Effects of connection orientation on optimization, performance, and robustness of novel tuned mass damper inerter

The inerter-based vibration mitigation system can effectively enhance vibration mitigation performance by optimizing the topological configuration of components such as the inerter, spring, and damper. However, when the inerter-based vibration mitigation system is reversely connected, the change in energy transfer path can affect its effectiveness. This study takes the novel tuned mass damping inerter (NTMDI) as the research object, reverses its connection direction with the primary structure and the ground, and constructs a reversely connected configuration (NTMDI-R). Then, the theoretical model of a single-degree-of-freedom (SDOF) structure with NTMDI-R is presented, and the analytical solution for the optimal parameters of NTMDI-R is derived based on fixed-point theory. Finally, the effectiveness and robustness of NTMDI and NTMDI-R under harmonic and white noise excitation are analyzed and compared with Variant Tuned Mass Damper (VTMD) and Tuned Viscous Mass Damper (TVMD). The results show that the optimal parameters and control performance of NTMDI and NTMDI-R differ significantly. Under the same physical mass and apparent mass, NTMDI outperforms NTMDI-R in both vibration mitigation performance and control frequency range, with physical mass being the primary factor leading to the reduced performance of NTMDI-R. NTMDI and NTMDI-R exhibit consistent robustness, showing strong robustness under damping detuning and positive frequency detuning, but weaker robustness under negative frequency detuning. In contrast, VTMD demonstrates lower robustness under frequency detuning compared to NTMDI, NTMDI-R, and TVMD, indicating that apparent mass plays a significant role in enhancing robustness.