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Title: Analysis of adaptive finite element solutions in elastoplasticity with reference to transfer operation techniques
Author: Orlando, A.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2003
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Key ingredients of an adaptive strategy in the finite element solution of history-dependent problems with incremental methods are: (i) the availability of an error estimator which accounts for the sources of error associated with the approximation, (ii) error indicators for the choice of the optimal discretization parameters, and finally (iii) a data transfer procedure when the current finite element mesh is different from the one of the previous time step. If the finite element mesh is changed at time tn, two finite element solutions are considered for the same load level: the one at tn- is associated with the old mesh Thn, and the other at tn+ is associated with the new mesh Thn+1. The latter is computed by equilibrating the data defined by the specific transfer procedure. Consequently, a discontinuity jump will appear in the time linear interpolation of the discrete values across the time node tn. The global accuracy in time of the solution, therefore, will have to depend not only on the time step and finite element mesh size but also on the value of the jump. In this work, an error estimator is proposed which allows the assessment of the effects of transfer procedures is displacement finite element solutions of rate-independent plasticity discretized in time with the backward Euler method. The proposed error measure belongs to the family of the error in the constitutive equations and presents a term which characterises the time discontinuity in the admissible solution. With the new theory, indications on how to change the finite element space and define the corresponding data can be given and the assessment of the several transfer operations can be finally framed in the context of the ensuing error.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available