The present study developes a mixed finite element formulation for the analysis of piezoelectric circular and annular plates. This formulation combines the conventional displacement-electric potential type variational principle and the piezoelectric Reissner`s principle with a weighting factor which represents ratio of weights imposed on the above two variational principles, and which can be adjusted by comparing with experiment results. With this formulation, stresses and electric displacements, like displacements and electric potential, are primary variables and are continuous across elements and element interfaces. Also, all displacement, stress, electric displacement, and electric potential boundary conditions can be easily and exactly imposed. Static deformations and vibration frequencies of some typical piezoelectric circular and annular plates are then obtained with the present approach and are compared with those by other methods. Based on experiment results in the literature, it is found that better results could be obtained in general by the present mixed finite element formulation than the others when 1 is chosen as the weighting factor.

The user programmable features (UPF) of the finite element code ANSYS® are used to generate a customized ANSYS-executable including a more general creep behaviour of materials and a damage module. The numerical approach for the creep behaviour is not restricted to a single creep law (e.g. strain hardening model) with parameters evaluated from a limited stress and temperature range. Instead of this strain rate - strain relations can be read from external creep data files for different temperature and stress levels. The damage module accumulates a damage measure based on the creep strain increment and plastic strain increment of the load step and the current fracture strains for creep and plasticity (depending on temperature and stress level). If the damage measure of an element exceeds a critical value this element is deactivated. Examples are given for illustration and verification of the new program modules.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes bibliographical references and vita.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains vii, 93 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 71-75).

Thesis (Ph.D.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 146-152.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: correlation; modal analysis; valve train. Includes bibliographical references (p. 157-158).

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains vi, 96 p. : ill. Includes abstract. Includes bibliographical references (p. 91-96).

Thesis (Ph.D.)--University of Texas at Arlington, 2008.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 181-188).

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 218-220). Available also in a digital version from Dissertation Abstracts.