Model assessment of a composite mock-up bladed rotor based on its vibration response and radial expansion

Gude

2018

Materials

Self Cite

Fibre-reinforced composite structures subjected to complex loads exhibit gradual damage behaviour with the degradation of the effective mechanical properties and changes in their structural dynamic behaviour. Damage manifests itself as a spatial increase in inter-fibre failure and delamination growth, resulting in local changes in stiffness. These changes affect not only the residual strength but, more importantly, the structural dynamic behaviour. In the 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, provide the fundamentals for a better understanding of unpredicted structural phenomena. The gradual damage behaviour of the example composite rotors and the resulting damage-dependent dynamic behaviour were experimentally investigated under propagating damage caused by a combination of out-of-plane and in-plane loads. A novel observation is the finding that a monotonic increase in damage results in a non-monotonic frequency shift of a significant number of eigenfrequencies.

Section: Methods For the Investigation Of Representative Damage Seqmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Gude

2018

Materials

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“…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%

“…As the fibre architecture has a refraction index similar to that of the epoxy matrix, which amounts to 1.548 -1.552, it is possible to use optical inspection to identify the inflicted damage [22]. A high-resolution optical camera NIKON D3100 is therefore used with an optical resolution of 4608 × 3072 pixel.…”

Section: High Resolution Optical Inspectionmentioning

confidence: 99%

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

Gude

2018

Preprint

Self Cite

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.

“…Therefore, a characterisation of the dynamic behaviour of rotors under different rotational speeds is an important factor for the optimal design and safe operation of rotors. Specifically, new experimental methods appropriate for the investigation of complex phenomena such as non-linear behaviour, gradual damage behaviour, internal friction and damping describing the structural behaviour of metallic and composite rotors are required [1,2]. These phenomena are not adequately considered in existing simulation models as they cannot be fully captured with existing measurement techniques not least due to a lack of suitable vibration excitation systems [3].…”

Section: Introductionmentioning

confidence: 99%

Design and Testing of a Co-Rotating Vibration Excitation System

Wollmann

Nguyen

et al. 2018

Sensors

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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.