Design of underwater magnetostrictive longitudinal-type transducers with circuit model considering eddy currents and multi-rod structure

•A comprehensive circuit model was proposed to design the magnetostrictive transducers.•The multi-physics coupling effects, inlcuding eddy current effect and the multi-rods structure are considered.•The cut-off frequency of the magnetostrictive is reduced by cutting, thus suppressing the eddy current loss.•An UMLT and the experimental platform were built. Results indicate that the proposed model offers higher accuracy.•The proposed model has a good prediction accuracy of TCR and impedance characteristics of UMLT. Underwater magnetostrictive longitudinal-type transducers (UMLT) are widely used for high-power sonar applications to generate sound waves. When designing an UMLT, to establish an effective model is one of the most necessary but difficult tasks. However, due to the special properties of giant magnetostrictive materials (GMM), the traditional design methods of transducer are completely inapplicable. Therefore, an electro-magneto-mechanical multi-field coupling model is established in this paper, and the eddy current effect, multi-GMM rod structure and other factors are fully considered. Based on the model, the resonant frequency, impedance characteristics and transmitting current response can be calculated to guide the design of UMLT. To verify the feasibility of the proposed model, a measurement experiment platform is constructed. The results validate that the proposed model is effective and more accurate than the conventional model. Thus, it can also be considered as a guideline for the design and analysis of UMLT.