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Title: An analysis of axisymmetric receding contacts
Author: Da Ponte Lopes, Jhonatan
ISNI:       0000 0004 9356 7419
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2020
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Bolted joints are one of the most used types of fixture in industry and when the contact area is small compared with the joint’s thickness, they represent an example of receding contacts, which are characterised by the reduction of the contact area when a loading is applied. Despite their ubiquity, axisymmetric receding contacts are not fully understand, and the current literature on the problem is limited either to plane problems or to frictionless cases. This thesis presents an analysis of the frictional behaviour of fundamental axisymmetric receding contacts. The geometry of the problem is represented in an idealised format, through the contact of a semi-infinite thin layer of material and an elastic half-space. This allows for a precise solution to be found. The methodology consists of assuming that the bodies are fully adhered and applying circular dislocation densities as nuclei of strain to correct the stresses when conditions of partial slip and separation are violated. Singular integral equations with Cauchy kernels are posed and solved in order to recover Signorini and orthogonality conditions. In Part I, the methodology is implemented and verified through the solution of ring cracks in a half-space and the frictional behaviour of a shaft/hub system under partial slip subjected to an extraction force and to a torque. Part II presents the solution for the thin layer resting against an elastic half-space under three different normal loadings: uniform pressure outside a disk (stamping loading); concentrated force; and uniform pressure over a disk. It was shown that the receding contacts modelled present the basic properties that the contact snaps upon the application of any load, the interfacial tractions are proportional to the applied load, the extent of the contact size and slip zone are independent of the load, and the tractions are independent of the material parameters (namely the Poisson’s ratio).
Supervisor: Hills, David Sponsor: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior ; Rolls-Royce
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Solid mechanics ; Contact mechanics