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The equations describing the behaviour of a hyperelastic dielectric under pre-existing mechanical and electrical fields are derived. The associated differential system is shown to be self-adjoint. This property, in turn, is used to establish the equivalence of linear static and dynamic stability criteria.

To describe the behavior of Shape Memory Alloy we use a thermomechanical model, founded on a free energy which is a convex function with respect to the strain and to the martensitic volume fraction, and a concave one with respect to the temperature. The material parameters of the model are experimentally determined. Mathematics Subject Classification (2000). 74-05, 75N30, 80A17.

To describe the behavior of SMA we use a thermomechanical model, founded on a free energy which is a convex function with respect to the strain and to the martensitic volume fraction, and a concave one with respect to the temperature. The material parameters of the model are experimentally determined. In part I we prove that the model can describe the existence of the hysteresis loop and the pseudoelastic behavior of the SMAs. In Part II we show that the model can predict stress relaxation and strain creep during martensitic transformation, and we compare this predictions with the corresponding experimental results obtained by us.Mathematics Subject Classification (1991). 80A22.

In Part I of the paper we use a simplified 1D thermomechanical model to describe the behavior of SMAs. We prove that this model can describe the existence of the hysteresis loop and the pseudoelastic behavior of SMAs. In Part II of the paper we show that the same model predicts the stress relaxation and the strain creep during martensitic transformation. We present experimental results concerning stress relaxation and strain creep. The theoretically calculated and the experimentally deduced stress relaxation and strain creep curves are in satisfactory agreement.Mathematics Subject Classification (1991). 80A22.