Analyzing the dynamics of the nonlinear absorber

A possible means to reduce vibrations in a main structure is the local attachment of an extra (damped) spring-mass system. This so called tuned mass damper (or vibration absorber), is most effective when mitigating sinusoidal excitations. It loses efficiency when transient vibrations (e.g. shock) need to be reduced. Furthermore, it is tuned to a single frequency which limits its use when multiple vibration modes have a significant contribution to the overall vibration. Numerical evidence shows these drawbacks can be overcome by replacing the linear vibration absorber with a nonlinear one. However, even for the simplest case (one-degree-of-freedom main structure + one-degree-of-freedom nonlinear absorber) the underlying dynamics are surprisingly complex. We explain some of the techniques that facilitate the analysis. The poster presents the method of averaging and the wavelet transform. Both techniques succeed in describing the dynamical behaviour of the overall system (main structure + nonlinear absorber) in an approximate way. Combined, they improve our understanding of the important phenomena present in the nonlinear system.

Publication year:2009