Impact of Sensor Geometric Dimensions and Installation Accuracy on the Results of Instantaneous SHM Based on Wave Propagation Using Wafer Active Sensors

Abstract

Since damage identification results can be impressed by the effects due to changes in environmental and operational conditions, developing an effective monitoring system without any prior measured baseline data, while a structure is in its pristine condition, has gained much attraction recently. The instantaneous baseline damage identification method is one of the advanced techniques that works based on the concept of identicality of measured signals of similar paths. To hold this concept true, not only must the material properties, electromechanical characteristics, and the structure geometric features be identical, but also other features such as the sensor distance between equivalent paths and the geometrical parameters of the sensors must be the same. In this work, the influence of uncertainties in the length of sensing paths, which can be caused by sensor installation and tolerances in the dimensions of transducers, on the accuracy of instantaneous damage identification results is thoroughly investigated. In this paper, two damage index algorithms, i.e., correlation-based and wavelet-based algorithms, are employed, and the sensitivity of the methods to the mentioned uncertainties are numerically examined utilizing finite element (FE) simulation. The results are verified with the existing experimental data. Conclusively, the instantaneous wavelet-based method is not much sensitive to the transducers’ dislocation, and no special requirement is needed for their installation. However, the instantaneous damage identification results obtained using the correlation-based method are independent of the inequality in the dimensions of the transducers.