Towards on-blade monitoring of Rotating blade systems – a dynamics based approach

Stefan Oosterik – University Twente (Nov 2013 - Nov 2014)


The development of advanced monitoring systems enables placing sensors on the blades of rotating blade system, such as the main rotor of a helicopter (Fig. 1). On-blade vibration monitoring can be used to reduce this uncertainty and provide additional on-blade data (e.g. blade strain data). However, the response of a rotating blade system remains complex and a successful rotor monitoring system has to be capable of coping with this complexity. Therefore the development of advanced monitoring systems (wireless, on-blade sensing) starts with a concise understanding of the dynamic behaviour, the influences of different operational conditions and possible failure/damage scenarios.

Figure 1 Helicopter main rotor

Figure 2 Function-Behaviour-Structure framework for monitoring

The first part of the research is concerned with identification of the (sub-)functions , components of the structure and the physics covering the helicopter rotor behaviour. The case study is limited to a articulated (hinged) rotor blade in hover flight. In the next part, the complexity of the behaviour of the helicopter rotor blade is studied using a physics based model. Moreover, the implications for vibration monitoring are identified. The final part involves the effect of a specific damage scenario on the behaviour of the helicopter rotor and the possibility of detecting the damage on-flight.



A framework for monitoring of complex systems (see Fig. 2)


A physics based model that describes the behaviour of a helicopter rotor blade in hover flight


It is shown that both rotation (see Fig. 3) and aerodynamics affect the dynamic characteristics of the rotor blade


The possibility for detecting local blade cracking on a free rotating blade is demonstrated, using both global and local methods


The implication of the rotor complexity on damage detection and performance monitoring are shown

Figure 3 Campbell graph for case study blade with