scholarly journals Prediction of the contact pressures and resource of metal-polymer linear cylindrical plain bearings

2021 ◽  
Vol 49 (3) ◽  
pp. 627-633
Author(s):  
M. Chernets ◽  
A. Kornienko ◽  
O. Radko ◽  
A. Radionenko
Keyword(s):  
Service Life ◽  
Sliding Friction ◽  
Theory Of Elasticity ◽  
Computational Method ◽  
Radial Clearance ◽  
Initial Contact ◽  
Base Diameter ◽  
Different Types ◽  
Contact Pressures ◽  
Metal Polymer

Different types of linear bearings (guides) are widely used in practice in various equipment, as in many other areas of human activity. In particular, this applies to cylindrical guides (linear plain bearings) of reciprocating motion. However, despite their considerable distribution, in fact, there are no reasonable methods for calculating the wear and service life of not only metal but also metal-polymer linear bearings. According to the author's method, the influence of load, base diameter and radial clearance on the maximum initial pressures in this bearing was investigated within the plane contact problem of the theory of elasticity. Further, using the computational method according to the author's tribokinetic model of wear during sliding friction, the effect of the composite bushing wear on the change of the initial contact characteristics (contact pressures and contact angle) was evaluated. The forecast calculation of the service life of the bearing depending on the above factors is also carried out. Quantitative and qualitative regularities of dependence of contact pressures and a resource on the accepted factors are established.

scholarly journals Predictive Estimation of Sliding Bearing Load-Carrying Capacity and Tribological Durability

2021 ◽  
Vol 67 (7-8) ◽  
pp. 363-368
Author(s):  
Myron Chernets ◽  
Marek Opielak ◽  
Anatolii Kornienko ◽  
Oleg Radko
Keyword(s):  
Contact Angles ◽  
Theory Of Elasticity ◽  
Computational Method ◽  
Radial Clearance ◽  
Initial Contact ◽  
Sliding Bearings ◽  
Load Carrying ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Increasing Load

A computational method is presented as a method for solving a plane contact problem of the theory of elasticity to determine the contact strength and tribological durability of sliding bearings. The effect of load and radial clearance on the initial contact pressures and their reduction due to wear is studied. The durability of the bearing is estimated. Qualitative and quantitative regularities of changes in contact parameters and durability from the factors under study are established. In particular, it has been shown that both contact angles and maximum contact pressures are approximately linearly dependent on the load, and the durability decreases nonlinearly with increasing load.

STUDY OF WEAR RESISTANCE OF REINFORCED POLYAMIDE COMPOSITES FOR METAL-POLYMER GEAR DRIVES

Tribologia ◽  
2018 ◽  
Vol 279 (3) ◽  
pp. 19-23
Author(s):  
Myron CHERNETS ◽  
Serge SHIL'KO ◽  
Mikhail PASHECHKO
Keyword(s):  
Wear Resistance ◽  
Sliding Friction ◽  
Gear Wheel ◽  
Gear Ratio ◽  
Carbon Fibres ◽  
Gear Drive ◽  
Glass Fibres ◽  
Gear Drives ◽  
Contact Pressures ◽  
Metal Polymer

An experimental study of the wear resistance of two dispersion-filled composite materials based on polyamide used in metal-polymer gear drives with a 30% volume content of short glass or carbon fibres was performed according to the technique proposed by the authors. As a result of tribotests in the “pin-disk” scheme, the mass wear of these composites was determined under dry friction conditions for steel 45 at room temperature in the range of contact pressures of 10–40 MPa, as well as the kinetics of the coefficient of sliding friction and the contact temperature of the tribosystem elements. It was established that polyamide strengthened by carbon fibres has almost four times higher wear resistance in comparison with a polyamide filled with glass fibres. The wear resistance characteristics that are the basic parameters of the tribokinetic wear model are calculated, using the durability of the straight spur metal-polymer gear drive on the basis of the original calculation method. It was established that gear drive durability with a pinion or a wheel reinforced with carbon fibres is more than eight times the durability of gear drive with gear wheels from polyamide filled with glass fibres. The gear drive durability with the steel pinion and the composite gear wheel increases in proportion to the gear ratio as compared to the gear drive with the composite pinion and the steel wheel. The change in the maximum contact pressures in the mesh interval was calculated.

Modelling of contact and tribotechnical parameters of metal–polymer gears taking into account wear and correction of teeth

2021 ◽  
pp. 135065012110546
Author(s):  
Myron Chernets ◽  
Anatolii Kornienko ◽  
Yuriy Chernets ◽  
Svetlana Fedorchuk
Keyword(s):  
Glass Fibers ◽  
Analytical Calculation ◽  
Computational Method ◽  
Linear Wear ◽  
Spur Gears ◽  
Optimal Values ◽  
Maximum Contact ◽  
Contact Pressures ◽  
Improved Methods ◽  
Metal Polymer

The estimation and the analysis of the arising contact pressures and tribotechnical parameters, that is, wear and durability, of metal-polymer spur gears using the author's computational method are presented in this study. Gears with a steel gear and pinion made of polyamide PA6 modified with dispersed carbon fibers (CF) or glass fibers (GF) whose content was 30%, PA6 + 30CF and PA6 + 30GF correspondingly, are studied. This took into account the parity of engagement, the effect of composite pinion teeth wear and gear correction. Quantitative and qualitative regularities of change of the specified parameters depending on composite type and gear correction type are established. It is found that the teeth wear of composite toothed wheels has a significant effect on reducing the values of the initial maximum contact pressures in the engagement. The distribution of linear wear along the teeth working profile and the localization of its maximum values, depending on the correction of engagement, are determined. The minimum durability of metal–polymer gears is calculated by simplified and improved methods. The optimal values of the correction coefficients at which the minimum durability is highest for both combination types of metal–polymer gears with height and angular teeth correction are established. The durability of metal–polymer gears with a driving pinion made of PA6 + 30CF composite calculated with the improved method is about seven times higher than the pinion made of PA6 + 30GF composite. In contrast to the methods of calculation of metal gears known from publications, the method presented in this study takes into account such practically significant factors as change of radii of tooth profile curvature owing to wear, their correction and number of teeth pairs at the engagement. In metal–polymer gears, there are no analytical calculation methods for modelling wear and tribological durability compared with that of the author's method.

Optimization of Cold-Formed Channel Sections Using Imperialist Competitive Algorithm

2012 ◽  
Vol 166-169 ◽  
pp. 493-496
Author(s):  
Roya Kohandel ◽  
Behzad Abdi ◽  
Poi Ngian Shek ◽  
M.Md. Tahir ◽  
Ahmad Beng Hong Kueh
Keyword(s):  
Sequential Quadratic Programming ◽  
Optimization Problems ◽  
Imperialist Competitive Algorithm ◽  
Computational Method ◽  
Compression Force ◽  
Sqp Method ◽  
Competitive Algorithm ◽  
Different Types ◽  
Formed Channel ◽  
Good Agreement

The Imperialist Competitive Algorithm (ICA) is a novel computational method based on the concept of socio-political motivated strategy, which is usually used to solve different types of optimization problems. This paper presents the optimization of cold-formed channel section subjected to axial compression force utilizing the ICA method. The results are then compared to the Genetic Algorithm (GA) and Sequential Quadratic Programming (SQP) algorithm for validation purpose. The results obtained from the ICA method is in good agreement with the GA and SQP method in terms of weight but slightly different in the geometry shape.

scholarly journals Wear Calculation for Sliding Friction Pairs

2014 ◽  
Vol 51 (2) ◽  
pp. 41-54 ◽  
Author(s):  
G. Springis ◽  
J. Rudzitis ◽  
A. Avisane ◽  
A. Leitans
Keyword(s):  
Service Life ◽  
Sliding Friction ◽  
Theoretical Calculations ◽  
Quality Level ◽  
Wear Process ◽  
Measuring Devices ◽  
Proposed Model ◽  
Wear Calculation ◽  
Production Technologies ◽  
Micro Topography

Abstract One of the principal objectives of modern production process is the improvement of quality level; this means also guaranteeing the required service life of different products and increase in their wear resistance. To perform this task, prediction of service life of fitted components is of crucial value, since with the development of production technologies and measuring devices it is possible to determine with ever increasing precision the data to be used also in analytical calculations. Having studied the prediction theories of wear process that have been developed in the course of time and can be classified into definite groups one can state that each of them has shortcomings that might strongly impair the results thus making unnecessary theoretical calculations. The proposed model for wear calculation is based on the application of theories from several branches of science to the description of 3D surface micro-topography, assessing the material’s physical and mechanical characteristics, substantiating the regularities in creation of the material particles separated during the wear process and taking into consideration definite service conditions of fittings.

Estimation of Service Life of Mechanical Engineering Components

2019 ◽  
Vol 799 ◽  
pp. 71-76
Author(s):  
Oskars Linins ◽  
Ernests Jansons ◽  
Armands Leitans ◽  
Irina Boiko ◽  
Janis Lungevics
Keyword(s):  
Service Life ◽  
Service Time ◽  
Surface Texture ◽  
Mechanical Engineering ◽  
Friction Pair ◽  
Theory Of Elasticity ◽  
New Approach ◽  
Material Fatigue ◽  
Texture Parameters ◽  
3D Surface Texture

The paper is aimed to the methodology for estimation of service life of mechanical engineering components in the case of elastic-plastic contact of surfaces. Well-known calculation methods depending on physics, theory of probability, the analysis of friction pair’ shape and fit include a number of parameters that are difficult or even impossible to be technologically controlled in the manufacturing of mechanical engineering components. The new approach for wear rate estimation using surface texture parameters as well as physical-mechanical properties and geometric parameters of components is proposed. The theoretical part of the calculations is based on the 3D surface texture principles, the basics of material fatigue theory, the theory of elasticity and the contact mechanics of surfaces. It is possible to calculate the service time of the machine, but the process of running-in of the components is relatively short (less than 5%), therefore, the service time is mainly determined by a normal operating period, which also was used to evaluate this period. The calculated input parameters are technologically and metrologically available and new method for calculating the service time can be used in the design process of the equipment. The results of approbation of the method for estimation service time of mechanical engineering, which prove the applicability of mentioned method, are offered as well.

scholarly journals Early-Age Cracking in Concrete: Causes, Consequences, Remedial Measures, and Recommendations

2018 ◽  
Vol 8 (10) ◽  
pp. 1730 ◽  
Author(s):  
Md. Safiuddin ◽  
A. Kaish ◽  
Chin-Ong Woon ◽  
Sudharshan Raman
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Real Life ◽  
Early Age ◽  
Structural Elements ◽  
Remedial Measures ◽  
Curing Conditions ◽  
Factors Affecting ◽  
Different Types ◽  
Service Conditions

Cracking is a common problem in concrete structures in real-life service conditions. In fact, crack-free concrete structures are very rare to find in real world. Concrete can undergo early-age cracking depending on the mix composition, exposure environment, hydration rate, and curing conditions. Understanding the causes and consequences of cracking thoroughly is essential for selecting proper measures to resolve the early-age cracking problem in concrete. This paper will help to identify the major causes and consequences of the early-age cracking in concrete. Also, this paper will be useful to adopt effective remedial measures for reducing or eliminating the early-age cracking problem in concrete. Different types of early-age crack, the factors affecting the initiation and growth of early-age cracks, the causes of early-age cracking, and the modeling of early-age cracking are discussed in this paper. A number of examples for various early-age cracking problems of concrete found in different structural elements are also shown. Above all, some recommendations are given for minimizing the early-age cracking in concrete. It is hoped that the information conveyed in this paper will be beneficial to improve the service life of concrete structures. Concrete researchers and practitioners may benefit from the contents of this paper.

scholarly journals Calculation of Contact Pressures in Cylindrical Metal-Polymer Sliding Guides

2021 ◽  
Vol 15 (3) ◽  
pp. 30-33
Author(s):  
Myron Chernets ◽  
Mykhaylo Pashechko ◽  
Anatolii Kornienko ◽  
Anatoly Ishchenko
Keyword(s):  
Cylindrical Metal ◽  
Contact Pressures ◽  
Metal Polymer

Theoretical Prediction of the Lift-Off Speed in Aerodynamic Compliant Foil Journal Bearings

2010 ◽  
Author(s):  
Shemiao Qi ◽  
Y. S. Ho ◽  
Haipeng Geng ◽  
Lie Yu
Keyword(s):  
Theoretical Prediction ◽  
Generalized Solution ◽  
Journal Bearings ◽  
Numerical Results ◽  
Computational Method ◽  
Radial Clearance ◽  
Eccentricity Ratio ◽  
Foil Bearings ◽  
Lift Off ◽  
Air Film

In aerodynamic bearings, since the supporting air film is generated by rotor motion, there is no support at the start of motion. As in all such bearings, there is dry rubbing until the rotor achieves sufficient speed to lift-off. Thus, the lower the lift-off speed, the less will be the rubbing and so the greater will be the life of the bearing. This paper focuses on the theoretical prediction of lift-off speed in aerodynamic compliant foil journal bearings based on a generalized solution of elasto-aerodynamically coupled lubrication for compliant foil bearings. A computational method is presented which is used to predict the lift-off speed in aerodynamic foil journal bearings with eccentricity ratio greater than or equal to 1.0. Special emphasis is placed on investigating the effects of the load imposed on the bearing, the nominal radial clearance and the bearing radius on the lift-off speed. The numerical results obtained indicate that lift-off speed decreases with the decrease of load and nominal radial clearance, but with an increase in bearing radius. The eccentricity ratios are all greater than 1.0 at the lift-off speed for the aerodynamic compliant foil journal bearings used in this study.

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