Improved Ground Vibration Testing Methods for Flight Structures

Professor John B. Kosmatka

Typical Ground Vibration Tests of flight vehicles are performed by attaching a moderate number (10 to 100) of discrete accelerometers to a free-free flight vehicle where the excitation is provided using one or more electro-mechanical shakers. A new approach involves using a noncontacting scanning laser vibrometer on the free-free flight vehicle.

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The SLV has the advantage over discrete accelerometers in that a near infinite number of data points can be measured without altering the mass configuration of the flight vehicle. This large number of data points makes it easy to: (a) correlate the experimental data with analytical (finite element) results, (b) investigate local modes, and (c) investigate the affects of subtle vehicle configuration changes on the modal properties. Dr Kosmatka is working with Northrop- Grumman to develop and use this new approach to evaluate their Hunter MQ-5B Unmanned Air Vehicle.