SITIS Archives - Topic Details
Program:  SBIR
Topic Num:  AF071-344 (AirForce)
Title:  Configurable Dynamic Strain System
Research & Technical Areas:  Materials/Processes, Sensors, Electronics

 The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 3.5.b.(7) of the solicitation.
  Objective:  Develop an on-board high-throughput 24-channel data acquisition system for turbine engine strain measurements.
  Description:  Current systems require extensive wiring from up to 200 stationary bonded-foil strain sensors carrying low-level signals across electrically noisy environments over tens to hundreds of feet. The wiring is ultimately terminated at remotely located instrumentation racks where the signals are then amplified, conditioned, digitized, and read by a data processing system. Migration of these signal processing functions from the remote location to the test cell is required to a) significantly decrease uncertainty and increase bandwidth performance, b) synchronize the sampling instance of many related sensing nodes, and c) reduce engine installation complexity and time. The need is for the development of an on-board high-throughput 24-channel data acquisition system for turbine engine strain measurements to replace the current data system. Benefits will be 1) a reduction in the number of wires between the test cell and the control room, 2) a reduction of exposure to an electrically noisy environment by the low-level signal wires, 3) automation of tedious tasks such as calibration history, signal conditioning parameters, and channel configuration, and 4) capability to synchronize data capture of physically separated sensors to within +/- 100 nanoseconds. The inputs to the system are 1/4–bridge 120 or 350 ohm sensing elements with a minimum analog bandwidth of 40 kHz. The system must operate in an environment with a temperature range of 0-65°C and a humidity range 0-60%, non-condensing. The system should have the following attributes: selectable analog filtering with AC coupling; common mode rejection ratio (CMRR) >80 dB above 1kHz; digitization to 16 bits (minimum) with error not to exceed +/- 2%; self-configuring upon start-up as described in IEEE-1451.4; synchronized sampling as described in IEEE-1588; and expandable to 200 channels. The system will require a host computer with system control, configuration, and data storage capability. Prove the system feasibility by providing an end to end block diagram with identification of critical components and software.

  PHASE I: Demonstrate feasibility of a multi-channel remote strain measurement system for a turbine test facility.
  
  PHASE II: Develop and demonstrate a prototype data acquisition system for turbine engine testing.

  DUAL USE COMMERCIALIZATION: Military application: A valid prototype system should rapidly find applications to the aerodynamics testing industry. Commercial application: On-board data acquisition systems could be used for myriad combustion engine development programs and for monitoring of vibration-prone components.

  References:  1. Lenarduzzi, R., Ward, C., "Turbine Engine Developmental Dynamic Strain System.”, Oak Ridge National Laboratory (Oak Ridge, TN, United States), September 2005. 2. “IEEE Standard for a Smart Transducer Interface for Sensors and Actuators,” September 16, 1997, IEEE-1451.2-1997. 3. Patterson, G., et al, “Preparations for Smart Sensor Usage in Aircraft Gas Turbine Testing”, ASME Turbo Expo conference paper GT2004-53601, Vienna, Austria, June 2004.

Keywords:  data acquisition, smart sensor, IEEE-1451

Additional Information, Corrections, References, etc:
The followings are some of the general questions and answers:

1) Can you give the clarification of on-board?
On-board means deployed within close proximity to the test article in a ground-based turbine test cell, as opposed to deployed remotely in a control room. Nominally, the distance between test article and signal conditioning shall be no greater than 10 feet.

2) Do the 0-65 degree C and 0-60% humidity requirements apply to everything?
Yes. However, the host computer is excluded.

3) What is the requirement of on-board storages?
Real time data transmission is required. Therefore, only enough data for real-time system health monitoring need to stored on the DAS. Off-line analysis and storage will be preformed after real time data streamed to a separate system.

4) Will any components be placed on the rotating part of the engine?
No, all parts are stationary.
The followings are some of the general questions and answers:

1) Can you give the clarification of on-board?
On-board means deployed within close proximity to the test article in a ground-based turbine test cell, as opposed to deployed remotely in a control room. Nominally, the distance between test article and signal conditioning shall be no greater than 10 feet.

2) Do the 0-65 degree C and 0-60% humidity requirements apply to everything?
Yes. However, the host computer is excluded.

3) What is the requirement of on-board storages?
Real time data transmission is required. Therefore, only enough data for real-time system health monitoring need to stored on the DAS. Off-line analysis and storage will be preformed after real time data streamed to a separate system.

4) Will any components be placed on the rotating part of the engine?
No, all parts are stationary.
Ref #1: Reference #1 is still under processing for public release. It should be available 4 Jan 2007.
Ref #1: Reference #1 is still under processing for public release. It should be available 4 Jan 2007.
Ref #3: ASME04.pdf
Ref #3: ASME04.pdf

Questions and Answers:
Q: 1. This is a request for clarification on the "sampling rate" question. I was wondering how many samples per second were required to be sampled per strain gage; how can 100 samples per second reconstruct 40 kHz data? Also, why "without synchronizing"? I thought synchronization was required.

2. What current data system is being used?

A: 1. This is a typo...100 kSamples per second was intended (100,000 samples per second). "Without synchronizing" means the sample instant is not synchronized with the signal peaks at a specific frequency. If you synchronize the sampling instant with the signal peak you only have to sample twice per cycle to get accurate amplitude data, which would be 80,000 samples per second with 40kHz signals. However the signals desired to be measured are not narrow-band therefore it is impossible to synchronize the sampling instant with a signal peak. The synchronization requirement refers to synchronizing the sampling instant among all channels.

2. The current data system design is proprietary. It comprises signal conditioning, digitization, storage, analysis hardware and software, user interface, and miscellaneous circuitry from a variety of manufacturers.
Q: Would the potential for replacing the existing bonded foil strain sensors with fiber optic sensors be considered under this effort?
A: No.
Q: What sampling rates are required for each sensor (is it at least twice the 40KHz required bandwidth?)
A: No sample rate is required, but 100 samples/second is expected to obtain 40kHz data accurately without synchronizing.
Q: 1. What is the available space envelope for equipment that would be installed locally at the test cell?
2. In addition to the temperature and humidity requirements noted in the solicitation, are there additional environmental factors that should be considered, such as vibration?
A: 1. A single instrument enclosure such as the 19-inch wide by 70"-tall cabinet will not be practical for the 200 channel configuration due to space limitations in the test cell.

2. Acoustic noise levels will be high and radiant heating from the engine may need to be considered.
Q: 1. This is a request for clarification on the "sampling rate" question. I was wondering how many samples per second were required to be sampled per strain gage; how can 100 samples per second reconstruct 40 kHz data? Also, why "without synchronizing"? I thought synchronization was required.

2. What current data system is being used?

A: 1. This is a typo...100 kSamples per second was intended (100,000 samples per second). "Without synchronizing" means the sample instant is not synchronized with the signal peaks at a specific frequency. If you synchronize the sampling instant with the signal peak you only have to sample twice per cycle to get accurate amplitude data, which would be 80,000 samples per second with 40kHz signals. However the signals desired to be measured are not narrow-band therefore it is impossible to synchronize the sampling instant with a signal peak. The synchronization requirement refers to synchronizing the sampling instant among all channels.

2. The current data system design is proprietary. It comprises signal conditioning, digitization, storage, analysis hardware and software, user interface, and miscellaneous circuitry from a variety of manufacturers.
Q: Would the potential for replacing the existing bonded foil strain sensors with fiber optic sensors be considered under this effort?
A: No.
Q: What sampling rates are required for each sensor (is it at least twice the 40KHz required bandwidth?)
A: No sample rate is required, but 100 samples/second is expected to obtain 40kHz data accurately without synchronizing.
Q: 1. What is the available space envelope for equipment that would be installed locally at the test cell?
2. In addition to the temperature and humidity requirements noted in the solicitation, are there additional environmental factors that should be considered, such as vibration?
A: 1. A single instrument enclosure such as the 19-inch wide by 70"-tall cabinet will not be practical for the 200 channel configuration due to space limitations in the test cell.

2. Acoustic noise levels will be high and radiant heating from the engine may need to be considered.

Record: of