Wednesday, 13 October 2004 - 9:40 AM

This presentation is part of : Wineman Symposium

Nonlinear deformations of electro-sensitive elastomers

Luis Dorfmann, Institute of Structural Engineering, Peter Jordan Str. 82, Vienna, 1190, Austria and Ray W. Ogden, Department of Mathematics, University of Glasgow, Glasgow, G12 8QW, United Kingdom.

Recently, growing interest in the mechanical and the electromagnetic properties of composites consisting of a dielectric matrix and a distribution of embedded ferrous micron-seized particles has been observed. Newly developed engineering applications, which involve, for example, sensors, vibration absorbers, and controllable membranes for use in automotive and biomedical engineering motivate the interest in these ‘smart materials’. The mechanical properties of these composites can be altered rapidly by a change in the magnitude or direction of an applied magnetic or electric field. This work focuses on the influence of an applied electric field on the mechanical response. The talk starts by first summarizing, in a simple form, the equilibrium equations for a compressible and an incompressible material capable of undergoing large electro-sensitive deformations. The general constitutive equation for an isotropic material in the presence of an electric field is described and expressed in compact form. The Cauchy stress tensor and the electric polarization of the material are given explicitly in terms of two independent variables, which we take to be the deformation gradient tensor and the electric induction vector. We also specialize the equations to the situation when there is no deformation but an applied electric field, resulting in a residual stress in the material. Then, we restrict attention to incompressible isotropic electro-sensitive materials and apply the equations to some simple deformations in order to illustrate the influence of the electric field on the mechanical response. The results show the stiffening of the mechanical response with increasing electric field strength.

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