Deformation (Optical Flow Method)
In general the deformation measurement technique relates to the determination of contour and shape of an object which deforms under a load. At the Institute of Fluid Mechanics and Aerodynamics this technique is used to determine the loading and deformation of systems under an aerodynamic load. Besides established methods which work in direct contact to the test object, contact-free and imaging measurement techniques prevail in recent years. The fundamental advantage is hereby the possibility to investigate an entire measurement field simultaneously without manipulating the behaviour of the test object due to direct contact. Also dynamic processes can thus be recorded. Here usually several cameras are used in order to record the measurement object from different points of view and in order to catch the 3-dimensional expanse.
The methods for the determination of the 3D surface of the measuring object (correlation between stereo images) and additionally the methods for the determination of the 3D deformation vector fields (correlation between images under varying loads) use established cross-correlation algorithms which are also applied within the Particle Image Velocimetry (PIV).
Besides the evaluation methods also diverse hardware systems in their according arrangement can be used for both PIV and the deformation measurement technique.
For the successful identification of image information digitally interpretable, artificial patterns are needed so far on the measuring object which are usually sprayed on or projected. The Institute of Fluid Mechanics and Aerodynamics enhances these techniques in the following fields:
• Add-on and adaptation of the digital evaluation methods
• Enhancement of the contour identification for complex wing geometries
• Development of a method for the identification by means of naturally available texture
• Enhancement of well-known methods for the evaluation of large deformations
• High-Speed Deformation Measurements
Funded by the Deutsche Forschungsgemeinschaft (DFG).
Partner: RWTH Aachen, DLR Göttingen
Contacts: Dipl.-Ing. Alexander Friedl