FOTO BLISK FULL

The blisk has been placed on three small rubber pads, to decouple the part from the environment, while minimizing the influence from the support. A high-resolution geometry scan showed only very slight geometrical deviations, in the order of 50 µm. It is manufactured out of stainless steel and has been milled with high precision at a company specialized in the manufacturing of these parts.

FOTO BLISK FULL

3D Scanning Laser Doppler Vibrometers (3D SLDVs) furthermore yield the complete 3D deflection shapes for all frequencies in a simple and accurate way, leading to a full dataset that can easily be used for correlation with FE models.Ī compressor blisk of 240 mm diameter, provided by the ITSM from the University of Stuttgart is studied. This is a mandatory condition for an accurate and detailed model correlation. No mass loading or increased damping as for conventional contact sensors like accelerometers appears. Laser Doppler vibrometers measure the vibration behavior reliably in a non-contact manner over the entire needed frequency range. Detailed FE correlation is therefore a crucial step and needs to be performed very accurately.ģD laser Doppler vibrometry for model correlation As a second step, it will then be adapted to account for the observed mistuning.

As a first step, a FE model for a symmetric part needs to be validated by test. To predict the real stresses under operation, detailed Finite Elements (FE) modelling is needed. During operation, this could lead to higher stress and ultimately to an earlier failure of the component (high cycle fatigue). If mistuning appears, the vibration energy might be concentrated in one or a few blades, leading to high vibration amplitudes. Very small imperfections in the manufacturing process lead to mistuning of the resonances. In such a case, the vibration modes show a symmetrical behavior as well, the vibration energy is distributed equally among all sectors. An ideal blisk is symmetric, meaning that all sectors have the same geometry and material properties. As they are made from one single piece, they show extremely low damping, leading to very sharp, pronounced vibration resonances. Need for vibration tests and model correlationīlisks reduce weight and complexity, but bring technical challenges. These components are milled from one single piece instead of being assembled like conventional parts. In order to reduce weight and build more economic engines, the use of blade integrated disks (blisks) is getting more widespread. An important factor is the design of the aircraft engine itself. Fuel consumption of aircrafts is a hot topic in the current discussion about global climate change.

Foto blisk