Finite element solutions for transient fluid-structure interaction
The objective of this thesis is to develop numerical tools capable of modelling the
nonlinear behaviour of bounded and unbounded transient fluid-structure interaction
systems. Towards this end, a numerical approach based on the finite element method
was developed and implemented into a general purpose computer program ASAS-NL.
Four main developments are reported:
(i) The Mixed-Eulerian-Lagrangian description of the continuum has been
developed to account for the nonlinear effects of fluid-structure interaction
systems and a mesh rezoning scheme derived to be used with it. In addition a
predictor-multi-corrector time marching scheme has been used for nonlinear
dynamic analysis and implicit temporal integration schemes based on Newmark
and a-Bossak methods have been reviewed and implemented. Nonlinear
iterative schemes based on the Modified Newton Raphson and full Newton
Raphson methods have also been included.
(ii) Two-dimensional and axi-symmetric fluid finite elements were developed. The
elements are compatible with the Mixed-Eulerian-Lagrangian description of the
continuum. In addition the free surface gravity wave (sloshing effect) has been
addressed. The purpose of these elements is to model the bounded fluid
medium in fluid-structure interaction problems.
(iii) Two-dimensional and axi-symmetric Mixed-Eulerian-Lagrangian four-noded
sliding interface elements have been developed. The purpose of these elements
is to prevent artificial penetration of the fluid into the structure during analysis
of fluid-structure interaction problems.
(iv) A non-radiating boundary has been developed. This is to be used for modelling
the unbounded fluid medium in fluid-structure interaction problems.
Furthermore, numerical techniques for modelling shock waves were reviewed
and included in the analysis.
This new analytical formulation has been applied to several problems for which
solutions are available to prove its versatility, accuracy and efficiency and has been
shown to give satisfactory results for the cases examined.