*Article* **Investigation on the Mechanical Properties of MRE Compounds** †

#### **Renato Brancati \*, Giandomenico Di Massa and Stefano Pagano**

Dipartimento di Ingegneria Industriale, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli, Italy; gdimassa@unina.it (G.D.M.); stefano.pagano@unina.it (S.P.)

**\*** Correspondence: renato.brancati@unina.it; Tel.: +39-81-7683683

† This paper is an extended version of our conference paper Brancati, R.; Di Massa, G.; Di Vaio, M.; Pagano, S.; Santini, S. Experimental Investigation on Magneto-Rheological Elastomers. In Proceedings of the International Conference of IFToMM ITALY, Cassino, Italy, 29–30 November 2018.

Received: 6 March 2019; Accepted: 24 May 2019; Published: 1 June 2019

**Abstract:** This paper describes an experimental investigation conducted on magneto-rheological elastomers (MREs) with the aim of adopting these materials to make mounts to be used as vibration isolators. These materials, consisting of an elastomeric matrix containing ferromagnetic particles, are considered to be smart materials, as it is possible to control their mechanical properties by means of an applied magnetic field. In the first part of the paper, the criteria adopted to define the characteristics of the material and the experimental procedures for making samples are described. The samples are subjected to a compressive static test and are then, adopting a testing machine specially configured, tested for shear periodic loads, each characterized by a di fferent constant compressive preload. The testing machine is equipped with a coil, with which it is possible to vary the intensity of the magnetic field crossing the sample during testing to evaluate the magneto-rheological e ffect on the materials' characteristics in terms of sti ffness and damping.

**Keywords:** magneto-rheological elastomers; smart materials; semi-active isolator; iron powder
