The main application of our thesis is in aerospace industry. This industry is under continuous pressure and has to develop aircrafts in shorter timeframes and at lower costs than ever before. A large part of aircraft development time is used for testing. This means if testing time can be reduced significantly  a shorter time to market can be achieved.

An aircraft has to be flutter certified. This is a certification at maximum flight speed to determine structural integrity and safety of the airplane. The first formal flutter test was carried out by Von Schlippe in 1935 in Germany. His approach was to vibrate the aircraft at resonant frequencies at progressively higher speeds and plot amplitude as a function of airspeed. This approach was sufficient untill a Junkers JU90 crashed in 1938 during flutter tests. Next a more advanced approach was used. The typical test procedure is visible in the figure. The full explanation is available in this NASA-report. It’s still based on the Von Schlippe methods. Firstly, structural excitation of the plane. The second part is the response measurement. This is done using hundreds of accelerometers. The last part is the data analysis.

flight_flutter_test_process

Before these tests can be started a ground vibration testing(GVT) is done to predict analytically the flutter behaviour. My next post will provide more details on ground vibration testing. You can also watch the flutter test of the A380 in the youtube video.

 

 

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