STRUCTURAL HEALTH MONITORING AND ESTIMATION OF DEGREE OF DAMAGE IN LOCALLY RESONANT METAMATERIALS

Metamaterials have the potential to protect the built environment from the vibration effects produced by seismic waves. The geometric and dynamic parameters of locally resonant metamaterials create attenuation effects as a consequence of frequency bandgap regions for effective vibration mitigation. Being scaled up, local resonant elements can be employed for improving earthquake-resistant performance in civil structures. Preserving the structural health condition of the metastructure in locally resonant metamaterials play a critical role in the long-term serviceability. Manufacturing defects, harsh environmental conditions, or severe wave impacts can modify geometry, mass, and stiffness, inducing then structural modifications to the metastructure configuration and disrupting the wave attenuation mechanism. Therefore, exploiting the benefits of structural health monitoring (SHM) to detect structural modifications and estimate a degree of damage in metamaterials is urged in order to accurately verify the current structural health and the dynamic response. This investigation seeks to monitor and detect different modifications to estimate a degree of damage in the locally resonant metastructure by performing dynamic experimental testing and exploring alterations in the transmittance spectrum. Then, mean square distance (MSD) ranges were determined based on the transmittance spectrum curves to estimate a degree of damage and correlate the mass modifications introduced intentionally. The metamaterial specimen is composed of a 3D-printed structural configuration of unit cells with local resonators. The results of this experimental study contribute to understanding the implications of structural changes at the locally resonant metastructure to the dynamic response of metamaterials for earthquake protection applications. It also reinforces the need to investigate SHM and damage detection in locally resonant metamaterials to reduce the uncertainty in the health condition, damage states, and performance based on actual dynamic information. This research has the potential to extend resilience of civil infrastructure while raising awareness of novel earthquake protection technology for future large-scale applications.