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Title: Issues on the finite element modelling
Author: Pires, F. M. A.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2005
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Aspects of constitutive modelling and numerical prediction of failure in finitely straining ductile metals are investigated in this thesis. Attention is focused on the construction of a framework for prediction of failure. The development of a model for finite strain elasto-(visco)plastic damage; a low order finite element for the numerical treatment of incompressibility and an adaptive mesh refinement strategy for this class of problems, constitute the building blocks of the overall approach. Emphasis is given to the efficient numerical simulation of the proposed theories in large scale problems. The characterisation of material response has to account for the interaction between the different phenomena that precede fracture initiation. The derivation of constitutive models is addressed within Continuum Damage Mechanics theory. Particular, the effect of micro-crack closure which may dramatically decrease the rate of damage growth under compression is emphasised. With regard to the computational treatment of incompressibility, a new technique which allows the use of simplex finite elements in the large strain analysis of nearly incompressible solids is proposed. It is based on relaxation of the excessive volumetric constrain by the enforcement of near-incompressibility over a patch of elements. The new elements are implemented within an implicit quasi-static and an explicit transient dynamic finite element environment. The algorithms for numerical integration of the corresponding path dependent constitutive equations are discussed in detail. The strategy for numerical simulation of the associated incremental boundary value problems relies on fully implicit and explicit displacement based finite element procedures.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available