A nonlinear X-shaped structure based tuned mass damper with multi-variable optimization (X-absorber)

Installing a tuned mass damper (TMD) is a promising vibration control method in many engineering applications which can suppress excessive vibration of a primary structure by transferring and dissipating vibration energy from the primary structure to the TMD. To overcome some limitations and drawbacks of traditional tuned mass dampers in practice, a bio-inspired X-shaped structure/mechanism is utilized to design a novel tunable and nonlinear TMD (X-absorber) in this study. To this aim, multi-variable optimization analysis, tunable stiffness and damping properties, nonlinear influence and vibration suppression performance of the new X-absorber are systematically investigated. The X-absorber can provide beneficial nonlinear damping and tunable quasi-zero stiffness which can significantly improve system parametric robustness, widen vibration suppression bandwidth with a widened anti-resonance, effectively suppress resonant peaks of very low frequencies, and eliminate potential instabilities (e.g., bifurcation, jump) inherently existing in Duffing systems, compared with traditional absorbers. The effectiveness and robustness of the X-absorber with different excitations compared with a traditional spring-mass absorber are verified in experiments. The X-absorber presents a new insight into the design of nonlinear passive absorbers of high performance, and a more flexible and reliable solution to many engineering problems.