on the manufacturing process and the fatigue property of mechanical products. To directly and correctly evaluate the deformation inhomogeneity of grain scale under cyclic loading, a statistical method is proposed and named as the normalized standard deviation. The method is comprised of the following steps: (1) Construct a representative volume element (RVE) of polycrystalline by Voronoi tessellation and electron backscatter diffraction, and calculate the grain strain by a constitutive model of crystal cyclical plasticity. (2) Deal with grain strain data of RVE by Min-max normalization method. (3) Compute the standard deviation of the normalized data as the identification of mesoscopic inhomogeneity. In order to validate the proposed normalized standard deviation, the contrastive analyses with the strain contours, the weighted standard deviation and the coefficient of variation are conducted at the same conditions of cyclic loading. The results demonstrated that the normalized standard deviation was the best as the indication of cyclic plasticity inhomogeneity among the above methods.