Active and passive vibration control of flexible structures using a combination of magnetostrictive and ferro-magnetic alloys

A combined passive and active damping strategy is proposed to control vibration in structures using a combination of layers of ferro-magnetic (passive) damping and smart (active) magnetostrictive material (Terfenol-D). Two types of combined damping systems are considered viz., a noninteractive system and an interactive or hybrid system. Numerical investigations on a cantilever beam model are carried out to investigate various aspects in combined damping scenario. Using variational principle, a beam Finite Element is developed to study the dynamic characteristics of a beam containing both the passive and active damping layers. It is shown that the combined system could be used effectively to dampen the structural vibration over a wide frequency range. Comparisons with only passive and only active damping schemes are also made. The influence and the mode dependence of control gain in a hybrid system is clearly brought out.