On a broadband vibration isolator with tunable stiffness: from quasi-zero-stiffness to zero-stiffness behavior

  • N. A. SAEED ,
  • Lei HOU ,
  • Haiming YI ,
  • A. A. SHUKUR ,
  • S. M. ALAMRY ,
  • S. M. EL-SHOURBAGY
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  • 1.Department of Physics and Engineering Mathematics, Faculty of Electronic Engineering, Menoufia University, Menouf 32952, Egypt
    2.School of Astronautics, Harbin Institute of Technology, Harbin 150001, China
    3.Applied Science Research Center, Applied Science Private University, Amman 11937, Jordan
    4.Faculty of Computer Sciences and Mathematics, University of Kufa, Kufa 54001, An-Najaf, Iraq
    5.Department of Mathematics and Statistics, College of Science, Taif University, Taif 21944, Saudi Arabia
    6.Department of Basic Science, Higher Technological Institute, Tenth of Ramadan City 44629, Egypt

Received date: 2025-07-20

  Revised date: 2025-12-08

  Online published: 2026-02-04

Supported by

Project supported by the National Key R&D Program of China (No. 2023YFE0125900)

Copyright

© The Author(s) 2026

Abstract

A novel vibration isolation system designed for superior performance in low-frequency environments is proposed in this work. The isolator is based on a unique hexagonal arrangement of linear springs, allowing for an adjustable geometric configuration via the initial inclination angle. Based on the principle of Lagrangian mechanics, the equation of motion governing the structural dynamics is rigorously derived. The system is modeled as a strongly nonlinear single-degree-of-freedom dynamical system, loaded with a normalized payload and subject to harmonic base excitation. To analyze the steady-state response, the harmonic balance method is employed, providing accurate predictions of the payload’s vibration amplitude and displacement transmissibility as functions of both the base excitation amplitude and frequency. The analysis reveals a direct relationship between the isolator’s geometric and stiffness parameters and its load-bearing capacity, leading to the identification of three distinct operational regimes. Depending on the unloaded initial inclination angle, the equivalent stiffness ratio, and the payload design configuration, the system can exhibit one of three vibration isolation modes: (i) the quasi-zero stiffness (QZS) isolation mode, (ii) the zero linear stiffness with controllable nonlinear stiffness, and (iii) the full-band perfect zero stiffness. The vibration isolation performance of the proposed structure is thoroughly discussed for all three oscillation modes in terms of frequency response curves, displacement transmissibility, and time-domain responses. The key novel finding is that this structure can operate as a full-band, high-performance vibration isolator when the initial inclination angle is designed to be a right angle, enabling full isolation of the maximum possible payload. Moreover, the analytical results and numerical simulations demonstrate that the isolator’s displacement transmissibility T with the unit dB tends to as the air-damping coefficient approaches zero, enabling ideal vibration isolation across the entire excitation frequency range. These analytical insights are validated through comprehensive numerical simulations, which show excellent agreement with the theoretical predictions.

Cite this article

N. A. SAEED , Lei HOU , Haiming YI , A. A. SHUKUR , S. M. ALAMRY , S. M. EL-SHOURBAGY . On a broadband vibration isolator with tunable stiffness: from quasi-zero-stiffness to zero-stiffness behavior[J]. Applied Mathematics and Mechanics, 2026 , 47(2) : 255 -282 . DOI: 10.1007/s10483-026-3351-9

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