Optimum passive and hybrid Tuned Mass Dampers for structural systems under impulse excitation

Tuned Mass Damper (TMD) devices have been widely studied and optimised in the literature within the framework of persistent dynamic loadings, such as harmonic and white noise excitations, in order to reduce as much as possible the stady state response of an assigned primary structure. In this sense, the present paper arises as an innovative, complementary study on the topic, since here a shock excitation is assumed as dynamic loading, so as to investigate the effectiveness of TMSs in reducing the impulse structural response. In particular, a unit impulse loading has been considered, acting as either point force on the primary structure or as base displacement, which are both situations that may occur in real applications. First, a comprehensive dynamic analysis and tuning process of the system comprising of a single-degree-of-freedom (SDOF) primary structure and an attached passive TMD are carried out. Focus is placed on the relationships between the obtained results and the system response, in order to explore the dynamic behaviour of such a system and to identify the main response trends, mostly as a function of the free TMD parameters, namely mass, frequency and TMD damping ratios. Subsequently, a hybrid TMD is considered, by adding a feedback closed-loop controller to the previously optimised passive TMD, so as to improve the performance of the device, especially in reducing the peak response of the primary structure. The contents of the present work have the final aim of identifying the potential level of effectiveness of TMD devices and supplying important guidelines towards their optimum design for reducing the structural response also to shock excitation. This should display significant relevance in different practical applications.