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You searched for subject:(Finite line contacts). Showing records 1 – 2 of 2 total matches.

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Loughborough University

1. Votsios, Vasilis. Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids.

Degree: PhD, 2003, Loughborough University

The thesis is concerned with the contact mechanics behaviour of non-conforming solids. The geometry of the solids considered gives rise to various contact configurations, from concentrated contacts with circular and elliptical configuration to those of finite line nature, as well as those of less concentrated form such as circular flat punches. The radii of curvature of mating bodies in contact or impact give rise to these various nonconforming contact configurations and affect their contact characteristics, from those considered as semi-infinite solids in accord with the classical Hertzian theory to those that deviate from it. Furthermore, layered solids have been considered, some with higher elastic modulus than that of the substrate material (such as hard protective coatings) and some with low elastic moduli, often employed as tribological coatings (such as solid lubricants). Other bonded layered solids behave in viscoelastic manner, with creep relaxation behaviour under load, and are often used to dampen structural vibration upon impact. Analytic models have been developed for all these solids to predict their contact and impact behaviour and obtain pressure distribution, footprint shape and deformation under both elastostatic and transient dynamic conditions. Only few solutions for thin bonded layered elastic solids have been reported for elastostatic analysis. The analytical model developed in this thesis is in accord with those reported in the literature and is extended to the case of impact of balls, and employed for a number of practical applications. The elastostatic impact of a roller against a semi-infinite elastic half-space is also treated by analytic means, which has not been reported in literature. Two and three-dimensional finite element models have been developed and compared with all the derived analytic methods, and good agreement found in all cases. The finite element approach used has been made into a generic tool for all the contact configurations, elastic and viscoelastic. The physics of the contact mechanical problems is fully explained by analytic, numerical and supporting experimentation and agreement found between all these approaches to a high level of conformance. This level of agreement, the development of various analytical impact models for layered solids and finite line configuration, and the development of a multi-layered viscoelastic transducer with agreed numerical predictions account for the main contributions to knowledge. There are a significant number of findings within the thesis, but the major findings relate to the protective nature of hard coatings and high modulus bonded layered solids, and the verified viscoelastic behaviour of low elastic modulus compressible thin bonded layers. Most importantly, the thesis has created a rational framework for contact/impact of solids of low contact contiguity.

Subjects/Keywords: 620.37; Contact mechanics; Layered elastic solids; Viscoelastic contacts; Impact dynamics; Semi-infinite solids; Hertzian contact; Finite line contact

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Votsios, V. (2003). Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids. (Doctoral Dissertation). Loughborough University. Retrieved from http://hdl.handle.net/2134/11815

Chicago Manual of Style (16th Edition):

Votsios, Vasilis. “Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids.” 2003. Doctoral Dissertation, Loughborough University. Accessed September 29, 2020. http://hdl.handle.net/2134/11815.

MLA Handbook (7th Edition):

Votsios, Vasilis. “Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids.” 2003. Web. 29 Sep 2020.

Vancouver:

Votsios V. Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids. [Internet] [Doctoral dissertation]. Loughborough University; 2003. [cited 2020 Sep 29]. Available from: http://hdl.handle.net/2134/11815.

Council of Science Editors:

Votsios V. Contact mechanics and impact dynamics of non-conforming elastic and viscoelastic semi-infinite or thin bonded layered solids. [Doctoral Dissertation]. Loughborough University; 2003. Available from: http://hdl.handle.net/2134/11815

2. Alakhramsing, Shivam Sharwien. Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts.

Degree: 2019, University of Twente

Cam-roller followers are part of the valve train mechanisms found in internal combustion engines. Valve train friction losses may contribute up to 10% of the total engine friction losses. The lubricated cam-roller follower unit consists of two lubricated contacts, namely the cam-roller contact and roller-pin contact. While the former is a non-conformal contact, the latter is a conformal contact. The traction induced by the cam-roller contact drives the roller. It is important to study friction between the cam and roller as it influences the engine efficiency and the onset of wear – and thus ultimately lifetime – of components. Understanding lubrication conditions in the cam-roller contact is complicated due to transient variations of the geometry, force and friction in the roller-pin contact. A very important variable, affecting the cam-roller lubrication performance, is the frictional force (which resists the motion of the roller) at the roller-pin contact. The lubricated cam-roller contact studied in this thesis is highly loaded with contact forces up to 16 kN. Important lubrication performance indicators of the cam-roller contact are the pressure, film thickness and frictional force. This thesis focuses on the factors influencing the aforementioned lubrication performance indicators. Relying on the aforementioned, the factors studied in this work are: •The influence of axial shape of the roller: The axial shape of the roller and its influence on the generated film thickness, pressure and friction in the cam-roller contact. This was done by means of a smooth surface finite element method (FEM)-based finite line contact elastohydrodynamic lubrication (EHL) model. The model shows the effects of parameters describing the axial shape of the roller, velocity, load and material properties on the lubrication performance indicators. •The influence of elastic deformation in the roller-pin contact: In order to better quantify the friction, film thickness and pressure in the roller-pin contact a similar smooth surface FEM-based EHL model was developed for the roller-pin contact. The model demonstrates the importance of allowing for elastic deformation of the conformal roller-pin contact and its effect on film thickness, pressure and friction coefficient. •The influence of roller-pin contact friction in the high slide-to-roll ratio (SRR) domain of the cam-roller contact: At increasing levels of friction in the roller-pin contact the amount of sliding at the cam-roller contact increases, in turn affecting the film thickness, pressure and cam-roller contact friction coefficient. In order to analyse the effects of higher values of roller-pin friction coefficient on the cam-roller lubrication performance, an infinite line contact mixed-thermo-elastohydrodynamic (TEHL) model was developed for the cam-roller contact. The mixed-lubrication model is based on the load-sharing concept and uses real surface roughness measurement data as input. The complete model is based on a smooth surface FEM-based EHL line contact model and a boundary… Advisors/Committee Members: de Rooij, Matthias B., Schipper, Dirk J..

Subjects/Keywords: Elastohydrodynamic lubrication; cam-roller; roller-pin; mixed-lubrication; roller slip; asperity contact; Friction; Stick-slip; slide-to-roll ratio; Finite Element Analysis; thermohydrodynamic; thermo-elastohydrodynamic; Finite line contacts; logarithmic rollers; coating

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Alakhramsing, S. S. (2019). Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts. (Doctoral Dissertation). University of Twente. Retrieved from https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html

Chicago Manual of Style (16th Edition):

Alakhramsing, Shivam Sharwien. “Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts.” 2019. Doctoral Dissertation, University of Twente. Accessed September 29, 2020. https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html.

MLA Handbook (7th Edition):

Alakhramsing, Shivam Sharwien. “Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts.” 2019. Web. 29 Sep 2020.

Vancouver:

Alakhramsing SS. Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts. [Internet] [Doctoral dissertation]. University of Twente; 2019. [cited 2020 Sep 29]. Available from: https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html.

Council of Science Editors:

Alakhramsing SS. Towards a fundamental understanding of the tribological behaviour of cam-roller follower contacts. [Doctoral Dissertation]. University of Twente; 2019. Available from: https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; 3ea78a51-f232-480d-80e3-5a27294d2f45 ; 10.3990/1.9789036546669 ; urn:isbn:978-90-365-4666-9 ; urn:nbn:nl:ui:28-3ea78a51-f232-480d-80e3-5a27294d2f45 ; https://research.utwente.nl/en/publications/towards-a-fundamental-understanding-of-the-tribological-behaviour-of-camroller-follower-contacts(3ea78a51-f232-480d-80e3-5a27294d2f45).html

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