A frequency domain-based correlation approach for structural assessment and damage identification

Abstract

Abstract The objective of this work is to demonstrate the feasibility of utilising vibration data to generate a set of spectral domain-based indicators purposed to assess the degradation and reinforcement on structures. These indicators are derived from the complex frequency domain assurance criterion (CFDAC) matrices, corresponding to the altered and pristine state of a monitored structure. The CFDAC operator is similar to the MAC (modal assurance criterion) but formulated in the complex spectral domain. The indicators, referred to as spectral correlation indices (SCI), are aimed to quantify the strength of correlation between an altered state and a reference state so structural alteration can be assessed. In this paper, a numerical and experimental investigation on the feasibility of the proposed approach for structural assessment is presented, by examining the spectral correlation indices in front of multiple alteration scenarios on a square aluminium plate under one-edge-clamped boundary conditions. A comprehensive parametric, sensitivity and stability analysis in front of the FRF synthesis and acquisition parameters is undertaken, both experimentally and numerically, to deepen the knowledge concerning stability properties of the indicators. Once stability thresholds are identified, experimental results are compared to numeric outcomes, allowing conclusions to be drawn regarding the capability and suitability of proposed SCI indicators for structural assessment and damage identification. This research is aimed to serve as a first step towards the development of a fully functional SHM system based on spectral domain indices.