Using Modal Parameters for Structural Health Monitoring

Abstract

In two recent papers, we introduced the idea of numerically comparing currently acquired operating data with archived data to identify faults in rotating machinery (Ganeriwala et al.: Using operating deflection shapes to detect unbalance in rotating equipment. In: IMAC XXVII. Orlando, FL (2009); Richardson et al.: Using operating data to locate and quantify unbalance in rotating machinery. In: IMAC XXXIV, January 25–28, 2016). We introduced a new metric for comparing two operating deflection shapes called the Shape Difference Indicator (SDI). In another previous paper (Richardson et al.: A new measure of shape difference. In: IMAC XXXII, February 3–6, 2014), we used SDI to measure the difference in modal frequencies from before and after a stiffness change was made to a mechanical structure.

In this paper we provide more details of how experimental modal frequency and damping parameters can be used together with the SDI metric as a means of detecting and quantifying changes in the physical properties of a structure.

Also, we have implemented SDI together with a search method for ranking the differences between currently acquired modal parameters and archived modal parameters. We call this new method Fault Correlation Tools (FaCTs™). FaCTs™ can be used in multiple applications, including structural health monitoring, production qualification testing, and recertification of machinery in field maintenance applications.