1/8” Ground Nitinol

Summary

Sphere Specs:

Manufacturer: Nitinol Technologies, Inc.

Size /

Material

/ Grade / Gage / Actual
.124 in. / Nitinol
Lot No. / Qty / Code / Scan #

Experiment Dates: 2/18/02 – 2/20/02

Labview Time Delay: 9.00

Strobe: 12000 fpm

Scale for tracking program: 161 pixels/cm

These Nitinol spheres were special ordered from the company that provided us with the Ultra Elastic Black Oxide Coated 1/8” Nitinol Spheres. To test how much the coating affected the properties of the material, we requested spheres of the same type of material, Nitinol, however had the coating removed by a special grounding process. The resulting sphere was smaller in diameter by one thousandths of an inch.

In general this experiment went very smoothly. We ran binary collision experiments with two of the Ground Nitinol spheres. Beginning from grazing positions we progressed to head-on collisions. Perhaps attestable to new setups, there was little adjustment in this lab. During grazing experiments the angle, α , was consistently less that 15 ˚. Towards head-on collisions a little adjustment was necessary; however, all in all this experiment ran generally smoothly.

We ran a total of 50 collisions. The data reduction was also smooth and we did not have to remove any pictures from the data set. Correcting the way we reduced the data in the Titanium experiment, we did not meet with any problems this time around.

Two sets of results were obtained. Partway through this semester it was realized that in one of the data reduction spreadsheets, “coefficient calc-binary.xls”, one value for π was not consistently used. In some places, 3.14159 was used and in others 3.1415. To correct this error, since small errors could potentially lead to greater errors, anywhere where a calculation used the value of π, we entered π as a function (i.e. “pi()”) which would use the full value of π in the calculation. After correcting this error, the data was reduced a second time and no significant changes occurred in resulting values for the properties. However, there were small changes in the actual numbers for values such as ψ1.

First Results

e / o / 
0.93 +/-0.01 / 0.33 +/- 0.12 / 0.17 +/-0.01

Second Results – with pi correction

e / o / 
0.93 +/-0.01 / 0.33 +/- 0.12 / 0.17 +/-0.01

The effective e, e’ where e’ = e – (π/2)*, for Ground Nitinol with no Black Oxide coating was about 0.663. For our experiments we’d prefer e’ > 0.7, making the Nitinol without the coating not an ideal subject.

Images
Extreme grazing
Picture No: 01 / Grazing
Picture No: 26
Collision
Picture No: 42 / Head-on collision
Picture No: 50
Results

“Ground Nitinol Results.xls”

“Ground Nitinol Results pi.xls”