Targeted energy pumping using a linear complex attachment

The present paper considers the problem of realizing an effective targeted energy pumping from a linear oscillator to a plurality of ungrounded linear resonators, attached to it in parallel. Theoretical as well as numerical results demonstrate the efficacy of using a complex attachment as a passive absorber of broadband energy, injected into the primary structure. The paper unveils also the existence of an instantaneous frequency associated to the master response characterized by intermittency: a rather surprising result for a linear autonomous system. A comparative analysis with a nonlinear energy sink demonstrates that the two systems present some analogies in this respect and that the complex attachment is a very efficient energy trap.