Abstract
-
An experimental investigation has been carried out on the nonlinear dynamics of a clamped–
clamped Magneto-Rheological Elastomer (MRE) sandwich beam with a point mass when
subjected to a point excitation. Three sets of experiments have been conducted namely for (i) an
aluminium beam, (ii) a MRE sandwich beam in the absence of a magnetic field and (iii) a MRE
sandwich beam in the presence of a magnetic field. An electrodynamic shaker was used to excite
each system and the corresponding displacement of the point mass was measured: for the third
experiment (iii), an array of magnets has been placed at various distances away from the centre of the
point mass to investigate the effect of changing stiffness and damping properties on the nonlinear
dynamical behaviour. An interesting feature for the third group is the beam point mass displacement
was no longer symmetric as the stiffness and damping of the system are increased when moving
towards the magnets. Both the first and second groups exhibited distinct nonlinear behaviour;
however, for the third group this work shows that for a low magnetic field the sandwich beam
exhibits two distinct resonance peaks, one occurring above and the other below the fundamental
natural frequency of the transverse motion, with the right one larger. For a larger magnetic field,
these peaks even out until the magnetic force was large enough that the hardening-type nonlinear
behaviour changes to a softening-type; a significant qualitative change in the nonlinear dynamical
behaviour of the system, due to the presence of the magnetic field, was observed.