Linear stroke extension of quasi-zero stiffness isolators through displacement scaling principle targeted on large amplitude excitation

Quasi-zero Stiffness (QZS) vibration isolators are proposed to significantly enhance low frequency vibration isolation performance while maintaining robust load-bearing capabilities. Traditional negative stiffness mechanisms, however, suffer from restricted linear operational stroke due to pronounced stiffness nonlinearity, which compromises vibration isolation performance under large amplitude excitation. To resolve this challenge, a displacement scaling mechanism (DSM) is introduced to extend the effective vibration isolation range. The proposed DSM scales the geometric stroke independently without changing the original physical mechanism. In this study, negative-stiffness magnetic spring is employed as the archetypal negative stiffness mechanism, with emphasis on analyzing on how DSM introduction modifies isolator performance under large amplitude excitation conditions. A static magnetic stiffness model is constructed using a multi-fitting modeling approach, coupled with a positive stiffness spring to realize QZS characteristics. By developing a dynamic model that accounts for inertia and stiffness nonlinearities, displacement transmissibility is derived through the harmonic balance method. Comparisons between QZS vibration isolator with and without displacement scaling mechanism reveal a trade-off between load capacity and linear stroke, alongside beneficial mass nonlinearity effects. Experimental validation across on different isolator types under sweep excitation validate model accuracy and demonstrate DSM’s role in enhancing performance. The DSM effectively extends QZS isolators’ linear stroke, improving large amplitude isolation. Our findings present an innovative and impactful approach to bolstering vibration isolation performance of various designed QZS vibration isolators in large amplitude scenarios through the strategic use of displacement scaling and inertia nonlinearity.