Multi-sensor system for in situ shape monitoring and damage identification of high-speed composite rotors

Langkamp

Kostka

et al. 2019

Entropy

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.

Section: Case Study Of a Composite Disc Rotormentioning

confidence: 99%

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

Langkamp

Kostka

et al. 2019

Entropy

“…Especially in aerospace industry, increasing economical demands in combination with high performance requirements have led to substantial breakthroughs in the design and development of high-speed composite rotors, such as rotor blades [17][18][19][20]. The main focus has been directed towards the in-plane and out-of-plane dynamic behaviour as well as the anisotropic material damping of undamaged composite rotors [21][22][23][24][25]. However, the gradual damage behaviour of composite rotors under unexpected loads has not been in the main scope of investigations of many researchers [26,27], and even less examined is the relation between gradual damage behaviour and corresponding dynamic behaviour of composite rotors.…”

Section: Composite Rotorsmentioning

confidence: 99%

Influence of Gradual Damage on the Structural Dynamic Behaviour of Composite Rotors: Experimental Investigations

Gude

2018

Preprint

Fibre-reinforced composite structures under complex loads exhibit gradual damage behaviour with a degradation of effective mechanical properties and change of their structural dynamic behaviour. Damage manifests itself as spatial increase of inter-fibre failure and delamination-growth, resulting in local changes of stiffness. These changes affect not only the residual strengths but more importantly the structural dynamic behaviour. In case of composite rotors, this can lead to catastrophic failure if an eigenfrequency coincides with the rotational speed. The description and analysis of the gradual damage behaviour of composite rotors therefore provides the fundamentals for a better understanding of unpredicted structural phenomena. The gradual damage behaviour on the example of composite rotors and the resulting damage-dependent dynamic behaviour is experimentally investigated under propagating damage for combined out-of-plane and in-plane loads. A novel observation is reported, where monotonic increase of damage results in non-monotonic frequency shift of significant amount of eigenfrequencies.

“…Four possible rotor geometries that can be measured using the developed system; ( a ) a generic steel rotor, ( b ) a composite rotor, ( c ) an industrial steel rotor and ( d ) a titanium disk with composite blades [15,32,33,34]. …”

Section: Figurementioning

confidence: 99%

Design and Testing of a Co-Rotating Vibration Excitation System

Wollmann

Nguyen

et al. 2018

Sensors

A vibration excitation system (VES) in a form of an active coupling is proposed, designed and manufactured. The system is equipped with a set of piezoelectric stack actuators uniformly distributed around the rotor axis and positioned parallel to each other. The actuator arrangement allows an axial displacement of the coupling halves as well as their rotation about any transverse axis. Through the application of the VES an aimed vibration excitation is realised in a co-rotating coordinate system, which enables a non-invasive and precise modal analysis of rotating components. As an example, the VES is applied for the characterisation of the structural dynamic behaviour of a generic steel rotor at different rotational speeds. The first results are promising for both stationary and rotating conditions.