Integrated mechanical and material design of quasi-zero-stiffness vibration isolator with superelastic Cu–Al–Mn shape memory alloy bars

Abstract

Quasi-zero-stiffness (QZS) vibration isolators avoid excessive deformation due to gravity, a critical issue in vertical vibration isolation, by providing restoring force with high initial stiffness and low tangent stiffness around the static equilibrium position. Effective use of geometric nonlinearity often plays a central role in QZS mechanisms. Design of such QZS mechanisms, however, tends to be complex, and it is difficult to realize large loading capacity as well as large stroke length at the same time. This paper attempts to resolve these issues by applying newly developed superelastic Cu-Al-Mn shape memory alloy (SMA) bars, characterized by excellent recoverable strain upon unloading along with small hysteresis and nearly flat stress plateau. These features are realized by material design tailored for obtaining mechanical properties required in QZS mechanisms. The use of such tailored superelastic Cu-Al-Mn SMA bars allows us to easily achieve large loading capacity as well as large stroke length while keeping the QZS mechanism simple and compact. In this paper, we derive design equations, produce a prototype, and conduct shaking table tests and numerical simulations to demonstrate the feasibility of QZS vibration isolator with superelastic Cu-Al-Mn SMA bars.

Adjustable vertical vibration isolator with a variable ellipse curve mechanism

“…Therefore, the horizontal mechanism has a lower risk of lack of stroke and realize a more compact isolator. These are advantages over other vertical isolators proposed in the literature including the authors' previous work . However, regardless of long stroke, an impact absorption mechanism should be installed for practical use.…”

“…In this section, we introduce a horizontal amplification mechanism using an ellipse curve and its advantages over the vertical amplification mechanism proposed in the literature . Then the restoring force produced by this mechanism is examined.…”

“…As stated before, for the vertical mechanism proposed in the literatures , trapezoidal plates are used to amplify the restoring force of springs. Next, we justify that an ellipse curve plate is suited for the horizontal amplification mechanism to produce QZS for the vertical vibration isolator.…”

“…The authors realized this variable mechanism by using cranks and a screw jack for the vertical vibration isolator and verified its effectiveness through shaking table tests and numerical simulations . Also, a similar mechanism was realized by using superelastic Cu‐Al‐Mn shape memory alloy bars instead of constant‐force springs .…”

Bifurcation and singularity analysis of HSLDS vibration isolation system with elastic base

“…Among these methods, singularity theory is of much importance and has been widely applied as a quanlative analysis method, which can solve the bifurcation problems uniformly and definitely. Yu et al studied the local bifurcation of nonlinear vibration isolation system with 1:2 internal resonance [7,8], Qin et al investigated two-degree-of-freedom (two-DOF) bifurcation equation for elastic cable with 1:1 internal resonance [9], Wang et al analyzed the bifurcation models of a class of power system by using C-L method [10], Zhou et al considered the local bifurcation of a nonlinear system based on MR damper [11], Volkov et al studied the bifurcation in the system of two identical diffusively coupled Brusselators [12].…”