THE EFFECT OF STIFFNESS AND LOADING DEVIATIONS IN A NONLINEAR ISOLATOR HAVING QUASI ZERO STIFFNESS AND GEOMETRICALLY NONLINEAR DAMPING


Donmez A., CİĞEROĞLU E., ÖZGEN G. O.

1st International Symposium on Ethnic Languages and Culture Under - Belt and Road Initiatives, Beijing, Çin, 18 - 21 Temmuz 2016 identifier identifier

  • Yayın Türü: Bildiri / Tam Metin Bildiri
  • Cilt numarası:
  • Basıldığı Şehir: Beijing
  • Basıldığı Ülke: Çin
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Static deflections due to static loadings limit the isolation performance of linear vibration isolation systems. Therefore, quasi-zero stiffness (QZS) mechanisms, i.e. nonlinear isolators with high static and low dynamic stiffness characteristic, are used to decrease the natural frequency of the isolation structure and improve the isolation performance of the system while having the same loading capacity. However, the resulting system is highly nonlinear and unstable solutions may as well occur. Although increasing the amount of linear viscous damping in the system reduces the nonlinearity, it has adverse effect on the isolation region. Geometrically nonlinear damping is effective when the response of the isolation system increases; hence, isolation region is unaffected. Combination of position depended nonlinear damping and QZS mechanism eliminates highly input depended response of QZS mechanism. In this study, a single degree of freedom system with a nonlinear isolator having QZS mechanism and geometrically nonlinear damping is considered. The nonlinear differential equations of motion of the isolation system are converted into a set of nonlinear algebraic equations by using harmonic balance method, which are solved by using Newton's method with arc-length continuation. Several case studies are performed and the effect of stiffness and loading deviations on the isolation performance is studied.