Parametric control of quasi-zero stiffness mechanisms for vibration isolation at near-zero frequencies

Abstract

Infra-frequency vibration, including near-zero frequencies, has become a critical limiting factor for developers of next-generation ultra-high precision measurement systems. Mechanisms involving quasi-zero stiffness show potential to solve this new vibration problem. An approach for designing a novel type of the mechanisms for this class is presented. An algorithm is developed and tested for numerical solution of nonlinear elasticity problem in designing the mechanism structural and parametric elements based on FEM models. The elements are spatially prestressed multi-layer designs of polymer composites for modeling elastic postbuckling in large and the effect of a “floating” binder. An algorithm and models following the Nelder-Mead method are used for optimizing the designs. Examples of Euler-beam-shaped composite elements under postbuckling demonstrate a qualitative leap in mechanisms design and efficiency, specifically, in terms of compactness, lightness, and strength. A dramatically expanded control range for the linear section of operating travel with quasi-zero stiffness is obtained. A damping threshold is evaluated, and an optimal type diagram of the mechanism is designed and enumerated as necessary conditions for vibration isolation at near-zero frequencies. The validity and effectiveness of the approach are demonstrated with the results of theoretical design and testing of the prototype for vibration isolation of the ultra-high precision optical system. The learning capability of the mechanisms is estimated by an adapted version of the Levenberg-Marquardt algorithm with stepwise refinement in the test mode using Rosenbrock’s function.