A ring vibration isolator enhanced by shape memory pseudoelasticity

Performance enhancement of vibration isolation of a circular ring by means of a shape memory alloy (SMA) wire rope is investigated. The restoring and the damping force of the SMA are approximated by two cubic polynomials. The ring with the SMA wire along the horizontal diametral line is mathematically modeled by two coupled nonlinear partial differential equations with the boundary conditions. The nonlinear partial differential equations are discretized via the Galerkin method. The method of harmonic balance is applied to derive the expressions for frequency response and the force transmissibility of the circular ring design. The developed vibration isolation approach is successfully implemented to change the path of vibration transmission to attenuate the transmitted motion. The effects of the introduced horizontal SMA stiffness and damping on vibration isolation are examined. The resultant SMA stiffness is shown to extend the isolation range to lower frequencies, while the horizontal SMA damping has the ability to reduce the resonance response. The numerical simulations support the analytical results. Then, the isolation performances obtained employing different types of NiTiNOL (i.e., NiTi7, NiTi19/NiTi1, ST49/NiTi7, ST49/NiTi1) are compared. The results demonstrate that the SMA composed of NiTi19/NiTi1 is optimum for the ring isolation design. The developed ring beam vibration isolator reduces the transmissibility around the resonance frequency and performs better at high frequencies for appropriate types of SMA.