Analysis and optimisation of Tuned Mass Dampers for impulsive excitation

Tuned Mass Damper (TMD) devices have been widely studied and optimised in the framework of persistent dynamic loadings, such as harmonic and white noise excitations, in order to reduce as much as possible the steady-state response of an assigned primary structure. In this sense, the present paper arises as a complementary study on the topic, since here shock input is assumed as dynamic loading, so as to investigate the effectiveness of TMDs in reducing the transient structural response. In particular, an impulsive loading has been considered, acting as a base displacement, which is a situation that may occur in real applications. First, a comprehensive dynamic analysis of the system comprising of a primary structure and an attached passive TMD is carried out in the time domain. Focus is placed on the relationships between the load input and the system properties, in order to explore the dynamic behaviour of such 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 has been considered, by adding a feedback controller to the previously optimised passive TMD, so as to improve the performance of such a 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 the TMD devices and to supply important guidelines towards their optimal design in reducing the structural response also to shock excitations. This should display significant relevance in different practical applications, including in the field of earthquake engineering.