GLOBAL AIRFRAME HEALTH CHARACTERIZATION

• US 20150105970A1
• Filed: 10/14/2013
• Published: 04/16/2015
• Est. Priority Date: 10/14/2013
• Status: Active Grant

• Current Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Original Assignee: Sikorsky Aircraft Corporation (Martin Marietta Corporation)
• Inventors: Harrigan, Matthew
• Granted Patent: US 9,284,048 B2
• Time in Patent Office: Days
• US Class Current: 701/32.8
• CPC Class Codes: B64C 2027/004 using actuators, e.g. active systems
• CPC Class Codes: B64C 27/001 Vibration damping devices
• CPC Class Codes: B64D 2045/0085 Devices for aircraft health monitoring, e.g. monitoring flutter or vibration
• CPC Class Codes: B64D 45/00 Aircraft indicators or protectors not otherwise provided for camouflage F41H3/00
• CPC Class Codes: F16F 1/00 Springs working with fluid F16F5/00, F16F9/00
• CPC Class Codes: F16F 15/002 characterised by the control method or circuitry control of mechanical oscillations per se G05D19/00

Abstract

According to one aspect, a controller, including a processor, sets an initial vibration frequency to be applied to an airframe. The controller commands one or more force generators to apply a vibratory load to the airframe at the initial vibration frequency. The controller determines a vibration response of the airframe at the initial vibration frequency using sensors. The controller sweeps through a range of vibration frequencies to be applied to the airframe. The one or more force generators are commanded to apply a plurality of vibratory loads to the airframe over the range of vibration frequencies. The controller determines a range of vibration responses of the airframe over the range of vibration frequencies using the sensors. A global stiffness of the airframe is determined based on the vibration response and the range of vibration responses. The controller reports results of the determined global stiffness of the airframe.

Claims

1. A method comprising:

setting, by a controller comprising a processor, an initial vibration frequency to be applied to an airframe;

commanding, by the controller, one or more force generators to apply a vibratory load to the airframe at the initial vibration frequency;

determining, by the controller, a vibration response of the airframe at the initial vibration frequency using a plurality of sensors;

sweeping, by the controller, through a range of vibration frequencies to be applied to the airframe;

commanding, by the controller, the one or more force generators to apply a plurality of vibratory loads to the airframe over the range of vibration frequencies;

determining, by the controller, a range of vibration responses of the airframe over the range of vibration frequencies using the plurality of sensors;

determining, by the controller, a global stiffness of the airframe based on the vibration response and the range of vibration responses; and

reporting, by the controller, results of determining the global stiffness of the airframe.

2. The method of claim 1, wherein an aircraft comprises the airframe, and the method is performed while the aircraft is positioned on a landing surface.

3. The method of claim 1, further comprising deriving a transfer function, by the controller, based on the vibration response and the range of vibration responses.

4. The method of claim 3, further comprising:

comparing the transfer function to a nominal design value for the airframe; and

determining a level of damage to the airframe based on a difference between the transfer function and the nominal design value.

5. The method of claim 3, further comprising:

comparing the transfer function to a stored baseline value of the airframe; and

determining a level of damage to the airframe based on a difference between the transfer function and the stored baseline value.

6. The method of claim 5, further comprising:

receiving a request to establish a new baseline value of the airframe; and

recording the transfer function as the new baseline value of the airframe.

7. The method of claim 1, further comprising:

comparing the global stiffness of the airframe to a threshold value; and

determining a level of damage to the airframe based on a difference between the global stiffness and the threshold value.

8. The method of claim 1, wherein the sensors are distributed throughout the airframe and are associated with a plurality of aircraft monitoring subsystems, and the method further comprises receiving data for at least one of the sensors from one or more of the aircraft monitoring subsystems.

9. The method of claim 1, wherein the one or more force generators are components of an active vibration control system configured to attenuate vibration of the airframe while in flight.

10. A system comprising:

one or more force generators configured to apply vibratory loads to an airframe;

a plurality of sensors coupled to the airframe; and

a controller configured to;

set an initial vibration frequency to be applied to the airframe;

command the one or more force generators to apply a vibratory load to the airframe at the initial vibration frequency;

determine a vibration response of the airframe at the initial vibration frequency using the plurality of sensors;

sweep through a range of vibration frequencies to be applied to the airframe;

command the one or more force generators to apply a plurality of vibratory loads to the airframe over the range of vibration frequencies;

determine a range of vibration responses of the airframe over the range of vibration frequencies using the plurality of sensors;

determine a global stiffness of the airframe based on the vibration response and the range of vibration responses; and

report results of determining the global stiffness of the airframe.

11. The system of claim 10, wherein an aircraft comprises the airframe, and the controller is configured to operate based on the aircraft being positioned on a landing surface.

12. The system of claim 10, wherein the controller is further configured to derive a transfer function based on the vibration response and the range of vibration responses.

13. The system of claim 12, wherein the controller is further configured to compare the transfer function to a nominal design value for the airframe, and determine a level of damage to the airframe based on a difference between the transfer function and the nominal design value.

14. The system of claim 12, wherein the controller is further configured to compare the transfer function to a stored baseline value of the airframe, and determine a level of damage to the airframe based on a difference between the transfer function and the stored baseline value.

15. The system of claim 14, wherein the controller is further configured to receive a request to establish a new baseline value of the airframe, and record the transfer function as the new baseline value of the airframe.

16. The system of claim 10, wherein the controller is further configured to compare the global stiffness of the airframe to a threshold value, and determine a level of damage to the airframe based on a difference between the global stiffness and the threshold value.

17. The system of claim 10, wherein the sensors are distributed throughout the airframe and are associated with a plurality of aircraft monitoring subsystems, and the controller is further configured to receive data for at least one of the sensors from one or more of the aircraft monitoring subsystems.

18. The system of claim 10, wherein the one or more force generators are components of an active vibration control system configured to attenuate vibration of the airframe while in flight.

19. A system comprising:

a first inertial measurement unit located at a nose section of an airframe of an aircraft;

a second inertial measurement unit located at an extending tail of the airframe; and

a controller configured to;

measure an angular deflection of the airframe during flight based on a relative difference between measurements from the first inertial measurement unit and the second inertial measurement unit;

determine a global stiffness of the airframe based on the angular deflection of the airframe in combination with a load state of the aircraft; and

report results of determining the global stiffness of the airframe.

20. The system of claim 19, further comprising:

one or more force generators configured to apply vibratory loads to the airframe while the aircraft is positioned on a landing surface;

a plurality of sensors coupled to the airframe; and

the system is further configured to;

set an initial vibration frequency to be applied to the airframe;

command the one or more force generators to apply a vibratory load to the airframe at the initial vibration frequency;

determine a vibration response of the airframe at the initial vibration frequency using the plurality of sensors;

sweep through a range of vibration frequencies to be applied to the airframe;

command the one or more force generators to apply a plurality of vibratory loads to the airframe over the range of vibration frequencies;

determine a range of vibration responses of the airframe over the range of vibration frequencies using the plurality of sensors; and

determine a global stiffness of the airframe based on the vibration response and the range of vibration responses.