-- DanielSantos? - 31 Aug 2006

YZ Adhesion Testing 3

Test Setup

  • 2-axis YZ stage.
  • Control loop at 1kHz embedded on Microchip PIC18F2620?
  • Control done using trajectory files with waypoints and linear interpolation
  • Sampling force plate at 1kHz.
    • Data filtered at 10 Hz using 3rd order Butterworth filter

Summary of results

mu' is the ratio between maximum preload and maximum adhesion; alpha is the angle relating maximum adhesion to shear under load: tan(alpha) = Fadhesion/Fshear (see K. Autumn et al., Frictional Adhesion paper for explanation).

  • See ScanningElectron? (Private web) for SEM pictures of long/short stalks

sample max adhesion (N) mu' max shear (N) alpha (deg) patch area (cm^2) max adhesion (kPa) max shear (kPa)
long stalks 1.5 4 3.5 22.5 4.52 3.32 7.74
short stalks 1 3.5 3 18 3.77 2.65 7.95

Experiment #1

Procedure

  • Pre-load along 45 degree approach angle to a specified depth in Z (0 to 1000um in 100um increments)
  • Pull-off at specified angle (0 to 180 degrees in 15 degree increments; 0 = drag with curvature; 180 = drag against curvature)

Materials

  • Sample - Directional Adhesive Pad, "Long"-type, #1A
  • Sample - Directional Adhesive Pad, "Short"-type, #2A
  • Substrate - Glass

Results for Sample 1A

  • Measured maximum forces in Y and Z at pull-off (i.e. Limit Surface)

ForceSpace1A.jpg

  • Mu Prime as a function of Pre-Load @ best pull-off angle (30 degrees)

MuPrime1A_30deg.jpg

  • Mu Prime as a function of Pull-Off angle @ best pre-load depth (700um)

MuPrime1A_700um.jpg

Results for Sample 2A

  • Measured maximum forces in Y and Z at pull-off (i.e. Limit Surface)

ForceSpace2A.jpg

  • Mu Prime as a function of Pre-Load @ best pull-off angle (30 degrees)

MuPrime2A_30deg.jpg

  • Mu Prime as a function of Pull-Off angle @ best pre-load depth (500um)

MuPrime2A_500um.jpg

 
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