Impact Fatigue of Viscoelastic Materials Subjected to Pounding

The pounding tuned mass damper (PTMD) is a novel vibration control device that can be used for many different structures. The PTMD utilizes a viscoelastic delimiter to enhance its vibration control effectiveness and robustness though pounding between the tuned mass and the viscoelastic material. However, the viscoelastic material is subjected to repeated poundings during its service life, which influences the property of the material and degrades its energy dissipation ability. Therefore, this study investigates the fatigue behavior of the viscoelastic material under impact loading. An experimental apparatus, which can generate and sense the lateral impacts, is designed and fabricated to facilitate the fatigue study of the viscoelastic material subject to impact loading. Based on experimental data, the pounding stiffness and the hysteresis loops are employed to characterize the behavior of the material. It is revealed that the impact fatigue process can be divided into two phases: the cyclic-hardening phases and the cyclic-softening phase. The energy dissipation is firstly reduced, and then increased, by the repeated impacts. In summary, with a total of 360,000 impacts, the viscous elastic material is still effective in dissipating impact energy.