Numerical evaluation of SMA-based multi-ring self-centering damping devices

This paper introduces the innovative concept of SMA-based multi-ring (SBMR) self-centering damping devices and numerically evaluates their performance and effective design. The SBMR devices are passive metallic dampers consisting of two types of concentric circular rings with rectangular cross-section: (a) superelastic (SE) rings and (b) supplemental energy dissipating (ED) rings. The rings are tightly fitted into each other such that their diametric deformations are constrained. The SE rings are made of SE shape memory alloys (SMA) (e.g., Nitinol), thereby providing the SBMR devices with both self-centering and hysteretic damping. The ED rings are made of metals with higher hysteretic damping capacity to supplement the damping of the SE rings. The SBMR devices can resist both tension and compression (without buckling) in multiple directions, allowing their installation via cross-bracing systems. To evaluate the SBMR devices, they were simulated through 3D nonlinear finite element models. The general response/behavior of the proposed devices and the effects of brace design and orientation on their response were examined. The SBMR devices were found capable of producing more than 100% higher damping compared to single SE SMA rings, particularly under small deformations. Moreover, brace design and orientation were found to have little to no effect on the performance of the SBMR devices.