Numerical and Experimental Study of an Omnidirectional Vibro-Impact Nonlinear Energy Sink ISAE-SUPMECA

Abstract

The objective of this work was to study an omnidirectional vibro-impact non- linear energy sink composed of an internal cylindrical mass moving inside a circular Host. The work was divided into two main parts: the development of numerical models and the experimental study of several OVINES configurations. First, a numerical OVINES model was developed in Python. The gravitational force was taken into account for the NES in order to perform different validation tests, including energy conservation and comparisons of rebound heights with the- oretical values. Friction was then added to the model, and a new configuration with springs and dampers between the Host and the ground was also studied. This model shows that successive impacts transfer part of the energy from the Host to the NES and redistribute the motion among the translational and rotational degrees of freedom. The second part of the work focused on the experimental study. A two-camera measurement setup was used to reconstruct the three-dimensional motion of the system. Several OVINES configurations were tested in order to reconstruct the relative trajectory of the NES, estimate its angular position and rotational velocity, detect impacts, and perform a first identification of the impact parameters. A preliminary parameter identification was performed using selected impacts. The normal restitution coefficient was identified from five impacts, giving a mean value of approximately 0.72 and a standard deviation of 0.12. The collision friction coefficient and the tangential restitution coefficient were estimated from two selected impacts, giving indicative mean values of approximately μc = 0.129 and β0 = 0.494. These values should be considered as preliminary estimates due to the limited num- ber of analysed impacts and the experimental limitations related to marker tracking, geometry reconstruction and measurement accuracy.