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Study of Contact Parameters in Metal-On-Plastic Hip Endoprosthesis with the Analytical-Numerical Method of Contact Mechanics

Chernets Myron, Zubrzycki Jarosław

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 3

145--153

EN

The purpose is to analyze the influence of the elastic characteristics of the materials of the tribological pair: acetabular–femoral head on the maximum pressures in the hip joint endoprosthesis. Based on the proprietary calculation method of hip joint endoprostheses, an analysis of the impact of UHMW-PE elasticity characteristics (Young's modulus and Poisson's ratio) on the contact parameters was carried out: maximum contact pressure, and contact angle. The study determined the value of contact pressures depending on the changes in the elastic characteristics of UHMW-PE and changes in the geometry of the tribological pair (variable radii of the Grade2TDN head and the UHMW-PE acetabulum). It was found that increasing Young's modulus of UHMWPE increases its stiffness, which causes a noticeable increase in contact pressures in the endoprosthesis. The quantitative and qualitative regularities of this impact were determined. The developed method allows for earlier estimation of contact pressures depending on the external load (patient's body weight), and geometric parameters of the artificial hip joint (diameter of the endoprosthesis head and the acetabulum). This allows you to make a personalized endoprosthesis resistant to damage. It is very important in modern medicine because life expectancy in developed countries is longer and the durability of endoprostheses should be 10–12 years. Hospital statistics show that the need for total hip replacement concerns even younger people. Implantation of a hip joint prosthesis is an invasive and costly procedure, hence the need to produce prostheses with a long service life (over 15-20 years) before re-arthroplasty. The obtained test results showed that the use of an endoprosthesis cup made of UMHW-PE with higher stiffness (high E1 value and low ν value) results in an increase in maximum contact pressures p(0). Increasing the Poisson's ratio in the tested range causes an increase in the contact pressure p(0) even 1.1 times. Increasing the diameter of the head of the D2 endoprosthesis decreases the contact pressure by an average of 2.32 times. On the other hand, a change in the radial clearance  in the tribological pair of the hip endoprosthesis from 0.1 mm to 0.2 mm causes an increase in contact pressures by an average of 1.35 times.

2

Evaluation of Wear Resistance of Functional Composite Polymeric Materials and Durability of Metal-Polymer Bearings

Chernets Myron, Świć Antoni, Kornienko Anatolii, Yurchuk Alina

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 2

258--267

EN

A method of tribological testing of models with such sliding friction using a simple pin-on-disc mechanism was presented. Wear resistance indicators of unfilled polyamides PA6, PA66 and composites based on polyamide PA6+30GF, PA6+30CF, PA6+MoS2, PA6 and oil coupled with steel C45 are determined. They, as polymeric materials with the property of self-lubrication, they are often used in metal-polymer dry friction bearings. Based on them, wear resistance characteristics of these polymeric materials at sliding friction are established. They are used as basic parameters for developed by authors mathematical model of material wear kinetics at sliding friction and analytical research method of metal-polymer sliding bearings research. For comparative assessment of wear resistance of the investigated polymeric materials, their wear resistance diagrams are constructed. Thef show the functional dependence of wear resistance on specific friction forces. It is proved that the wear resistance of materials nonlinearly depends on specific pressure, i.e., the specific friction forces. Qualitative and quantitative influence of the type and structure of fillers (which improve the tribological properties of the base polymer PA6) on their wear resistance has been established. The forecast estimation of durability of metal polymer bearings made of the specified polyamides by the author's method of calculation taking into account their various wear resistance, characteristics of elasticity and conditions of dry friction is carried out. The research results are presented graphically, which facilitates their understanding and analyses.

3

Investigation of the Effect of Young’s Modulus on the Contact Strength of Metal Polymer Plain Bearings

Chernets Myron, Pashechko Mykhaylo, Kornienko Anatolii, Borc Jarosław, Zakhariia Roman

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

67--73

EN

Using the author's method of research of hybrid (metal-polymer) plain bearings the calculation of their load carrying capacity (contact pressures) is carried out. Studies have been conducted for metal-polymer bearings with a bushing of two types of polymer composites: epoxy based antifriction composite materials DIAMANT Moglice (DIAMANT Metallplastic GmbH) and DK6 (PT) (fillers - graphite, MoS2, Zr). The elastic constants of composite materials, in particular the Young's modulus, have a noticeable effect on the contact pressures in metal-polymer bearings. The Young's modulus is significantly different in these composite materials. In accordance with this factor, the influence of load, bushing diameter and radial clearance on the maximum contact pressures was studied. Quantitative and qualitative regularities of maximum contact pressures from the accepted factors of influence: Young's modulus, loading, bushing diameter, radial clearance, type of bushing material are established. The obtained results are compared with the results obtained by known conventional calculating methods of contact pressures.

4

Calculation of Contact Pressures in Cylindrical Metal-Polymer Sliding Guides

Chernets Myron, Pashechko Mykhaylo, Kornienko Anatolii, Ishchenko Anatoly

Advances in Science and Technology. Research Journal

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2021

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Vol. 15, no 3

30--33

EN

Guides (linear plain bearings) of reciprocating motion are widely used in many areas of human activity. However, at present there are no reasonable methods for their calculation, in particular metal-polymer guides. The author's method of contact strength calculation of cylindrical metal-polymer sliding guides is presented in the article. The effect of load, bushing diameter and radial clearance on the maximum contact pressures and their distribution in the guide was studied on the example of epoxy-based polymer composite material Moglice of the German company DIAMANT Metallplastic GmbH, which is used to restore tribotechnical sliding systems elements. Quantitative and qualitative regularities of dependence of contact pressures on the accepted factors of influence are established: at loading increase four times the maximum contact pressures and contact angles will increase twice irrespective of change of sizes of a radial clearance and diameter of a base; increasing the base diameter leads to a directly proportional decrease in maximum contact pressures; doubling the radial clearance leads to a -fold increase in pressure, regardless of changes in the magnitude of the load and the diameter of the base. Regularities of change of contact parameters from the specified factors are given graphically.

5

Prediction of the Service Life of Metal-Polymer Gears Made of Glass and Carbon Fibre-Reinforced Polyamide, Considering the Impact of Height Correction

Chernets Myron, Kornienko Anatolii

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 3

15--21

EN

Calculation methods for predicting the service life of metal-polymer gears with height correction are proposed. Two methods for gear service life estimation are presented: a simplified method that assumes constant tooth interaction conditions and an improved method that takes into account wear-induced changes in tooth interaction conditions. Spur cylindrical gears with a steel gear and a pinion made of polyamide composite reinforced with carbon and glass fibres are studied. The effect of height correction on the service life of the gears is examined, considering the type of tooth engagement. It is established that with the improved method the service life of the gear is by up to 1.3 times longer than that calculated by the simplified method at optimal height correction coefficients. Optimal service life of the gear is achieved when the correction coefficients are x1 = – x2 = 0.1. The effect of the coefficient of friction on gear service life is investigated. It is found that the service life of the gear with a carbon fibre-reinforced pinion is by 8.1...9.3 times longer than that of the gear with a glass fibre-reinforced pinion.

6

On the Question of Methodology of Hybrid Sliding Bearings Estimated Load Capacity and Durability Evaluation

Chernets Myron, Pashechko Mykhaylo, Kornienko Anatolii, Chernets Juriy, Fedorchuk Svetlana

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 4

177--184

EN

The computational method of hybrid (metal-polymer) sliding bearings according to the load capacity and durability of the bushing made of polyamide filled with glass or carbon dispersed fibers was presented. The initial contact pressures were calculated and the influence of bushing wear on their relative reduction was investigated. The wear resistance of bearings with bushings made of both polymer composites was also evaluated. Regularities of their change from loading, diameter of the bushing and radial clearance were established.

7

Experimental estimation of wear resistance of polyamide composites, reinforced by carbon and glass fibres used in metal-polymer gearings

Chernets Myron, Kindrachuk Myroslav, Kornienko Anatolii, Yurchuk Alina

Acta Mechanica et Automatica

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2020

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Vol. 14, no. 4

206--210

EN

The method of model triboexperimental studies to determine the basic mathematical model parameters of materials wear resistance at sliding friction is considered. The quantitative relative experimental characteristics of wear resistance of glass fibre and carbon fibre reinforced polyamide used in metal-polymer gear couple have been determined. Wear resistance functions of these functional polymeric composites have been established as the basic ones in the tribokinetic mathematical model of material wear for sliding friction conditions. Also, according to the conducted researches, wear resistance diagrams were constructed. They may be used as graphical indicators of wear resistance in the required range of specific friction forces. The dependences that connect the characteristic functions of wear resistance of these materials (obtained by the developed mathematical tribokinetic wear model) with linear wear and gearing service life are presented.

8

Method of calculation of tribotechnical characteristics of the metal-polymer gear, reinforced with glass fiber, taking into account the correction of tooth

Chernets Myron

Eksploatacja i Niezawodność

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2019

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Vol. 21, no. 4

546-552

EN

The paper proposes a new method for calculating the service life, wear and contact pressures of metal-polymer gear drives with a correction profile. The effects of height and angular modification in a gear drive made of dispersive glass fibre-reinforced polyamide and steel on its contact and tribocontact parameters are determined. A numerical solution obtained for the gear with height correction has shown that the life of such gear is the longest when the profile correction coefficients x1 = −x2 = 0.1. It has been found that the service life of the gear with angular correction is shorter than that of the gear with correction height. The effects of gear tooth height and angular correction on maximum contact pressures and pinion wear are examined and determined.

PL

Predstawiono opracowaną nową metodę obliczeniową resursu, zużycia oraz nacisków stykowych przekładni walcowej metal – polimerowej z korekcja uzębienia. Dla przekładni z kołami zębatymi z poliamidu wzmocnionego dyspersyjnym włóknem szklanym i stali zostało przeprowadzone oszacowanie wpływu korekcji technologicznej oraz konstrukcyjnej uzębienia na wskazane parametry kontaktu oraz tribokontaktu. Na podstawie numerycznego rozwiązania zagadnienia dla przypadku korekcji technologicznej zębów kół określono, że największa trwałość przekładni będzie, gdy współczynniki korekcji x1 = −x2 = 0.1. Ustalono, że wtedy przy korekcji konstrukcyjnej zębów trwałość przekładni będzie mniejsza nieżeli przy korekcji technologicznej. Został przebadany charakter wpływu korekcji technologicznej oraz konstrukcyjnej zębów na maksymalne naciski stykowe, zużycie zębnika oraz ustalono jego prawidłowości.