Seminar: Direct and Inverse Problems in Piezoelectricity

Speaker: Tom Lahmer,

Friedrich-Alexander-Universität Erlangen, Germany.

Date/Time: 13th June 2007, 13:00-14:00.

Location: Room G74, Philip Lyle Building (Building 32), Whiteknights Campus.

Map: http://www.info.rdg.ac.uk/maps/maps-display.asp

Abstract:

In all applications based on the piezoelectric effect, in particular in sensor and actuator technologies, couplings of electrical with mechanical signals and vice versa are present. The finite element method has turned out to be an indispensable tool for a detailed investigation of piezoelectric transducers and in particular for the designing process of new devices.

However, simulation results are only valuable if one works with precise material parameters. The standard parameter determination methods in piezoelectricity are a difficult, time and money consuming procedure and the results are not always suitable for finite element calculations as we will show. We therefore propose simulation based material parameter identification routines which calculate the electrical, mechanical and piezoelectric properties out of electrical and mechanical measurements.

Parameter identification is usually a typical ‘ill-posed’ problem, since stable dependency of the results on the measured data (which are besides contaminated with data noise) cannot be guaranteed.

The talk will elaborate on appropriate regularizing methods (e.g. inexact Newton methods and modified Landweber iterations) for ill-posed problems and their applications to parameter identification in piezoelectricity will be given.

For the piezoelectric problem both the linear and nonlinear case will be discussed. In the latter case the identification is extended from constant coefficients to the determination of parameter curves.

During this talk theoretical analysis goes along with numerical results.