Influence of lubrication on the friction and wear of car rolling bearings

The goal of the work is to develop computational and experimental approaches to determine the wear resistance of friction units with internal contact of cylinders with slip. The scientific novelty consists in taking into account the slip for calculating the friction path and the wear of the cylinders with internal contact and the proposed method for identifying the parameters of the wear law based on the test results. Practical value is the proposed methods to account load, slip and lubrication conditions on the resource for the design of friction units. The dependences for determining the friction path for internal rolling of cylinders have been considered. The design of an experimental setup for studying friction and wear of cylinders with slip has been proposed. Experimental studies have been carried out: paths of friction; wear of surfaces both with a key and without a key; the effect of lubricants on wear has been studied. The form of the wear model is proposed to determine the effectiveness of methods for increasing wear resistance. The method for determining the parameters of the wear law has been implemented based on the test results. The results show the efficiency of copper powder as an additive to a lubricant. It has been established that the wear of cylinders with a key is greater than the wear of cylinders without a key due to different friction paths. A practical example of determining the wear of a car hub shaft using the wear patterns is presented.

Analysis of radial roller bearing rating life in complex loading conditions

An approach for accurate life analysis of radial roller bearings in complex loading conditions is presented. It employs ISO~16281 and accounts not only for external radial loads applied to the inner ring, but also for (i) internal bearing clearance, (ii) flexibility of the bearing rings, (iii) rings out-of-roundness, (iv) inertia effects, (v) rolling elements profile and (vi) rings misalignment. In the last decades these factors have been becoming more and more important for modern high-performance jet engines, whose shafts are commonly hollow and the housing and the rings thicknesses may be of comparable magnitudes. To obtain the distribution of internal contact forces, an advanced static model of a bearing with deformable, potentially misaligned, rings is developed. The bending deformations of the rings are reproduced superimposing deformed shapes from each of the arising internal contact force applied individually. Bearing rollers are allowed to have non-cylindrical profile, its geometry is approximated by means of slices each having constant diameter. A robust numerical scheme for solving the resultant set of equations with the aid of the barrier functions method is constructed. To increase even further the accuracy of rating life analysis, distributions of the contact stresses between the roller and the ring surfaces, obtained by solving numerically the problem of non-Hertzian interaction, are added to computations. A numerical benchmark test is presented to demonstrate the applicability of the developed approach. It shows how the aforementioned factors influence the bearing contact forces and its rating life.

MODERNIZATION THE STAGE OF METHYLAMINES RECTIFICATION IN JSC «ANHK»

The article describes the experience of JSC «ANHK» in modernizing the most en ergy-intensive stage of methylamine production in replacing the outdated grooved plates. The low productivity of the installation and the large diameters of the columns for the production of methyla mines forced to take a non-standard approach to the selection and replacement of internal contact devices. The modernization made it possible to obtain a significant economic effect several times greater than the costs of developing and implementing the project

Scanning Electron Microscopic Evaluation of the Internal Fit Accuracy of 3D-Printed Biphasic Calcium Phosphate Block: An Ex Vivo Pilot Study

The aim of this study was to assess the internal fit accuracy of a three-dimensional (3D)-printed biphasic calcium phosphate (BCP) block compared with a 3D-milled poly methyl methacrylate (PMMA) block by scanning electron microscope (SEM) analysis. In a total of 20 porcine rib bones, two different types of defects having two adjacent walls and a floor were produced: a defect with a flat floor (flat defect; N = 10) and a defect with a concave floor (curved defect; N = 10). Each defect was grafted with either the 3D-printed BCP block or the 3D-milled PMMA block fabricated following the computer aided design. The defects were then cut cross-sectionally and evaluated under the SEM. The extents of internal contact and gap were measured and statistically analyzed (p < 0.05). All blocks in both BCP and PMMA groups were successfully fit to the flat and curved defects. The internal contact ratio was significantly higher in the BCP group (flat defect: 0.47 ± 0.10; curved defect: 0.29 ± 0.05) compared with the PMMA group (flat defect: 0.21 ± 0.13; curved defect: 0.17 ± 0.04; p < 0.05). The internal gap area was similar between the two groups regardless of the defect types ( p> 0.05). The internal fit accuracy of the 3D-printed BCP block was reliable in both the flat and curved defects when compared with the accuracy of the 3D-milled PMMA block.

A Disc-Type High Speed Rotary Ultrasonic Motor with Internal Contact Teeth

This paper presents a disc-type ultrasonic piezoelectric motor, which is designed for micro flying vehicles. It provides a high output rotation speed under low operating voltage, compared with common piezoelectric devices, by employing a “contact teeth” wave transmission structure. The ultrasonic motor (USM) consists of a trimorph disc stator, with triple internal contact teeth, a shaft and two hemispheric hard-wearing rotors. The operating principle of the USM is based on the superposition of the in-plane B03 vibration mode of the trimorph disc, and the first longitudinal vibration of the contact teeth. An optimization method of the stator structure parameters was proposed and validated by numerical modeling. The diameter and thickness of the stator are 20 mm and 1 mm, respectively. A prototype with the weight of 2 g was made for this experimental test. The optimal frequency of the excitation signal and the preload force are 98.5 kHz and 0.5 N, respectively. The minimum operating voltage was tested under 7.5 V and reached the speed of 225 rpm, and the maximum unloaded rotational speed of the USM reached 5172 rpm when 30 V driving voltage was applied. The maximum lifting force generated by this USM was measured as 46.1 mN, which is 2.35 times bigger than its weight.

Through a Black Hole into Parallel Universes

The Anglo-Saxon immigration of the 5th-6th centuries AD led to a dual contact situation in the British Isles: with the native inhabitants of the settlement areas in south-eastern England (internal contact zone), and with the Celtic polities outside the Anglo-Saxon areas (external contact zone). In the internal contact zone, social and ethnogenetic processes resulted in a complete acculturation of the natives by the 9th century. By contrast, the external contact zone between Anglo-Saxon and Celtic polities resulted in a cultural and linguistic split right across the British Isles up to the 7th century, and arguably well beyond. The cultural boundary between these two domains became permeable in the 7th century as a consequence of Anglo-Saxon Christianization which created a northern communication zone characterized by a distinct art style (Insular Art). In the early medieval British Isles, contact resulting from migration did not lead to cultural exchange for about two centuries, and it took profound ideological and social changes to establish a basis for communication.

MODELLING OF METHYLAMINE RECTIFICATION PROCESS

The article considers the results of the survey and simulation of the unit for rectification of metilamines in the conditions of JSC "ANHK" with the issuance of recommendations on replacement of internal contact devices, change of material flows and decommissioning of two rectification columns. The implementation of the recommendations allowed to ensure continuous operation of the plant and to reduce the costs of heating steam, electricity and water

PROBLEM POINTS OF LIGHT-NAPHTHA RECTIFICATION PROCESS OF ISOMERIZATION TECHNOLOGY

Approaches of problem points estimation for increasing productivity and increasing the accuracy of isolating the C5-C6 fraction in light naphtha isomerization technology are considered. It is shown that the elimination of these problem points is possible by increasing the efficiency of existing internal contact devices of the distillation column, or by increasing the efficiency of the furnace. The final solution to the problem should be determined on the basis of mathematical modeling of the process.