Sensitivity Analysis of a Nonlinear Obstacle Plate Problem

¹ Departamento de Matemática, Universidade de Coimbra, Apartado 3008, 3000 Coimbra, Portugal; isabelf@mat.uc.pt.
² Departamento de Matemática, Universidade de Coimbra, Apartado 3008, 3000 Coimbra, Portugal; carlosl@mat.uc.pt

Received: 27 December 2000
Revised: 12 July 2001

Abstract

We analyse the sensitivity of the solution of a nonlinear obstacle plate problem, with respect to small perturbations of the middle plane of the plate. This analysis, which generalizes the results of [9,10] for the linear case, is done by application of an abstract variational result [6], where the sensitivity of parameterized variational inequalities in Banach spaces, without uniqueness of solution, is quantified in terms of a generalized derivative, that is the proto-derivative. We prove that the hypotheses required by this abstract sensitivity result are verified for the nonlinear obstacle plate problem. Namely, the constraint set defined by the obstacle is polyhedric and the mapping involved in the definition of the plate problem, considered as a function of the middle plane of the plate, is semi-differentiable. The verification of these two conditions enable to conclude that the sensitivity is characterized by the proto-derivative of the solution mapping associated with the nonlinear obstacle plate problem, in terms of the solution of a variational inequality.