Design and control of adaptive vibration absorber for multimode structure

In this study, we used two tunable vibration absorbers composed of shape memory alloy to reduce vibration of a platform structure. The natural frequency of the shape memory alloy absorber can be tuned online using a fuzzy logic controller to change the axial force of the shape memory alloy wires through phase transformation. In addition, we employed the finite element method to analyze the dynamic characteristics of the multimode platform structure and to evaluate the effectiveness of the shape memory alloy vibration absorber in terms of platform vibration attenuation. Experimental testing of the platform structure was conducted to verify its modal characteristics. By setting the two shape memory alloy tunable vibration absorbers on two adjacent sides of the platform at 90degrees to each other and offset from the platform's center axes, it is shown that all six modes can be covered for vibration absorption. The experiments show that the vibration due to all six mode modal excitations can be attenuated by more than 7.49dB using the shape memory alloy tunable vibration absorber. Specifically, at the fourth, fifth, and sixth resonant modes, an average of 16.68dB vibration suppression is observed. Overall, an average of 12.69dB vibration suppression is achieved for resonant excitation of the entire platform structure when using the designed shape memory alloy tunable vibration absorber.