Experimental Method to Evaluate Effective Dynamic Properties of a Meta-Structure for Flexural Vibrations

In this study, a laboratory method to evaluate the effective dynamic properties for flexural vibrations of a meta-structure is presented. The flexural vibration of a beam with periodically spaced resonators was investigated using wave propagation analysis. After analyzing vibration interactions between the resonators and the homogeneous beam, the effective dynamic properties of the meta-structure were evaluated using the transfer function method. The comparison of the measured and predicted results allowed for an understanding of the proposed vibration control mechanism. The effective bending stiffness was not affected by the attached resonators. The effective mass exhibited significant frequency-dependent variation near the natural frequency of the resonators. The effective mass becomes complex when the stiffness of the resonators is viscoelastic. The reflected wave from the metamaterial was completely blocked when the real part of the effective mass became negative. The effective mass decreased as the loss factor of the attached resonators increased. The proposed evaluation method can be used to analyze the effects of resonators on structural vibrations.