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Computer Automation of a Tribometer

Computer Automation of a Tribometer. Michael Eng, TJHSST With Nimel Theodore, Kathy Wahl NRL Code 6176. Objective. Main goal- integrate positional data w/ friction collection Using LabVIEW program Can be applied to microscopic or spectroscopic analysis of frictional events.

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Computer Automation of a Tribometer

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  1. Computer Automation of a Tribometer Michael Eng, TJHSST With Nimel Theodore, Kathy Wahl NRL Code 6176

  2. Objective • Main goal- integrate positional data w/ friction collection • Using LabVIEW program • Can be applied to microscopic or spectroscopic analysis of frictional events http://www.rpi.edu/dept/materials/COURSES/NANO/oja/nanocrys.gif

  3. Outline • Reciprocating stage • Tribometer • Circuit board • Program structure • Sample output • Applications

  4. Stage sends voltage signal to controller Controller transforms signal into position value Computer receives position value via USB Stage and Controller • Aerotech ALS 130-150 stage • Moves tribo arm • Soloist motion controller • Processes stage’s digital voltage signal into position

  5. M Tribometer • Arm + probe • 4 strain gauges • Moving stage/platform- 1-D motion • Motion controller sends position to computer as +V

  6. Signal Conditioning Board Figure 2-1. SC-2043-SG Parts Locator Diagram- NI manual Int/ext excitation jumpers • Powers strain gauges, receives strain signal from strain gauges • Excitation voltage (Vin) controlled via potentiometers (1.25-2.5 V)‏ • Output voltage (Vg) nulled via potentiometers Vin potentiometer +Vin Cable to PCI Vg Potentiometer +Vg

  7. M Ff Bending ΔR Computer- LabVIEW program Signal board- Wheatstone bridge Microsoft ClipArt ΔR ΔV ΔV  Ff Ff / FN = μ http://sine.ni.com/images/products/us/1sc567a1m.jpg

  8. LabVIEW • Programming environment • Data acquisition/analysis focus • Logging, graphing, etc. • Graphical programming language • Human-Machine Interface http://www.mathworks.com/company/newsletters/news_notes/dec04/images/mlint_srccode_wl.gif http://www.mezintel.com/LVCode01.png

  9. Data structure Input voltage signals stage and signal conditioning board Position data Friction data Converted by motion controller Convert w/ calibration

  10. Program Structure Run Stage/controller: Oscillate DAQ card: Collect Receive, convert friction data Calculate position data w/ # data points collected, start point Record as (x, y) pts, graph Re-sync every half-cycle

  11. Calibration • Arm turned on side • Multiple loads applied • Linear regression • Y-intercept, slope convert voltage to friction

  12. Friction vs. cycle • Friction (y) vs. cycle (x) • Allows analysis over many cycles • Account for debris, reactions, etc.

  13. Friction vs. position • Friction (y) vs. position (x) • Updates real-time • Provides coordinates of friction anomalies

  14. Intensity plot • Pseudo-3D • Friction (color) vs. position (y) vs. cycle (x) • Combines previous two graphs

  15. Conclusion • LabVIEW program • Integrates positional and frictional data • Extracts data as CSV and TXT files • Graphs friction vs. cycle, friction vs. position, friction vs. position vs. cycle

  16. Future Applications • Integrate with microscopy or spectroscopy • Use coordinates of frictional event in other analysis instrument • Example- FTIR of nanocrystalline diamond films

  17. Acknowledgements • Nimel Theodore • Kathy Wahl • Irwin Singer • Jeffrey Weimer • SEAP • ONR

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