Baseline-Free Damage Identification Method for Lattice Sandwich Structures Based on Operational Deflection Shapes

Abstract

ABSTRACT A novel baseline-free damage identification method based on high frequency operational deflection shapes (ODSs) is presented for debonding detection in lattice sandwich structures (LSSs). Two numerical models with different unit cells are constructed to analyze the vibration characteristics of a structure with debonded defect in the high-frequency band. The mode shapes and ODSs are computed numerically to investigate the local defect vibration effects. The results show that there will be obvious local vibration at the damaged location at a certain and appropriate frequency band. A baseline-free damage index calculated from ODSs is originally proposed for damage imaging. For experimental validation, we suggested an intermittent periodic excitation signal for vibration actuating, which may excite multiple ODSs at different frequencies using one measurement that significantly improve the detection efficiency. The experimental results also indicated that the proposed damage identification method is effective to locate the debonding damage in LSSs. The conclusions derived from this study are expected to provide an efficient vibration measurement technique and a practical damage detection method for LSSs, as well as other plate-like structures.