METHOD FOR PERFORMING A GROUND VIBRATION TEST IN AIRPLANES

• US 20080257051A1
• Filed: 04/22/2008
• Published: 10/23/2008
• Est. Priority Date: 04/23/2007
• Status: Active Grant

• Current Assignee: Airbus Operations GmbH (Airbus SE)
• Original Assignee: Airbus Deutschland GmbH (Airbus SE)
• Inventors: Schierenbeck, Detlef
• Granted Patent: US 7,856,884 B2
• Time in Patent Office: Days
• US Class Current: 73/663
• CPC Class Codes: G01M 7/00 Vibration-testing of structures; Shock-testing of structures G01M9/00 takes precedence
• CPC Class Codes: G01N 2291/2694 Wings or other aircraft parts
• CPC Class Codes: G01N 29/045 by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks measuring resonant frequency G01H13/00; measuring strength properties by application of mechanical stress G01N3/00
• CPC Class Codes: G01N 29/4463 Signal correction, e.g. distance amplitude correction [DAC], distance gain size [DGS], noise filtering

Abstract

The invention relates to an improved method for a ground vibration test (so-called “ground vibration test”) on an airplane. In the method according to the invention, the airplane is jacked up essentially undamped (“rigidly”) in conventional holding points with lifting devices. For purposes of the ground vibration test, the airplane is then excited to vibrate in a known manner using a plurality of vibration exciters, and the vibrations are acquired with a plurality of measuring transducers, in particular accelerometers. A dynamic vibration model of the airplane theoretically calculated beforehand can here be adjusted. The boundary conditions are removed during or after the ground vibration test, meaning the influence of the lifting device is “mathematically canceled out”, so that the determined measured values reflect the so-called “free-free” state of the airplane, as if the airplane had actually been in free flight during the ground vibration tests.

Claims

1. A method for performing a ground vibration test on an airplane, comprising the following steps:

a) placing measurement transducers in an area of the airplane,

b) keeping the airplane rigidly in place in at least three holding points

c) exciting the airplane to vibrate with a plurality of vibration exciters,

d) measuring values and evaluating the measured values obtained by the measuring transducers, and

e) mathematically canceling out influence of rigid holding at the holding points during the ground vibration test and/or after the ground vibration test.

2. The method according to claim 1, wherein holding takes place at each of the at least three holding points by means of a respective hydraulic lift.

3. The method according to claim 1 wherein the measured values are acquired with accelerometers.

4. The method according to claim 1, wherein the airplane is excited to vibrate by means of a plurality of electromagnetic exciters.

5. The method according to claim 1, wherein a vibration model of the airplane is adjusted to the measured values determined by the measuring transducers during the ground vibration test.

6. The method according to claim 1, wherein forces acting on the lifting devices during the ground vibration test are acquired with accelerometers and/or dynamometers, and the ground vibration test is immediately terminated if preset limits are exceeded.

7. The method according to claim 1, wherein the vibration exciters are positioned in an area of wing ends, elevator unit ends, a rudder unit end, an aft fuselage, engines as well as a nose of the airplane.

8. The method according to claim 1, wherein the measuring transducers are arranged on and/or in the airplane.

9. The method according to claim 1, wherein up to 1,000 measuring transducers are used.

10. The method according to claim 1, wherein a vibration model of the airplane encompasses up to 5·

10⁶ node points, each with 6 degrees of freedom.