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.

摘要

提出了一种基于高频操作偏转形状 (ODS) 的新型无基线损伤识别方法，用于晶格夹层结构 (LSS) 的脱粘检测。构建了两个不同晶胞的数值模型，分析了高频段脱粘缺陷结构的振动特性。模式形状和 ODS 被数值计算以研究局部缺陷振动效应。结果表明，在一定的合适频段，损坏部位会出现明显的局部振动。从 ODS 计算的无基线损伤指数最初被提议用于损伤成像。为了实验验证，我们建议使用间歇性周期性激励信号来驱动振动，这可能会使用一次测量以不同频率激发多个 ODS，从而显着提高检测效率。实验结果还表明，所提出的损伤识别方法可有效定位 LSS 中的脱粘损伤。本研究得出的结论有望为 LSS 以及其他板状结构提供有效的振动测量技术和实用的损伤检测方法。