Magnetic and dynamic mechanical properties of a highly coercive MRE based on NdFeB particles and a stiff matrix

Abstract

This study concerns a magnetorheological elastomer (MRE) consisting of a magnetically hard powder and a stiff polymer matrix, so called STH-MRE. This material exhibits some strong constitutive differences with the behavior of MRE based on soft polymer matrix and magnetically hard powder (SOH-MRE). This paper presents a manufacturing process for such a STH-MRE, describes testing procedures to get the magnetic properties, the viscoelastic behavior and the magneto-mechanical coupling, and shares the STH-MRE properties with the scientific community. Firstly, the manufacturing process is detailed. Then, the homogenized magnetic properties and their dependence on the volume fraction and the temperature are discussed. Thereafter, dynamic mechanical analysis is explained and the viscoelastic properties are discussed considering the polymer matrix properties, the volume fraction and the temperature. Magneto-mechanical couplings are investigated in absence of an external magnetic field. The coercive field strenth of composite material and powder are almost equal while the remanent flux density depends on volume fraction. The temperature dependence of the magnetic properties is given as well as homogenization rules. The viscoelastic data of the STH-MRE are provided in a large temperature range and in the mechanical vibration frequency range. The magneto-mechanical coupling due to the remanent magnetization is shown to be negligible.

Magnetically induced friction damping based on magnetoactive elastomers — A proof of concept

“…The MAE in the present study is magnetically hard and initially magnetized. The magnetization has no significant influence on the elastic modulus of the MAE used in the present study [21]. This behavior is due to the comparatively high stiffness of the elastomer matrix, which has a high influence on the intensity of magneto-elastic couplings in MAE [35].…”

“…H-MAEs are composed of magnetic particles and a viscoelastic matrix. Their magnetic behavior is comparable to the behavior of permanent magnets [21]. Their elastic modulus, however, is much lower (order of magnitude: 2 MPa to 10 MPa).…”

“…The H-MAE is composed of a two-part silicone elastomer MED-4014, provided by NuSil T M , and of magnetically hard NdFeB particles (MQFP-14-12 from Magnequench T M ). Details about the elaboration process can be found in [21]. The H-MAE in the present study has a volume fraction of 36 % of NdFeB particles and shows a residual flux density of 0.3 T. The patches used in this study are magnetized in their direction of thickness.…”

“…In this work we present a new concept for friction damping in assembled structures. It is based on the use of permanently magnetized elastomer composites, also known as magnetically Hard MagnetoActive Elastomers (H-MAEs) [21]. H-MAEs are composed of magnetic particles and a viscoelastic matrix.…”

Shape memory through contact: introduction of MagnetoFriction Shape Memory Polymers (MF-SMPs)

“…After being exposed to a strong magnetic field, the composite remains magnetized, comparable to a stiff permanent magnet. 14,15 Fig. 2a illustrates the flexibility of the H-MAE as well as its response to magnetic stimuli.…”