Multi-field coupling behavior of electromagnetic materials

The mechanical behavior of electromagneic materials is usually sensitive to the electric, magnetic as well as temperature field. It is found by the experiments in this paper that the grads of the non-uniform electric field can increase or decrease the speed of the heat conduction in conductors, and the environment temperature and the varying-time excitation magnetic field have obvious influence on the strain of the giant magnetostrictive materials. Our theoretical prediction on the induced body and boundary forces in ferromagnetic materials and on the constitutive behavior of the giant magnetostrictive materials also exhibited a strong effect of multi-field coupling, which makes the mechanical responses of electromagnetic materials are very different from the uncoupling ones. Furthermore, our theoretical investigations show that the effect of the multi-field coupling is not only in macroscales but also in microscales. For the elastic properties of nanowires, it is found in this paper that the negative pressure on the surfaces stemmed from the transverse electric field modifies the Young's modulus and Poisson's ratio of nanowires significantly. The relative change of elastic properties is also strongly dependent on the diameter of nanowires.