EXPERIMENTAL INVESTIGATION OF FLIGHT AND PHYSICAL PARAMETERS AFFECTING THE VIBRATION RESPONSE SEVERITY OF SUBSYSTEM CARRIED BY JET AIRCRAFT

Engin Metin KAPLAN and Mehmet Bulent OZER

In this study, Experimental Modal Analysis (EMA) of a subsystem carried by a jet aircraft which is in real flight condition is performed. The main purpose of this study is to investigate relationship between vibration response of the subsystem and flight parameters like mach number, attitude, propulsion severity and number of the jet engine of the jet type aircraft, also physical parameters as mass, mass moment of inertia in three axes of the subsystem. Parameters are collected in real flight condition by data storage system. In signal processing, vibration response is expressed as power spectral density functions in frequency domain. Root mean square of values in terms of gravitational acceleration (GRMS) is also used to define vibration response severity in singular number. Time history data is checked, if the signal is stationary or not. Data are filtered to clean static effects like jet maneuver. It is seen that mach number and flight attitude of the jet has strong effect on subsystem vibration response magnitude. Also, results show that, change of the external geometry of the subsystem influence the vibration response. According to results, it can be said that, subsystem physical parameters have small impression on vibration response.

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