Design of a quasi-zero stiffness isolation system for supporting different loads

The quasi-zero stiffness (QZS) vibration isolation system using negative stiffness structure can generally increase the workable frequency range and improve the isolation performance, in comparison with a linear vibration isolator. However, most of the QZS isolation systems are sensitive to the loads applied for achieving effective isolation. A QZS system designed for a certain load supported cannot provide an effective vibration isolation for another load, as the designed QZS region is not suitable for the new load and thus it no longer demonstrates the anticipated isolation performance. This paper presents an optimized structure for the QZS system to adaptively respond to different loads based on a cam-roller mechanism. Innovation of the present design is the capacity of supporting multi-load levels to isolate the vibrations in low frequency range. Frictional force occurring on the cam-roller contact is considered in the modelling to represent practical application situations. Both static and dynamic responses are theoretically studied for the QZS characteristic and isolation performance. A prototype of the proposed QZS structure is designed, fabricated and tested to verify its isolation performance. Experimental results demonstrate an excellent agreement with the theoretical results, which promotes the implementation of the proposed design into engineering applications. (C) 2020 Elsevier Ltd. All rights reserved.