Theoretical investigation of magnetostrictive bilayers sensitive to bending or temperature changes

The paper concerns theoretical investigations of the bending sensitivity and the temperature sensitivity of magnetostrictive bilayer materials, the basic element of novel multifunctional sensor families. The bilayers consist of a magnetostrictive layer and a non-magnetic counter layer. In the discussed case, there is an additional agglutination layer as a result of the production procedure. The sensitivity is determined by the stress in the magnetostrictive layer induced due to bending or temperature changes. With approximate analytic models, it is shown that the sensitivity depends on several specific layer parameters, e.g. Young´s modulus, thermal expansion coefficient and size dimensions. The influence of the agglutination layer was studied in more detail by means of two dimensional finite element analysis. The results provide an indication for the optimal bilayer composition for specific sensor applications.