Jesus Benhumea

Kevin StokelyMatt Aggleton

Advisor: Dr. Scott Franklin

Jamming in 2-D Prolate Granular Material Systems.

*Petroleum Research Fund #39132-GB9

Outline

• Background

• Experimental Setup

• Video

• Data Analysis

• Data

• Conclusion

Background

• Prolate particles are characterized by large aspect ratio ( = L/W > 10)

– Piles are much more rigid than ordinary granular materials

• Jamming: To cause (moving parts, for example) to lock into an unworkable position

– Oil industry– Farming– Manufacturers of items such as Nails, pens, etc..– Timber Industry– Anywhere prolate granular materials are found

• What Triggers Jamming to occur more frequently?

Experimental Setup

• 2-D flat surface • Dimensions 12”x20”• Square Brass Rods 2.5” X .125” = 20• Packing fraction = Area of rods/ Total Area

• A .5” probe is driven through the pile.

• The rods are laid and spread out by hand• An initial image is taken and analyzed to ensure

randomness and isotropy

Angular Distribution

What Are we are Looking for

• Total number of Particles that are disturbed in a run?

• How far ahead, above, and below does the disturbance reach?

• How many particles are pushed off the plate?

• What force is felt by the probe from the particles?

Video Data

= 40%

Video Data

= 13%

• We Subtract Images to determine which rods have moved.

• Bright Spots Indicate Disturbance

Video Analysis

Subtracted Video

• More particles lead to more moving in disturbance

Total Disturbance

1

1.5

2

2.5

3

3.5

4

4.5

5

0.2 0.25 0.3 0.35 0.4

Packing Fraction

Arb

. Un

its

• Motion of Particles ahead of the Dot

Disturbance Ahead Of the Dot

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0.2 0.25 0.3 0.35 0.4

Packing Fraction

Ro

d L

en

gth

• Motion of particles above and below the dot.

Disturbance Above the dot

0

0.2

0.4

0.6

0.8

1

1.2

0.2 0.25 0.3 0.35 0.4Packing Fraction

Ro

d L

eng

th

• Rods pushed off of the plate.

Rods Pushed off Plate

0

5

10

15

20

25

30

35

40

0.2 0.25 0.3 0.35 0.4

Packing Fraction

# o

f ro

ds

off

Conclusion

• Jamming and more body like movements occur around 26%

• Future Plans– We plan to include a force sensor to measure the

forces that occur– Track the movement of one or more particles with

fluorescent paint.– Make the transition to multi-level piles