A Sequence-Based Damage Identification Method for Composite Rotors by Applying the Kullback–Leibler Divergence, a Two-Sample Kolmogorov–Smirnov Test and a Statistical Hidden Markov Model

Angelos Filippatos,Albert Langkamp,Pawel Kostka,Maik Gude

doi:10.3390/e21070690

Abstract

Composite structures undergo a gradual damage evolution from initial inter-fibre cracks to extended damage up to failure. However, most composites could remain in service despite the existence of damage. Prerequisite for a service extension is a reliable and component-specific damage identification. Therefore, a vibration-based damage identification method is presented that takes into consideration the gradual damage behaviour and the resulting changes of the structural dynamic behaviour of composite rotors. These changes are transformed into a sequence of distinct states and used as an input database for three diagnostic models, based on the Kullback–Leibler divergence, the two-sample Kolmogorov–Smirnov test and a statistical hidden Markov model. To identify the present damage state based on the damage-dependent modal properties, a sequence-based diagnostic system has been developed, which estimates the similarity between the present unclassified sequence and obtained sequences of damage-dependent vibration responses. The diagnostic performance evaluation delivers promising results for the further development of the proposed diagnostic method.

Highlights

Composite rotors have numerous applications, reliable methods for the on-line damage identification of critical high-performance composite rotors are still at an early stage of development.A number of promising approaches already exist based on vibration-based diagnostics, but their basic disadvantage is a high performance loss due to the existence of ambiguities in the diagnostic data
The leave-one-out cross validation technique was selected, which is a model validation technique for assessing how the results of a statistical analysis can be generalised to an independent dataset, and how accurately a diagnostic model performs in practice
The present work provides a contribution to the area of vibration-based damage identification methods for composite rotors

Summary

Introduction

A number of promising approaches already exist based on vibration-based diagnostics, but their basic disadvantage is a high performance loss due to the existence of ambiguities in the diagnostic data. Investigations demonstrate that such ambiguities in the relationship between the inflicted damage and the resulting change of the modal properties for different damage configurations are most common in composite rotors [1]. The distinction of two different damage states with similar diagnostic feature values is only possible if past damage events with increasing loads are considered. It is essential to consider past damage events and their effect to the dynamic behaviour as a sequence and not as isolated events

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