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The coupling of the direct boundary element method with the finite element displacement technique in elastostatics

The coupling of the direct boundary element method with the finite element displacement technique in elastostatics
The coupling of the direct boundary element method with the finite element displacement technique in elastostatics

This work is concerned with the formation of an 'equivalent' stiffness matrix for a body, using a Direct Boundary Element method approach, which only requires a surface discretisation. This 'equivalent' stiffness matrix may then be treated in the same way as a Finite Element, and coupled into a global Finite Element formulation. 

The thus derived, equivalent stiffness matrix is not found to exhibit the inherent symmetry properties generally expected of a stiffness formulation, and this problem is examined in depth. A simple symmetrisation process is adopted, the validity and accuracy of which is also examined in the context of the overall symmetry considerations. 

The difficulties arising due to surface geometry discontinuities are also examined, and a technique is proposed for their solution. This is implemented for 2-Dimensional problems, but may readily be extended to 3-Dimensions. 

3-Dimensional problems involving finite and semi-infinite regions are treated using constant Boundary Elements, and both constant and linear element formulations are presented for the 2-D case. Finally an explicit formulation is presented for a 2-D half-space, loaded at the free surface, using constant, linear or quadratic elements, which does away with the necessity of numerical integration.

University of Southampton
Georgiou, Panos
5a7c8192-f19b-4bfd-a195-f50d0163bdb7
Georgiou, Panos
5a7c8192-f19b-4bfd-a195-f50d0163bdb7
Brebbia, C.A.
af8a7358-1c4e-431c-92f0-83206b962787

Georgiou, Panos (1981) The coupling of the direct boundary element method with the finite element displacement technique in elastostatics. University of Southampton, Doctoral Thesis, 267pp.

Record type: Thesis (Doctoral)

Abstract

This work is concerned with the formation of an 'equivalent' stiffness matrix for a body, using a Direct Boundary Element method approach, which only requires a surface discretisation. This 'equivalent' stiffness matrix may then be treated in the same way as a Finite Element, and coupled into a global Finite Element formulation. 

The thus derived, equivalent stiffness matrix is not found to exhibit the inherent symmetry properties generally expected of a stiffness formulation, and this problem is examined in depth. A simple symmetrisation process is adopted, the validity and accuracy of which is also examined in the context of the overall symmetry considerations. 

The difficulties arising due to surface geometry discontinuities are also examined, and a technique is proposed for their solution. This is implemented for 2-Dimensional problems, but may readily be extended to 3-Dimensions. 

3-Dimensional problems involving finite and semi-infinite regions are treated using constant Boundary Elements, and both constant and linear element formulations are presented for the 2-D case. Finally an explicit formulation is presented for a 2-D half-space, loaded at the free surface, using constant, linear or quadratic elements, which does away with the necessity of numerical integration.

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Georgiou 1981 Thesis - Version of Record
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Published date: 1981

Identifiers

Local EPrints ID: 459571
URI: http://eprints.soton.ac.uk/id/eprint/459571
PURE UUID: 57b90b0a-d8ac-4da0-ac1c-b9b960ae9aa2

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Date deposited: 04 Jul 2022 17:14
Last modified: 20 Mar 2024 18:13

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Contributors

Author: Panos Georgiou
Thesis advisor: C.A. Brebbia

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