Modelling variability in vibration-based PBSHM via a generalised population form

• Published in: Journal of sound and vibration Vol. 538; p. 117227
• Main Authors: Dardeno, T.A., Bull, L.A., Mills, R.S., Dervilis, N., Worden, K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 10-11-2022
• Subjects: Gaussian processes; Population-based SHM; Repeatability; Uncertainty; Repeatability; Population-based SHM; Uncertainty; Gaussian processes
• ISSN: 0022-460X; 1095-8568
• DOI: 10.1016/j.jsv.2022.117227

Structural health monitoring (SHM) has been an active research area for the last three decades, and has accumulated a number of critical advances over that period, as can be seen in the literature. However, SHM is still facing challenges because of the paucity of damage-state data, operational and environmental fluctuations, repeatability issues, and changes in boundary conditions. These issues present as inconsistencies in the captured features and can have a huge impact on the practical implementation, but more critically, on the generalisation of the technology. Population-based SHM has been designed to address some of these concerns by modelling and transferring missing information using data collected from groups of similar structures.
In this work, vibration data were collected from four healthy, nominally-identical, full-scale composite helicopter blades. Manufacturing differences (e.g., slight differences in geometry and/or material properties), among the blades presented as variability in their structural dynamics, which can be very problematic for SHM based on machine learning from vibration data. This work aims to address this variability by defining a general model for the frequency response functions of the blades, called a form, using mixtures of Gaussian processes.
•A novel, generalised population form for PBSHM is proposed.•The approach is based on overlapping mixtures of Gaussian processes (OMGP).•The OMGP can characterise benign variations in dynamics within a population.•From experimental data, an OMGP form is developed for helicopter blades.•A novelty detector is used to test the form against simulated damaged states.