Vibration Absorption using KDamper-based Devices with Extreme Geometric Nonlinearity

A KDamper oscillator is proven to be a more effective alternative to conventional Tuned Mass Damper (TMD) approaches and Quazi Zero Stiffness (QZS) or negative stiffness isolators. In this paper, an extended version of the KDamper (EKD) concept is employed to control the dynamic responses of an undamped (or low damper) SDoF system subjected to various dynamic loads. The KDamper consists of an additional mass, artificial dampers, and positive and negative stiffness elements. The additional implemented mass is one order of magnitude smaller as compared to most mass related vibration absorbers (TMDs, TMDIs, KDampers, etc.). The artificial dampers and the stiffness element values are selected following an engineering-criteria driven optimization procedure that accounts for geometric constraints and manufacturing limitations. The negative stiffness element is realized with an articulated mechanism that employs pre-stresses conventional stiffness elements (spiral springs) and generates controlled negative stiffness (NS). In order to exploit the advantages that the inherent nonlinear nature the NS offers, such as robustness, broadband response and energy sinks, the proposed dynamic vibration absorber is designed to present significant geometric nonlinearity, that varies from none (linear system) to extreme. Thus, different test cases are presented with respect to the desired nonlinearity of the generated NS, as well as to the type of the external load subjected to the structure. This way we can determine in which cases extreme geometric nonlinearity is beneficial to the dynamic behavior of the controlled structure.