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This study’s relevance lies in the possibility of obtaining a smart sandwich structure with controllable dynamic properties, without compromising the main characteristics of conventional thin viscoelastic sandwiches. The proposed sandwich is composed of a micron-size viscoelastic-magnetorheological layer, which is obtained by adding spherical iron particles to a viscoelastic layer. Thin sandwiches with identical base layers and a viscoelastic core, with and without magnetic particles, are fabricated. Both the viscoelastic sandwich structure and viscoelastic-magnetorheological sandwich structure are experimentally characterised by a forced vibration test with resonance in a bandwidth between 0 and 1 kHz. This work analyses the influence of adding iron particles to obtain a smart thin sandwich. In addition, the vibrational response of the viscoelastic-magnetorheological sandwich structure under an external partial magnetic field, and the controllability of its dynamic properties by means of the magnetic field intensity and position, are studied.

A new numerical magneto-dynamic model of viscoelastic-magnetorheological sandwiches is developed and validated with experimental results. The novelty of the model is that, in addition to the magnetorheological effect of the core, it also contemplates the magneto-elastic force generated in the sandwich as a result of the interaction between the magnetic vibrating sandwich and the applied magnetic field. The numerical results show the effect of magneto-elastic force on the magneto-dynamic behaviour of the sandwich in decreasing the natural frequency of the structure. Increasing the intensity of the magnetic field, the natural frequency and the vibration amplitude of the sandwich decrease in the first vibration mode, which agrees with experimental results observed in the literature. To the author's best knowledge, this is the first time magneto-elastic force has been identified as the mechanism responsible for decreasing the natural frequencies of viscoelasticmagnetorheological sandwiches and that this magneto-dynamic behaviour has been represented.