Method and system to measure dynamic loads or stresses in aircraft, machines, and structures

• US 6,354,152 B1
• Filed: 11/26/1999
• Issued: 03/12/2002
• Est. Priority Date: 05/08/1996
• Status: Expired due to Fees

• Current Assignee: Herlik, Edward Charles
• Original Assignee: Herlik, Edward Charles
• Inventors: Herlik, Edward Charles
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US09/450,116
• Time in Patent Office: 837 Days
• Field of Search: 737/61, 737/72, 737/78, 737/86, 735/97, 736/29, 738/625.9, 737/71, 738/02
• US Class Current: 73/597
• CPC Class Codes: G01N 2291/011 Velocity or travel time
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/02827 Elastic parameters, strength or force
• CPC Class Codes: G01N 2291/2691 Bolts, screws, heads
• CPC Class Codes: G01N 2291/2694 Wings or other aircraft parts
• CPC Class Codes: G01N 29/223 Supports, positioning or alignment in fixed situation mounting transducers per se G10K11/004
• CPC Class Codes: G01N 29/227 related to high pressure, tension or stress conditions

Abstract

The system and method of this invention determines stress within the load bearing members of an aircraft, machine or structure in order to improve their design, safety and efficiency as well as enhancing their operation. Load or stress is calculated from signals generated in fasteners fitted with piezoelectric crystals. Rather than indirect stress indication through approximations from accelerometers, optical fibers, position sensors, strain gages and the like, this invention calculates load or stress from sensors installed directly into load bearing elements. This invention can perform stress indicating function in machines and structures such as, but not limited to, aircrafts, buildings, bridges, power generating stations, ships and engines.

Claims

1. In combination, an aircraft and a system for measuring dynamic stresses in the structure of said aircraft, said aircraft comprising a fuselage and a pair of wings attached thereto, said system comprising a plurality of fixed elements embedded in predetermined locations of said fuselage and said wings, an ultrasonic or acoustical sensor attached to each of said elements, an acoustical signal processing means, a transmission means connected between each of said ultrasonic or acoustical sensors and said acoustical signal processor wherefrom ultrasonic pulses are transmitted to each of said fixed elements through said attached ultrasonic or acoustical sensor and back to said acoustical signal processing means which, in turn, is connected to a computer programmed to convert said returned ultrasonic pulses into stress measurement information.

2. The combination of claim 1 wherein said ultrasonic sensor is a piezoelectric crystal.

3. The combination of claim 1 wherein each of said plurality of elements is a fastener.

4. The combination of claim 3 wherein said fastener is threaded.

5. The combination of claim 1, wherein said acoustical signal processing means comprises a central processor, an ultrasonic pulse generator, an ultrasonic pulse receiver and a multiplex controller, said central processor controlling the operation of each of said ultrasonic pulse generator, said ultrasonic pulse receiver and said multiplex controller, said ultrasonic pulse generator and said ultrasonic pulse receiver being electrically connected to said multiplex controller, and said multiplex controller being electrically connected to said transmission means for sending and receiving acoustical signals to respective ones of said plurality of fixed elements.

6. The combination of claim 5, wherein said acoustical signal processing means is connected to a fixed, computer in said aircraft.

7. The combination of claim 5, wherein said acoustical signal processing means is connected to a mobile maintenance computer.

8. The combination of claim 1, wherein said stresses are measured and monitored constantly by said system during operation of said aircraft.

9. In combination, a machine or static structure and a system for measuring stresses in predetermined locations of said machine or structure, said system comprising a plurality of fixed elements embedded in said predetermined locations of said machine or structure, an ultrasonic or acoustical transceiver attached to each of said elements, an acoustical signal processing means, a transmission means connected between each of said ultrasonic or acoustical transceivers and said acoustical signal processing means wherefrom ultrasonic pulses are transmitted to each of said fixed elements through said attached ultrasonic or acoustical transceiver and back to said acoustical signal processing means which, in turn, is connected to a computer programmed to convert said returned ultrasonic pulses into stress measurement information.

10. The combination of claim 9 wherein said ultrasonic transceiver is a piezoelectric crystal.

11. The combination of claim 9 wherein each of said plurality of elements is a fastener.

12. The combination of claim 11 wherein said fastener is threaded.

13. The combination of claim 9 wherein some of said plurality of elements are non-threaded.

14. The combination of claim 9, wherein said acoustical signal processing means comprises a central processor, an ultrasonic pulse generator, an ultrasonic pulse receiver and a multiplex controller, said central processor controlling the operation of each of said ultrasonic pulse generator, said ultrasonic pulse receiver and said multiplex controller, said ultrasonic pulse generator and said ultrasonic pulse receiver being electrically connected to said multiplex controller, and said multiplex controller being electrically connected to said transmission means for sending and receiving acoustical signals to respective ones of said plurality of fixed elements.

15. The combination of claim 9, wherein said stresses are measured and monitored constantly by said system.

16. A method for measuring stresses at predetermined locations of a structure under load conditions, said method comprising the steps of:

providing a plurality of fixed elements within said structure at said predetermined locations,

providing an ultrasonic or acoustical transducer in each of said elements,

providing a transmission means, an acoustical signal processing means and a programmed computer,

electrically connecting said transmission means between each of said ultrasonic or acoustical transducers and said acoustical signal processing means,

electrically connecting said acoustical signal processing means to said programmed computer,

generating and transmitting ultrasonic pulses from said acoustical signal processing means to each of said ultrasonic or acoustical transducers to provide an acoustical response signal from each of said elements,

receiving each of said acoustical response signals at said acoustical signal processing means, and

converting each of said acoustical response signals into stress measurement information by said programmed computer.

17. The method of claim 16 wherein each of said ultrasonic or acoustical transducers is a piezoelectric crystal.

18. The method of claim 16 wherein each of said plurality of elements is a fastener.

19. The method of claim 16 further comprising measuring said stresses more often than once per second while the machine or structure is in operation.

20. In combination, an aircraft and a system for measuring dynamic stresses in the structure of said aircraft, said aircraft comprising a fuselage and at least one lifting device, said system comprising a plurality of fixed elements embedded in predetermined locations of said aircraft, an ultrasonic or acoustical transducer attached to each of said elements, an acoustical signal processing means, a transmission means connected between each of said ultrasonic or acoustical transducers and said acoustical signal processing means wherefrom ultrasonic pulses are transmitted to each of said fixed elements through said attached ultrasonic or acoustical transducer and back to said acoustical signal processing means which, in turn, is connected to a computer programmed to convert said returned ultrasonic pulses into stress measurement information.