Interval Type-2 fuzzy vibration control of multiple-degree-of-freedom structure using shape-memory-material absorber

A tunable vibration absorber (TVA) is developed in this study. The TVA is composed of a vibrator mass and two helical springs. The helical spring is made of shape memory alloy (SMA) and shape memory polymer (SMP). When an external current source is applied to the SMA + SMP helical spring, the temperature of the shape memory materials (SMMs) increases and the TVA's dynamic characteristics can be tuned for control on demand. Therefore, we can use the tunable property of the TVA to absorb the vibration of other structures, because Young's modulus of the SMA + SMP helical spring is controllable. However, the relationship between the applied current and the TVA stiffness is nonlinear. Therefore, to understand the vibration characteristic of the TVA, the experiments are designed to establish an expert database of the interval type-2 fuzzy controller, which will be used to describe the nonlinear mapping between the input and the output. In the case studies, the TVA is applied to suppress the vibrations of a planar structure with multiple degrees of freedom. The resulting experiments validated the ability of the proposed method of vibration control.