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Non-Contact Torque Sensor for Unmodified Composite Shafts and Non-Ferrous Metal Shafts

Description:

 
 

TECHNOLOGY AREA(S): Air Platform, Sensors

ACQUISITION PROGRAM: PMA-265, F/A-19 Hornet/Super Hornet

OBJECTIVE: Develop a non-contact torque sensing capability for pre-existing, flight-qualified, rotating drive shafts made from carbon fiber reinforced composites, titanium alloys, and aluminum alloys.

DESCRIPTION: A torque sensing solution for both nonferrous metals and carbon-fiber reinforced composite shafts that does not install onto, or modify the drive shaft is needed. The Navy currently does not have the ability to measure and monitor torque of these shaft types. It is necessary that the solution not contact the shafts so that dynamic balance of the shaft under measurement would not be affected; the shaft deflections common during operation would be less likely to damage the shaft or the instrumentation; and no changes would be required in the approved production design and quality build control of the drive shafts. Since no modifications would be done directly to the drive shafts, no expensive, time-intensive requalification of the drive shafts would be required.

The goal is to deliver a non-invasive torque sensing capability that has the least possible impact on existing and next generation US Navy aircraft designs, while also enabling practical upgrades to existing platforms to meet expanding mission requirements. The sensor should measure torque up to a minimum of 2kHz with recorded data rates exceeding a minimum of 5kHz. The sensing solution should provide sufficient dedicated data storage for a single extended operation, as well as mechanisms to retrieve and access the data. The torque measurement system should accommodate a shaft that is no more than 10 inches long and between 2 and 5 inches in diameter, operating at a nominal speed of 18,000 RPM with torque values of +/-5000 in-lb. The torque measurement accuracy error must be no more than 2% of full scale value. The system should maintain this accuracy over varying operating temperatures, -25 degrees C to 80 degrees C; utilizing temperature compensation as required. The system must operate within this accuracy for pressure altitudes from sea level to 40,000 feet.

The goal is to deliver a non-invasive torque sensing capability that has the least possible impact on existing and next generation US Navy aircraft designs, while also enabling practical upgrades to existing platforms to meet expanding mission requirements. The sensor should measure torque up to a minimum of 2kHz with recorded data rates exceeding a minimum of 5kHz. The sensing solution should provide sufficient dedicated data storage for a single extended operation, as well as mechanisms to retrieve and access the data. The torque measurement system should accommodate a shaft that is no more than 10 inches long and between 2 and 5 inches in diameter, operating at a nominal speed of 18,000 RPM with torque values of +/-5000 in-lb. The torque measurement accuracy error must be no more than 2% of full scale value. The system should maintain this accuracy over varying operating temperatures, -25 degrees C to 80 degrees C; utilizing temperature compensation as required. The system must operate within this accuracy for pressure altitudes from sea level to 40,000 feet.

Working with original equipment manufacturers (OEM) is highly recommended but is not required.

PHASE I: Design, develop and demonstrate feasibility of a non-contact torque sensor concept that meets the parameters outlined in the Description.

PHASE II: Based upon the design from Phase I, develop and demonstrate a prototype non-contact torque sensor in a laboratory setting. A laboratory bench top capability demonstration should clearly establish the feasibility of the method on both a non-ferrous metal shaft and a composite shaft in a realistic operating environment. This demonstration must include a non-ferrous spinning shaft with variable applied torque and non-contact torque monitoring. Data collected from this test should be compared to calibrated strain-gauge measurements, in-line torque sensors or a suitably accurate dynamometer, and taken during the same tests to meet above mentioned accuracy requirements. This full-scale demonstration should use shaft materials that are both typical of current nonferrous metal shafts and of next generation composite shafts.

PHASE III DUAL USE APPLICATIONS: Installation of a ruggedized and calibrated prototype torque sensor and any associated devices on in-service Navy aircraft and initial flight testing should be accomplished in coordination with an aircraft OEM. Flight testing should include day/night operations and should exercise the authorized aircraft flight envelope to account for expected airframe and driveshaft distortions. If any expected temperature limitations exist with the torque sensor system, these limitations should be tested during flight test to the extent feasible in prevailing ambient temperatures. Data should be reviewed and compared to any existing data for verification of performance. A cost analysis for future production incorporation or retrofitting within current propulsion systems and commercial applications should be conducted to demonstrate benefits. Private Sector Commercial Potential: Commercial rotorcraft would benefit from a reliable non-contact torque measurement solution. There are also numerous applications where non-contact torque measurement would be beneficial, to include industrial, agricultural and automotive industries.

REFERENCES:

  • Goldfine, N., Lovett, T., et al. “Noncontact Torque Sensing for Performance Monitoring and Fault Detection.” ASME 2009 Power Conference, POWER2009, Albuquerque NM, July 21-23, pp 479-486.
  • Caruntu, G., Panait, C., (2005). The Measurement of the Torque at the Naval Engine Shaft. Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications. IDAACS 2005. IEEE. Digital Object Identifier: 10.1109/IDAACS.2005.282937. Publication Year: 2005, Page(s): 41 – 44
  • MIL-STD-810G – Department of Defense Test Method Standard: Environmental Engineering Considerations Laboratory Tests (31 Oct 2008). Retrieved from http://everyspec.com/MIL-STD/MIL-STD-0800-0899/MIL-STD-810G_12306/
  • MIL-PRF-461F – Department of Defense Interface Standard: Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment (10 Dec 2007). Retrieved from http://everyspec.com/MIL-STD/MIL-STD-0300-0499/MIL-STD-461F_19035/

KEYWORDS: Composite; condition-based maintenance; non-contact; non-ferrous; torque; drive shaft

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